Method and apparatus for a talkgroup call in a wireless communication system

ES 2 281 408 T3

DESCRIPTION

Calling method and apparatus for a talkgroup in a radiocommunication system.

Cross Reference Regarding Related Co-Pending Requests

This application is an application for a co-pending application entitled "Calling method and apparatus for a talk group in a radiocommunication system", serial number 09/535924 (proxy file number CE08345R), registered on the same date, owned from the dealer.

Field of the invention

The present invention relates generally to code division multiple access radio systems, and in particular to a method and apparatus for talkgroup calls within such systems.

Background of the invention

Two-way radio communication systems, incorporating group dispatch services, are known in the art. Group forwarding services typically provide communications within a talkgroup. A talkgroup is a set of logically linked subscriber units (eg, a mobile in a vehicle and / or portable handheld radiotelephones) capable of engaging in group communications. In normal talkgroup communications, the talkgroup subscriber unit transmits the voice information, which is received by a fixed infrastructure and relayed to the other subscriber units in the talkgroup. Typically, such systems use frequency division multiple access (FDMA) and / or time division multiple access (TDMA) methods to receive and transmit the transmission. In FDMA systems, an input channel is normally paired with an output channel, and the input channel can be used by only one subscriber unit at a time. Similarly, in TDMA systems, the input and output time slots are paired and only one subscriber unit at the same time can transmit an input message for retransmission.

While these systems usefully provide group communications, they force communications to be somewhat regulated because only one subscriber "owns" the call at any one time. That is, natural group style communications where there are multiple simultaneous parties and multiple listeners are not possible because only one subscriber unit can transmit at any one time. Although there are currently numerous prioritization methods to allow high priority users, or users generating high priority traffic (i.e. emergency calls), to declare as the owner of a talkgroup call, communications are still restricted. to single-party / multiple-listener configurations.

Today's telephony services provide conference calls where multiple parties and multiple listeners can simultaneously participate in the call. Conference calls can be extended to today's radio systems by assigning a separate channel or time slot to each potential speaker and a separate outbound channel or time slot for potential listeners. Furthermore, independent full duplex channels (input and output resources) could be assigned for each subscriber unit in the talkgroup. Although these solutions are functional, they are highly inefficient in terms of resource utilization. For example, it is not unusual for public security organizations to have talkgroups that span up to 100 subscriber units. Obviously, setting up a group conference call using independent input and / or output resources for up to 100 independent subscriber units would require communication resources beyond the capacity of most communication systems.

One solution to the aforementioned problem is that provided by Grube et al. In US Patent No. 6005848, entitled "Method and Apparatus for Calling a Talk Group in a Radio CDMA System", issued to the licensee of the present invention. As described by Grube et al., A talkgroup talkgroup is assigned with at least one entry code, where the entire talkgroup is assigned an exit code. Members of the talk subgroup can simultaneously transmit voice information using entry codes. The voice information of the callers is summed up and transmitted to all users in the talk group. Although the aforementioned technique provides a more natural conversation between users, a drawback in the solution is that individuals who are actively speaking have their voice transmitted to themselves, which can be annoying for the interlocutor.

US-5924041 discloses a method and apparatus for providing a dispatch system in a cellular radiotelephone system.

Document US-6026295 discloses a mobile communication system, in which a mobile station communicates through a base station connected to a switching system.

ES 2 281 408 T3

Thus, there is a need for duplex communications between members of a talkgroup in radio communication systems, which allows multiple users to simultaneously broadcast to the talkgroup, yet does not allow an active party to hear the talk. transmission of your voice.

Brief description of the drawings

Figure 1 is a block diagram of a radio communication system in accordance with the present invention.

Figure 2 is a flow chart illustrating a method for use by a fixed infrastructure in accordance with the present invention.

Figure 3 shows a table that can be incorporated when establishing a talk group call in accordance with the present invention.

Figure 4 is a block diagram showing the operation of the radio communication system of Figure 1, in accordance with the present invention.

Fig. 5 is a flow chart showing a method for use by a subscriber unit in accordance with the present invention.

Figure 6 is a block diagram showing the operation of the radio communication system of Figure 1, in accordance with an alternative embodiment of the present invention.

