System and method of group calling in mobile communications

[Technical field]

【0001】

The present invention relates to mobile communications, and more particularly to systems and methods for group calling during mobile communications.

[Background technology]

【0002】

All current mobile communication systems have a hierarchical arrangement in which the geographical "communication range" is divided into a number of small geographical areas called "cells". With reference to FIG. 1, preferably, each cell is serviced by the base transceiver station (BTS) 102a. Some BTS 102b ~ n are connected to the base station controller (BSC) 106a by fixed links 104a ~ n. In some cases, BTS and BSC may be collectively referred to as Base Station Subsystem (BS) 107. Some BSC106b ~ n can be connected to the mobile exchange (MSC) 110 through fixed links 108a ~ n.

【0003】

The MSC110 acts as a local exchange (including additional features for handling mobility management requirements described below) and communicates with the telephone network (PSTN) 120 through trunk groups. In the US mobile communication network, there is the concept of home MSC and service MSC. A home MSC is an MSC that corresponds to an exchange associated with a mobile station (MS). This association is based on a phone number, such as an MS area code. (The home MSC is responsible for the HLR described below.) On the other hand, the service MSC is (a different MSC performs the functions of the service MSC when the subscriber moves within the area covered by the service provider). An exchange used to connect MS calls to the PSTN. Therefore, in some cases the home MSC and the service MSC are the same entity, but in other cases they are not the same entity (eg, if the MS is moving). The visiting location register (VLR) 116 is typically installed with the MSC110, and logically prominent HLRs are used in mobile communications networks. As described below, HLRs and VLRs are used to store many types of subscriber information and profiles.

【0004】

Briefly, one or more radio channels 112 are provided over the entire notification range. Radio channels are divided into multiple channel groups and assigned to individual cells. The channel is used to transfer signal information to establish a call connection or the like, and to transfer voice and data information when a call connection is established.

【0005】

At a relatively high level of extraction, mobile communication network signaling schemes include at least two main concepts. One concept concerns the signaling scheme between the MS and the rest of the network. In the case of 2G (2G is an industrial term for second generation) and newer technologies, this signaling scheme is the access method used by the MS (eg, time division multiple access, or TDMA). Related to code division multiple access, ie CDMA), radio channel allocation, authentication, etc. The second concept includes signaling schemes between various entities within a mobile communication network, such as signaling schemes between MSCs, VLRs, HLRs, etc. This second part is called the Mobile Communication Application Unit (MAP) in some cases, especially when it relates to the context of Signaling System No. 7 (SS7).

【0006】

Various forms of signals (and data and voice communications) are transmitted and received according to various standards. For example, the Electronic Industries Alliance (EIA) and the American Telecommunications Industry Association (TIA) have contributed to the definition of a number of US standards, including the MAP standard IS-41. Similarly, CCITT and ITU contribute to the definition of international standards such as the international MAP standard GSM-MAP. Information on these standards is publicly known and available from relevant organizations and literature. See, for example, Bosse, SIGNALING IN TELECOMMUNICATIONS NETWORKS (1998, Wiley).

【0007】

To make a call from the MS114, the user dials the number on a mobile phone or other MS and presses the "Send" button. The MS114 sends a dial number through the BS107 to indicate the service requested to the MSC110. The MSC110 checks the associated VLR116 (located below) to determine if it is possible to receive the service requested by the MS114. The service MSC routes the call to the dialed user's local exchange on the PSTN120. The local exchange warns the calling user terminal and the response signal is routed to MS114 through the serviced MSC110. The MSC110 then completes the voice path to the MS. When setup is complete, the call will continue.

【0008】

To make a call to the MS114 (assuming the call was made from the PSTN120), the PSTN user dials the phone number for that MS. At least according to US standards, the PSTN120 routes the call to the MS home MSC (which may or may not be servicing the MS). The MSCs then query the HLR118 to determine which MSCs are currently servicing the MS. This query also serves to inform the service MSC that an upcoming call will be made. The home MSC then routes the call to the service MSC. The service MSC paging to the MS through the appropriate BS. The MS responds and an appropriate signal link is set.

【0009】

During the call, BS107 and MS114 can work together to change the channel or BTS102, for example, if necessary for signal conditions. These changes are called "handoffs" and these changes involve their own types of known message and signaling changes.

【0010】

One aspect of MAP includes "movement management". Briefly, since the MS114 moves to different locations, it may require and use some BS and MSC to service an MS. Mobility management allows the service MSC to obtain the subscriber profile and other information that the MSC needs to ensure that the MSC services (and charges) the call accurately. To do so, the MSC uses the Visiting Location Register (VLR) 116 and the Home Location Register (HLR) 118. The HLR is specifically used to store and retrieve mobile identification numbers (MIN), electronic sequence numbers (ESN), MS status, and MS service profiles. The VLR stores similar information in addition to storing the MSC identification that identifies the (home) MSC. In addition, in the case of a suitable MAP protocol, a location update procedure (or registration notification) is performed to allow the mobile phone subscriber's home MSC to know its user location. These procedures are performed when the MS moves from one location to another, or when the MS turns on the power to access the network and performs its own registration procedure. For example, the location update procedure can be continued by MS114 sending a location update request to VLR116 through BS107 and MSC110. The VLR116 sends a location update message to the HLR118 servicing the MS114, and the subscriber profile is downloaded from the HLR118 to the VLR116. An acknowledgment of successful location update is sent to MS114. The HLR 118 requires the VLR (if any) to delete the previously held profile data in order to delete the data about the MS114 that has changed position.

【0011】

FIG. 2 shows in more detail the signal scheme and user traffic interface between BS107 and MSC110 in a CDMA mobile communication network. BS107 transmits signal information via the A1 interface. The A2 interface carries user traffic (eg, audio signals) between the MSC's switch components 204 and BS107. The A5 interface is used to provide a route for user traffic to circuit-switched data calls (as opposed to voice calls) between the source BS and MSCs.

