Generation of Code by Graphical Representation

This invention relates to protocols employed in the transmission of messages such as telephonic control signals of a communication system and, more particularly, to the generation of a set of instructions for operation of the digital signal processor of a radio telephone for encoding and decoding telephonic command signals in various protocols.

Communication via radiotelephone is in wide use today for both domestic and international communication. In order to enable telephones in various countries to communicate, international standards of communication protocols have been developed. The protocols establish the digitally formatted signals transmitted among radiotelephones and their respective base stations via control channels for various control purposes, such as for dialing a distant party and for initiating a conversation. Implementation of a protocol is accomplished by programming the digital signal processor (DSP) of a radio telephone to encode outgoing telephone control signals in accordance with the protocol and to decode incoming telephone control signals in accordance with the protocol. While the foregoing example is in terms of a radio or cellular telephone system, similar uses of protocol apply to other forms of communication systems.

A problem arises in that the programming of a computer, such as the computer in a DSP, to accomplish the encoding and decoding functions of a specific protocol is a long and cumbersome task involving many hours of a programmer's time. Thus, in the event that a proposed improvement to a communication system is to be accomplished by a change of the protocol, there is considerable expense and effort involved in the reprogramming of the DSP or other computer which performs the encoding and the decoding functions.

The aforementioned problem is overcome and other advantages are provided by a method and system of the invention employing a graphical representation of protocol and syntax of a communication language (such as the well known international language ASN.1) together with a programming language referred to as Transfer Syntax Notation (TSN). TSN is a programming language useful for treating data transmitted by the bits of a sequence of bytes having equal bit length as is employed in the ASN.1 language, and can be compiled to both encoding and decoding functions of a communication system, such as a telephone communication system. In accordance with the invention, the graphical representation of protocol and syntax of the communication language together with the TSN language facilitate the programming of a computer for performing the functions of encoding and decoding as required by international protocol. The invention is most readily explained by consideration of some of the elements present in the messages transmitted by digital control channels of a radiotelephone system.

A control channel message comprises a set of words, wherein each word consists of one, two, three, or more binary digits or bits. The transmission of the message takes place by a transmission of a series of bytes wherein each byte comprises usually eight bits and may be referred to as an octet. Thus one byte may carry one or more words or a fraction of a word. For example, in the case of a word of twelve bits, the word would extend from one byte into the next byte. The protocol dictates various attributes of the message, such as the lengths of various words, the positions of individual ones of the words in a sequence of the words, the use of an extension bit to indicate that a word extends into the next byte, and the use of diagnostic words, by way of example. A change in protocol is accomplished, by way of example, by adding additional words, deleting words, changing the length of words, and changing the order of words.

In the programming of the DSP, or other computer used in control of a communication, there is a program memory for storing the program. The various words and their lengths are to be identified, and their order is to be established. In the case of an outgoing message, the DSP, in response to its programming, encodes information in a sequence of octets (data), with the logic states of the individual bits being established according to data, such as a dialed number, and system operating parameters as may be established by the local telephone company. In the case of an incoming message, the DSP, in response to its programming, decodes the digital bit stream of the control channel by recognizing various octets and identifying the logic states of the various digits in the bit stream.

In accordance with the invention, it is recognized that in all of the messages to be communicated by the various protocols, the protocols share a common feature in that each message is composed as a sequence of octets wherein various ones of the bits are designated for specific words. A change in protocol involves only a change in the allocation of the bits which constitute the various words. As a result, it has been possible to develop a compiler which outputs the encoding and decoding programs. The compiler accepts a series of logic statements describing the protocol, and then generates the machine code program steps for operation of the DSP. The one compiler can handle the encoding and decoding of all of the protocols which can be described by use of TSN primitives. Thus, in order to adapt a DSP to operate with a new or revised protocol, the logic statements describing the protocol are entered into the compiler which then operates to output the desired set of instructions for operation of the DSP.

The logic statements are in the form of constraints which specify the length of a message or data frame or word, by way of example. This permits entry of the logic statements in a simplified manner, in accordance with a further feature of the invention, by use of a computer display showing an arrangement of blocks into which the values of the constraints are entered. Thereby, the constraints of the logic statements describing the protocol are entered into the compiler. In the arrangement of the blocks, the locations of various ones of the blocks facilitate visualization of the various constraints, such as the order of the words in a message, thereby to facilitate generation of the logic statements and entry of the values of the various constraints.

The aforementioned aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawing figures wherein:

FIG. 1 shows diagrammatically various steps in the procedure for practicing the invention;

FIG. 2 is a block diagram showing implementation of the invention for use in control of a telephonic instrument of a communication system, a cellular telephone being shown by way of example;

Identically labeled elements appearing in different ones of the figures refer to the same element but may not be referenced in the description for all figures.