Figure 7 is a block diagram showing the time slot distribution of the TDMA radio communication system of Figure 6.

Description of the preferred embodiment

The present invention generally provides duplex communications within talkgroups, where the caller's voice is not transmitted to the caller. A sub-talkgroup of the subscriber units, which are part of the talkgroup, is assigned at least one entry code. The talkgroup receives the exit code assignment. Members of the talkgroup can simultaneously transmit voice information using at least one entry code, the voice information of which is summed up and forwarded to the talkgroup, using the exit codes. The voice information is summed so that the individual party receives the summed voice information without the content of the individual subscriber's voice. The subscriber units in the talkgroup, although not included in the talkgroup (listening subgroup) are allowed to transmit the voice information only after their request, and receipt, of an additional entry code.

The present invention encompasses a method for the fixed infrastructure for the establishment of a talk group call. The method comprises the steps of receiving, from a first subscriber unit of the plurality of subscriber units, a request for the talk group call, the request comprising an identity of the first subscriber unit, and an identity of a talkgroup, identifying on the basis of the talkgroup identity, a talkgroup of subscriber units, comprising at least two subscriber units of the plurality of subscriber units, identifying on the basis of the identity of the first subscriber unit, a talkgroup of the subscriber units of the talkgroup, and assigning a time slot of output on a frequency channel to subscribers in the listening subgroup. In the preferred embodiment of the present invention, a plurality of outgoing time slots on the frequency channel are assigned individually to the subscribers in the talk subgroup if there is more than one speaker, and assigning at least one time slot input on the frequency channel individually in the talk subgroup.

The present invention further encompasses a method for the fixed infrastructure, to establish a talk group. The method comprises the steps of receiving incoming voice data from a plurality of subscriber units within a talk group, wherein the incoming voice data comprises voice data from a first subscriber. The input voice data is summed to generate the summed voice data. Finally, the summed voice data is transmitted to the subscribers within the talkgroup, without transmitting the summed voice data to the first subscriber.

The present invention further encompasses a method comprising the steps of receiving incoming voice data from a plurality of subscriber units within a talk group, wherein the incoming voice data comprises the voice data from a first subscriber, transmitting the first added voice data to the subscribers in the talk subgroup, wherein the first summed voice data comprises a sum of a plurality of subscriber units that are actively transmitting the incoming voice, and ceasing transmission of the voice data to the subscribers in the talk subgroup.

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The present invention can be more fully described with reference to Figures 1-5. FIG. 1 is a block diagram of a radio communication system 100 in accordance with the present invention. In the preferred embodiment of the present invention, the communication system 100 utilizes a next generation CDMA architecture, as set forth in the Radio Transmission Technology (RTT) candidate submission document of the Telecommunication Union communication. International CDMA 2000, although in an alternative communication of the embodiments, the system 100 may use other protocols of the analog or cellular communication system, such as but without limitation for the protocol of the next generation Global System for Mobile Communications (GSM), or the protocol of the CDMA system, as set forth in the document "Compatibility Requirements for Personal Base Stations for Personal Communication Systems Multiple Access by code division from 1.8 to 2.0 GHz ”(American National Standards Institute (ANSI) J-STD-008).

The radio communication system 100 comprises a plurality of subscriber units 104-109 configured in at least one talkgroup 101 in radio communication with a fixed infrastructure 103. The talkgroup further comprises a talkgroup 102 and a talkgroup subgroup. listen 130. In the example the subscriber units identified by the reference numerals 104-106 are included in the talk group 101 and the sub talk group 102, while the subscriber units identified by the reference numerals 107-109 are included in the listening subgroup. In the preferred embodiment, each of the subscriber units 104-109 are physically capable of duplex communications. However, as discussed in more detail hereinafter, only those subscriber units included in the sub talkgroup are authorized to engage in duplex communications with respect to the talkgroup 101.

As is known in CDMA systems, communication channels 117-125 are actually provided through the use of spreading codes. As described in further detail below, the exit codes are used to actually provide the outgoing communication channels 117-122 to each subscriber unit in talkgroup 101. Additionally, the input codes (three are used in the example illustrated in FIG. 1) are used to provide input communication channels 123-125 to each subscriber unit in talk subgroup 102.

