Implementation of Mutual Rate Adaptations in Data Services Between GSM and DECT

The invention relates in general to the operation of a switching center and base station equipment in data communication networks, an in particular to the arrangement of their rate and protocol adaptations required for using data services provided by a cellular telecommunication system, especially the GSM system, from a terminal belonging to another cellular telecommunication system, especially the DECT system.

In digital data communications there are known several internationally standardized systems and network implementations based on them. A user of a data communication service is usually not interested in the technical details of the system or network that conveys his or her message. From the user's point of view user-friendliness means that various networks and systems can be made to work together in a versatile and reliable way, thus making it possible to use a variety of services from a terminal of any one system. In the description below we will use the GSM and DECT systems as examples.

The data communication services of both the GSM (Groupe Speciale Mobile/Global System for Mobile Communications) system and the DECT (Digital European Cordless Telecommunications) system are widely used in Europe. In both systems the principle is the same: the user has a small and lightweight portable terminal which for data communication purposes is radio-linked to a fixed base station which in turn is linked in a fixed manner to a switching centre equipment controlling the operation of the system. The systems employ different standardized functions for packetizing, encoding and modulating the data to be transferred. Data is handled according to so-called protocols, which are known to those skilled in the art. The GSM system protocols relevant to this invention and instructions for their implementation are described e.g. in the "The GSM System for Mobile Communications" by Michel Mouly and Marie-Bernadette Pautet, published by the authors, ISBN 2-9507190-0-7, Palaiseau 1992, 701 pp. The DECT system protocols relevant to this invention and instructions for their implementation are described e.g. in the following standards and documents: ETS 300 175-1 to 300 175-8, prETS 300 444, prETS 300 331, I-ETS 300 176, ETR 015, ETR 043, ETR 056, prETS 300 466, ETS 300 370 and ETS 300 xxx: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Data services profile, Generic data link service, Service Type C, Class 2".

It is known to connect a DECT base station, called a fixed part (FP), directly to a GSM mobile switching centre (MSC), thus making it possible to have a speech connection from a mobile telephone in a DECT system to another telephone through a GSM network. The methods so far have not, however, provided the possibility of using the varied range of GSM system data services during such a connection since there has not been a method of implementing the rate adaptations required by these services in the data communication between the systems.

It is an object of this invention to provide a method for using data services provided by a first telecommunication system from a terminal belonging to a second system. It is also an object of this invention to provide a method for implementing the rate adaptations required by the GSM system in the data communication between the DECT and GSM systems. It is a further object of the invention to provide a particularly advantageous method for implementing said rate adaptations.

These objects are achieved by placing the adaptation functions and communication protocols required by said first system in the base station of said second system, preferably in its interworking unit (IWU).

It is characteristic of the method according to the invention that the rate adaptations and mappings for converting the transferred data from/to the format of said first telecommunication system to/from the format of said second telecommunication system take place in said base station.

The invention also relates to equipment for implementing the method mentioned above. It is characteristic of the equipment according to the invention, including a base station, that said base station includes means for carrying out the rate adaptations and mappings with which the transferred data are converted from/to the format of said first telecommunication system to/from the format of said second telecommunication system.

The GSM system includes very precisely standardized definitions of data communication protocols and their implementation. One of the advantageous features of the GSM system is the permanence of its standards: changing of definitions is not common. On the other hand, this has been considered a disadvantage because it has been felt that adapting the system to interwork with another system is difficult. For example, in the interworking adaptation of the GSM and DECT systems, the aim has been not to make any changes in the standard GSM switching centre.

The invention is based on an idea according to which the GSM standards are partly transferred to the DECT system. In order for the changes in the DECT system to be as small as possible from the point of view of an ordinary user, the adaptation between the DECT and GSM standards is proposed to be placed near the system interface. In a preferable embodiment of the invention the adaptations are placed in the DECT base station, advantageously in its interworking unit (IWU).

The idea of the invention can be applied to all systems in which the switching centre equipment is standardized so rigorously that no changes can be made in it, but in which changes in the base station equipment are possible. When applying the idea of the invention to data communication between systems other than the DECT and GSM, the standards mentioned in this description that refer to said systems naturally have to be replaced by standards of the systems in question.

The invention is further described using the embodiment mentioned above as an example and referring to the accompanying drawing in which

FIG. 1 shows a known arrangement for providing transparent circuit switched data services in a GSM network,

FIG. 2 shows a known arrangement for providing non-transparent circuit switched data services in a GSM network,

FIG. 3 shows an arrangement according to the invention for providing transparent circuit switched data services between the GSM and DECT systems,

FIG. 4 shows an arrangement according to the invention for providing non-transparent circuit switched data services between the GSM and DECT systems,

FIG. 5 shows an arrangement according to the invention for providing transparent fax services between the GSM and DECT systems,

FIG. 6 shows an arrangement according to the invention for providing non-transparent fax services between the GSM and DECT systems,

FIG. 7 shows more closely the flow of data between the functional blocks of a base station using the method according to the invention in a case according to FIG. 3,

FIG. 8 shows more closely the flow of data between the functional blocks of a base station using the method according to the invention in a case according to FIG. 4,

FIG. 9a shows the messages exchanged between a terminal, a base station using the method of the invention and a switching centre when the terminal is setting up a data call,

FIG. 9b shows an alternative procedure for the case of FIG. 9a,

FIG. 9c shows a second alternative procedure for the case of FIG. 9a,

FIG. 9d shows the messages exchanged between a terminal, a base station using the method of the invention and a switching centre when the terminal is receiving a data call, and

FIG. 9e shows an alternative procedure for the case of FIG. 9d, and

FIG. 10 shows a profile reference configuration showing (U-plane) inter-working to GSM data services,

FIG. 11 shows general inter-working model for bearer services for FP GSM PLMN attachment,

FIG. 12 shows the rejection of a negotiation request from the MSC,

FIG. 13 shows the exchange attributes negotiation procedure in outgoing call,

FIG. 14 shows the extended exchange attributes negotiation in the case of outgoing call,

FIG. 15 shows the exchange attributes negotiation procedure in incoming call,

FIG. 16 shows the extended exchange attributes negotiation in the case of incoming call,

FIG. 17 shows the rate adaptation for the DECT/GSM inter-working of GSM transparent (T) service, and

FIG. 18 shows the rate adaptation for the DECT/GSM inter-working of GSM non-transparent (NT) service.

Corresponding parts in the figures have the same reference numbers. The description below and the accompanying drawing concentrate on describing circuit switched data services which are used as an example. However, the method according to the invention can also be used in connection with packet switched data services.

First, referring to FIGS. 1 and 2, arrangements are described which, though they are known, are essential for understanding the invention, namely, arrangements for implementing data communication in the GSM system.

The following bearer services are known in the GSM system:

data circuit duplex asynchronous: rates 300, 1200, 1200/75, 2400, 4800 and 9600 bit/s, transparent and non-transparent (T/NT),

data circuit duplex synchronous: rates 1200, 2400, 4800 and 9600 bit/s, transparent and non-transparent (T/NT),

PAD access circuit asynchronous (PAD=packet assembler/disassembler): rates 300, 1200, 1200/75, 2400, 4800 and 9600 bit/s, transparent and non-transparent (T/NT),

data packet duplex synchronous: rates 2400, 4800 and 9600 bit/s, transparent and non-transparent (T/NT),

alternate speech/unrestricted data: during a call it is possible to alternate between speech and data connection, transparent and non-transparent (T/NT),

speech followed by data: after a speech connection of a certain duration the user can switch to a data connection during the same call but not back to speech again, transparent and non-transparent (T/NT),

12 kbit/s unrestricted digital, used only inside GSM.

Transparent and non-transparent data transmission imply that it is possible to have automatic error correction in the data communication. Error correction is not used in transparent data transmission, whereby the transmission rate is constant and the error ratio varies according to the network load situation and connection quality. In non-transparent data transmission the sending device packetizes the data into radio link protocol (RLP) frames which are numbered. If the receiving device does not receive a frame correctly, it may request a retransmission of the frame in question. In non-transparent data transmission the error ratio is constant, but the transmission rate varies according to the network load situation and connection quality.

Teleservices of a higher hierarchy level, such as the facsimile group 3 known to one skilled in the art, use one of the above-mentioned bearer services to convey the data from the sending terminal through a GSM network to the receiving terminal. With the exception of the 12 kbit/s unrestricted digital data transmission all services mentioned are based on synchronous/asynchronous and transparent/non-transparent data communication at 9600 bit/s at the most. However, since the communication between the switching centre equipment (MSC) and the base station controller (BSC) controlling the operation of the base station occurs at 64 kbit/s, various rate adaptations (RA) are needed in the system.

FIG. 1 is a schematic representation of a known transparent circuit switched connection between a GSM switching centre 1 and GSM terminal 2. The switching centre 1 is connected to a base station controller 3. The interface 4 between the switching centre 1 and base station controller 3 is generally called the A interface. It conforms to the CCITT (ComiteConsultatif International Telegraphique et Telephonique) standard G.703 and is capable of providing 64 kbit/s connections multiplexed at 2 Mbit/s. The base station controller 3 is further connected to a GSM base transceiver station 5 (BTS), and the interface 4a between them is called the Abis interface. Between the base transceiver station 5 and terminal 2 there is a radio interface 6.

As shown in FIG. 1, the interworking functions part IWF in the GSM switching centre includes three basic rate adaptations specified in the GSM system standards, performing adaptation according to the CCITT recommendation V.110. The first rate adaptation 7, which will be called RA0 in accordance with the GSM standards, adapts asynchronous data for synchronous transmission. The second rate adaptation 8, called RA1 in accordance with the GSM standards, changes the transmission rate into an intermediate rate, which is 8 or 16 kbit/s, and the third rate adaptation 9, called RA2 in accordance with the GSM standards, changes the transmission rate into 64 kbit/s for transmission across the A interface 4 and Abis interface 4a.

The base transceiver station 5 includes an RA2-type adaptation which adapts the data back to the intermediate rate. The data are taken to a handling block 11, in which the frame according to the V.110 standard is adapted for transmission across the radio interface 6. Before the radio interface 6 the data are taken to a forward error correction (FEC) block 12, which together with a corresponding block 13 on the terminal 2 side improves the reliability of the transmission across the radio interface 6. The terminal 2 includes an RA1 and RA0 type adaptation 14, 15, the first of which reconstructs synchronous data and status information and the latter reconstructs asynchronous data. Transmission in the opposite direction includes substantially the same stages in the reverse order.

FIG. 2 is a schematic representation of a known non-transparent circuit switched connection between a GSM switching centre 1 and GSM terminal 2. The arrangement differs from that of FIG. 1 in that both the switching centre 1 and the terminal 2 include a data protocol block 16, 17; 18, 19 consisting of two sub-blocks which are called L2R (Layer 2 Relay Function) 16; 19 and RLP (Radio Link Protocol) 17; 18. The L2R block 16 of the switching centre 1 arranges the data into protocol data units (PDU) consisting of state octets according to the GSM standard GSM 07.02 which are taken one at a time to the RLP block 17. There the data are arranged into RLP frames according to the GSM standard GSM 04.22, comprising a 16-byte header, a 200-byte information part and a 24-byte frame check sequence (FCS). The complete RLP frames are taken to a rate adaptation including an RA1 type adaptation 8; 14 in the switching centre 1 and terminal 2, and in addition, an RA2 type adaptation 9 in the switching centre.

Below it will be described arrangements according to the invention for implementing data communication between the DECT and GSM, referring to FIGS. 3 to 8.

A DECT base station, which is called a fixed part (FP) includes an interworking unit 20a to provide data communication in the direction of the switching centre. If a DECT base station 20 (FP) is connected via an interworking unit 20a to a GSM switching centre 1 in a manner which is known, the transmission rate between them is 64 kbit/s and the interface 21 is called an A interface in the same way as in the GSM system described above. According to the invention, RA0, RA1 and RA2 type rate adaptation blocks 24, 23, 22 corresponding to those in the GSM switching centre 1 are added, as shown in FIG. 3, to the DECT base station 20, preferably to its interworking unit 20a. When data are transferred from the GSM system to a DECT base station, synchronous data and status information flow from the output of an RA1 type block 23 to DECT protocol blocks (not shown) and from there further in the form required by DECT standards across the DECT radio interface 25 to a DECT terminal 26, which is called a portable part (PP). Asynchronous data are obtained from the output of an RA0 type adaptation block 24. When transferring data in the opposite direction, the DECT protocol blocks (not shown) of the base station 20 forward asynchronous data to the RA0 type block 24 and/or synchronous data and status information to the RA1 type block 23, which send the data via the RA2 type block 22 across the A interface 21 towards the GSM base station 1.

FIG. 4 is a schematic representation of the arrangement according to the invention for implementing non-transparent data communication between a GSM switching centre 1 and a DECT base station 20. The same blocks as those in the arrangement of FIG. 2 take part in the operation in the GSM switching centre 1. The DECT base station includes a data protocol block comprising an RLP block 27 and an L2R block the operation of which corresponds to that depicted in FIG. 2 with the exception that the data transferred in the direction of the terminal 26 are taken from the L2R block 28 of the base station further to the protocol blocks (not shown) of the DECT system and further in the form required by the DECT standards across the DECT radio interface 25 to the DECT terminal 26.