FIGS. 1 and 2 present, respectively, methodology and apparatus in the conduction of the invention. The invention deals with the generation of instructions for insertion into a program memory of a communication device, thereby to enable the device to transmit and to receive messages in accordance with a protocol previously established for a communication system. The invention is applicable to any of various communication devices having an internal computer or digital signal processor which controls response of a communication device in the generation of messages to be transmitted, particularly the encoding of transmitted messages, and for the interpretation of messages to be received, particularly the decoding of received messages. A cellular telephone is a common example of a suitable communication device and will be employed hereinafter for describing the construction of the invention. A particular feature of the invention is the enablement of a programmer who is knowledgeable of the technical specifications governing a communication to convert the technical specifications to a programming language for operation of the DSP of the communication device. The conversion of the technical specifications to the programming language is implemented by means of a graphic interface which facilitates the conversion process.

The technical specifications concern the communication protocol specifications which control the encoding and the decoding functions of the communication device. The invention is practiced by the development of a specification language which is referred to hereinafter as a Transfer Syntax Notation (TSN) which can be compiled automatically to both encoding and decoding functions with corresponding data structure definitions needed for translation between bit oriented protocol data units (PDU's) and an internal programming language. The internal programming language is described by standard language, Abstract Syntax Notation One (ASN.1), as set forth in the international communication standard ISO8824. The system of the invention operating with the TSN in conjunction with appropriate code generators may be used, by way of example, for rapid implementation of executable TTCN-test suites and communication protocols, wherein TTCN is set forth in the international communication standard ISO9646.

An aspect of the ASN.1 language is the use of constraints in terms of the length of bytes, the length of words, and the arrangement of words within a message, by way of example. Thus, programming a DSP to encode a message and to decode a message in accordance with the ASN.1 language entails a form of programming known as constraint programming. The concept of constraints suits well to the two part problem of specifying encoding and decoding functions for a mapping between bit oriented transfer syntax and internal standard of the communication protocol. The constraint programming lends itself to an expressive form of codec functions describable in a set of declarative expressions. This can be expressed in the form of a graphical interface wherein a programmer enters data and constraints to be employed in the development of the encoding and decoding functions. The TSN language implemented in a compiler generates accurate substitutions to encoding and decoding functions by analyzing the constraints in an abstract domain. This is readily adapted for providing the requisite encoding and decoding programs for various communication devices.

With reference to FIG. 1, the technical specification, shown at block 20, is employed by a programmer 22 in the operation of a visual editor 24 for implementing the procedure of the invention with the TSN language to produce the encoding and decoding instructions for use by a DSP of a communication device, such as a telephone. FIG. 2 shows the visual editor 24 connected to a computer system 26 for implementing the functions of the visual editor 24. The visual editor 24, as shown in FIG. 2, comprises a display 28 presenting rectangular arrays of cells 30 wherein individual ones of the cells may vary in length to accommodate descriptive terminology and/or bits of words to be employed in setting up the constraints for implementation of the TSN compiling. FIG. 3 shows a further presentation on the visual editor display 28 which, by way of example, includes several lines of both binary digits and descriptive terminology useful in presenting Cause indicators information element in the ISDN user part communication protocol as set forth in the International Communication Specification Section Q.761-Q.764.

As shown in FIG. 1, the visual editor 24 is employed to enter the appropriate constraints into the TSN language, indicated at block 32. From block 32 the TSN expressions are processed in accordance with the functions of a static analyzer as indicated at 34. The functions of the static analyzer 34 are implemented, as shown in FIG. 2, by a first processing section 36 and a second processing section 38 of the computer system 26 wherein the first processing section 36 provides the declarative form of the TSN language based on inputted quantities at the visual editor 24. By way of example, the visual editor 24 may include a keyboard 40 and a mouse 42 interconnected to each other by an electrical signal cable 44 and connected to the display 28 via an electrical signal cable 46 for inserting the requisite data into the visual editor 24. The mouse 42 may be employed to position a cursor 48 to designate a cell 30 wherein data is to be entered via the keyboard 40. This data, after having been entered into the declarative form of the TSN of the first processing section 36 is then applied to the second processing section 38 to convert the declarative form of the TSN language to an imperative form of the TSN language.

With reference to FIG. 1, the imperative form of the TSN language is identified as ITSN at block 50. Debugging of the TSN programming is accomplished by implementing the functions of an interpreter shown at 52, the interpreter 52 being connected between block 50 and the visual editor 24.

The function of the interpreter 52 is to convert back from the imperative form to the declarative form of the TSN language, and to produce the initial data on the display 28 (FIG. 2) so that the programmer 22 can compare the inputted data and the regenerated data to insure that the conversion between the declarative and the imperative forms of the TSN language is accomplished correctly. The function of the interpreter 52 is accomplished by a third processing section 54 (FIG. 2) of the computer system 26. The third processing section 54 is connected between an output port of the second processing section 38 and the display 28 to enable the inputting of the imperative form of the TSN language to the third processor processing section 54, and an outputting of the data in a form recognizable by the programmer 22 from the display 28.