The fixed infrastructure 103 comprises those elements normally necessary to support communications within the radioelectric system 100, and in the preferred embodiment complying with the CDMA architecture. In particular, the fixed infrastructure 103 comprises a switching center 110 in communication with a controller 111 which, in turn, is in communication with the base transceiver systems (BTS) 112-113. The exchange 110 (often referred to as a Mobile Switching Center or MSC), controller (often referred to as a Base Station Controller or BSC) 111 and the BTS 112-113, which are well known in the art. In practice, switchboard 110 typically communicates with more than one controller, and may communicate with other equipment not shown. For the sake of simplicity, the fixed infrastructure 103 has been limited to that shown in Figure 1. The infrastructure 103 may optionally also include a dispatch controller 114 in communication with the BTS 112-113. A suitable dispatch controller 114 is the Dispatch Application Processor used in radio communication systems "iDEN", ​​manufactured by Motorola, Inc. Group call processing management is preferably managed by controller 111, or if used , by the dispatch controller 114. Additionally, the group call management functionality, as described below, can be distributed across the fixed infrastructure 103.

Figure 2 is a flow chart illustrating a method for use in fixed infrastructure 103. Although the method described in Figure 2 is generally implemented in fixed infrastructure 103, the method is preferably carried out by controller 111 or by dispatch processor 114, if used. Likewise, the functionality illustrated in figure 2 can be distributed through the fixed infrastructure 103. In general, the method illustrated in Figure 2 is implemented as stored software routines by the platforms on which the software is stored.

In step 202, the fixed infrastructure 202 receives a request for a talk group call from a subscriber unit of talk group 101. The requesting subscriber unit may be one of the subscriber units 104-106 included in the Talk subgroup 102, or it may be one of the subscriber units 107109 that is not a member of the talk subgroup 102. Nevertheless, the request includes an identification of the requesting subscriber unit, and an identification of the talkgroup for which communications are established. In step 204, the fixed infrastructure 103 determines, using a table and the talkgroup identifications, and the requesting subscriber unit, whose units within the talkgroup 101 are to be established as duplex participants of the call group of talk group, that is, those subscriber units included in the talk subgroup 102. The table used for this purpose is described in figure 3.

Figure 3 shows a table 300 that can be used by the fixed infrastructure 103 when establishing a talk group call. Table 300 comprises a series of entries 301-303 that correlate the identifications of the talk groups 301 with the identifications of the requesting subscriber units 302, and the talk groups corresponding to each requesting subscriber unit 303. An advantage of this structure is that by changing the entries in the table 300, various configurations of the talk subgroups can be provided on a dynamic basis. With reference to the example shown in figure 3, the talkgroup

ES 2 281 408 T3 identified as TG 001 includes the subscriber units identified as SU 001, SU 002, SU 003, SU 004, SU 008, and SU 009. Thus, when the subscriber unit SU 003 requests a call from the group talkgroup, subscriber units SU 001, SU 002, SU 003, SU 004, SU 008, and SU 009 will be included in the talk group, and subscriber units SU 001 and SU 008 will be set as duplex talk subgroups . Alternatively, when any of the SU 002, SU 004 or SU 009 subscriber units request a talk group call, the SU 001, SU 002, SU 003, SU 004, SU 008 and SU 009 subscriber units will be included in the talkgroup, and only subscriber unit SU 001 will be established as a member of the duplex talkgroup.

The data entered into the duplex talk subgroup inputs 303 may be entered by a system manager, or it may be entered automatically as a dynamic function of various events. One way to perform dynamic updates to the subgroup entries 303 is to continuously store the identities of subscriber units that have recently paired in communications with the requesting subscriber unit. That is, when one-to-one communications are established with a given unit, the sub talkgroup entries may be updated to include the identity or identities of those subscriber units that have participated in such one-to-one communications. Alternatively, any subscriber units that request to be added to a talkgroup call by the requesting unit (described in more detail below) may be added to the appropriate sub-talkgroup entry. The time window for such "recent" communications is a matter of design selection, and can be based on an absolute time (for example, only subscriber units that have communicated in the last X minutes) or in sequence (for example , only the last X subscriber units that have communicated). Another method is to update the talkgroup entries 303 based on the relative priorities of the subscriber units within the talkgroup. Thus, for a given subscriber unit, the talkgroup will only comprise those subscriber units within the talkgroup that have a priority at least as high as the given unit. As the priorities of the subscriber units change, the entries in the talk subgroup 303 can be updated accordingly. Another method is even to update the talk subgroup entries 303 at subscriber unit locations with each other. So that. Thus, as a given subscriber unit updates its current location, the talk subgroup corresponding to that subscriber unit will be updated to include those subscriber units within a predetermined distance (eg, one mile) from the subscriber unit. Dadaist. Of course, other methods may be apparent to those skilled in the art.