【0012】

In addition, subscribers are demanding new services, such as "data calls" to the Internet. The cost performance of MSC is not high for some of these services. This is because MSCs are designed primarily for voice calls. Incorporating new services into MSCs is either complex or infeasible, as many MSC software architectures use dedicated and closed-fitting designs. That is, it is not easy to add the software logic needed to provide the service to the MSC110. Exchange accessories are often used to provide such services. For example, the interaction function (IWF) is an accessory for routing data calls to the Internet. Both the approach of incorporating functionality within the MSC and the approach of adding accessories to the trunk side involve the MSC in service delivery. New services are expected to spur demand, so incorporating new services by redesigning the MSCs or adding accessories on the trunk side will intensify network congestion at the MSCs and cost expensive MSC resources. Is likely to be needed.

【0013】

In the case of the Internet, multicast communication means sending the same data packet to multiple destinations selected on the Internet Protocol network. (On the contrary, broadcast communication means indiscriminate transmission of data packets to all destinations, and unicast communication means transmission of data packets to one destination.) Each participant in multicast , Receives information sent by any other participant in the multicast. Users who are connected to the network but are not participants in a particular multicast will not receive the information sent by the participants in the multicast. In this way, multicast communication uses only the network components actually required for multicast transmission (eg, switches and trunks).

【0014】

In multicast processing, if a potential participant (the "host") is specified to join a particular IP multicast group, the host can request the closest multicast to join that multicast group. Send a "join request" message to the router and receive the information sent to this group. For example, Host A sends a message to join Multicast Group Y, and Host B sends a message to join Multicast Group X. If the data path has not yet been established, Router R propagates the request to the multicast source.

【0015】

For example, when an IP packet for Group X is received, Router R maps the IP multicast group address within the Ethernet multicast address and sends the resulting Ethernet to one or more appropriate switches. Send a packet.

【0016】

With the current Internet Group Management Protocol (IGMP), membership of a host in a multicast group expires when the router no longer receives periodic membership reports from the host.

【0017】

For MS-to-MS interactions, a two-version Nextel service has already been proposed for special connection calls between MSs (this service is Nextel Direct). Connect®, which uses a special mobile wireless technology and is listed at http://www.nextel.com/phone_services/directconnect.shtml). Both versions of the special connection call require all members to be located in the same area served by one BSC. In the case of the first version, for example, two mobile telephone subscribers such as A and B can have a one-to-one conversation. If A wants to make a special connection with B, A enters B's dedicated identification number, presses the Push-to-Talk ("PTT") button, and B is ready to receive. Start the conversation when you hear the audible warning that means. When he hears, A releases the PTT button. If B wants to speak, B presses the PTT button and waits until A hears an audible confirmation that it is ready to receive. With this service, subscribers can also select a dedicated identification number from the scrollable list displayed on their mobile handset, or search the subscriber's pre-remembered list of names. You can also do it.

【0018】

In the second version, conversations can be made between members of a subscriber's predefined group called a Talkgroup, which is identified by a number. Using a mobile phone handset, the talk group number can be searched by the control surface of the handset. To make a group call, the first subscriber to take action, such as A, finds the talk group number in the handset, presses the PTT button, and begins the conversation when it receives an audible confirmation such as a chirp. Can be done. All other talk group members on the group call can only hear the conversation while A holds down the PTT button. If A releases the PTT button, other members on the group call can press the PTT button, be notified by audibility confirmation, take control, and be able to start a conversation.

[Disclosure of Invention]

[Problems to be Solved by the Invention]

【0019】

The present invention provides systems and methods for performing mobile communications in general, and more specifically, systems and methods for group calling.

[Means for solving problems]

【0020】

Information is retrieved from the list of members of the group call group. Based on the retrieved information, a group call is established between the first mobile station (MS) and the second mobile station (MS). The first MS receives service from the first base station controller (BSC) and the second MS receives service from the second BSC. Voice data for the group call is transmitted during the multicast session. Based on the history of group calls between two points in the mobile communication network, for example, in anticipation of future group calls, a decision is made as to whether or not to establish a multicast session between the two points.

【0021】

By initiating a single call, a member of a group can establish a group call among all contactable members of the group. Group calls are established between different BSCs, and perhaps between members who may be serviced by different access methods (eg, TDMA or CDMA), and who may be located within different areas. It is possible. Inter-BSC voice traffic between members within a group call can be carried by other communication networks, such as the Internet Protocol network.

[Best mode for carrying out the invention]

【0022】

Explaining FIG. 3, the system and method is for setting up a call between members of a predefined group of mobile phone users. As described in more detail below, a device such as a proxy switch that implements the group call logic 1010 detects the start of a group call by a member 1012A of group 1014 and all members of the group within the group call 1012A, 1012B, Automatically try to connect to 1012C. In certain implementations, the communication within a group call is half-duplex communication (ie, communication that only one member can speak at a time), and voice traffic to that group is multicast. Carried by the Internet Protocol (IP) network during the session.

【0023】

When a group call logic is implemented in a proxy switch, the proxy switch is a system for servicing mobile communications by the proxy switch, dated November 22, 2000, which is incorporated herein by reference. And Methods, as described in US Simultaneous Proxy Application No. 09/721329. As described in the co-pending application and shown in FIG. 4 of this application, the exchange 1034 operation is at least one mobile exchange (MSC) 1030 and at least one base station subsystem (BS"". ) To be done with 1032. This exchange can transfer communication traffic to and from another network 1036, such as an IP network. Since the exchange is transparent, neither the MSC nor the BS requires any modification to work with the exchange of the present invention.

【0024】

The proxy switch described in the co-pending application has signal message processing logic 1038 for receiving signal messages from MSCs and BSs by mobile signal protocol. The message interception logic 1040 works with the signal message processing logic to send an acknowledgment message to the MSC or BS that sent the signal message. The message interception logic also prevents signal messages from being sent to the other of the BS and MSC, respectively. The message conversion logic 1042, in cooperation with the signal message processing logic, converts the signal message into a converted signal message for transmission from one of the MSCs and BSs to the other of the BSs and MSCs, respectively. The message transmission logic 1044 cooperates with the signal message processing logic to transmit a signal message from one of the MSCs and BSs to the other of the BSs and MSCs, respectively.