As shown in FIG. 1, a set of back-end compilers 56, 58, and 60 are employed for converting the ITSN language at block 50 to common programming languages, including C++, as shown at blocks 62, 64, and 66. Any one of the languages outputted by the back-end compilers 56, 58, and 60 may be referred to as a host language, the host language being suitable for operating the DSP of a communications device. The function of back-end compiling is provided by a fourth processing section 68 (FIG. 2) which receives the output of the second processing section 38 and outputs the desired host language. With respect to the back-end compiler 56, its host language is suitable for testing in accordance with the run-time system (RTS) wherein TC is a compiler for TTCN test description language as set forth in international communication specification ISO9646. The back-end compiler 58 produces C language suitable for simulation purposes, such as CVOPS simulation. The back-end compiler 60 produces the C++ language which is intended for operation of the product such as the cellular telephone 70 of FIG. 2. The four processing sections 36, 38, 54, and 68 may be constructed as separate modules, or may be part of a single computer programmed to provide the respective functions.

With reference to FIG. 2, a communication system 72 is represented by a base station 74 communicating via an RF (radio frequency) link 76 to the aforementioned cellular telephone 70. The telephone 70 includes a microphone 78 and a speaker 80, respectively, for enabling a person to speak into the telephone 70 and to hear sounds from the telephone 70. The telephone 70 further comprises a baseband unit 82, an RF unit 84, a codec 86 and a control unit 92. The control unit 92 may be formed as a digital signal processor, and includes a computer 94 with a memory 96 having both a dynamic memory section 96A and a static memory section 96B. An operating system 98 for the computer 94 is included within the control unit 92.

In the operation of the telephone 70, the codec 86 serves to convert audio signals of the microphone 78 into digital signals which are inputted to the baseband unit 82. The baseband unit 82 provides for encoding and multiplexing of speech signals from the microphone 78, as well as data from another source 100 such as, by way of example, possibly a fax machine or a computer modem. Outgoing signals from the telephone 70 are coupled from the baseband unit 82 to the RF unit 84 to be placed on a suitable outgoing carrier at an outgoing carrier frequency for transmission via the RF link 76 to the base station 74. Signals received from the base station 74 via the link 76 to the RF unit 84 are converted from an incoming carrier frequency down to a baseband signal frequency by the RF unit 84 and are applied to the baseband unit 82. The incoming signals to the telephone 70 are demultiplexed and decoded by the baseband unit 82 to obtain the voice signal which is applied to the codec 86 and converted to analog format for presentation to the speaker 80. Internal control signal lines 102A, 102B, and 102C provide for control, respectively, of the codec 86, the baseband unit 82, and the RF unit 84 by the control unit 92. Specific instructions in the form of code for the operation of the baseband unit 82, in accordance with requisite protocol for transmission of signals via the communication system 72, are applied by the control unit 92 to the baseband unit 82 by a control line 104.

Instructions for the encoding and the decoding functions, as provided by the host language in the fourth processing section 68 of the computer system 26, are outputted by the fourth processing section 68 via line 106 to the static memory section 96B of the program memory 96 of the control unit 92. The memory 96 stores a program for operation of the computer 94. In the event that the control unit 92 has its own operating system 98 installed within the control unit 92, then the host language, such as C++ can be inputted directly into the control unit 92. Thereupon, the operating system converts the instructions of the host language into machine language for operating the computer 94. In the event that the control unit 92 does not have an operating system installed therein, then the host language must be processed further by the computer system 26 to produce the machine language for instructing the computer 94 in accordance with the encoding and the decoding functions, as set forth in the imperative form of the TSN language outputted by the second processing section 38 of the computer system 26. In the control unit 92, the dynamic memory section 96A stores the present state of the operation of the various units of the telephone 70, while the static memory section 96B stores the encoding and decoding functions for control of the data, and the state machine code.

It is understood from the foregoing description that the TSN language provides for an important part of the practice of the methodology and the system of the invention to enable a facile programming of the control unit 92 in accordance with a protocol of the ASN.1 language and subsequent modifications thereof. It is noted, in the use of systems for which coding can be provided by means of the TSN language, that such a system may include a single digital signal processor (DSP) or it may consist of many DSP modules, codec, baseband unit and RF unit, by way of example. Thus, the TSN language is useful for providing code for systems of various configurations. In particular, the TSN language is related to control of information to be sent over a radio or other form of communication link or interface. In the ensuing description, there is provided an explanation of the construction and the utilization of the TSN language so as to enable its employ in the practice of the invention. This description is provided in the form of three appendices wherein the first appendix deals with the general theory of the coding by use of the TSN language, the second appendix is directed to more specific details in the use of the TSN language for carrying forth the present invention, and the third appendix presents examples in the use of the TSN language for generating the coding and the decoding functions.

It is to be understood that the above described embodiment of the invention is illustrative only, and that modifications thereof may occur to those skilled in the art. Accordingly, this invention is not to be regarded as limited to the embodiment disclosed herein, but is to be limited only as defined by the appended claims. ##SPC1##