A subscriber can dynamically switch between the talk subgroup and the listening subgroup. If a subscriber requires membership in the listening subgroup, a new input and output channel will be assigned to this subscriber. The subscriber will then switch from the listening subgroup to the talking subgroup. In order to save RF resources, if a subscriber who is in the talking subgroup requires only listening, the input and output channels of this subscriber will be released and the outgoing channel in the listening subgroup will be assigned to the subscriber. . The subscriber will then switch from the conversion subgroup to the listening subgroup.

Turning now to FIG. 2, having determined the listening subgroup 130 and the talking subgroup 102, the fixed infrastructure 103 assigns a plurality of input and output codes to the listening subgroup and the talking subgroup, respectively. In the preferred embodiment of the present invention, users in listening subgroup 130 are assigned a single multicast output channel. However, users in talk subgroup 102 are assigned a single channel for outgoing transmission. If there is only one subscriber / talker in the talk subgroup, there is no need to assign an outgoing channel to this subscriber / talker. To this end, the fixed infrastructure 103, in step 206, determines a plurality of exit codes for use in talkgroup 101, and at least one entry code for use in sub-talkgroup 102. the infrastructure Fixed 103 can determine a single entry code to be used by sub talkgroup 102, or preferably separate entry codes will be assigned to each member of sub talkgroup 102. The exit codes are used to create exit channels 117-122 (often referred to as a downlink or forward channel) to each subscriber unit in talkgroup 101. At least one entry channel is used (frequently referred to as an uplink or reverse channel) for the members of the talkgroup 102. The exit code and at least one entry code are announced to the talkgroup 101 in step 208. This announcement can be achieved using a control channel based on a PN code known to each subscriber unit, the control channel of which can be monitored by the subscriber units. In the preferred embodiment of the present invention if the maximum number of subscribers in the talk subgroup is 1, the group call is similar to the iDEN send call. This requires only one input channel and one output channel. If the maximum number of subscribers in the talkgroup is equal to the number in the talkgroup, the group call will be similar to the full duplex conference call. This requires N input channels and N output channels, where N is the number of subscribers in the talkgroup. However, if the maximum number of subscribers, M in the talk subgroup is between 1 and N, the group call is identified as an N-master send call. This design requires M input channels and M + 1 output channels.

Having made the code assignments, only the subscriber units included in the talkgroup 102 will be able to make the incoming transmissions for the talkgroup call. Accordingly, in step 210, the sending controller 114 receives the streams of voice information from one or more subscriber units in the talk subgroup 102. The voice streams are passed to the sending controller through the base stations 112-113. Assuming at least two subscriber units within the talk subgroup

ES 2 281 408 T3

102 are assigned unique entry codes, the voice information streams received by the fixed infrastructure 103 may arrive concurrently, that is, in a manner representative of normal group-style communications. Such units within talk subgroup 102 that do not transmit voice in progress will transmit a sleep pattern, as is known in the art. In step 212, the fixed infrastructure 103 (dispatch controller 114) adds the streams of the voice information to produce the summed voice information. Various summation techniques can be used including, but not limited to, conference bridging or arithmetic addition within a signal processor. If the streams of the voice information are of a form not suitable for summing, for example compressed digital voice, at least one temporary transcoder, as is known in the art, may be necessary to convert the streams of the information voice in a format that can be easily added. It will be appreciated that when the Enhanced Variable Rate Encoder (EVRC) is used, only two signals are combined, since the vocoder can only encode a maximum of two subscriber voices. In case more than two subscriber voices are added together, the patch panel information will be beyond the limitation of the EVRC vocoder. Thus, when using an EVRC vocoder, only the two highest-energy speech signals are added together. In the preferred embodiment of the present invention a determination is made as to whether the resulting summed signal is to be transmitted, and whether the resulting signal is to be transmitted to an ongoing party within subgroup 102, the resulting summed voice will have the voice of the party removed from the summed signal (step 213). If the resulting signal is to be transmitted to a subscriber unit that is not speaking in progress, then in step 213 no voice signal will be removed from the summed signal.