【0025】

A pair of bearer lines 1046 from BS is assigned to a proxy exchange. Signal messages between the MSC and BS are received and analyzed to determine if these signal messages correspond to a set of assigned bearer lines. When corresponding, the control information in the signal message is sent to another communication network, and the information carried by the above-mentioned pair of bearer lines is sent to different networks.

【0026】

FIG. 5 shows one preferred arrangement of the proxy switch 300 where the proxy switch 300 is located between the BS 107 and the MSC 110. Only one subset 306 of the trunk carrying user traffic must be terminated on the proxy switch. The other trunk 308 can directly connect the MSC110 and BS107. All control links 312 from BS107 are terminated at proxy switch 300. The proxy switch includes a control surface 302 and a data surface 304 (also referred to as a "bearer surface"). The control surface 302 handles all signal traffic, and the data surface 304 handles all user traffic to the trunk connected to the proxy switch.

【0027】

In some embodiments, there is a one-to-one correspondence between the MSC and the proxy switch. Some BSs can work with one proxy switch. The proxy switch 300 includes software that accepts all signal messages and performs at least one of the following, depending on the message and the state of the system. 1. Sending to the MSC or BS whose destination is listed in the message of the unchanged message. 2. Interception of messages between MSC and BS. 3. For some intercepted messages, the conversion of the intercepted message to a different message, and the converted message to MSC or BS whose destination is described in the intercepted message instead of the original intercepted message. Send. 4. Sending messages from mobile station-based networks and PSTN-based networks to other networks, such as IP networks.

【0028】

The types of actions taken in each case with the triggering event are described below. In many cases, the proxy switch 300 acts as the MSC110, especially if the message is sent from the MS114 and the traffic is destined for another network. For such roles, the proxy switch carries out the responsibilities and roles that traditional MSCs perform. Some of these functions and roles relate to mobility management. Considering a moving MS, when a mobile station moves from one cell to another, it may move to a cell that is serviced by a different MSC. Therefore, a handoff is required between the source and the target MSC. If the proxy switch 300 moves the message and the call / session is destined for another network, the proxy switch manages the handoff in a manner similar to the traditional MSC managing the handoff. The proxy switch updates the appropriate database with the new location of the MS.

【0029】

Another feature of proxy exchanges is related to resource allocation. In particular, if the MS initiates a message requesting a new call / session, the appropriate line (channel) should be assigned to this session. Depending on the configuration of the system and the state of the system, the proxy exchange allocates lines in a manner similar to that of conventional MSCs.

【0030】

FIG. 6 illustrates an arrangement in which a proxy switch 300 is connected to several other networks, such as an IP backbone 412, such as a different carrier, or a network 414, which is based on another line. These other networks, along with the expensive resources of the MSC110, can be used to carry voice and / or data traffic to the desired destination while avoiding all or part of the PSTN120. Alternatively, these arrangements can be used to allow line traffic to be routed back to different networks. For example, line traffic from Nashua, New Hampshire can be sent back to the MSC in Waltham, Massachusetts. Alternatively, these arrangements can be used to connect to other networks. For example, the IP backbone 412 can communicate with the IP voice network 418 or the Internet 416. As described in the co-pending application, when transmitting traffic to another network, both control information (eg, from a signal message) and voice or data from the bearer line on link 306 are transmitted through the other network. be able to.

【0031】

In the specific implementation of the group communication system described above, mobile communication users (users) belonging to a closed user group (group or CUG) have the ability to communicate quickly and easily with each other. And thereby can start a conversation with each other. Each group has two or more users (members), and the users may belong to a plurality of CUGs. Conversations can be between two members of a group (private mode) or between all available members of the CUG (public mode). The group communication system uses conventional mobile communication devices such as mobile phones and mobile PDAs.

【0032】

In certain implementations, the group communication system intercepts the group call start, bypasses the MSC and PSTN, and performs the group call as a multicast session execution voice over IP (VoIP), as described above. The group call logic is executed in the proxy switch logically arranged between the MSC and the BSC. Users in the group are separated by multiple MSCs covering a collective network that relies on one or more wireless technologies, such as CDMA, TDMA (including IS-136 and GSM), GPRS, and third generation technologies. You can receive the service at the geographical location. For example, between group members who participated in an arbitrary group call, one or more users may be moving in the GSM network at the same time while one or more users are moving in the CDMA network. .. While the group call is in progress, control information about the group call can be made available to one or more users, such as display participants in the group call. Standard numbering schemes such as MIN, IMSI, ESN allow group call users to dynamically generate and modify group call lists.

【0033】

FIG. 7 illustrates the general architecture of an exemplary embodiment of a group communication system. FIG. 7 shows four users in a group call using wireless devices 1060A-1060D connected to different BTS systems 1062A-1062D. For the purposes of the following discussion, it is assumed that the wireless device has both an audio display function and a text display function. BTS is connected to base station controllers (BSC) 1064A-1064D, and these base station controllers are connected to proxy exchanges (group call exchanges) 1066A-1066C that perform group call logic. .. Each group call switch is connected to an MSC such as the MSC1068A, 1068B, 1068C. At least one group call switch is for each MSC in the group call service available network. For signaling information, each group call switch is logically located between the corresponding BSC and the corresponding MSC. The group call switch receives signals and data from the MSC and, in the opposite direction, signals and data from the wireless device through the BTS and BSC. Each group call switch operates as if neither the BSC nor the MSC were aware of the group call switch located between the BSC and the MSC. Signals and control information from the MSCs and BSCs are intercepted by the group call switch and seamlessly sent to the relevant elements as needed, with no identifiable changes.