It is a substantial feature of the described embodiment of the method according to the invention that the transmission chain conforming to the GSM standards ends in a DECT base station 20, advantageously in its interworking unit 20a. Above it has been described the implementation of RA0, RA1 and RA2 type rate adaptations 24, 23, 22 as well as L2R and RLP type data protocols 28, 27 in an interworking unit 20a of a DECT base station. These blocks are used to implement at the rate of 9600 bit/s at the most the asynchronous or synchronous and transparent or non-transparent data communication mentioned above in connection with the description of GSM bearer services. Above it was also mentioned that these provide a basis for the bearer services listed, and the higher-level telecommunication services in turn use said bearer services. According to the invention, the higher-level blocks that are needed to use said higher-level telecommunication services are also included in the DECT base station 20, preferably in its interworking unit 20a. According to the order specified in the GSM standards, these blocks are placed above the rate adaptations in the base station hierarchy.

A fax service according to FIGS. 5 and 6 is presented as an example. FIG. 5 shows an arrangement according to the invention for implementing transparent fax transmission between a GSM switching centre 1 and a DECT base station 20. Both the switching centre 1 and the base station 20 include a fax adapter (FA) 29; 30 conforming to the T.30 standard, placed above the RA1 type rate adaptation block 8; 23 in the hierarchy. Letters S and D emphasize that according to the T.30 standard the connection can be used to transmit both status information (S) and data (D). In non-transparent fax service there is, as shown in FIG. 6, between the RA1 type rate adaptation 8; 23 and the fax adapter 29; 30 a data protocol block 31; 32 that includes L2R and RLP type sub-blocks for implementing error correction in the same way as described above with reference to FIG. 4.

Next, referring to FIGS. 7 and 8, it will be described in greater detail the implementation of the method according to the invention with emphasis on how the data flow between the DECT and GSM blocks in a DECT base station. The arrangement of FIG. 7 is a more detailed representation of the case depicted in FIG. 3 dealing with transparent data communication according to the invention between a GSM switching centre 1 and a DECT base station 20. FIG. 7 includes the lower levels 33, 34 which were not shown in the earlier figures but which in all cases participate in the physical transmission of the signal between different devices, as is clear to a person skilled in the art. In a situation depicted in FIG. 7, the status information included in the data flows in a DECT base station 20 between an RA1 type rate adaptation block 23 conforming to the GSM standards and a Ctrl block 36 conforming to the DECT standards. Similarly, synchronous data flow between said RA1 block 23 and a BPAD block 37 conforming to the DECT standards, and asynchronous data flow between an RA0 type adaptation block 24 conforming to the GSM standards and a PAD block 38 conforming to the DECT standards. The base station 20 also includes other blocks conforming to the DECT standards which in the operations hierarchy are placed below said Ctrl, BPAD and PAD blocks 36, 37, 38 and the Fl.ctrl block 35 at the same level with them.

Similarly, FIG. 8 is a more detailed representation of the situation depicted in FIG. 4 dealing with non-transparent data communication according to the invention between a GSM switching centre 1 and a DECT base station 20. In FIG. 7 an L2R protocol block 28 as shown in FIG. 4 is further divided into a synchronous sub-block 39 (L2BOP, Layer 2 Bit Oriented Protocol) and an asynchronous sub-block 40 (L2COP, Layer 2 Character Oriented Protocol), the first of which is connected to a BPAD block 37 conforming to the DECT standards and the second to a PAD block 38 conforming to the DECT standards. FIGS. 7 and 8 show that the arrangement according to the invention is both in transparent (FIGS. 3 and 7) and in non-transparent data communication (FIGS. 4 and 8) connected to the same blocks 36, 37, 38 conforming to the DECT standards since in the DECT system the radio interface 25 and accordingly the operation of the DECT base station conforming to the standards is identical in both transmission methods.

Data communication conversions between the GSM format and DECT format are shown in detail in tables of the accompanying Appendices A and B of which the "DECT/GSM interworking of bearer services: implementation description, complete coding mapping of GSM and DECT elements" (Appendix A) concerns the first embodiment of the method according to the invention and the "DECT/GSM interworking of bearer services: implementation description, transparent coding transportation of the Bearer Capability" (Appendix B) concerns the second embodiment of the method according to the invention.

Next, referring to FIGS. 9a to 9e, it will be described in greater detail the setting up of a data call between a DECT terminal, a base station employing the method of the invention and a GSM switching centre. The purpose of this description is to illustrate those new functions related to the setup of a data call that are included in a base station employing the method of the invention. FIGS. 9a to 9e show a DECT terminal 26, a base station 20 employing the method of the invention and a GSM switching centre 1. The arrows represent messages between equipment and they are arranged in temporal order so that in each figure time flows from top down. For reasons of clarity, the message, parameter and record names related to the DECT standard are typed in upper-case letters in the description, and the corresponding names related to the GSM standard are typed in lower-case letters.

Setting up of a data call originated by a terminal 26 (FIGS. 9a to 9c) is performed largely in the same manner as defined in the ETS 300 370 standard, but in the so-called service negotiation procedure there are some differences depending on what kind of operation the base station 20 supports. The negotiable parameter is in this case the code <<modem type>> referring to the type of the modem. The minimum requirement for the base station operation is the "negotiation not possible" function according to FIG. 9a. To provide this function, no changes are required in the operation of the base station 20 as regards the ETS 300 370 standard. As the interworking unit 20a (not shown) of the base station 20 receives the CC-SETUP message 41 sent by the terminal 26, and the <<NEGOTIATION INDICATOR FIELD>> of the message indicates that the service negotiation is not possible, the interworking unit sends a "Setup" message 42 to the switching centre but prevents negotiation with the switching centre 1. This means that if the switching centre 1 indicates in the "Call proceeding" message 43 that it cannot provide the service requested by the terminal 26, the connection is disconnected using the CC-RELEASE-COM message 44 to the terminal 26 (with the notice "Incompatible service" in the <<RELEASE REASON>> field) and the "Release Complete" message 45 to the switching centre 1.

A second possible procedure for the base station 20 is shown in FIG. 9b. When the interworking unit 20a (not shown) of the base station 20 receives the CC-SETUP message 46 sent by the terminal 26, and the <<NEGOTIATION INDICATOR FIELD>> contains a value representing the message "Exchange parameter negotiation", the interworking unit either rejects the negotiation request directly with the message "Negotiation not supported" (not shown) if the base station does not support service negotiation, or it maps the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> records conforming to the DECT standard into the <<bearer capability>> record conforming to the GSM standard in the manner described in tables 7, 11 and 12 of the accompanying document "DECT/GSM interworking of bearer services: implementation description, complete coding mapping of GSM and DECT elements" (Appendix A) and sends this record to the switching centre 1 in the "Setup" message 47.

If after that the switching centre 1 sends to the base station 20 a "Call proceeding" message 48 with new values in the <<bearer capability>> record, the base station will map those values into the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> records in the CC-RELEASE-COM message 49 sent to the terminal 26 and send a "Release complete" message 50 toward the switching centre 1. Then the terminal 26 may start the process anew by sending a CC-SETUP message 51 containing the new values, after which the data call setup continues according to the manner 52, 53 defined in the ETS 300 370 standard. If the switching centre did not send a "Call proceeding" message or if the message sent did not contain the <<bearer capability>> record, the intermediate stage 49, 50, 51 is not included in the data call setup procedure.

FIG. 9c shows a third possible procedure for the base station 20. When the interworking unit 20a (not shown) of the base station 20 receives a CC-SETUP message 54 from the terminal 26 with a value representing the message "Extended exchange parameter negotiation" in the <<NEGOTIATION INDICATOR FIELD>>, it either rejects the negotiation request directly with the message "Negotiation not supported" (not shown) if the base station does not support extended service negotiation, or it maps the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> records conforming to the DECT standard into the <<bearer capability>> record conforming to the GSM standard in the manner described in tables 7, 11 and 12 in the accompanying document "DECT/GSM interworking of bearer services: implementation description, complete coding mapping of GSM and DECT elements" (Appendix A) and sends this record to the switching centre 1 in the "Setup" message 55.

If after that the switching centre 1 sends to the base station 20 a "Call proceeding" message 56 with new values in the <<bearer capability>> record, the base station will map those values into the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> records in the CC-CALL-PROCEEDING message 57 sent to the terminal 26 in the manner described in tables 5, 9 and 10 in the accompanying document "DECT/GSM interworking of bearer services: implementation description, complete coding mapping of GSM and DECT elements" (Appendix A). If the switching centre did not send a "Call proceeding" message or if the message did not contain the <<bearer capability>> record, the switching centre has accepted the parameters and the mapping of values into the CC-CALL-PROCEEDING message 57 to the terminal 26 is not required.

According to the second embodiment of the method of the invention the <<IWU-ATTRIBUTES>> record conforming to the DECT standard is redefined in the manner described in Chapter 6 of the accompanying document "DECT/GSM inter-working of bearer services: implementation description, transparent coding transportation of the Bearer Capability" (Appendix B), whereafter the <<IWU-ATTRIBUTES>> record conforming to the new definition fully complies with the requirements of the GSM standard bearer services. The <<IWU-ATTRIBUTES>> record conforming to the new definition makes the selection of the bearer service easier and the <<END-TO-END-COMPATIBILITY>> record need then not be used.

Setting up of a data call received by the terminal 26 (FIGS. 9d and 9e) is also performed largely as defined in the ETS 300 370 standard, but also in this case there are certain differences in the service negotiation procedure depending on what kind of operation the base station 20 supports. The negotiable parameters in this case are the number of data, stop and parity bits, use of the user layer 2 protocol and modem type; the codes for these are, respectively, <<number of data bits>>, <<number of stop bits>>, <<number of parity bits>>, <<user layer 2 protocol>> and <<modem type>>. The minimum requirement for the operation of the base station 20 is still the "negotiation not possible" function. To provide this function, no changes are required in the operation of the base station as regards the ETS 300 370 standard because the terminal 26 decides to disconnect if there is the code <<Negotiation not possible>> in the <<NEGOTIATION INDICATOR FIELD>> of the the CC-SETUP message received by the terminal and the values of said parameters are not suitable.

In the case illustrated by FIG. 9d the base station 20 supports service negotiation. First it maps the "Setup" message 58 from the switching centre 1 into a CC-SETUP message 59 conforming to the DECT standard and sends it to the terminal 26. If the terminal 26 does not support service negotiation it rejects the negotiation request directly with the message "Negotiation not supported" (not shown). Otherwise, the terminal 26 adds the appropriate parameters to the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> records in the CC-RELEASE-COM message 60 sent by it to the base station 20. The base station 20 does not map the parameters into any message sent to the switching centre 1 but sends a new CC-SETUP message 61 to the terminal 26 with new values in the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> records. The base station 20 must be able to associate this new CC-SETUP message 61 with the GSM data call that has arrived from the switching centre 1 and is waiting for a response. When the terminal 26 responds to the new CC-SETUP message 61 by sending to the base station 20 a CC-ALERTING or CC-CONNECT message 62, the base station 20 maps the new parameters into the <<bearer capability>> record in the "Call Confirmed" message 63 sent to the switching centre 1 in the manner described in tables 8, 11 and 12 in the accompanying document "DECT/GSM interworking of bearer services: implementation description, complete coding mapping of GSM and DECT elements" (Appendix A).

FIG. 9e shows an alternative procedure for the case described above. The "Setup" 64 and CC-SETUP 65 messages are handled as above. If the terminal 26 does not support service negotiation it rejects also in this case the service request directly with the message "Negotiation not supported" (not shown). Otherwise, the terminal 26 adds the appropriate parameters to the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> records in the CC-CONNECT message 67 sent to the base station 20. The base station 20 does not send to the switching centre 1 a "Call Confirmed" 68 or "Alerting" 69 message before it has received said parameters. The base station 20 maps the new parameters into the <<bearer capability>> record in the "Call Confirmed" message 68 sent to the switching centre 1 in the manner described in tables 8, 11 and 12 in the accompanying document "DECT/GSM interworking of bearer services: implementation description, complete coding mapping of GSM and DECT elements" (Appendix A). Other mappings conform to the ETS 300 370 standard. If the terminal 26 accepts the first parameter values that it received in the CC-SETUP message 65, it will not use the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> records of the CC-CONNECT message 67, whereby the data call setup proceeds as defined by the ETS 300 370 standard.

With the method according to the invention it is possible to use data services of the GSM system from a terminal belonging to the DECT system because the rate adaptations required by the GSM data services are included in the DECT base station and the transmission format conversions are performed between functional blocks of the base station.

The interface to a GSM switching centre of a DECT base station applying the method according to the invention conforms to the GSM standards and, therefore, no changes are needed in the GSM switching centres, and a GSM switching centre does not even have to know that it is transferring data to or from the DECT system. Neither does the method of the invention require changes in the radio interface of the DECT base station to the terminal and, hence, to the user, and so the user does not have to replace his or her DECT terminal with a new one. The DECT terminal can also be used for using non-GSM-based data services in the same way as before.