Regardless of the summation method used, the summed voice information will then be transmitted over the fixed infrastructure 103 using an exit code. Because the output code is used, only the subscriber unit using the particular code will be able to receive and reproduce the summed voice information. Because the summed voice information is representative of multiple parties, more realistic group communications will be achieved. Additionally, each individual user's voice will be removed from its output signal, thus preventing the user's voice from being emitted to it.

The present invention anticipates that it may be necessary for subscriber units that are not current members of the talk subgroup 102, and therefore unable to transmit voice information, to request the ability to transmit. Thus, in step 214, the fixed infrastructure 103 will determine whether any subscriber units in the listening subgroup may have transmitted a request to speak. The request to speak is transmitted on a channel based on a code other than the input codes assigned to sub talk group 102 (eg, a control channel). The request for speech includes the talkgroup identification 101, and an identification of the subscriber unit requesting to speak. If such a request is received, the fixed infrastructure will determine an additional entry code, preferably unique from the previously assigned entry codes, in step 216. The additional entry code will then be announced to the requesting unit in step 208, and the talkgroup call will proceed as before, but with the addition of the request unit as the party on the call. As described above, the table set forth with respect to Figure 3 can be updated to include the requesting unit (i.e., the unit that was assigned to the additional entry code) in the sub-talkgroup entry used to set the call. Talk group call in progress. The operation of the supplemental subscriber unit in steps 214 and 216 is discussed with respect to Figure 5 shown below.

Assuming that no requests to speak have been received in step 214, the fixed infrastructure 103 will determine in step 218 whether the subscriber / caller in the talk subgroup requires only listening rather than speaking. If a subscriber / caller in the talk subgroup requires only listening, the input and output channels of this subscriber will be released and the output channel of the listening subgroup will be assigned to the subscriber in step 220. The subscriber will be removed from the talk subgroup by passing it to the listening subgroup.

The fixed infrastructure 103 will then determine (step 222) if the talk group call has ended. It will be understood that various techniques can be used to detect the end of the talk group call. For example, a time limit may be used after all units have stopped transmitting sleep patterns or voice information. Alternatively, a decoded detection could be used by all subscriber units in the talkgroup 102. Regardless, assuming the talkgroup has ended, the fixed infrastructure 103 will release the exit code and entry codes at the step 224. Similar to step 208, release of exit and entry codes can be done through a control access channel, using known PN codes.

The operation of the present invention can be further described with reference to Fig. 4. In Figure 4, the fixed infrastructure 103 comprises a receiver 409 that provides independent streams of voice information 410-411 based on the transmission by the members of the talk subgroup 102, the adders 412 and 415 that sum the streams of the voice information. voice information 410-411, and a transmitter 414 that transmits the summed voice information 413 to talkgroup 101, using exit codes 415 (labeled Code A, D, and E). Transmissions by members of Talking Subgroup 102 are based on entry codes 416417 (labeled "Code B" and "Code C"). In the preferred embodiment of the present invention, adders 412 and 415 are part of send controller 114 external to base stations 112-113.

As shown in Figure 4, each of the subscriber units 104-109 has a set of common elements. In particular, the control and processing element 401, which typically comprises one or more dis6