【0034】

The MSC is connected to the public land mobile communication network (PLMN) 1070, and the group call switch is connected to the backbone multicast-enabled IP network (backbone network) 1072, which is the backbone network 1072. Provides access to the CUG active network 1074 and the enhanced home location register (HLR) 1076.

【0035】

As already described for proxy exchanges in co-pending applications, group call exchanges have control and data aspects. The function at the control side is the termination of signal messages from the BSC and / or MSC. For example, in a CDMA network, signal messages are defined by the IS-634 protocol specification. The control surface terminates the input signal and generates a new signal message for forward transmission to the MSC or other element. The control aspect also supports the multicast features described below.

【0036】

In certain embodiments, the data side of the group call switch receives TDM traffic from the BSC and / or MSC, and TDM cross-connect (DACS) (DACS) to interface the input traffic to the output destination. Figure 5) is used. In other embodiments, the data side also receives an input IP traffic from the base station complex (also referred to as a radio access network or "RAN") and switches the input IP traffic to the output IP traffic. Programmatic control within the control plane determines the cross-connection between the input TDM traffic and the output destination, especially between the traditional MSCs and / or destinations on the IP network.

【0037】

In the case of providing the MSC service as an output destination from the DACS, the group call switch is essentially transparent to the network. Traffic and control flow seamlessly from the BSC to the MSC and from the MSC to the BSC. Instead, if the output destination is located on an IP network, the media gateway on the data side (described in the concurrent application) bypasses the selected portion of the input TDM traffic from the MSC and inputs it. Convert TDM traffic to RTP / UD / IP traffic and insert RTP / UD / IP traffic into the gateway IP network.

【0038】

The CUG active directory (CUG AD) 1074, also known as the group call registration (GCR), is a database system that contains CUG data. In certain implementations, CUG AD in Figure 15 is implemented as a distributed database system for scalability. CUG AD contains the definitions of all CUGs in the group call network. When querying CUG AD, specify the CUG identifier. That is, the query requests the definition of the specified CUG and the result is a list of group user IDs for all members of the specified CUG. For example, a query specifying CUG ID 2347 can cause CUG AD to generate a result that identifies the move identification number (MIN) xxx, yyy, zzz, and www for four users in the CUG. For certain implementations, the MIN number is assigned to the user of the GIR service by the service provider.

【0039】

Each CUG is identified to the system by a unique identifier ID from the CUG namespace, which is divided so that different partitions are assigned to different distribution parts of the CUG AD. All group call exchanges can use the split index of the split scheme. If the group call switch needs to look up the definition of CUG, the group call switch can use the index to determine the component of the CUG AD to query.

【0040】

Enhanced HLR1076 is an enhanced version of the standard HLR database (Standard HLR) used in mobile phones. The standard HLR field position is updated by the moving user on the move. The traditional route these updates cross is from the mobile phone to BTS, from BTS to BSC, and then to the MSC, which sends the update message to the HLR. In the case of a particular implementation of the group call network, the group call switch is located between the BSC and the MSC, allowing the group call switch to see updates in all positions. For users subscribed to the group call service, the group call exchange intercepts location update messages and copies these messages to the HLR. In addition to thereby storing the location of the group call user's mobile phone, the HLR also stores a list of all CUGs to which each group call user belongs. The query to the HLR specifies a MIN that identifies the group-calling user and generates a response containing a list of CUGs of which the group-calling user is a member.

【0041】

In certain implementations, the HLR is a distributed database whose data distribution is based on the MIN hierarchy. Alternatively, the HLR can also be based on an international mobile telephone subscriber ID (IMSI), or device sequence number (ESN). An index similar to the split index above for the CUG namespace allows the group call exchange to determine which HLR to query when processing an input request.

【0042】

In the case of an example for a family, each CUG can be defined to include the father, mother and teenager of the user carrying the mobile phone. By pressing a special series of keys on his cell phone (or by pressing one special key if installed on the phone), the father is in the position of the mother and teenager. Can be found and the group call initiation process can be performed to involve mothers and teens in the group call. In the case of the half-duplex implementation described below, if the group communication system confirms that at least one member of the CUG is participating in the group call, the conversation with the father as the first participating member Controls are assigned and the conversation can be initiated when one or more other participating members are listening to the conversation. If the father relinquishes control of the conversation, any other participating member of the CUG (for example, the teenager if the teenager is participating in the call) will take control of the conversation. You can get and have a conversation. Therefore, in the case of half-duplex implementation, only the participating members who are assigned the right to speak can speak. Other participating members will not be able to speak until the member's say control has been relinquished and reassigned. As described in more detail below, in order to claim control of speech, the user making the group call can press the standard number key on the phone, if installed by the phone manufacturer. You can press a special key, or if your phone has the ability to send text messages, you can send a text message to the person who is currently speaking asking you to speak next. .. If, at some point during the call, speech control remains unassigned for a given period of time (ie, when the conversation ends), the call ends.

【0043】

If all members of the CUG are located in the same exchange area, that is, in a geographic area controlled by one MSC or proxy exchange, or if they are located in different exchange areas, make a group call. Can be arranged. For example, if the CUG has users A, B, C, D, A, B may currently be moving within the exchange area S1 and C is moving within the exchange area S2. In some cases, D is moving within the exchange area S3. When all S1, S2, S3, S4 exchange areas are operated by the same service provider, or managed by operators who have agreed to cooperate with each other by providing group calling services. Can establish a group call connecting A, B, C, D. In such a case, the individual members may be widely dispersed in a physical positional relationship. For example, A and B may be in Boston, C in Texas, and D in California.

【0044】

Group communication systems provide shared use of calls across different network technologies. That is, a group call can be established even if CUG members are moving across multiple networks based on different technologies. For example, user A can be in Boston and travel within a code division multiple access (CDMA) -based network, and B can be in the UK (UK), a global system for mobile communications. It can move within a network based on (GSM) (GSM uses Time Division Multiple Access (TDMA) technology). If A and B belong to the same CUG and the CDMA operator and GSM operator have agreed to cooperate in providing the group call service, a group call is made between A and B. Can be established.

