Group call for a wireless mobile communication device using bluetooth

[0002] 1. Field of the Invention

[0003] The present invention relates to a mobile communication device or handset capable of at least two wireless communication links, at least one of which is with another communication device over a direct device-to-device link without any intervening base station. In its particular aspects, the present invention relates to such a mobile communication device in which the wireless direct device-to-device link is implemented in accordance with the Bluetooth Intercom profile.

[0004] 2. Description of the Related Art

[0005] Such a wireless communication device is known from Bluetooth Specification, Version 1.0, Foundation, Jul. 22, 1999, adopted by the Bluetooth Special Interest Group, (hereafter the “Bluetooth specification”), in particular at Volume 2 (Profiles), page 148.

[0006] The Bluetooth specification includes the definition of the protocols and procedures to be used by devices implementing the wireless intercom part of a use case called “3-in-1 phone”, typically including a direct speech link between two devices, established using telephony based signaling. A typical scenario is a speech call between two (cellular) phones implemented by a direct phone-to-phone wireless connection using Bluetooth only.

[0007] However, the Bluetooth specification does not consider the possibility of a group call functionality to allow a first phone to use a Bluetooth link to conference a second phone into a cellular call with a remote third phone, or to allow three or more phones to participate in a group conversation implemented entirely via Bluetooth Intercom links.

[0008] It is known to include conference or multi-party call functionality in networks, PBXs, multi-line wired phones, and cordless base stations, but not in mobile phones or entirely wireless communication terminals.

[0009] It is an object of the present invention to provide a communication device configured for communicating over a first wireless link, and also configured for communicating with one or more other communication devices over other respective wireless direct device-to-device second links, with functionality to carry on a group call by appropriately combining speech signals carried by the various links.

[0010] It is a further object that this group call functionality be provided in the case where the one or more second links are implemented by the Bluetooth Intercom Profile and/or the first wireless link is a direct device-to-device link implemented by the Bluetooth Intercom Profile to still another communication device.

[0011] These and other objects of the present invention are satisfied by providing such a communication device wherein means for carrying a local side of a call over the first wireless link and the local sides of the one or more second wireless links may be active simultaneously, and includes group call combining means for forming the signals applied to a local end, the signals applied to a first call over the first link, and the signals applied to a second call over the second link, such that the signals applied to the local end include contributions from the signals derived from the remote ends of the first and second calls, the signals applied to said first call include contributions from the signals derived from the local and second ends, and the signals applied to the second call include contributions derived from the local and first ends.

[0012] The present invention is also characterized in that said first link either includes a cellular or PCS or cordless wireless link to a base station or is a direct device-to-device link to still another communication device, without any intervening base station.

[0013] The present invention is further characterized in that the one or more wireless direct device-to-device links are implemented in accordance with the Bluetooth Intercom Profile. In a further embodiment, the first link is a cordless link implemented in accordance with the Bluetooth Telephony profile.

[0014] Other objects, features and advantages of the present invention will become apparent upon perusal of the following detailed description when taken in conjunction with the appended drawing, wherein:

[0015] FIG. 1A is a schematic diagram illustrating a communication device in the form of a mobile handset D₀engaged in a group call with a plurality of other communication devices D₁through D_nover respective communication paths in accordance with a first aspect of the present invention, wherein the communication path between handset D₀and device D₁includes a wireless link to an intervening base station, and the respective communication paths between handset D₀and the devices D₂to D_nare wireless direct device-to-device links;

[0016] FIG. 1B is a schematic diagram illustrating communication device D₀engaged in a group call with a plurality of other communication devices D₁through D_nover respective communication paths all of which are wireless direct device-to-device links, in accordance with a second aspect of the present invention;

[0017] FIG. 2 is a mobile handset D₀capable of implementing a group call in accordance with FIG. 1A or in accordance with FIG. 1B; and

[0018] FIG. 3 is a flow chart of acts for setting up and maintaining a group call in accordance with FIG. 1A, between mobile handset D₀and communication devices D₁through D₃.