ES 2 281 408 T3 processing positives (eg, microprocessors, digital signal processors, etc.) are coupled to memory 402. Control and processing element 401 is coupled to transmitter 403, receiver 404, speaker 405, microphone 406 , and input device 407. Each of these elements are well known in the art. Under the control of software algorithms stored in memory 402, the control and processing element 401 executes the tasks necessary for the operation of the subscriber unit. Receiver 404 is used to receive assignments of exit and / or entry codes for use in talkgroup calls and subsequently to receive de-assignments of exit and / or entry codes. Additionally, in all subscriber units included in talkgroup 101, the summed voice information 413, modulated in accordance with output codes 415 and received through receiver 404, is processed and provided to loudspeaker 405. In this way, subscriber units included in talkgroup 101 cannot monitor outbound communications corresponding to talkgroup call-in device 407, which may comprise a keyboard, menu-operated display, or similar device. , which allows users to transmit requests to speak. In subscriber duplex units (i.e., members of talk subgroup 102), voice input through microphone 406 is processed and provided as a flow of voice information to transmitter 403 for transmission based on a talk code. entry 416-417. The duplex subscriber units can also make use of the voice activated switching element (VOX) 408, such that the continuous stream of voice information is transmitted (when the voice is picked up by the microphone 406) or a sleep pattern (when voice is not picked up by microphone 406).

In the example of FIG. 4, two unique input codes, Code B and Code C, are used by the subscriber units in talk subgroup 102 to transmit voice information streams 410-414. In practice, the input codes, Code B and / or Code C, are used not only to transmit the input voice information, but can also be used to transmit the power control information, such that the fixed infrastructure 103 know the status of the exit code. That is, the fixed infrastructure 103 can adjust the output transmitted power with respect to the output codes, in order to maintain communications. Additionally, various output codes 426-427 (Codes A, D and E) are used to transmit the resulting summed voice information. In practice, the output codes are used not only to transmit the summed voice information 413, but can also be used to transmit the control information, such as the input code assignments and the power control information, to the members of the 102 conversation subgroup.

As described above, multiple subscriber units that are members of the talk subgroup 102 can simultaneously transmit voices to the fixed infrastructure 103. In the preferred embodiment of the present invention, the voice signals are received by the receiver 104 and pass processor 418. Processor 418 can pass all codes to adder 412, however when using an EVRC speech coder, only the highest power speech signals will be passed from processor 418 to be summed in adder 412. Speech The resulting summed is then passed to the second adder 415, where the individual speech signal is removed from the summed signal 413. In the preferred embodiment of the present invention, the control and processing unit 418 passes an individual voice signal to the adder 415 so that it is removed from the summed signal 413 even though the individual voice signal has the highest power of voice. The individual speech signal that is passed to the adder 415 is determined based on the resulting signal 419 sent. For example, if the signal using a particular code (Code D) is being transmitted to subscriber 104, then the voice signal from subscriber 104 is passed to adder 415 and removed from signal 413. The resulting signal (signal 419) is spread with a particular code (Code D) and transmitted to subscriber 104. The result is a signal received at subscriber 104 which is a combined signal from all simultaneous parties (or the two highest power) without sending any signal from subscriber 104 input channel.

Thus, in accordance with the preferred embodiment of the present invention, a particular speaker in subgroup 102 receives an output signal that comprises the combined voice of all speakers in sub-speech group 102, but nonetheless the voice of the speaker. in particular it will be removed from the output signal. The aforementioned 107-109 units in the listening subgroup will receive a combined signal from all parties, without removing the voice from signal 413. This is accomplished by processing unit 418 which does not pass the signal to adder 415 when transmission to units 107-109 is desired.

As described above, the subscriber unit in the listening subgroup can transmit a request to speak to the fixed infrastructure 103, in order to participate in the talkgroup call. The operation of a subscriber unit for this purpose is further discussed in FIG. 5. In step 502, the subscriber unit receives an assignment of an exit code with respect to a talk group call. As described above, such an assignment is typically transmitted over a control access channel established through the use of a known code.

In step 504, the subscriber unit may optionally monitor the outgoing communications with respect to the talk group call. This step is optional because the subscriber unit user may choose not to monitor the talk group call, or outbound communications may not proceed immediately after receipt of the outbound code assignment. Nevertheless, in step 506, the subscriber unit detects a need to transmit a request to speak, the request for which is directed to the talk group call. After transmitting the request to speak to the fixed infrastructure 103 in step 508, the subscriber unit subsequently receives, from the fixed infrastructure 103, an assignment of an additional entry code, and an additional exit code if there are more than one caller in the conversation subgroup,

ES 2 281 408 T3 in step 510. Upon receiving the assignment, the subscriber unit can start transmitting an additional stream of voice information, using the entry code, and receive an additional stream of voice information, using the exit code if there is more than one partner in step 512. In this way, any given subscriber unit will be able to remain a listening-only participant or, if desired, alter its state to become an active participant (ie, a party) on the talkgroup call.