【0045】

The system may include one or more of the following enhancements, described in more detail below. As you can see from the above description, a group call can be established with or without all members of the CUG participating in the call. If some members of the CUG are unable to participate in a group call, the system can generate and record an exception list that includes the members who cannot participate. If one or more members of the CUG have a phone with a display screen, the exception list can be displayed on the display screen. In addition, various actions can be taken based on the exception list. For example, a voicemail message can be sent to a member on the exception list during or after a call. For example, the caller can record a voice mail message once and send it to the voice mailbox with the previously specified voice mail phone number by the group communication system to the members on the exception list. be able to. Instead or in addition, to inform each participating member which other members are participating in the call, the members of the CUG who participated in a particular group call are being called on the phones of all participating members. It can be displayed in the form of a list on the available display screen. A visual display can be displayed on a display screen that can be used to identify the member who currently has say control.

【0046】

A user of a group communication system can establish a dedicated call with another user of the group communication system. Therefore, the user can discuss confidential or personal information outside the group call. Therefore, the two participants in the output group call can temporarily make a dedicated call and then return to the output group call.

【0047】

A user of a group communication system can request a list of ongoing group calls (active group calls) to a CUG of which the user is a member, and participate in one of such calls. Can be done. A user of a group communication system can initiate or participate in a public group call, i.e., a group call to a CUG that includes each user of the group communication system. Operators can define any number of public user groups (PUG). Each user of the group communication system becomes a member of all PUGs automatically. To participate in an active public group call, the user requests a list of active public group calls and selects the call to join.

【0048】

When the user of the group communication system has a call standby function, the user can put the group call in the standby state and respond to the input call signal. A user who does not want to accept any input call signal, including one for a group call, can activate call transfer or call blocking. The user can choose to block only the input call signal for group calls, dedicated calls, or both.

【0049】

The group communication system incorporates voice-to-text conversion within the group call for the convenience of users in noisy environments, users in public places where the use of audible telephones is restricted, and users with hearing impairments. It can have a built-in language conversion function (for example, from English to French).

【0050】

A user of a group communication system can assign a special group communication during group service sign-up based on the contact information stored in the user's mobile phone number or the telephone directory of the user's telephone. You can contact by the system identification number (group user ID). Instead of or in addition to using the web-based supply system described below, the group user ID can be self-setup (self-supply).

【0051】

As described above, the group communication system provides three modes of operation: closed user group (CUG) mode, dedicated mode and public user group (PUG) mode. Except for the user-controlled calls described below, the user presses a number key (or a special phone key, if installed) to talk and the user is given control of the speech. Wait to hear the tone that indicates that. When the user ends the conversation, the user can press one key, which causes other participating users to hear a tone informing them that voice control is available. .. Other participating users can then press a key, hear the tone, and start the conversation. The caller initiates speech control after at least one other user has participated in the call, as the tone indicates. The call ends if all participating users hang up their phones or, as already explained, no one requests control of the conversation for a period of time. The above system resolves a conflict between requests when a plurality of users simultaneously request control of speech. For example, a "human protocol" can be used if full-duplex mode is available for conversation. In such cases, control is ultimately passed to multiple users, just as all but one user stop speaking and control of the conversation is passed to the speaking user.

【0052】

In CUG mode, the group-calling user generates a unique group ID for the list and uses the member's group-calling ID and its mobile phone number to assign members to the list to create a closed user group. To form. As long as a signal can be sent to the handset via a radio access network (RAN) under the direction of a proxy exchange, and because RAN uses a mobile phone number to make such a signal transmission, CUG information includes mobile phone numbers. Each CUG includes two or more users with the maximum size imposed by the service provider, if desired.

【0053】

In certain implementations, if the group-calling user wants to contact a group of users in the user's community (ie, CUG mode), the user may, for example,^*Key in (enter) the call start sequence, which is followed by a CUG ID, and press the send key. (The call start sequence can also be remembered and dialed from the speed dial directory on the user's phone.) When first notified, a member with a CUG who cannot participate in the call will be able to make the call. If is still active, you can join the call later by entering the call start sequence and pressing the send key.

【0054】

In CUG mode, the caller can request a user-controlled call, which is a call with a "barge-in" function, if he wishes to do so. According to the barge-in feature, the listening user can configure a multi-key service to inform the talking user that the listening user wants to gain control of the conversation. You can send a warning message to the talking user by pressing the DTMF sequence. At this point, the talking user can press a key to relinquish control of the speech or continue the conversation. Therefore, the barge-in feature provides the talking user with an audible notification of the request that the listening user wants to talk, and in the case of phones with text display, a barge-in message. You can provide a text message displaying the name of the user listening to the conversation you sent. Therefore, the user in conversation does not have to presume whether the user listening to the conversation wants to have a conversation. If the user in the conversation does not want to be interrupted (for example, while announcing to a large group of people), the barge-in feature can be disabled.

【0055】

As described above, the CUG mode can also provide an identification function of the person who is talking to the participation report, and can provide a broadcast communication function for the participation exception. Call transcription during CUG mode to use voice-text technology to transcribe group calls in real time capability) can be provided. A member of a group who has a text-display telephone and is notified of a group call can make the call inaudible and request to receive a text transcription instead. In certain embodiments, no text display phone sends or receives audio-only and text-only devices, and the call transcription feature is not turned on, so that the text pager receives the text. In some cases, the text-only device will not be notified of the group call. A full transcript of the call is available at the end of the call and can be sent to all CUG members or callers who did not participate in the call (based on the participation exception list). This feature can be extended to translation services using suitable language indicators available with IS-41-C. A suitable language indicator is the information stored in the HLR database that is included in the subscriber's profile to show the subscriber's priority over the language in which the announcement and other reports should be displayed. It is an element. The switch uses a suitable language indicator when making pre-stored announcements. Additional resources such as humans or automatic translators can be provided by the service provider.