[1] ETS 300 175-1: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 1: Overview".

[2] ETS 300 175-2: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 2: Physical layer".

[3] ETS 300 175-3: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 3: Medium access control layer".

[4] ETS 300 175-4: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 4: Data link control layer".

[5] ETS 300 175-5: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 5: Network layer".

[6] ETS 300 175-6: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 6: Identities and addressing".

[7] ETS 300 175-7: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 7: Security features".

[8] ETS 300 175-8: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 8: Speech coding and transmission".

[9] prETS 300 444: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT): Generic Access Profile (GAP)".

[10] prETS 300 331: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface: DECT Authentication Module".

[11] I-ETS 300 176: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications Approval Test Specification".

[12] 91/263/EEC: "Council Directive of Apr. 29, 1991 on the approximation of the laws of the Member states concerning telecommunications terminal equipment, including the mutual recognition of their conformity". (Terminal Directive).

[13] ETR 015: "Digital European Cordless Telecommunications Reference document".

[14] ETR 043: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Services and Facilities requirements specification".

[15] ETR 056: "Digital European Cordless Telecommunications System description document".

[16] prETS 300 466: "Digital European Cordless Telecommunications/Global System for Mobile Communications (DECT/GSM) Inter-working profile: General Description of Service Requirements, Functional Capabilities and Information flows".

[17] Reserved.

[18] ECMA TR/44 (1989): "An architectural framework for private networks".

[19] GSM 01.02: "European digital cellular telecommunication system (Phase 2); General Description of a GSM PLMN".

[20] GSM 01.04: "European digital cellular telecommunication system (Phase 2); Abbreviations and acronyms".

[21] ETS 300 522: "European digital cellular telecommunication system; Network architecture GSM 03.02--phase 2".

[22] ETS 300 551: "European digital cellular telecommunication system; GSM PLMN Access Reference Configuration GSM 04.02--phase 2".

[23] PH2 GSM 04.08 (v4.8.0): "European digital cellular telecommunication system; Mobile Radio Interface--Layer 3 Specification GSM 04.08--phase 2".

[24] ETS 300 580-1: "European digital cellular telecommunication system; Speech Processing Functions: General Description GSM 06.01--phase 2".

[25] ETS 300 590: "European digital cellular telecommunication system; BSS-MSC Layer 3 Specification GSM 08.08--phase 2".

[26] PH2 GSM 11.11: "European digital cellular telecommunication system; Specifications of the SIM/ME interface GSM 11.11--phase 2".

[27] ISO IS 9646-1: "Information Technology--OSI Conformance Testing Methodology and Framework, Part 1: General Concepts".

[28] ISO IS 9646-6: "Information Technology--OSI Conformance Testing Methodology and Framework, Part 6: Protocol Profile Test Specification".

[29] ISO/IEC 9646-7 (1992): "Information Technology--OSI Conformance Testing Methodology and Framework, Part 7: Implementation Conformance Statements" (working draft for CD 9646-7).

[30] Draft prETS 300 xxx Version 5.00: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Data services profile, Generic data link service, Service Type C, Class 2".

[31] ETS 300 370: Radio Equipment and Systems (RES); Digital European Cordless Telecommunications/Global System for Mobile Communcations (DECT/GSM) Interworking profile, Access and mapping (Protocol/procedure description for 3.1 Hz speech service).

[32] ETS 300 582: European digital cellular telecommunication system (Phase 2); General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS) (GSM 07.01).

[33] ETS 300 583: European digital cellular telecommunication system (Phase 2); Terminal Adaptation Functions (TAF) for services using asynchronous bearer capabilities (GSM 07.02).

[34] ETS 300 584: European digital cellular telecommunication system (Phase 2); Terminal Adaptation Functions (TAF) for services using synchronous bearer capabilities (GSM 07.03).

2.1. DECT Definitions

Attach: the process whereby a PP within the coverage area of a FP to which it has access rights, notifies this FP that it is operative. The reverse process is detach, which reports the PP as inoperative.

NOTE 1: An operative PP is assumed to be ready to receive calls.

Authentication: the process whereby a DECT subscriber is positively verified to be a legitimate user of a particular FP.

NOTE 2: Authentication is generally performed at call set-up, but may also be done at any other time (e.g. during a call).

Bearer service: a type of telecommunication service that provides a defined capability for the transmission of signals between user-network interfaces.

NOTE 3: The DECT user-network interface corresponds to the top of the network layer (layer 3).

C-plane: the control plane of the DECT protocol stacks, which contains all of the internal DECT protocol control, but may also include some external user information.

NOTE 4: The C-plane stack always contains protocol entities up to and including the network layer.

Call: all of the NetWork (NWK) layer processes involved in one network layer peer-to-peer association.

NOTE 5: Call may sometimes be used to refer to processes of all layers, since lower layer processes are implicitly required.

DECT NetWork (DNW): a network that uses the DECT air interface to interconnect a local network to one or more portable applications. The logical boundaries of the DECT network are defined to be at the top of the DECT network layer.

NOTE 6: A DECT NetWork (DNW) is a logical grouping that contains one or more fixed radio termination plus their associated portable radio termination. The boundaries of the DECT network are not physical boundaries.

Fixed Part (DECT Fixed Part) (FP): a physical grouping that contains all of the elements in the DECT network between the local network and the DECT air interface.

NOTE 7: A DECT FP contains the logical elements of at least one fixed radio termination, plus additional implementation specific elements.

Fixed Part GSM PLMN Attachment (DECT Fixed Part attached to a GSM MSC): a definition of a functional environment where a DECT system (FP) is attached to an GSM MSC. The MSC in this case refers to a functional entity providing the required MM and CC functionality defined in this ETS in order to communicate with the FP.

Fixed radio Termination (FT): a logical group of functions that contains all of the DECT processes and procedures on the fixed side of the DECT air interface.

NOTE 8: A fixed radio termination only includes elements that are defined in the DECT CI standard. This includes radio transmission elements together with a selection of layer 2 and layer 3 elements.

Generic Access Profile (GAP): a defined part of the DECT Common Interface standard (DECT CI) that ensures inter-operability between FPs and PPs for public business and residential access services.

Geographically unique identity: this term relates to FP identities, Primary Access Rights Identities (PARIs) and Radio Fixed Part Identities (RFPIs). It indicates that two systems with the same PARI, or respectively two RFPs with the same RFPI, can not be reached or listened to at the same geographical position.

Global NetWork (GNW): a telecommunication network capable of offering a long distance telecommunication service.

NOTE 9: The term does not include legal or regulatory aspects, nor does it indicate if the network is a public or a private network.

Globally unique identity: the identity is unique within DECT (without geographical or other restrictions).

Handover: the process of switching a call in progress from one physical channel to another physical channel. These processes can be internal (see internal handover) or external (see external handover).

NOTE 10: There are two physical forms of handover, intra-cell handover and inter-cell handover. Intra-cell handover is always internal. Inter-cell handover can be internal or external.

Incoming call: a call received at a PP.

Inter-cell handover: the switching of a call in progress from one cell to another cell.

Internal handover: handover processes that are completely internal to one Fixed radio Termination (FT). Internal handover re-connects the call at the lower layers, while maintaining the call at the NWK layer.

NOTE 11: The lower layer reconnection can either be at the Data Link Control (DLC) layer (connection handover) or at the MAC layer (bearer handover).

Inter-operability: the capability of FPs and PPs, that enable a PP to obtain access to teleservices in more than one location area and/or from more than one operator (more than one service provider).

Inter-operator roaming: roaming between FP coverage areas of different operators (different service providers).

Inter-Working Unit (IWU): a unit that is used to interconnect sub-networks.

NOTE 12: The IWU will contain the inter-working functions necessary to support the required sub-network inter-working.

Intra-cell handover: the switching of a call in progress from one physical channel of one cell to another physical channel of the same cell.

Intra-operator roaming: roaming between different FP coverage areas of the same operator (same service provider).

Local NetWork (LNW): a telecommunication network capable of offering local telecommunication services.

NOTE 13: The term does not include legal or regulatory aspects, nor does it indicate if the network is a public network or a private network.

Locally unique identity: the identity is unique within one FP or location area, depending on application.

Location area: the domain in which a PP may receive (and/or make) calls as a result of a single location registration.

Location registration: the process whereby the position of a DECT portable termination is determined to the level of one location area, and this position is updated in one or more databases.

NOTE 14: These databases are not included within the DECT FT.

Medium Access Control (MAC) Connection: an association between one source MAC Multi-Bearer Control (MBC) entity and one destination MAC MBC entity. This provides a set of related MAC services (a set of logical channels), and it can involve one or more underlying MAC bearers.

Outgoing call: a call originating from a PP.

Portable Application (PA): a logical grouping that contains all the elements that lie beyond the DECT network boundary on the portable side.

NOTE 15: The functions contained in the portable application may be physically distributed, but any such distribution is invisible to the DECT network.

Portable Part (DECT Portable Part) (PP): a physical grouping that contains all elements between the user and the DECT air interface. PP is a generic term that may describe one or several physical pieces.

NOTE 16: A DECT PP is logically divided into one portable termination plus one or more portable applications.

Portable radio Termination (PT): a logical group of functions that contains all of the DECT processes and procedures on the portable side of the DECT air interface.

NOTE 17: A PT only includes elements that are defined in the DECT CI standard. This includes radio transmission elements (layer 1) together with a selection of layer 2 and layer 3 elements.

Radio Fixed Part (RFP): one physical sub-group of an FP that contains all the radio end points (one or more) that are connected to a single system of antennas.

Registration: an ambiguous term, that should always be qualified. See either location registration or subscription registration.

Roaming: the movement of a PP from one FP coverage area to another FP coverage area, where the capabilities of the FPs enable the PP to make or receive calls in both areas.

NOTE 18: Roaming requires the relevant FPs and PP to be inter-operable.

Subscription registration: the infrequent process whereby a subscriber obtains access rights to one or more FPs.

NOTE 19: Subscription registration is usually required before a user can make or receive calls.

2.2. Abbreviations

For the purposes of this document, the following abbreviations apply:

2.3. GSM Abbreviations and Definitions

Definition and specific GSM abbreviations may be found in GSM 01.04 [20].

2.4. Symbols for Status Columns

The symbols defined in this subclause are applied for procedures, features, messages, information elements, fields and field codings in this document if not explicitly otherwise stated. The interpretation of status columns in all tables is as follows:

M for mandatory to map/support/use;

O for optional to map/support/use;

I for out-of-scope (not subject for testing);

X for prohibited or excluded to map/support/use (the message, information element may be allowed to be used in the standard/standards but it is not allowed to be mapped/used depending on the environment/dynamic conditions etc.);

N/A or -(dash) for not applicable to map/support/use;

C for conditional to map/support/use (the message, information element mapping depends on the selection of other optional or/and conditional items).

NOTE: The symbol "-" in the mapping section of this ETS means that there is no message, information element or coding specified in this column.

This document specifies how GSM circuit switched bearer services are provided over the DECT air interface.

This document is made up of 5 main clauses:

Clause 4: Inter-working requirements--includes reference configurations and the protocol architecture models. Also describes the main service requirements.

Clauses 5: Inter-Working Unit (IWU) mappings--shows the C plane and U plane mappings needed in addition to the ETS 300 370 [31] for the FP GSM PLMN attachment in respective order. Two IWUs are considered; the FP IWU and the PP IWU, although the FP IWU is expected to be the largest. The signalling mappings are described in terms of IWU procedures with informative data flow diagrams. Detailed descriptions follow using tables of what is mapped, what is ignored, and what is transferred transparently.

Clause 6: Additions to the base standard--this clause defines the optional changes needed in the ETS 300 175-5 [5] for a full interworking in service negotiation. Also some new attributes/parameter codings are proposed to widen the service range closer to GSM PLMN bearer services.

Clause 7: Connection types--this clause identifies the main DECT connection types (U plane+C plane) at the air interface and defines the attributes codings used in the DECT air interface for identification of the different GSM bearer services.

Clause 8: GSM Bearer Capability default values--this clause lists the default values for GSM BC information element fields.

4.1. General

This document defines the mandatory requirements to the FP interworking functions if the GSM circuit switched bearer services are interworked to DECT. The interworking shall comply completely with ETS 300 370 [31] in terms of MM and CC message mappings with the additions presented in this document. The additional interworking mapping are based on the GSM phase 2 standards.

The mandatory minimum requirement of this document is compatible with the DECT/GSM interworking profile ETS 300 370 [31], ETS 300 xxx DECT C.2. data profile [30] and ETS 300 175-5 DECT Network Layer [5]. However, if full interworking with service negotiation is needed some changes/additions listed in subclause 6 of this document are required to ETS 300 175-5 [5]. The procedures utilizing these changes are optional.

4.2. Reference Configurations

4.2.1. FP functional attachment to the GSM PLMN

The configuration is shown in FIG. 10.