Figure 6 is a block diagram showing the operation of the radio communication system of Figure 1, in accordance with an alternative embodiment of the present invention. In the alternate embodiment of the present invention, communication system 100 uses a Time Division Multiple Access (TDMA) system protocol. The alternative embodiment will be described below with the communication system 100, which will preferably be an iDEN® system, commercially available from Motorola, Inc. The 112113 base points preferably comprise the "iDEN" Enhanced Base Transceiver Points (EBTS), which are commercially available from Motorola, Inc., and which provide at least the dispatch communication services to subscriber units 104-109. Communication units 104-109 preferably comprise two-way radio or radiotelephone devices, such as Motorola's "iDEN" portable or mobile radio units.

In Figure 6 the infrastructure 103 comprises a receiver 609, which provides independent flows of voice information 610-611, based on the transmissions by the members of the sub-talkgroup 102, with the adder 612 adding the flows of the voice information 610-611, switch 615, and transmitter 614, which transmits the summed voice information 613 to talkgroup 101, using output channels 615 (labeled Channel A, D, and E). Unlike the preferred embodiment where the CDMA system architecture is used, in the alternative embodiment the channels comprise a particular frequency / time slot combination. Transmissions by members of talk subgroup 102 are based on input channels 616-617 (labeled "Channel B" and "Channel C").

As shown in Figure 8, each of the subscriber units q04-109 has a set of common elements. In particular, a control and processing element 601, which typically comprises one or more processing devices (eg, microprocessors, digital signal processors, etc.), which is coupled to memory 602. Control and processing element 601 is coupled to transmitter 603, receiver 604, speaker 605, microphone 606, input device 607, time split switches 608 and 609. Each of these elements are well known in the art. Under the control of the software algorithms stored in memory 602, the control and processing element 601 executes the tasks necessary for the operation of the subscriber unit. Receiver 604 is used to receive input and / or output channel assignments for use in talkgroup calls, and subsequently to receive input and / or output channel assignments. Additionally, in all subscriber units included in talk subgroup 101, summed voice information 613, modulated in accordance with output channels 615 and received through receiver 604, is processed and provided to speaker 605, processed and provided to loudspeaker 605. In this way, subscriber units included in talkgroup 101 can monitor the outgoing communications corresponding to the talkgroup call. Input device 607, which may comprise a keyboard, menu-operated display, allows users to transmit requests to speak. In duplex subscriber units (i.e., members of talk subgroup 102), voice input through microphone 606 is processed and delivered as a voice information stream to transmitter 603 for transmission based on an input channel. 616617. Duplex subscriber units also make use of a voice activated switching element (VOX) 608, such that a continuous stream of voice information is transmitted (when voice is picked up by microphone 606) or a sleep pattern ( when the voice is not picked up by the microphone 606).

In the example of FIG. 6, two exclusive input channels, Channel B and Channel C, are used by the subscriber units in talk subgroup 102 to transmit the voice information streams 610-611. In practice, the input channels, Channel B and / or Channel C, are used not only to transmit the input voice information, but they can also be used to transmit the information of the power control, in such a way that the infrastructure fixed 103 know the status of the output channel. That is, the fixed infrastructure 103 can adjust the output transmitted power with respect to the output channels in order to maintain communications. Additionally, various output channels 625-627 (Channels A, D and E) are used to transmit the resulting summed voice information.

As described above, multiple subscriber units that are members of the talk subgroup 102 can simultaneously transmit voices to the fixed infrastructure 103. In the preferred embodiment of the present invention, the voice signals are received by the receiver 604 and are passed to processor 618. Processor 618 can pass all channels to adder 612, however when using an EVRC speech coder, only the two highest power speech signals are passed from processor 618 for summation at adder 612. The summed speech The resulting signal then passes to switch 615, where the summed signal 613 is passed to transmitter 414 or not, based on the current speaker and whether the resulting signal 619 is being sent. For example, if the signal using a particular channel (Channel D) is being transmitted to subscriber 104, then the voice signal from subscriber 104 will not pass through switch 615 to transmitter 614. The result is a signal received at subscriber 104 who will have no audible component when subscriber 104 is speaking.