[0019] Referring first to FIG. 1A of the drawing, there is shown a first group call arrangement 10 in which communication device or terminal D₀is a Bluetooth enabled mobile cellular or PCS (e.g. AMPS, GSM, TDMA, CDMA) or cordless handset (e.g. FM, spread spectrum, DECT, Bluetooth telephony profile) configured for carrying on a local side of a call to a remote communication device D₁, such as a telephone, over a communication path which includes a wireless cellular, PCS, or cordless duplex link L₁to a base station 12. As is conventional for such a call, the communication path also includes network infrastructure 14 interposed between base station 12 and remote communication device D₁, which infrastructure typically includes the public switched telephone network (PSTN) 16.

[0020] Further in FIG. 1A, the communication devices or terminals D₂through D_nare engaged in calls with handset or device D₀over respective wireless direct device-to-device duplex links, each using the Bluetooth Intercom profile. Devices D₂through D_nmay be any mobile or fixed Bluetooth enabled communication terminals, including but not limited to Bluetooth enabled mobile cellular, PCS, or cordless handsets like D₀. However, only the Bluetooth intercom call capability of devices D₂through D_nis pertinent to group call arrangement 10. Most conveniently, device D₀simultaneously participates in the calls with devices D₂through D_nby acting as the master of a single Bluetooth piconet including those devices. However, it also possible for the group call to be maintained where devices D₂to D_nare not in a same piconet mastered by device D₀.

[0021] Each of devices D₀and devices D₂through D_nhave its own transmit and receive antenna for supporting the various wireless duplex links L₂to L_nfor Bluetooth Intercom Profile communications. In general, device D₀also has a separate transmit and receive antenna A′ for supporting the cellular or PCS or cordless link L₁with a corresponding antenna A′ of base station 12. If the cordless link L₁is implemented using the Bluetooth Telephony Profile, link L₁can also be supported by antenna A. Thus, in that case device D₀need have only one antenna A and the antenna of base station 12 will also be a Bluetooth antenna A.

[0022] Further, each of the communication devices or terminals D₀through D_nhas its own acoustic-to-electrical transducer or microphone M and its own electrical-to-acoustic transducer or speaker S. The electrical signals produced by acoustic-to-electrical transducers M of the devices D₀to D_nare denominated I₀to I_n, respectively, whereas the electrical signals applied to electrical-to-acoustic transducers S of the devices D₀to D_nare denominated O₀to O_n, respectively. From the point of view of device D₀, the signal I₀may be viewed as being derived from a local end, and the signals I₁through I_nas being derived from respective far ends of calls over or including the links L₁to L_n. Similarly, the signal O₀may be viewed as being applied to the local end, and the signals O₁through O_nas being applied to the respective calls for ultimate application to the far ends thereof.

[0023] In order to carry on a group call, device D₀includes group call combining means C for forming the signals applied to the local end, and the signals applied to each call such that the signals applied to the local end is or includes the sum of the signals derived from the remote ends of the calls, and the signals applied to each call is or includes the sum of the signals derived from the local end and from the remote ends of the other calls.

[0024] The following equations set forth the relationships for forming the signals O₀through O_nfrom the signals I₀through I_n: $\begin{array}{c}{O}_0=I_1+I_2+I_3+\dots I_{n-1}+I_n\\ O_1=I_0+I_2+I_3+\dots I_{n-1}+I_n\\ O_2=I_0+I_1+I_3+\dots I_{n-1}+I_n\\ ⋮\\ O_n=I_0+I_1+I_2+I_3+\dots I_{n-1}\end{array}$

[0025] In an exemplary case where n=3, such that there are four parties to a group call corresponding to the flow chat of FIG. 3, the foregoing equations simplify to:

[0026] O₀=I₁+I₂+I₃

[0027] O₁=I₀+I₂+I₃

[0028] O₂=I₀+I₁+I₃

[0029] O₃=I₀+I₁+I₂

[0030] FIG. 1B shows an arrangement 20 which differs from arrangement 10 in FIG. 1A principally in that device D₁is a Bluetooth enabled communication device similar to devices D₂through D_nand wireless duplex link L₁between device D₀and device D₁is also a direct device-to-device link implemented in accordance with the Bluetooth Intercom Profile. Thus, for this configuration, all of wireless links L₁through L_nare Bluetooth intercom links, preferably but not necessarily in a same Bluetooth piconet mastered by device D₀, and any other communication modes of devices D₀through D_nare not pertinent to the illustrated group call. Therefore in FIG. 1B, communication device D₀is merely denominated a Bluetooth enabled mobile handset. As in FIG. 1A, device D₀includes group call combining means C which is arranged for forming the signals applied to the local end, and the signals applied to each call such that the signals applied to the local end includes contributions from the signals derived from the remote ends of the calls, and the signals applied to each call includes contributions from the signals derived from the local end and from the remote ends of the other calls.