4.3. General Inter-working Model for FP GSM PLMN Attachment

The general interworking model is shown in FIG. 11. It describes a general interworking model containing both control and user planes. The figure also shows the locations of the interworking units (IWUs).

The FP IWU provides mappings between GSM CC/MM and DECT CC/MM messages. The mappings defined in this document in subclause 5 are additions to the ETS 300 370 [31]. The PP TAF defined in the ETS 300 xxx C.2 profile annex C.2 [30] provides a CCITT V.24 connection to the DECT data application.

4.4. Inter-working Context

4.4.1. General

The PP complying with this standard shall be compatible with the requirements of the ETS 300 xxx C.2 data profile [30] and ETS 300 370 [31], those which are based on the minimum requirements of GAP [9] when regarding the MM aspects. The CC requirements are based on the C.2 data profile [30] which are GAP [9] with some data transmission specific additional requirements. This document does not require the support of the GAP based voice services i.e. the PP may be a data only terminal with the GSM access capabilities and a GSM subscription as defined in ETS 300 370 [31].

4.4.2. Basic-Inter-Working Rules

The interworking rules are as defined in ETS 300 370 [31].

Table 1 defines the GSM bearer services supported by this document. Both, GSM transparent (T) and non-transparent (NT) bearer services are supported while DECT is interworking with GSM. The DECT air interface does not separate the NT or T cases thus the C.2 profile will be used for both cases. Both rate adaptation schemes are terminated of the FP IWU and are introduced in the FP IWU U-plane section, however, to support both is not a mandatory requirement.

The selection of a GSM bearer service is done in the mobile originated call by defining the services requirements in the <<iwu-attributes>> and <<end-to-end-capatibility>> information elements as defined in subclause 7. Part of the values of these elements are mapped to GSM <<Bearer capability>> element as defined in subclause 5.1.4.. Since not all DECT fields are mappable with GSM fields some of the values are utilized i.e they are ignored in the GSM part of the connection establishment. Due to the same reason some GSM Bearer capability fields use default values as defined in subclause 8.

The selection of a GSM bearer service is done in the mobile terminated call by defining the service requirements in the GSM <<Bearer capability>> element. Part of the values of this element are mapped to <<iwu-attributes>> and <<end-to-end-compatibility>> information elements as defined in subclause 5.1.4. Since not all GSM fields are mappable with DECT fields some of the values are not utilized i.e they are ignored in the DECT part of the connection establishment. Due to the same reason some fields of DECT <<iwu-attributes>> and <<end-to-end-compatibility>> use default values as defined in subclause 7.

4.4.3.. Interpretation of broadcast attributes

This subclause refers to Annex F of ETS 300 175-5 [5] (Broadcast attributes coding). The coding are done as defined in ETS 300 370 [31] with the exceptions listed here.

a32 ADPCM/G.721 Voice service: may be set to value "1". (NOTE 1)

a33 PAP/GAP voice supported: may be set to value "1". (NOTE 1)

a34 Non-voice circuit switched service: shall be set to value "1";

NOTE 1. This document does not require the support of the voice service, however, it is not prohibited either.

4.4.4. Interpretation of Terminal capability

If <<TERMINAL CAPABILTY>> information element is used the following codings indicated the support of the GSM bearer services:

Profile Indicator.sub.-- 1 Coding (Octet 4) of TERMINAL CAPABLITY information element:

5.1. FP C-plane IWU Procedures

5.1.1. CC IWU procedures

The CC procedures are compatible with ETS 300 370 [31] with the exceptions described here.

The <<IWU ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> information elements included in the {CC-SETUP} message will define the GSM bearer service to be requested. The coding combinations used for alternate bearer services is defined in the subclause 7 of this document.

Only BEARER CAPABILITY 1 is recognized in the GSM messages. That is, if a GSM Call Control message contains multiple BEARER CAPABLITY information elements only the first one is mapped and conveyed to DECT PP.

Only the first <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBILITY>> information elements are mapped into GSM BEARER CAPABILITY element.

The LOWER LAYER COMPATIBILITY and HIGHER LAYER COMPATIBILITY information elements, if present in a GSM CC message, are carried with no mappings over the air interface as described in subclauses 5.1.5.1.3, 5.1.5.1.4, 5.1.5.2.3 and 5.1.5.2.4. The FP will not do any mapping of these elements. The utilization of these elements is completely a matter of the DECT data application in PP i.e this document does not define their usage.

5.1.1.1. Outgoing data call

The call procedures for outgoing data call (PP originated) are compatible with the procedures of containing the <<CALLED-PARTY-NUMBER>> in the {CC-INFO} message as defined in the ETS 300 370 [31]. This procedure is compatible with ETS 300 xxx C.2 data profile [30] call establishment.

5.1.1.2. Service negotiation in the case of outgoing call

There are three alternate options in the services negotiation procedures in (PP originated) outgoing call. Minimum mandatory requirement is to support the negotiation not possible case defined in clause 5.1.1.2.1. The alternate service negotiation procedures are indicated/requested with <<Negotiation indicator>> field in the <<IWU-ATTRIBUTES>> information element. In order to facilitate the optional service negotiations defined in subclauses 5.1.1.2.2. and 5.1.1.2.3. changes/additions defined in subclause 7 of this document to DECT network layer ETS 300 175-5 [5] have to be implemented.

The negotiable parameters in the case of mobile originated call is <<Modem type>>.

5.1.1.2.1. Negotiation not possible

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Negotiation not possible" in the <<Negotiation indicator field>> from the CC entity the FP IWU will reject all negotiation towards/from MSC. That is, if the MSC cannot provide the PP the requested service the connection is disconnected by using CC-REJECT-req with <<Release reason>> Hex 05 "Incompatible service" towards PP.

It is then the responsiblity of the FP IWU in the case the {Call proceeding} contains new service parameter values to disconnect the connection towards the GSM PLMN by issuing {Release complete} message with cause 79; "Service or option not implemented, unspecified".

If no {Call proceeding} message is received from MSC or it does not contain <<BEARER CAPABILITY>> information element the service parameters have been accepted by the MSC IWF and the call establishment proceeds as defined in ETS 300 370 [31]. (See FIG. 12)

5.1.1.2.2. Exchange attributes negotiation

The following procedures require the additions defined in subclause 6.

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Exchange parameter negotiation" in the <<Negotiation indicator field>> from the CC entity the FP IWU will reject the request immediately issuing MNCC-REJECT-req with <<Release reason>> Hex 07 "Negotiation not supported" if the FP cannot support exchange attributes negotiation as defined in the subclause 15.2.3 of ETS 300 175-5 [5].

If the FP can support the Exchange parameter negotiation the FP IWU will map the <<IWU-ATTRIBUTES>> and the <<END-TO-END-COMPATIBLITY>> information elements contained in {CC-SETUP} to the GSM BEARER CAPABILTY element of GSM {Setup} message as described in subclause 5.1.4.2.1.

1) Upon receipt of the GSM {Call proceeding} message with new values in <<Bearer capabilty>> information element the FP IWU will release the connection by using MNCC-REJECT-ind with new values in the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBLITY>> information elements.

2) Whereupon the FP IWU will send the MSC {RELEASE COMPLETE} message with cause code 31 "Normal, unspecified". The PP may now initiate a new call with new parameter values following the normal call establishment precedures defined in this document and in ETS 300 370 [31].

If no {Call proceeding} message is received or it does not contain <<BEARER CAPABILITY>> information element the service parameters have been accepted by the MSC IWF and the call establishment proceeds as defined in ETS 300 370 [31]. (See FIG. 13)

5.1.1.2.3. Extended exchange parameter negotiation

The following procedures require the additions defined in subclause 6.

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Extended exchange parameter negotiation" in the <<Negotiation indicator field>> from the CC entity the FP IWU will reject the request immediately issuing MNCC-REJECT-req with <<Release reason>> Hex 07 "Negotiation not supported" if the FP cannot support Extended exchange attributes negotiation.

If the FP can support the Extended exchange parameter negotiation the FP IWU will map the <<IWU-ATTRIBUTES>> and the <<END-TO-END-COMPATIBLITY>> information elements contained in {CC-SETUP} message to the GSM <<BEARER CAPABILTY>> element of GSM {Setup} message as described in subclause 5.1.4.2.1.

1) Upon receipt of the GSM {Call proceeding} message the FP IWU will map the new values of the <<Bearer capability>> into the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBLITY>> information elements of the DECT <<CC-CALL-PROCEEDING>> message as defined in subclause 5.1.4.1.3.

If no {Call proceeding} message is received or it does not contain <<BEARER CAPABILITY>> information element the service parameters have been accepted by the MSC IWF and no mapping between the <<BEARER CAPABILITY>> and <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBLITY>> information elements is needed. (See FIG. 14)

5.1.1.3. Incoming data call

The call procedures for incoming data call (network originated) are compatible with the procedures defined in the ETS 300 370 [31]. This procedure is compatible with ETS 300 xxx C.2 data profile [30] call establishment.

5.1.1.4. Service negotiation in the case of incoming call

There are three alternate options in the services negotiation procedures in (network originated) incoming call. Minimum mandatory requirement is to support the negotiation not possible case defined in clause 5.1.1.4.1. The alternate service negotiation procedures are indicated/requested with <<Negotiation indicator>> field in the <<IWU-ATTRIBUTES>> information element. In order to facilitate the optional service negotiations defined in subclauses 5.1.1.4.2. and 5.1.1.4.3. changes/additions defined in subclause 6 of this document to DECT network layer ETS 300 175-5 [5] have to be implemented.

The negotiable parameters in the case of mobile terminated call are <<number of data bits>>, <<number of stop bits>>, <<number of parity bits>>, <<user layer 2 protocol>> and <<Modem type>>.

5.1.1.4.1. Negotiation not possible

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Negotiation not possible" in the <<Negotiation indicator field>> from the CC entity the PP IWU will reject all negotiation. That is, if the PP cannot accept the parameters indicated in the <<IWU-ATTRIBUTES>> and the <<END-TO-END-COMPATIBLITY>> information elements the connection is disconnected by using CC-REJECT-req with <<Release reason>> Hex 05 "Incompatible service".

If the PP IWU accepts the parameters proposed by MSC the call establishment proceeds as defined in ETS 300 370 [31].

5.1.1.4.2. Exchange attributes negotiation

The following procedures require the additions defined in subclause 6.

1). Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Exchange parameter negotiation" in the <<Negotiation indicator field>> from the CC entity the PP IWU will reject the request immediately issuing MNCC-REJECT-req with <<Release reason>> Hex 07 "Negotiation not supported" if the PP cannot support exchange attributes negotiation as defined in the subclause 15.2.3 in ETS 300 175-5 [5].

If the PP can support the Exchange parameter negotiation the PP IWU will add the new desired values into the <<IWU-ATTRIBUTES>> and the <<END-TO-END-COMPATIBLITY>> information elements of the {CC-RELEASE-COM} message.

2). Upon receipt of the {CC-RELEASE-COM} message with indication of "Exchange parameter negotiation" in the <<Negotiation indicator>> field of the <<IWU-ATTRIBUTES>> element the FP will not directly map the message according to 300 370 [31] but issue immediately a new CC-SETUP-ind with new set parameters in <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBLITY>> elements. It is then the responsibility of the FP IWU to join the GSM call waiting for response and the new DECT call with new parameters.

3) Upon receipt of the {CC-ALERTING} or {CC-CONNECT} as a response to the new {SETUP} message the procedure will proceed as illustrated in ETS 300 370 [31] with new parameter values mapped into the <<BEARER CAPABILITY>> element in the {Call Confirmed} message.

If the PP IWU accepts the parameters proposed by MSC the call establishment proceeds as defined in ETS 300 370 [31]. (See FIG. 15)

5.1.1.4.3. Extended exchange parameter negotiation

The following procedures require the additions defined in subclause 6.

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Extended exchange parameter negotiation" in the <<Negotiation indicator field>> from the CC entity the PP IWU will reject the request immediately issuing MNCC-REJECT-req with <<Release reason>> Hex 07 "Negotiation not supported" if the PP cannot support Extended exchange attributes negotiation.

If the PP can support the Extended exchange parameter negotiation the PP IWU will add the new desired attributes values to the <<IWU-ATTRIBUTES>> and the <<END-TO-END-COMPATIBLITY>> information elements of the {CC-CONNECT} message.

2) and 3). It is then the responsibility of the FP IWU to suspend the submission of the {Call confirm} and {Alerting} message towards the GSM network until the new desired values have been received in the {CC-CONNECT} message. The new values in the <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBLITY>> information elements of the {CC-CONNECT} message are mapped into the GSM BEARER CAPABILTY element of {Call Confirmed} message as described in subclause 5.1.8.3. Other mappings between {CC-CONNECT} and {Connect} message as well as {CC-ALERTING} and {Alerting} messages are done as described in ETS 300 370 [31].