【0056】

The group call ID and associated list of members can be set by a web-based offering application from a personal computer or from a WAP-enabled device. The user can also set up a list from the user's mobile phone. The service provider specifies an upper limit on the number of members on the list, one or more networks to which the members belong, and the number of lists that the group calling user can maintain.

【0057】

In the dedicated mode, the group call user connects to the group call available network by, for example, inputting a group call start sequence such that * 4 is followed by the group call ID of the target receiving member and pressing send. You can quickly call a call to any member of your group of users. The target recipient member is notified of the call from the user, and in certain embodiments, the user hears a chirp sound when the target recipient member answers the call.

【0058】

In PUG mode, the group caller can see the list of current chat groups and decide to join the chat group. The group call user can generate a new chat group that can be obtained by any group call user by specifying a unique group call ID and providing a short text description of the subject of the group. Subscribers can associate the text name with the group call ID if they wish, as long as the text name is unique across the current active chat group.

【0059】

The group call function does not supersede current mobile phone functions such as call transfer, no interruption and call prevention. The caller on the group call can switch to an input call if the call wait can be made operational. During a group call for security reasons, the three-way call, call conference, and call transfer become inoperable and become operational again when the highest point of the group call is reached.

【0060】

The group call service supports conversation encryption with the IS-41-C voice privacy (VP) feature, as requested by the mobile phone, if the corresponding base station supports VP.

【0061】

In the specific implementations described in more detail below, the group call service operates within an IP network that uses IP multicast. As mentioned earlier, IP multicast allows a source to send a copy of a stream of VoIP packets received by multiple recipients who have explicitly registered to receive the stream. Multicast is a recipient-based concept in which a recipient joins a particular multicast session group and the stream is sent by the network infrastructure to all members of that group. Only one copy of the multicast stream goes through any link in the IP network, and if necessary, multiple copies are made only at the IP multicast enabled media gateway.

【0062】

In the case of wireless networks, the service has some features of any conventional wireless pager. As already explained, the person who started the group call is followed by the ID of the group call list of the user who the person who started the group call wants to contact (for example, "* 4" is followed by the user group ID), DTMF. Invokes a group call by sending a functional escape sequence. A functional escape sequence is one in which the call is a group call and queries the global call registration ("GCR" or "CUG AD") to find a list of mobile phones to contact and their current location. Used by proxy exchanges to detect that. The current location information determines which media gateway and BSC are associated with the group call. A bearer channel is established between each such BSC and the corresponding media gateway through the group call switch data side. Group calls are presented to each BSC as having traditional two-point call setup and decomposition characteristics, but not to the MSCs.

【0063】

8A-8C are calling flowcharts as an example of basic services in a wireless network. WCS-1 and WCS-2 represent group call exchanges. As shown in FIGS. 9 to 10, the main entities in the flowchart are the group call exchanges WCS-1 and WCS-2 equipped with the respective media gateways MG1 and MG2, and the GCR accessible by WCS-2. BSCs BSC-1 and BSC-2, and mobile stations (for example, telephones) MS-A and MS-B. In the case of this example, MS-A and MS-B happen to be covered by the same group call switch WCS-1, but even if MS-A and MS-B are covered by different group call switches. The procedure is the same.

【0064】

FIG. 10 is a logical flowchart of the group call, which is a simplified flow chart of the calls of FIGS. 10A to 10C for setting up the group call. The left side is the share of the logic processed by WCS-1, and the right side is the share of the logic processed by WCS-2. WCS-1 detects that MS-A has requested a group call (step 3010) and notifies WCS-2 (group call coordinator) of this (step 3020). WCS-2 refers to the GCR to determine other members of the MS-A CUG and their last known location (step 3030). (In this simple example, MS-B represents only the other members.) WCS-2 creates a media gateway connection to WCS-1 (group call switch for MS-A) (step 3040). ). WCS-1 acquires a radio channel for MS-A (step 3050). WCS-2 tells WCS-1 (a group call exchange for MS-B) to page MS-B (step 3060). WCS-1 paging MS-B (step 3070) and then notifies WCS-2 that MS-B was found (step 3080). WCS-2 creates a media gateway connection to WCS-1 (a group call switch for MS-B) (step 3090). WCS-1 acquires the radio channel for MS-B (step 4000) and notifies WCS-2 that the acquisition is complete (step 4010). WCS-2 tells WCS-1 to indicate to MS-A that it has arrived at MS-B (step 4020) and activates the tone to MS-A through the media gateway (step 4030). ..

【0065】

The calling flow as an example will be described below with reference to FIGS. 12 to 15. As mentioned earlier, in the case of a group call, only one participating user can speak at a time. Participating users with speech control may waive such speech control by sending a predefined DTMF digit (eg, "1"), and then other participating users may renounce the DTMF digit. You can claim control of your voice by sending (eg, "8"). Participating users with speech control hear a success tone that sounds when the transmission path is established, as shown in FIG.

【0066】

Prior to the group call, the group call user may or may not be able to operate one or more of the following functions described above: participation exception reporting, participation reporting, call transcription, and barge-in functions: You can choose whether to do it.

【0067】

In the case of a web-based setup system that can be used by end users to establish that GCR list, the web server will be able to update the user's swarm list in real time. Connect to the GCR through the IP link. The setup system supports the WAP protocol and standard industrial browsers.

【0068】

Call logs for all participants in the group call are collected for billing and network engineering. FIG. 12 shows an example of the group call service application described below. In the case of this example, CUG1 is a CUG containing four users A, B, C, D. Users A and B are currently receiving service from the group call exchange G1, user C is receiving service from the group call exchange G2, and user D is receiving service from the group call exchange G3. The user is already assigned a unique MIN by the group call service provider. For the sake of brevity, the unique MINs are referred to herein as A, B, C and D. CUG1 is assigned by the service provider and has a unique identifier, represented herein as CUG1. The definition of CUG1, i.e. the list of CUG member status, is maintained within a distributed component of CUG AD called AD1.