Thus, in accordance with the preferred embodiment of the present invention, a particular subscriber in subgroup 102 receives an output signal comprising the combined voice of all callers in subgroup of

However, when the particular subscriber is speaking, the switch 615 will not pass the combined signal 413, resulting in no audible signal received by the subscriber. Those units 107-109 in the listening subgroup will receive a combined signal from all parties, where the switch 615 will pass the combined signal 613 through.

In order to save RF resources, the transmission and reception operations use different time slots. For example, referring to Figure 7, when an iDEN system places a call, the mobile incoming frame 702 uses one time slot (for example, time slot 3) and its outgoing frame 701 uses the same time slot. time (eg time slot 3) as well. In the preferred embodiment of the present invention, the exit time interval (time interval 3) in the input frame 702 is designed with a time interval delay after the input time interval (701) (time interval 3 ). Since the input and output time slots differ in time, RD diplexers in mobiles are avoided by using time switches 608 and 609.

When a mobile makes a 2-master forwarding telephone call (more than one party), the called party belongs to the talk subgroup 102 initially (the called party is defined as the first master). The called party makes use of one of the entry time slots (eg time slot 3) from the fixed infrastructure 103. The exit time slot (time slot 3) with the same number as the entry time slot of the other called subscribers belonging to the listening subgroup 130 is also broadcast from the fixed infrastructure 103. When one of the listeners in the listening subgroup 130 requires being able to speak and its request is authorized from the fixed infrastructure 103, the listener moves from the listening subgroup 130 to the talking subgroup 101. In the preferred embodiment of the present invention, a pair of entry and exit time slots (eg, time slot 4) is broadcast to the new party (the second party is defined as the second master). In order to provide the first party (first master) with listening capability, the same time slot is broadcast as the entry time slot for the first party (first master). The new exit time slot (time slot 2) different from the same exit time slot (time slot 3) has to be broadcast to the listening subgroup 130.

If the first party (first master) stops talking, their entry and exit time slots (Tx / Rx time slot 3) will be released. The exit time interval (time interval 4 Rx) of the second party (second master) is also released. In order to save resources for other calls, the number of the entry time interval (number 4 of the Tx time interval) of the second party is changed to the same number of the exit time interval (number 2 of the time interval) of the listening subgroup 130. Then the second party (second master) will be referred to as the first party (first master).

If N participants wish to speak, N pairs of transmission and reception time slots plus one more reception time slot will be required, where N is the number of members of the talk subgroup 103. In the iDEN system, there are only 6 slots time on a frequency channel. If N is greater than 5, some of the participants in talk subgroup 103 will have to be reassigned to other frequency channels, since an exit time slot will have to be reserved for listening subgroup 130.

In the traditional iDEN send group call, there is a monitoring mode. If a participant has the priority of a supervisor, his voice from an input time interval to replace the voice of the current sending party will be sent to the listeners of the listening subgroup 130. In the present invention, the voice of the supervisor and The current party's voice will be added for all listeners in the listening subgroup.

The present invention generally provides a method and apparatus for duplex communications within talkgroups. Through the use of an efficient method of allocating resources from the CDMA or TDMA system, the present invention enables a subset of subscriber units to speak on a radio duplex conference call, while other members, potentially in a group of very large conversation, they can listen and if you want to be able to join the call. In this way, group-style communications can be achieved more naturally, without putting undue burden on the use of radio communications resources.

Although the present invention has been described with reference to certain preferred embodiments, numerous modifications and variations can be made by those skilled in the art, without departing from the new spirit and scope of the present invention. For example, while the preferred embodiment has been discussed above with subtraction of the individual user's voice signal from a summed signal, other techniques can be used to construct a summed signal without the individual user's voice. For example, instead of subtracting a subscriber voice signal at adder 415, in an alternative embodiment adder 415 is removed, and processing unit 418 simply does not pass the subscriber voice signal to adder 412, when the resulting summed signal has to be sent to the subscriber.