The PP IWU shall not use <<IWU-ATTRIBUTES>> and/or <<END-TO-END-COMPATIBILITY>> information elements in the {CC-CONNECT} message if it agrees with the service parameters proposed in the {CC-SETUP} message. If the PP IWU accepts the parameters proposed by MSC the call establishment proceeds as defined in ETS 300 370 [31]. (See FIG. 16)

5.1.1.5. Other CC procedures

Other CC procedures are done according to ETS300 370 [31]. Additional cause code mappings required are presented in subclause 5.1.6.1.20.

5.1.2. MM IWU procedures

The MM procedures follow the procedures defined in the C.2 profile and ETS 300 370 [31].

5.1.3. Other IWU procedures

5.1.4. Message mappings

5.1.4.1. GSM to DECT

1.4.1.1. SETUP--CC-SETUP

NOTE 1: The GSM bearer capability information element has to be mapped into two DECT elements.

All other message mappings are done according to ETS 300 370 [31].

5.1.4.1.2. CALL PROCEEDING-CC-RELEASE-COM

5.1.4.1.3. CALL PROCEEDING-CC-CALL-PROCEEDING

5.1.4.2. DECT to GSM

5.1.4.2.1. CC-SETUP--SETUP

5.1.4.2.2. CC-CONNECT--CALL CONFIRMED

5.1.5. Information element mappings

5.5.1. GSM to DECT

5.1.5.1.1. Bearer capability 1--Iwu-attributes

5.1.5.1.2. Bearer capability 1--end-to-end-compatibility

5.1.5.1.3. Lower layer compatibility--Iwu-to-iwu

If the <<Lower layer compatibility>> information element is contained in GSM CC messages, it is mapped intact into <<iwu-to-iwu>> packet <<iwu-to-iwu-information>> field. The information element <<Protocol discriminator>> in <<iwu-to-iwu>> packet will contain coding "010001"B "GSM Recommendation 04.08, elements".

5.1.5.1.4. Higher layer compatibility--Iwu-to-iwu

If the <<Higher layer compatibility>> information element is contained in GSM CC messages, it is mapped intact into <<iwu-to-iwu>> packet <<iwu-to-iwu-information>> field. The information element <<Protocol discriminator>> in <<iwu-to-iwu>> packet will contain coding "010001"B "GSM Recommendation 04.08, elements".

5.1.5.2. DECT to GSM

5.1.5.2.1. Iwu-attributes--Bearer capability 1

5.1.5.2.2. End-to-end-compatibility--Bearer capability 1

5.1.5.2.3. Iwu-to-iwu--lower layer compatibility

See subclause 5.1.5.1.3.

5.1.5.2.4. Iwu-to-iwu--Higher layer compatibility

subclause 5.1.5.1.4.

5.1.6. Fields in information element coding

5.1.6.1. GSM to DECT and DECT to GSM

5.1.6.1.1. Coding standard--Coding standard

5.1.6.1.2. Transfer mode--transfer mode

5.1.6.1.3. Information transfer capability--information transfer capability

5.1.6.1.4. Structure--Structure

5.1.6.1.5. Configuration--Configuration

5.1.6.1.6. Establishment--Establishment

5.1.6.1.7. Rate adaptation--User protocol ID

5.1.6.1.8. User information layer 2 protocol--L2 protocol ID

5.1.6.1.9. Duplex mode--Duplex mode (DUP)

5.1.6.1.10. Synchronous/asynchronous--Synchronous/asynchronous (S/A)

5.1.6.1.11. Number of stop bits--stop bit coding

5.1.6.1.12. Negotiation--Negotiation (Neg)

5.1.6.1.13. Number of data bits exI. parity--data bits coding

5.1.6.1.14. User rate--User rate coding

5.1.6.1.15. Intermediate rate--intermediate rate

5.1.6.1.16. Network independent clocking (NIC) on transmission (Tx)--Network independent clocking on transmission (NIC Tx)

5.1.6.1.17. Network independent clocking (NIC) on reception (Tx)--Network independent clocking on reception (NIC Tx)

5.1.6.1.18. Parity information--parity coding

5.1.6.1.19. Modem type--Modem type

5.1.6.1.20. Cause-value--Release Reason-code

The following mappings are additions to ETS 300 370 [31] subclause 6.1.8.2.23.

5.2. FP U-plane IWU Procedures

5.2.1. General

This section defines the functional requirements of the FP IWU for the mapping of the user data and the C.2 data profile U-plane flow. Both Transparent and Non-Transparent options have been decribed. However, it is not a mandatory requirement to support both options. It is recommended to provide the Non Transparent interworking since its functionality is closer to the DECT air interface opreration of LAPU.

5.2.2. Transparent service (T)

5.2.2.1. General

Due to usage of LAPU no complete synchronism between the endpoints can be guaranteed.

The rate adaptation of the GSM data flow will be done in the FP IWU. A general structure of the rate adaptation function is illustrated in FIG. 17. In the figure it is assumed that the FP is connected to the MSC through the A interface. The functionality of the IWU is to map the synchronous, asynchronous and status data to respective DECT C.2 profile functionality. FP seen by the MSC correspond to the GSM MS TAF functionality.

5.2.2.1.1. Asynchronous

The FP IWU will contain the V.110 RA2, RA1 and RA0 adaptation functions. The information of the RA0 and RA1 will be mapped as follows:

the CCITT V series status information of RA1 will be mapped to the C.2 LAPU Control frame as defined in subclause 5.2.2.3 of this document. The status octets are not carried in the LAPU information frames.

user information of the RA0 will be forwarded C.2 PAD function defined in the subclause 10.1 of the DECT C.2 data profile [30] following the rules defined in the same subclause. The LAPU frame lengths should be adjusted to fit the buffering requirements related to the transparent service.

5.2.2.1.2. Synchronous

The FP IWU will contain the V.110 RA2 and RA1 adaptation functions. The information from the RA1 will be mapped as follows:

the CCITT V series status information of RA1 will be mapped to the respective DECT function defined in the subclause 5.2.2.2 of this document. The status octets are not carried in the LAPU information frames.

user information of the RA0 will be forwarded C.2 BPAD function defined in the subclause 10.2 of the DECT C.2 data profile [30] following the rules defined in the same subclause. The LAPU frame lengths should be adjusted to fit the buffering requirements related to the transparent service.

5.2.2.2. CCITT V.24 Interchange circuit signalling mapping

The CCITT V.24 signalling status information will be mapped between the DECT LAPU control frame function and respective GSM function as follows.

DECT C.2 Data profile Control Status octet defined in C.2 data profile [30] subclause 10.3 is used with <<Frame type coding>> indicating V.24 status interworking.

the status change of the V.24 interface circuits 108, 107, 105, 109 and 106 mapping will be done as shown in tables 24 and 25.

In the direction of GSM to DECT only in the change situation of a status of each SA, SB or X bit will be mapped thus if not change has occurred in the status bit of GSM data flow not LAPU control frame is sent.

In the direction of DECT to GSM the FP IWU will map the old status of a status bit towards GSM if no LAPU control frames with new value has received.

the status of the CCITT V.24 circuits 106 and 105 is mapped into/from the PAD/BPAD flow control

NOTE 1. DECT provides its own flow control mechanism and end-to-end flow control is not recommended. See subclauses 5.2.2.3 and 5.2.3.3.

5.2.2.3. Flow control

The flow control situation indicated by the X-bit or buffers backpressure are mapped into the C.2 data profile [30] PAD/BPAD flow control functionality as defined in respective C.2 profile PAD/BPAD subclauses. It is the matter of implementation to ensure that no data loss occur in flow control.

5.2.2.4. Call establishment signalling mapping

The mapping between DECT call establishment in the FP IWU is done as defined in the ETS 300 370 [31] and in this document in subclause 5.

5.2.3. Non-transparent service (NT)

5.2.3.1. General

The rate adaptation of the GSM data flow will take place in the FP IWU. A general figure of the rate adaptation functions of GSM non-transparent (NT) case is illustrated in FIG. 18. In the figure it is assumed that the FP is connected to the MSC through the A interface.

The RLP entity and LAPU entity in FP will function completely independently. That is, frame retransmissions and control information regarding RLP and LAPU functions are not dependent of each other.

5.2.3.1.1. Asynchronous

The FP IWU will contain the RA2, RA1, RLP and L2COP functions. The information from the L2COP will be mapped as follows:

The status octets are not carried in the LAPU information frames.

the status bit (3 first bits) information of the status octet will be mapped to the respective DECT function defined in the subclause 5.2.2.3.

character octets will be forwarded to the C.2 PAD function as defined in the subclause 10.1 of the DECT C.2 data profile [30] following the rules defined in the same subclause.

fill octets are not forwarded to the C.2. PAD function.

break signal status received from GSM direction is mapped into the LAPU control frame <<Break coding>> with indication of "Break condition occurred". The duration of the break signal in the BREAK/PAUSE duration octet should be in between 135 ms and 200 ms as defined by GSM 07.02 [33].

break signal status received from DECT direction is mapped into the L2COP address field as defined in the GSM 07.02 [33]. The duration information is ignored.

5.2.3.1.2. Synchronous

The FP IWU will contain the RA2, RA1, RLP and L2BOP functions. The information of the L2BOP will be mapped as follows:

The status octets are not carried in the LAPU information frames.

the status bit (3 first bits) information of the status octet will be mapped to the respective function defined in the subclause 5.2.2.3.

the address bit (5 last bits) information of the status octet is utilized as follows: if address has the value 31 no L2BOP remaining information is forwarded to LAPU information frame. Other address values are ignored.

user information will be forwarded to the C.2 BPAD function as defined in the subclause 10.1 of the DECT C.2 data profile [30] following the rules defined in the same subclause.

fill octets are not inserted to the C.2 LAPU octets.

5.2.3.2. Interchange circuit signalling mapping

See sublause 5.2.2.2.

5.2.3.3. Flow control

The flow control situation indicated by the X-bit or buffers backpressure are mapped into the C.2 data profile [30] PAD/BPAD flow control functionality as defined in respective C.2 profile PAD/BPAD subclauses. It is the matter of implementation to ensure that no data loss occur in flow control.

5.2.3.4. Call establishment signalling mapping

See subclause 5.2.2.4.

5.2.4. Synchronization

It is the responisbilty of the FP to guarantee that no user data is conveyed before both RLP and LAPU links have been succefully established. No CCITT V.24 signalling information is conveyed before information regarding the ready status of the MSC-network connection is guaranteed.

5.3. PP C-plane IWU Procedures

For CCITT V.24 interworking of the PP C-plane procedures are recommended as defined in the C.2 data profile C.2 TAF annex [30].

The mapping between the PP C-plane and V.25bis commands is done according to the C.2 data profile annex C.2 [30].

5.4. PP U-plane IWU Procedures

For CCITT V.24 interworking of the PP U-plane procedures are recommended as defined the C.2 data profile C.2 TAF annex.

The following changes and additions should be done to the DECT Common interface standard in order to facilitate the optional service negotiation options.

6.1. Exchange Attributes Negotiation

6.1.1. {CC-RELEASE-COM} message

A new structure of the {CC-RELEASE-COM} message is presented below. The subclause

numbers are referring the respective clauses in the ETS 300 175-5 [5] standard.

6.3.2.9 CC-RELEASE-COMplete

This message indicates that the sending entity has released the call and the call reference, and the receiving entity shall release the call and call reference.

6.2. Extended Exchange Parameter Negotiation

A new structure of the {CC-CALL-PROCEEDING} and {CC-CONNECT} messages is presented below. The subclause numbers are referring the respective clauses in ETS 300 175-5 [5] standard. A new coding has to be added into the <<IWU-ATTRIBUTES >>.

6.2.1. {CC-CALL-PROCEEDING} message

6.3.2.4 CC-CALL-PROCeeding

This message indicates that the requested (onward) connection establishment has been initiated by the fixed side interworking unit.

6.2.2. {CC-CONNECT} messages

6.3.2.6 CC-CONNECT

This message is sent by the FT to indicate completion of the connection through the WCPE network, and by the PT to request such completion.

6.3. New <<IWU-ATTRIBUTES >> Coding

Negotiation indicator (octet 4):

Layer 2 protocol ID (octet 6):

6.4. New <<END-TO-END-COMPATIBLITY >> Coding

Modem type (octet 4):

Authors note: charaters in the coding selection indicate that a new unused coding set has to be selected.

7.1. Connection Type Definitions

The supported bearer services are defined in subclause 4.4.2 in table 1. The default coding using the <<IWU-ATRIBUTES>> and <<END-TO-END-COMPATIBLITY>> information elements for all the bearer services are defined in the table Q. These codings should be used in the DECT air interface in order to facilitate connection to GSM bearer services 21-26, 31-34 and 41-45. The values presented here are not all mapped into the respective GSM value but they have importance in the DECT environment. The presence of multiple values in the Field value column indicates options.