【0069】

In the case of the first example, the group call is made from A to group CUG1, ie B, C, D. FIG. 12 is a call flowchart of the group call. A makes a group call request to the closed user group CUG1. For the IS-634 interface, the request is represented by a CM_service_request containing CUG1. In the case of a radio access network (RAN), the request is very similar to any other call request. The IS-634 command and associated information element, along with other information items, include a calling number and a called number (eg, CUG1 in this example). In at least some cases, the RAN has no logic to distinguish a valid numbering plan from an invalid numbering plan as to what logic can be implemented within the MSC. In such cases, the RAN transfers the number information to the MSC as part of the IS-634 message set. As long as the proxy exchange is intercepting such messages, the proxy exchange can use the number information. Since the proxy exchange can act as an MSC in at least some way, the proxy exchange can determine that the input call request is not a traditional call request but a group call request to a closed user group. In such an example, the proxy switch acts as a group call switch and starts processing for the group call.

【0070】

The group call switch G1 issues a channel allocation request return to A. G1 also starts directory processing to retrieve the definition of group CUG1 from CUG AD component AD1. The response from AD1 is expected to include a list of members of group CUG1, ie, MINs corresponding to B, C and D. Upon receiving the response, G1 has already obtained the following information:

【0071】

CUG1 includes members B, C and D (in addition to A). MIN B is in charge of the exchange G1 (ie, itself). MIN C is in charge of the exchange G2.

【0072】

MIN D is in charge of the exchange G3. G1 initiates a call setup request to B (in charge of G1 itself) and sends a call setup request to G2 and G3 for C and D, respectively. Therefore, G2 and G3 act as proxy exchanges for G1 for this particular group call. G1 also ensures that TDM traffic is sent from the RAN to the media gateway. The media gateway translates the TDM traffic into RTP / UDP / IP packets and sends the RTP / UDP / IP packets to the multicast router. The multicast router receives the packet, adds A to the multicast group, and is instructed to multicast the packet to the specified multicast group. In the case of the call flowchart of FIG. 18, the above instructions are collectively shown in "Join Multicast Group (TDM A)".

【0073】

Next, G1 waits for connection messages from B, G2, and G3. You can receive any of these three messages in any order, or just a subset of them. In the case of this example, G1 first receives the connection message from B, and then receives the connection message from G2 and G3. When receiving a connection message from B, G1 sends a "Join Multicast Group (TDM B)" message, which causes the media gateway to accept RTP / UDP / IP traffic from the multicast router and RTP / Converts UDP / IP multicast to TDM and sends TDM to switch G1. Thereby, TDM is transmitted to B through BSC and BTS. The multicast router is instructed to add B to the current multicast group. Therefore, for the current group call, the switch G1 acts as a source for TDM traffic and the switch G2 acts as a sink for TDM traffic.

【0074】

In the case of this example, C sends a connection message to G2 (ie, C's switch), and G2 sends a connection message to G1. The G1 then sends a "Join Multicast Group (TDM C)" message to have C participate in the group call in receive mode. Similarly, the connection message from D to G3 is relayed to G1, which adds D to the multicast group.

【0075】

The media gateway is instructed by the control surface to receive or send packets on some RTP ports only in certain contexts. Packets are multicasts by routers to members of a multicast group.

【0076】

At this time, G1 has already received at least one confirmation of the user who has already participated in the group call, so G1 sends A a success tone to inform A that the group call can continue. .. The mode of A is the transmit mode, the modes of B, C and D are the receive modes, and the multicast router can perform multicast to B, C and D.

【0077】

In the case of another example, the control of speech is transferred as shown in the calling flowchart of FIG. More specifically, A relinquishes control of the voice and C regains it. To relinquish control of speech, A signals G1, which puts the current group call into inactive mode. (As explained above, if the user does not obtain the control of speech within the specified time measured by the system timer, the group call ends.) C issues a conversation acquisition command to the exchange G2 in charge. Issue. For the current group call, the exchanges G2 and G3 are on behalf of the control exchange G1, so the conversation acquisition command is relayed to G1. G1 issues a context modification command to the media gateway, so that the media gateway associated with the switch G2 accepts the input TDM traffic from C, converts the TDM traffic to RTP / UDP / IP, and RTP / UDP. Send / IP to the multicast router. The media gateway is instructed to stop receiving TDM traffic from A. The multicast router is instructed to change A's mode to receive mode and C's mode to transmit mode. G1 issues a conversation permission message to G2, which sends a success tone to C to let C know that the conversation can continue at this point. At this point, as shown in the figure, the multicast session can be continued with C as the talking user and A, B and D as the listening users.

【0078】

For example, if B issues a conversation acquisition message and C has speech control, the message is sent to B's switch G1 and G1 denies the request (C gives speech control). Send a failure tone message to B (because I haven't abandoned it).

【0079】

In the case of the other example, the situation is simple and the group call is made between two participants A and B. In this case, A has the right to speak. The network includes one group call switch G1 including the control surface CS and controls two media gateways MG1 and MG2. As shown in the call flowchart of FIG. 14, the traffic from / to A travels through MG1, and the traffic from / to B travels through MG2.

【0080】

Since A has say control, the system responds to control relinquish commands only from A. This command is received by the control surface CS of G1, which instructs MG1 to correct the context of the call by issuing a context correction command and revoking the permission of TDM traffic from A to MG1. The system goes into a non-operational state and waits for a control acquisition command. If the above command is not received within the specified time measured by the non-operation timer, a call release request is sent from CS to A and MS-B. In addition, a context discard command is sent to MG1 and MG2. When the release completion message is received from A and B and the context destruction completion message is received from MG1 and MG2, the group call release sequence ends.