[0031] The mobile handset D₀illustrated in FIG. 2 is seen to comprise in communication with a baseband section 30, the microphone M and speaker S, a numeric keypad 31, and a driver 32 for a display 33, e.g. an LCD screen. Baseband section 30 includes a digital signal processor (DSP) 30aand microprocessor 30b,a non-volatile memory or ROM 30c,at least a portion of which is programmable, in which is stored firmware constituting programs and data for operation of DSP 30aand microprocessor 30b,including for steering the setup of a cellular or PCS or cordless call, for steering the set up of one or more Bluetooth intercom calls, and for combining these calls into a group call by appropriately combining and distributing audio signals, and also a volatile memory or RAM 30d,for temporary storage in conjunction with program execution. Device D₀also includes a cellular or PCS (e.g. AMPS, GSM, TDMA, CDMA) or cordless (e.g. FM, spread spectrum, DECT, Bluetooth telephony profile) RF section 34 and a Bluetooth RF Section 35, typically operating in the unregulated 2.4 GHz band. RF sections 34 and 35 are interposed between baseband section 30 and antennas A′ and A, respectively. As should now be apparent, if the cordless functionality is implemented by the Bluetooth Telephony Profile, this can be done via Bluetooth RF Section 35 and antenna A. In that case, RF section 34 and antenna A′ can be dispensed with.

[0032] FIG. 3 is an exemplary flow chart showing setup of a group call in accordance with the arrangement 10 of FIG. 1A simplified to four devices D₀, D₁, D₂, and D₃, wherein a cellular call between devices D₀and D₁is set up before the Bluetooth intercom calls between devices D₀and D₂and between devices D₀and D₃are successively set up. It should also be appreciated that the cellular call could be set up after one or both of the Bluetooth calls. Further, if the cordless call were dispensed with, there would result a group call among three communication devices solely via Bluetooth intercom links in the nature of the arrangement of FIG. 1B.

[0033] Referring to FIG. 3, the setup of the exemplary group call begins with the user of device D₀at block 40 viewing a list of available services on the display 33, which would list among other things e.g. “cellular call” and “Bluetooth call”. The user would select “cellular call” at block 42, e.g. by pressing one or more keys of keypad 31 or by virtue of speech recognition implemented by baseband section 30, and dial device D₁at block 44. Then at block 46 the user of device D₁would answer the call, and this would be detected by device D₀at block 48.

[0034] Next, the cellular call with device D₁could be placed in an “on hold” state by device D₀at block 50 in which state device D₀provides any necessary control signaling to maintain the cellular call, and the user of device D₀then selects “Bluetooth call” from the list at block and causes a Bluetooth connection request to be issued to device D₂at block 54.

[0035] At block 56, the user of device D₂causes the Bluetooth connection request to be accepted, and this acceptance is detected and the connected is completed by device D0 at block 58. Then, this Bluetooth call may be placed “on-hold” or in an idle state at block 60, in which state device D₀provides any necessary control signaling to maintain the Bluetooth intercom call.

[0036] The user of device D₀then selects “Bluetooth call” again from the list at block 62 and causes a Bluetooth connection request to be issued to device D₃at block 64. Then at block 66, the user of device D₃causes the Bluetooth connection request to be accepted, and this acceptance is detected and the connected is completed by device D0 at block 68.

[0037] Lastly, the device D₀releases the calls with devices D₁and D₂from their “on hold” states and maintains the group call among devices D₀through D₃by appropriately combining and distributing audio signals in accordance with the relationships aforementioned.

[0038] It should now be appreciated that the objects of the present invention have been satisfied. While the present invention has been described in particular detail, it should also be appreciated that numerous modifications are possible within the intended spirit and scope of the invention. In interpreting the appended claims it should be understood that:

[0039] a) the word “comprising” does not exclude the presence of other elements or acts than those listed in a claim;

[0040] b) the word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

[0041] c) any reference signs in the claims do not limit their scope; and

[0042] d) several “means” may be represented by the same item of hardware or software implemented structure or function.