7.1.1. IWU-ATTRIBUTES information element for BS 21 . . . 26 UDI

7.1.2. END-TO-END-COMPATIBLITY information element for BS 21 . . . 26, UDI

7.1.3. IWU-ATTRIBUTES information element for BS 21 . . . 26 3.1 kHz

7.1.4. END-TO-END-COMPATIBLITY information element for BS 21 . . . 26, 3.1 kHz

7.1.5. IWU-ATTRIBUTES information element for BS 31 . . . 34, non X.32, UDI

7.1.6. END-TO-END-COMPATIBLITY information element for BS 31 . . . 34, non X.32, UDI

7.1.7. IWU-ATTRIBUTES information element for BS 31 . . . 34, X.32, UDI

7.1.8. END-TO-END-COMPATIBLITY information element for BS 31 . . . 34, X.32, UDI

7.1.9. IWU-ATTRIBUTES information element for BS 31 . . . 34, non X.32, 3.1 kHz

7.1.10. END-TO-END-COMPATIBLITY information element for BS 31 . . . 34, non X.32, 3.1 kHz

7.1.11. IWU-ATTRIBUTES information element for BS 31 . . . 34, X.32, 3.1 kHz

7.1.12. END-TO-END-COMPATIBLITY information element for BS 31 . . . 34, X.32, 3.1k kHz

7.1.13. IWU-ATTRIBUTES information element for BS 41 . . . 46, PAD

7.1.14. END-TO-END-COMPATIBLITY information element for BS 41 . . . 46, PAD

7.1.15. IWU-ATTRIBUTES information element for BS 51 . . . 53, Packet

7.1.16. END-TO-END-COMPATIBLITY information element for BS 51 . . . 53, Packet

If mapping has not been defined or field is missing the following values are used in GSM Bearer capability 1 information element as specified in GSM 07.01 [33].

[1] ETS 300 175-1: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 1: Overview".

[2] ETS 300 175-2: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 2: Physical layer".

[3] ETS 300 175-3: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 3: Medium access control layer".

[4] ETS 300 175-4: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 4: Data link control layer".

[5] ETS 300 175-5: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 5: Network layer".

[6] ETS 300 175-6: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 6: Identities and addressing".

[7] ETS 300 175-7: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 7: Security features".

[8] ETS 300 175-8: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Part 8: Speech coding and transmission".

[9] prETS 300 444: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT): Generic Access Profile (GAP)".

[10] prETS 300 331: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface: DECT Authentication Module".

[11] I-ETS 300 176: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications Approval Test Specification".

[12] 911263/EEC: "Council Directive of 29 Apr. 1991 on the approximation of the laws of the Member states concerning telecommunications terminal equipment, including the mutual recognition of their conformity". (Terminal Directive).

[13] ETR 015: "Digital European Cordless Telecommunications Reference document".

[14] ETR 043: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Common Interface Services and Facilities requirements specification".

[15] ETR 056: "Digital European Cordless Telecommunications System description document".

[16] prETS 300 466: "Digital European Cordless TelecommunicationslGlobal System for Mobile Communications (DECT/IGSM) Inter-working profile: General Description of Service Requirements, Functional Capabilities and Information flows".

[17] Reserved.

[18] ECMA TR/44 (1989): "An architectural framework for private networks".

[19] GSM 01.02: "European digital cellular telecommunication system (Phase 2); General Description of a GSM PLMN".

[20] GSM 01.04: "European digital cellular telecommunication system (Phase 2); Abbreviations and acronyms".

[21] ETS 300 522: "European digital cellular telecommunication system; Network architecture GSM 03.02--phase 2".

[22] ETS 300 551: "European digital cellular telecommunication system; GSM PLMN Access Reference Configuration GSM 04.02--phase 2".

[23] PH2 GSM 04.08 (v4.8.0): "European digital cellular telecommunication system; Mobile Radio Interface--Layer 3 Specification GSM 04.08--phase 2".

[24] ETS 300 580-1: "European digital cellular telecommunication system; Speech Processing Functions: General Description GSM 06.01--phase 2".

[25] ETS 300 590: "European digital cellular telecommunication system; BSS-MSC Layer 3 Specification GSM 08.08--phase 2".

[26] PH2 GSM 11.11: "European digital cellular telecommunication system; Specifications of the SIM/ME interface GSM 11.11--phase 2".

[27] ISO IS 9646-1: "Information Technology--OSI Conformance Testing Methodology and Framework, Part 1: General Concepts".

[28] ISO IS 9646-6: "Information Technology--OSI Conformance Testing Methodology and Framework, Part 6: Protocol Profile Test Specification".

[29] ISO/IEC 9646-7 (1992): "Information Technology--OSI Conformance Testing Methodology and Framework, Part 7: Implementation Conformance Statements" (working draft for CD 9646-7).

[30] Draft prETS 300 xxx Version 5.00: "Radio Equipment and Systems (RES); Digital European Cordless Telecommunications (DECT) Data services profile, Generic data link service, Service Type C, Class 2".

[31] ETS 300 370: Radio Equipment and Systems (RES); Digital European Cordless Telecommunications/Global System for Mobile Communcations (DECT/GSM) Interworking profile, Access and mapping (Protocol/procedure description for 3.1 kHz speech service).

[32] ETS 300 582: European digital cellular telecommunication system (Phase 2); General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS) (GSM 07.01).

[33] ETS 300 583: European digital cellular telecommunication system (Phase 2); Terminal Adaptation Functions (TAF) for services using asynchronous bearer capabilities (GSM 07.02).

[34] ETS 300 584: European digital cellular telecommunication system (Phase 2); Terminal Adaptation Functions (TAF) for services using synchronous bearer capabilities (GSM 07.03).

2.1. DECT Definitions

Attach: the process whereby a PP within the coverage area of a FP to which it has access rights, notifies this FP that it is operative. The reverse process is detach, which reports the PP as inoperative.

NOTE 1: An operative PP is assumed to be ready to receive calls.

Authentication: the process whereby a DECT subscriber is positively verified to be a legitimate user of a particular FP.

NOTE 2: Authentication is generally performed at call set-up, but may also be done at any other time (e.g. during a call).

Bearer service: a type of telecommunication service that provides a defined capability for the transmission of signals between user-network interfaces.

NOTE 3: The DECT user-network interface corresponds to the top of the network layer (layer 3).

C-plane: the control plane of the DECT protocol stacks, which contains all of the internal DECT protocol control, but may also include some external user information.

NOTE 4: The C-plane stack always contains protocol entities up to and including the network layer.

Call: all of the NetWork (NWK) layer processes involved in one network layer peer-to-peer association.

NOTE 5: Call may sometimes be used to refer to processes of all layers, since lower layer processes are implicitly required.

DECT NetWork (DNW): a network that uses the DECT air interface to interconnect a local network to one or more portable applications. The logical boundaries of the DECT network are defined to be at the top of the DECT network layer.

NOTE 6: A DECT NetWork (DNW) is a logical grouping that contains one or more fixed radio termination plus their associated portable radio termination. The boundaries of the DECT network are not physical boundaries.

Fixed Part (DECT Fixed Part) (FP): a physical grouping that contains all of the elements in the DECT network between the local network and the DECT air interface.

NOTE 7: A DECT FP contains the logical elements of at least one fixed radio termination, plus additional implementation specific elements.

Fixed Part GSM PLMN Attachment (DECT Fixed Part attached to a GSM MSC): a definition of a functional environment where a DECT system (FP) is attached to an GSM MSC. The MSC in this case refers to a functional entity providing the required MM and CC functionality defined in this ETS in order to communicate with the FP.

Fixed radio Termination (FT): a logical group of functions that contains all of the DECT processes and procedures on the fixed side of the DECT air interface.

NOTE 8: A fixed radio termination only includes elements that are defined in the DECT CI standard. This includes radio transmission elements together with a selection of layer 2 and layer 3 elements.

Generic Access Profile (GAP): a defined part of the DECT Common Interface standard (DECT CI) that ensures inter-operability between FPs and PPs for public business and residential access services.

Geographically unique identity: this term relates to FP identities, Primary Access Rights Identities (PARIs) and Radio Fixed Part Identities (RFPIs). It indicates that two systems with the same PARI, or respectively two RFPs with the same RFPI, can not be reached or listened to at the same geographical position.

Global NetWork (GNW): a telecommunication network capable of offering a long distance telecommunication service.

NOTE 9: The term does not include legal or regulatory aspects, nor does it indicate if the network is a public or a private network.

Globally unique identity: the identity is unique within DECT (without geographical or other restrictions).

Handover: the process of switching a call in progress from one physical channel to another physical channel. These processes can be internal (see internal handover) or external (see external handover).

NOTE 10: There are two physical forms of handover, intra-cell handover and inter-cell handover. Intra-cell handover is always internal. Inter-cell handover can be internal or external.

Incoming call: a call received at a PP.

Inter-cell handover: the switching of a call in progress from one cell to another cell.

Internal handover: handover processes that are completely internal to one Fixed radio Termination (FT). Internal handover re-connects the call at the lower layers, while maintaining the call at the NWK layer.

NOTE 11: The lower layer reconnection can either be at the Data Link Control (DLC) layer (connection handover) or at the MAC layer (bearer handover).

Inter-operability: the capability of FPs and PPs, that enable a PP to obtain access to teleservices in more than one location area and/or from more than one operator (more than one service provider).

Inter-operator roaming: roaming between FP coverage areas of different operators (different service providers).

Inter-Working Unit (IWU): a unit that is used to interconnect sub-networks.

NOTE 12: The IWU will contain the inter-working functions necessary to support the required sub-network inter-working.

Intra-cell handover: the switching of a call in progress from one physical channel of one cell to another physical channel of the same cell.

Intra-operator roaming: roaming between different FP coverage areas of the same operator (same service provider).

Local NetWork (LNW): a telecommunication network capable of offering local telecommunication services.

NOTE 13: The term does not include legal or regulatory aspects, nor does it indicate if the network is a public network or a private network.

Locally unique identity: the identity is unique within one FP or location area, depending on application.

Location area: the domain in which a PP may receive (and/or make) calls as a result of a single location registration.

Location registration: the process whereby the position of a DECT portable termination is determined to the level of one location area, and this position is updated in one or more databases.

NOTE 14: These databases are not included within the DECT FT.

Medium Access Control (MAC) Connection: an association between one source MAC Multi-Bearer Control (MBC) entity and one destination MAC MBC entity. This provides a set of related MAC services (a set of logical channels), and it can involve one or more underlying MAC bearers.

Outgoing call: a call originating from a PP.

Portable Application (PA): a logical grouping that contains all the elements that lie beyond the DECT network boundary on the portable side.

NOTE 15: The functions contained in the portable application may be physically distributed, but any such distribution is invisible to the DECT network.

Portable Part (DECT Portable Part) (PP): a physical grouping that contains all elements between the user and the DECT air interface. PP is a generic term that may describe one or several physical pieces.

NOTE 16: A DECT PP is logically divided into one portable termination plus one or more portable applications.

Portable radio Termination (PT): a logical group of functions that contains all of the DECT processes and procedures on the portable side of the DECT air interface.

NOTE 17: A PT only includes elements that are defined in the DECT CI standard. This includes radio transmission elements (layer 1) together with a selection of layer 2 and layer 3 elements.

Radio Fixed Part (RFP): one physical sub-group of an FP that contains all the radio end points (one or more) that are connected to a single system of antennas.

Registration: an ambiguous term, that should always be qualified. See either location registration or subscription registration.

Roaming: the movement of a PP from one FP coverage area to another FP coverage area, where the capabilities of the FPs enable the PP to make or receive calls in both areas.

NOTE 18: Roaming requires the relevant FPs and PP to be inter-operable.

Subscription registration: the infrequent process whereby a subscriber obtains access rights to one or more FPs.

NOTE 19: Subscription registration is usually required before a user can make or receive calls.

2.2. Abbreviations

For the purposes of this ETS, the following abbreviations apply:

2.3. GSM Abbreviations and Definitions

Definition and specific GSM abbreviations may be found in GSM 01.04 [20].

2.4. Symbols for Status Columns

The symbols defined in this subclause are applied for procedures, features, messages, information elements, fields and field codings in this document if not explicitly otherwise stated. The interpretation of status columns in all tables is as follows:

M for mandatory to map/support/use;

O for optional to map/support/use;

I for out-of-scope (not subject for testing);

X for prohibited or excluded to map/support/use (the message, information element may be allowed to be used in the standard/standards but it is not allowed to be mapped/used depending on the environment/dynamic conditions etc.);

N/A or -(dash) for not applicable to map/support/use;

C for conditional to map/support/use (the message, information element mapping depends on the selection of other optional or/and conditional items).

NOTE: The symbol "-" in the mapping section of this ETS means that there is no message, information element or coding specified in this column.

This document specifies how GSM circuit switched bearer services are provided over the DECT air interface. The difference between this and the document "DECT/GSM interworking of bearer services: implementation decription, complete coding mapping of GSM and DECT elements" is that this implementation does not utlilize the old DECT <<iwu-attributes>> coding but defines a new coding of the element for GSM interworking. The new coding defined in subclause 6 fulfills completely the requirements of the GSM bearer services thus simplifies the selection of a service.

This document is made up of 4 main clauses:

Clause 4: Inter-working requirements--includes reference configurations and the protocol architecture models. Also describes the main service requirements.

Clauses 5: Inter-Working Unit (IWU) mappings--shows the C plane and U plane mappings needed in addition to the ETS 300 370 [31] for the FP GSM PLMN attachment in respective order. Two IWUs are considered; the FP IWU and the PP IWU, although the FP IWU is expected to be the largest. The signalling mappings are described in terms of IWU procedures with informative data flow diagrams. Detailed descriptions follow using tables of what is mapped, what is ignored, and what is transferred transparently.

Clause 6: Additions to the base standard--this clause defines the optional changes needed in the ETS 300 175-5 [5] for a full interworking in service negotiation. Also some new attributes/parameter codings are proposed to widen the service range closer to GSM PLMN bearer services.

Clause 7: Connection types--this clause identifies the main DECT connection types (U plane+C plane) at the air interface and defines the attributes codings used in the DECT air interface for identification of the different GSM bearer services.

4.1. General

This document defines the mandatory requirements to the FP interworking functions if the GSM circuit switched bearer services are interworked to DECT. The interworking shall comply completely with ETS 300 370 [31] in terms of MM and CC message mappings with the additions presented in this document. The additional interworking mapping are based on the GSM phase 2 standards.

The mandatory basic requirements of this document are compatible with the DECT/GSM interworking profile ETS 300 370 [31], ETS 300 xxx DECT C.2. data profile [30] and ETS 300 175-5 DECT Network Layer [5]. In addition the new codings defiened in subclause 6.2. are required. However, if full interworking with service negotiation is needed some changes/additions listed in subclause 6 of this document are required to ETS 300 175-5 [5]. The procedures for service negotiation utilizing these changes are optional.

4.2. Reference Configurations

4.2.1. FP functional attachment to the GSM PLMN

The configuration is shown in FIG. 10.

4.3. General Inter-working Model for FP GSM PLMN Attachment

The general interworking model is shown in FIG. 11. It describes a general interworking model contained both control and user planes. The figure also shows the locations of the interworking units (IWUs).

The FP IWU provides mappings between GSM CC/MM and DECT CC/MM messages. The mapping defined in this document in subclause 5 are additions to the ETS 300 370 [31]. The PP TAF defined in the ETS 300 xxx C.2 profile annex C.2 "Network interworking to connection oriented bearer services" [30] provides a CCITT V.24 connection to the DECT data application.

4.4. Inter-working Context

4.4.1. General

The PP complying with this standard shall be compatible with the requirements of the ETS 300 xxx C.2 data profile [30] and ETS 300 370 [31], those which are based on the minimum requirements of GAP [9] when regarding the MM aspects. The CC requirements are based on the C.2 data profile [30] which are GAP [9] with some data transmission specific additional requirements. also the additions defined in subclause 6.2 are required. This document does not require the support of the GAP based voice services i.e. the PP may be a data only terminal with the GSM access capabilities and a GSM subcription as defined in ETS 300 370 [31].

4.4.2. Basic inter-working rules

The interworking rules are as defined in ETS 300 370 [31].

Table 1 defined the GSM bearer services supported by this document. Both, GSM transparent (T) and non-transparent (NT) bearer services are supported while DECT is interworking with GSM. The DECT air interface does not separate the NT or T cases thus the C.2 profile will be used for both cases. Both rate adaptation schemes are terminated to the FP IWU and are introduced in the FP IWU U-plane section, however, to support both is not a mandatory requirement. With <<Connection element>> filed of <<IWU-ATTRIBUTES>> as defiend in subclause 6.2. the PP can receive information/select the NT/T option in FP IWU.

The selection of a GSM bearer service is done in the mobile originated call by defining the service requirements in the <<iwu-attributes>> information element with coding standard field indicating GSM coding as defined in subclause 6. The values of these elements are mapped to GSM <<Bearer capability>> element as defined in subclause 5.1.4.

The selection of a GSM bearer service is done in the mobile terminated call by defining the service requirements in the GSM <<Bearer capability>> element. The values of this element are mapped to <<iwu-attributes>> information element with coding standard field indicating GSM coding. The mapping of the elements is defined in subclause 5.1.4. New field/coding requirements of DECT <<iwu-attributes>> are defeined in subclause 6.

4.4.3. Interpretation of broadcast attributes This subclause refers to Annex F of ETS 300 175-5 [5] (Broadcast attributes coding).

The coding are done as defined in ETS 300 370 [31] with the exceptions listed here.

a32 ADPCM/G721 Voice service: may be set to value "1". (NOTE 1)

a33 PAP/GAP voice supported: may be set to value "1". (NOTE 1)

a34 Non-voice circuit switched service: shall be set to value "1";

NOTE 1. This document does not require the support of the voice service, however, it is not prohibited either.

4.4.4. Interpretation of Terminal capability

If <<TERMINAL CAPABILTY>> information element is used the following codings indicated the support of the GSM bearer services:

Profile Indicator.sub.-- 1 Coding (Octet 4) of TERMINAL CAPABLITY information element:

Both codings are required.

5.1. FP C-plane IWU Procedures

5.1.1. CC IWU procedures

The CC procedures are compatible with ETS 300 370 [31] with the exceptions described here.

The <<IWU ATTRIBUTES>> information element included in the {CC-SETUP} message will define the GSM bearer service to be requested. The coding combinations used for alternate bearer services is defined in the subclause 7 of this document.

Only BEARER CAPABILITY 1 is recognized in the GSM messages. That is, if a GSM Call Control message contains multiple BEARER CAPABLITY information elements only the first one is mapped and conveyed to DECT PP.

Only the first <<IWU-ATTRIBUTES>> information element is mapped into GSM BEARER CAPABILITY element.

The LOWER LAYER COMPATIBILITY and HIGHER LAYER COMPATIBILITY information elements, if present in a GSM CC message, are carried with no mappings over the air interface as described in subclauses 5.1.5.1.3, 5.1.5.1.4, 5.1.5.2.3 and 5.1.5.2.4. The FP will not do any mapping of these elements. The utilization of these elements is completely a matter of the DECT data application in PP i.e this document does not define their usage.

5.1.1.1. Outgoing data call

The call procedures for outgoing data call (PP originated) are compatible with the procedures of containing the <<CALLED-PARTY-NUMBER>> in the {CC-INFO} message as defined in the ETS 300 370 [31]. This procedure is compatible with ETS 300 xxx C.2 data profile [30] call establishment.

5.1.1.2. Service negotiation in the case of outgoing call

There are three alternate options in the services negotiation procedures in (PP originated) outgoing call. Minimum mandatory requirement is to support the negotiation not possible case defined in clause 5.1.1.2.1. The alternate service negotiation procedures are indicated/requested with <<Negotiation indicator>> field in the <<IWU-ATTRIBUTES>> information element. In order to facilitate the optional service negotiations defined in subclauses 5.1.1.2,2. and 5.1.1.2.3. changes/additions defined in subclause 7 of this document to DECT network layer ETS 300 175-5 [5] have to be implemented.

The negotiable parameters in the case of mobile originated call is <<Modem type>>.

5.1.1.2.1. Negotiation not possible

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Negotiation not possible" in the <<Negotiation indicator field>> from the CC entity the FP IWU will reject all negotiation towards/from MSC. That is, if the MSC cannot provide the PP the requested service the connection is disconnected by using CC-REJECT-req with <<Release reason>> Hex 05 "Incompatible service" towards PP.

It is then the responsiblity of the FP IWU in the case the {Call proceeding} contains new service parameter values to disconnect the connection towards the GSM PLMN by issuing {Release complete} message with cause 79; "Service or option not implemented, unspecified".

If no {Call proceeding} message is received from MSC or it does not contain <<BEARER CAPABILITY>> information element the service parameters have been accepted by the MSC IWF and the call establishment proceeds as defined in ETS 300 370 [31]. (See FIG. 12)

5.1.1.2.2. Exchange attributes negotiation

The following procedures require the additions defined in subclause 6.

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Exchange parameter negotiation" in the <<Negotiation indicator field>> from the CC entity the FP IWU will reject the request immediately issuing MNCC-REJECT-req with <<Release reason>> Hex 07 "Negotiation not supported" if the FP cannot support exchange attributes negotiation as defined in the subclause 15.2.3 of ETS 300 175-5 [5].

If the FP can support the Exchange parameter negotiation the FP IWU will map the <<IWU-ATTRIBUTES>> information element contained in {CC-SETUP} to the GSM BEARER CAPABILTY element of GSM {Setup} message as described in subclause 5.1.4.2.1.

1) Upon receipt of the GSM {Call proceeding} message with new values in <<Bearer capabilty>> information element the FP IWU will release the connection by using MNCC-REJECT-ind with new values in the <<IWU-ATTRIBUTES>> information element.

2) Whereupon the FP IWU will send the MSC {RELEASE COMPLETE} message with cause code 31 "Normal, unspecified". The PP may now initiate a new call with new parameter values following the normal call establishment precedures defined in this document and in ETS 300 370 [31].

If no {Call proceeding} message is received or it does not contain <<BEARER CAPABILITY>> information element the service parameters have been accepted by the MSC IWF and the call establishment proceeds as defined in ETS 300 370 [31]. (See FIG. 13)

5.1.1.2.3. Extended exchange parameter negotiation

The following procedures require the additions defined in subclause 6.

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Extended exchange parameter negotiation" in the <<Negotiation indicator field>> from the CC entity the FP IWU will reject the request immediately issuing MNCC-REJECT-req with <<Release reason>> Hex 07 "Negotiation not supported" if the FP cannot support Extended exchange attributes negotiation.

If the FP can support the Extended exchange parameter negotiation the FP IWU will map the <<IWU-ATTRIBUTES>> information element contained in {CC-SETUP} message to the GSM <<BEARER CAPABILTY>> element of GSM {Setup} message as described in subclause 5.1.4.2.1.

1) Upon receipt of the GSM {Call proceeding} message the FP IWU will map the new values of the <<Bearer capability>> into the <<IWU-ATTRIBUTES>> information element of the DECT <<CC-CALL-PROCEEDING>> message as defined in subclause 5.1.4.1.3.

If no {Call proceeding} message is received or it does not contain <<BEARER CAPABILITY>> information element the service parameters have been accepted by the MSC IWF and no mapping between the <<BEARER CAPABILITY>> and <<IWU-ATTRIBUTES>> information element is needed. (See FIG. 14)

5.1.1.3. Incoming data call

The call procedures for incoming data call (network originated) are compatible with the procedures defined in the ETS 300 370 [31]. This procedure is compatible with ETS 300 xxx C.2 data profile [30] call establishment.

5.1.1.4. Service negotiation in the case of incoming call

There are three alternate options in the services negotiation procedures in (network originated) incoming call. Minimum mandatory requirement is to support the negotiation not possible case defined in clause 5.1.1.4.1. The alternate service negotiation procedures are indicated/requested with <<Negotiation indicator>> field in the <<IWU-ATTRIBUTES>> information element. In order to facilitate the optional service negotiations defined in subclauses 5.1.1.4.2. and 5.1.1.4.3. changes/additions defined in subclause 6 of this document to DECT network layer ETS 300 175-5 [5] have to be implemented.

The negotiable parameters in the case of mobile terminated call are <<number of data bits>>, <<number of stop bits>>, <<number of parity bits >>, <<user layer 2 protocol>> and <<Modem type>>.

5.1.1.4.1. Negotiation not possible

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Negotiation not possible" in the <<Negotiation indicator field>> from the CC entity the PP IWU will reject all negotiation. That is, if the PP cannot accept the parameters indicated in the <<IWU-ATTRIBUTES>> information element the connection is disconnected by using CC-REJECT-req with <<Release reason>> Hex 05 "Incompatible service".

If the PP IWU accepts the parameters proposed by MSC the call establishment proceeds as defined in ETS 300 370 [31].

5.1.1.4.2. Exchange attributes negotiation

The following procedures require the additions defined in subclause 6.

1). Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Exchange parameter negotiation" in the <<Negotiation indicator field>> from the CC entity the PP IWU will reject the request immediately issuing MNCC-REJECT-req with <<Release reason>> Hex 07 "Negotiation not supported" if the PP cannot support exchange attributes negotiation as defined in the subclause 15.2.3 in ETS 300 175-5 [5].

If the PP can support the Exchange parameter negotiation the PP IWU will add the new desired values into the <<IWU-ATTRIBUTES>> and the <<END-TO-END-COMPATIBLITY>> information elements of the {CC-RELEASE-COM} message.

2). Upon receipt of the {CC-RELEASE-COM} message with indication of "Exchange parameter negotiation" in the <<Negotiation indicator>> field of the <<IWU-ATTRIBUTES>> element the FP will not directly map the message according to 300 370 [31] but issue immediately a new CC-SETUP-ind with new set parameters in <<IWU-ATTRIBUTES>> and <<END-TO-END-COMPATIBLITY>> elements. It is then the responsibility of the FP IWU to join the GSM call waiting for response and the new DECT call with new parameters.

3) Upon receipt of the {CC-ALERTING} or {CC-CONNECT} as a response to the new {SETUP} message the procedure will proceed as illustrated in ETS 300 370 [31] with new parameter values mapped into the <<BEARER CAPABILITY>> element in the {Call Confirmed} message.

If the PP IWU accepts the parameters proposed by MSC the call establishment proceeds as defined in ETS 300 370 [31]. (See FIG. 15)

5.1.1.4.3. Extended exchange parameter negotiation

The following procedures require the additions defined in subclause 6.

Upon receipt of CC-SETUP-ind with <<IWU-ATTRIBUTES>> containing the value "Extended exchange parameter negotiation" in the <<Negotiation indicator field>> from the CC entity the PP IWU will reject the request immediately issuing MNCC-REJECT-req with <<Release reason>> Hex 07 "Negotiation not supported" if the PP cannot support Extended exchange attributes negotiation.

If the PP can support the Extended exchange parameter negotiation the PP IWU will add the new desired attributes values to the <<IWU-ATTRIBUTES>> information element of the {CC-CONNECT} message.

2) and 3). It is then the responsibility of the FP IWU to suspend the submission of the {Call confirm} and {Alerting} message towards the GSM network until the new desired values have been received in the {CC-CONNECT} message. The new values in the <<IWU-ATTRIBUTES>> information element of the {CC-CONNECT} message are mapped into the GSM BEARER CAPABILTY element of {Call Confirmed} message as described in subclause 5.1.8.3. Other mappings between {CC-CONNECT} and {Connect} message as well as {CC-ALERTING} and {Alerting} messages are done as described in ETS 300 370 [31].

The PP IWU shall not use <<IWU-ATTRIBUTES>> information element in the {CC-CONNECT} message if it agrees with the service parameters proposed in the {CC-SETUP} message. If the PP IWU accepts the parameters proposed by MSC the call establishment proceeds as defined in ETS 300 370 [31]. (See FIG. 16)

5.1.1.5. Other CC procedures

Other CC procedures are done according to ETS300 370 [31]. Additional cause code mappings required are presented in subclause 5.1.6.1.20.

5.1.2. MM IWU procedures

The MM procedures follow the procedures defined in the C.2 profile and ETS 300 370 [31].

5.1.3. Other IWU procedures

5.1.4. Message mappings

5.1.4.1. GSM to DECT

5.1.4.1.1. SETUP--CC-SETUP

All other message mappings are done according to ETS 300 370 [31].

5.1.4.1.2. CALL PROCEEDING-CC-RELEASE-COM

5.1.4.1.3. CALL PROCEEDING-CC-CALL-PROCEEDING

5.1.4.2. DECT to GSM

5.1.4.2.1. CC-SETUP--SETUP

5.1.4.2.2. CC-CONNECT--CALL CONFIRMED

5.1.5. Information element mappings

5.1.5.1. DECT to GSM and GSM to DECT

5.1.5.1.1. Iwu-attributes--Bearer capability 1

The mapping is done between GSM standard element and a new IWU-ATTRIBUTES elements defiend in the subclause 6.

5.1.5.1.2. Lower layer compatibility--Iwu-to-iwu

If the <<Lower layer compatibility>> information element is contained in GSM CC messages, it is mapped intact into <<iwu-to-iwu>> packet <<iwu-to-iwu-information>> field. The information element <<Protocol discriminator>> in <<iwu-iwu>> packet will contain coding "010001"B "GSM Recommendation 04.08, elements".

5.1.5.1.3. Higher layer compatibility--Iwu-to-iwu

If the <<Higher layer compatibility>> information element is contained in GSM CC messages, it is mapped intact into <<iwu-to-iwu>> packet <<iwu-to-iwu-information>> field. The information element <<Protocol discriminator>> in <<iwu-to-iwu>> packet will contain coding "010001"B "GSM Recommendation 04.08, elements".

5.1.6. Fields in information element coding

5.1.6.1. GSM to DECT and DECT to GSM

5.1.6.1.1. Coding standard--Coding standard

5.1.6.1.2. Transfer mode--transfer mode

5.1.6.1.3. Information transfer capability--information transfer capability

5.1.6.1.4. General coding priciple for other fields

This field does not require mapping between DECT and GSM. That is, the coding of GSM field and DECT field are identical thus the value of the field does not change in IWU and it can be copied as it is between systems.

5.2. FP U-plane IWU Procedures

5.2.1. General

This section defines the functional requirements of the FP IWU for the mapping of the user data and the C.2 data profile U-plane flow. Both Transparent and Non-Transparent options have been decribed. However, it is not a mandatory requirement to support both options. It is recommended to provide the Non Transparent interworking since its functionality is closer to the DECT air interface opreration of LAPU. The PP may select the interworking of T or NT services with the coding in the field <<Connection element>> of <<iwu-attributes>>.

5.2.2. Transparent service (T)

5.2.2.1. General

Due to usage of LAPU no complete synchronism between the endpoints can be guaranteed.

The rate adaptation of the GSM data flow will be done in the FP IWU. A general structure of the rate adaptation function is illustrated in FIG. 17. In the figure it is assumed that the FP is connected to the MSC through the A interface. The functionality of the IWU is to map the synchronous, asynchronous and status data to respective DECT C.2 profile functionality. FP seen by the MSC correspond to the GSM MS TAF functionality.

5.2.2.1.1. Asynchronous

The FP IWU will contain the V.110 RA2, RA1 and RA0 adaptation functions. The information of the RA0 and RA1 will be mapped as follows:

the CCITT V series status information of RA1 will be mapped to the C.2 LAPU Control frame as defined in subclause 5.2.2.3 of this document. The status octets are not carried in the LAPU information frames.

user information of the RA0 will be forwarded C.2 PAD function defined in the subclause 10.1 of the DECT C.2 data profile [30] following the rules defined in the same subclause. The LAPU frame lengths should be adjusted to fit the buffering requirements related to the transparent service.

5.2.2.1.2. Synchronous

The FP IWU will contain the V.110 RA2 and RA1 adaptation functions. The information from the RA1 will be mapped as follows:

the CCITT V series status information of RA1 will be mapped to the respective DECT function defined in the subclause 5.2.2.2 of this document. The status octets are not carried in the LAPU information frames.

user information of the RA0 will be forwarded C.2 BPAD function defined in the subclause 10.2 of the DECT C.2 data profile [30] following the rules defined in the same subclause. The LAPU frame lengths should be adjusted to fit the buffering requirements related to the transparent service.

5.2.2.2. CCITT V.24 Interchange circuit signalling mapping

The CCITT V.24 signalling status information will be mapped between the DECT LAPU control frame function and respective GSM function as follows.

DECT C.2 Data profile Control Status octet defined in C.2 data profile [30] subclause 10.3 is used with <<Frame type coding>> indicating V.24 status interworking.

the status change of the V.24 interface circuits 108, 107, 105, 109 and 106 mapping will be done as shown in tables 24 and 25.

In the direction of GSM to DECT only in the change situation of a status of each SA, SB or X bit will be mapped thus if not change has occurred in the status bit of GSM data flow not LAPU control frame is sent.

In the direction of DECT to GSM the FP IWU will map the old status of a status bit towards GSM if no LAPU control frames with new value has received.

the status of the CCITT V.24 circuits 106 and 105 is mapped into/from the PAD/BPAD flow control

5.2.2.3. Flow control

The flow control situation indicated by the X-bit or buffers backpressure are mapped into the C.2 data profile [30] PAD/BPAD flow control functionality as defined in respective C.2 profile PAD/BPAD subclauses. It is the matter of implementation to ensure that no data loss occur in flow control.

5.2.2.4. Call establishment signalling mapping

The mapping between DECT call establishment in the FP IWU is done as defined in the ETS 300 370 [31] and in this document in subclause 5.

5.2.3. Non-transparent service (NT)

5.2.3.1. General

The rate adaptation of the GSM data flow will take place in the FP IWU. A general figure of the rate adaptation functions of GSM non-transparent (NT) case is illustrated in FIG. 18. In the figure it is assumed that the FP is connected to the MSC through the A interface.

The RLP entity and LAPU entity in FP will function completely independently. That is, frame retransmissions and control information regarding RLP and LAPU functions are not dependent of each other.

5.2.3.1.1. Asynchronous

The FP IWU will contain the RA2, RA1, RLP and L2COP functions. The information from the L2COP will be mapped as follows:

The status octets are not carried in the LAPU information frames.

the status bit (3 first bits) information of the status octet will be mapped to the respective DECT function defined in the subclause 5.2.2.3.

character octets will be forwarded to the C.2 PAD function as defined in the subclause 10.1 of the DECT C.2 data profile [30] following the rules defined in the same subclause.

fill octets are not forwarded to the C.2. PAD function.

break signal status received from GSM direction is mapped into the LAPU control frame <<Break coding>> with indication of "Break condition occurred". The duration of the break signal in the BREAK/PAUSE duration octet should be in between 135 ms and 200 ms as defined by GSM 07.02 [33].

break signal status received from DECT direction is mapped into the L2COP address field as defined in the GSM 07.02 [33]. The duration information is ignored.

5.2.3.1.2. Synchronous

The FP IWU will contain the RA2, RA1, RLP and L2BOP functions. The information of the L2BOP will be mapped as follows:

The status octets are not carried in the LAPU information frames.

the status bit (3 first bits) information of the status octet will be mapped to the respective function defined in the subclause 5.2.2.3.

the address bit (5 last bits) information of the status octet is utilized as follows: if address has the value 31 no L2BOP remaining information is forwarded to LAPU information frame. Other address values are ignored.

user information will be forwarded to the C.2 BPAD function as defined in the subclause 10.1 of the DECT C.2 data profile [30] following the rules defined in the same subclause.

fill octets are not inserted to the C.2 LAPU octets.

5.2.3.2. Interchange circuit signalling mapping

See sublause 5.2.2.2.

5.2.3.3. Flow control

The flow control situation indicated by the X-bit or buffers backpressure are mapped into the C.2 data profile [30] PAD/BPAD flow control functionality as defined in respective C.2 profile PAD/BPAD subclauses. It is the matter of implementation to ensure that no data loss occur in flow control.

5.2.3.4. Call establishment signalling mapping See subclause 5.2.2.4.

5.2.4. Synchronization

It is the responisbilty of the FP to guarantee that no user data is conveyed before both RLP and LAPU links have been succefully established. No CCITT V.24 signalling information is conveyed before information regarding the ready status of the MSC-network connection is guaranteed.

5.3. PP C-plane IWU Procedures

For CCITT V.24 interworking of the PP C-plane procedures are recommended as defined in the C.2 data profile C.2 TAF annex [30].

The mapping between the PP C-plane and V.25bis commands is done according to the C.2 data profile annex C.2 [30].

5.4. PP U-plane IWU Procedures

For CCITT V.24 interworking of the PP U-plane procedures are recommended as defined the C.2 data profile C.2 TAF annex.

The following changes and additions should be done to the DECT Common interface standard in order to facilitate the optional service negotiation options.

6.1. Extended Exchange Parameter Negotiation

A new structure of the {CC-CALL-PROCEEDING} and {CC-CONNECT} messages is presented below. The subclause numbers are referring the respective clauses in ETS 300 175-5 [5] standard. A new coding has to be added into the <<IWU-ATTRIBUTES>>.

6.1.1. {CC-CALL-PROCEEDING} message

6.3.2.4CC-CALL-PROCeeding

This message indicates that the requested (onward) connection establishment has been initiated by the fixed side interworking unit.

6.1.2. {CC-CONNECT} messages

6.3.2.6CC-CONNECT

This message is sent by the FT to indicate completion of the connection through the WCPE network, and by the PT to request such completion.

6.2. New GSM Coding of the <<IWU-ATTRIBUTES>>

The following new coding that is a combination of DECT and GSM coding is required for GSM interworking.

InterWorking Unit (IWU) attributes

The purpose of the <<IWU-ATTRIBUTES>> element is to provide a means for service compatibility information to be exchanged (e.g. between a PP application and a FP interworking unit). This element is transferred transparently by the DECT protocol entities. ##STR1##

01 GSM standard coding

All other values reserved.

The requesting end (e.g. the one sending the SETUP message) should use the 4 values depending on its capabilities to support the different modes. The answering party shall only use the codings 00 or 01, based on its own capabilities and the proposed choice if any. If both MS and network support both transparent and non transparent, priority should be given to the MS preference.

7.1. Connection Type Definitions

The supported bearer services are defined in subclause 4.4.2 in table 1. The codings used for the bearer services are as defiend in GS 07.01 [32].

<<Radio channel requirement>> field

The <<Radio channel requirement>> field GSM <<Bearer capability>> element use the standard value defined for it in 07.01 [32]. That is, the element mapping has not been defined in this document thus the value of the field is ignored in the direction from GSM to DECT and the standard value is used in the direction from DECT to GSM mapping.

<<Negotiation indicator>> field

The <<Negotiation indicator>> field of the <<iwu-attributes>> element contains information important only to DECT part. That is, the GSM PLMN does not use this field.

<<Information transfer rate>> field

<<Informaton transfer rate>> field of the <<iwu-attributes>> element contains the value unspecifed in this context. That is, the GSM PLMN does not use this field and it has no meaning in DECT air interface nor in GSM interworking.