【0081】

FIG. 15 is an example of a flow chart of a call for roaming, i.e., a database record that maintains location updates. Three mobile stations A, B and C are related. A and B are in charge of the control surface CS1 of the group call exchange, and C is in charge of the control surface CS2 of the other group call exchange. A roams and issues a location update, which CS1 receives through BTS and BSC. CS1 references the index based on the IMSI / MIN / ESN and issues a position update request to HLR'1 to determine the appropriate HLR' for A, for example HLR'1. HLR'1 determines all CUGs to which A belongs based on its database. With this information, HLR'1 issues a location update request to CUG AD. Therefore, CUG AD contains the updated position of A in the CUG to which A belongs.

【0082】

While roaming, B also issues a location update, which is sent to CS1. Based on the IMSI / MIN / ESN, CS1 determines the appropriate HLR'for B, i.e. HLR'2. CS1 issues a location update request to HLR'2 that discovers all the CUGs to which B belongs. HLR'2 issues a location update request to CUG AD, asking CUG AD to update all CUGs to which B belongs with B's new location.

【0083】

The position update from C is received by CS2. CS2 determines a suitable HLR', such as HLR'2, sends a location update to HLR'2, and asks CUG AD to update the corresponding CUG for C.<u style="single">Modification example</u>All of the above embodiments facilitate the execution of the group call of the present invention. However, the subset of features still has some advantages over the state of the art. For example, group calls on IP networks using techniques other than multicast still offer many of the above benefits. More specifically, standard telephone connections using the PTSN can be used instead of IP multicast connections.

【0084】

In other cases, the group call switch can be located on the trunk (back) side of the MSC. In the case of such an embodiment, the group calling function operates as described below.

【0085】

FIG. 16 shows a group call switch located on the back of the MSC. In this case, the fixed link uses a standard ISDN user portion (ISUP) landline signal. The MSC is connected to a home location register (HLR) that uses the IS-41 (also known as MAP) protocol. The group call switch and the MSC also interconnect bearer trunks that carry voice traffic between the two switches. The group call switch includes a TDM connection to the PSTN and an IP connection from the data side (also called the media gateway) to the IP network. The group call switch can also use IS-41 to query the HLR. (Figure 16 shows two MSC exchanges that are separately connected to the PSTN, but both of these exchanges can also be connected to the same PSTN.) Both group call exchanges are active directories (through the IP network). Access CUG AD).

【0086】

The arrangement of FIG. 16 can be used for group calls. For example, mobile station (MS) A can be connected to MSC-1 through RAN-1, or two mobile stations B and C can be connected to MSC-2 through RAN-2. Subscriber A can include CUGs, including B and C, as members. As described above, A can use a special group call start sequence to inform the MSC that he wants to make a group call. The logic of MSC-1 determines that the input call request is a group call, and bypasses the call request to the group call exchange GCS-1 by the ISUP protocol. The group call switch GCS-1 uses its internal logic to access the active directory CUG AD for the purpose of determining the members of the calling CUG.

【0087】

In the case of this example, the MIN numbers of members B and C can be obtained by inquiry. In this arrangement on the back of the MSC, the group call switch does not have access to location updates. Therefore, HLR'does not include the current location of the called mobile station. However, the HLR contains this information. Therefore, the group call switch GCS-1 can make an IS-41 inquiry (position request) to the HLR to inquire about the positions of mobile stations B and C. For the purposes of this example, mobile stations B and C can currently be located within the exchange area controlled by MSC-2. With standard mobile phone technology, this information is contained in the HLR database, at which point the HLR contacts the MSC-2 (through a "route request"). As long as the MSC-2 is using the GCS-2 on the trunk side, route requests from the HLR will be received by the GCS-2. GCS-2 returns a temporary local directory number (TLDN) to HLR, which forwards this information to the sender of the original location request (GCS-1). GCS-1 determines that TLDN belongs to GCS-2 and notifies GCS-2 of the group call. GCS-2 instructs MSC-2 to set up group calls to mobile stations B and C. In addition, the interaction with the non-backal side continues as described above, in which case the MSC-1 and MSC-2 are effectively transparent to the purpose of the group call.

【0088】

The back of the switch arrangement for group calls has ancillary advantages that can be seen in FIG. In such an arrangement, a conventional landline telephone such as the telephone D in FIG. 16 can also be associated with a group call. Therefore, CUG members can register landline telephone numbers as their "arrival" numbers in the CUG active directory. If such a subscriber, such as D, is to be included in the group call, the associated group call exchange will make a PSTN call to D by the arrival number remembered by the subscriber to the MSC providing the service. You can request it to end.

【0089】

As described above, IP multicast technology can be used as a basic forwarding technology for group calls. However, in at least some cases, standard implementation of IP multicast technology has been found to not fully meet the needs of widely distributed CUG members. The dynamic per-invocation setup of a multicast tunnel to carry traffic between multicast-enabled routers can take a very long time. A subscriber who has taken a long time to set up a group call can hang up the phone or make another call, which is unsatisfactory to the user. Also, if the call setup takes a long time, the network that sends the signal cannot be used efficiently.

【0090】

For example, as shown in FIG. 17, there are a large number of multicast-enabled routers in an IP network, such as MCR-1, MCR-2, and MCR-3. In the case of this example, the positions of these routers are fixed and unchanged. The multicast router is connected to a group call switch (in front of the MSC or on the back of the MSC as described above) and therefore connected to the mobile phone through the corresponding radio access network (RAN). There is. (Figure 17 shows individual multicast routers connecting to one group calling switch, but multiple group calling exchanges can also be connected to one router.) A subscriber is a member of the associated CUG. If a group call is initiated based on, one or more multicast routers can be associated with the call. More specifically, tunnels are set up between the corresponding multicast routers, as described above. Excessive delay in setting up these tunnels will degrade the quality of group calls.

【0091】

As just described, IP tunnels can be pre-set up in such a way that they can serve a large number of subsequent group call start requests. As long as the tunnel is set up in advance in anticipation of future group call requests, it can reduce or eliminate post-start setup delays. Relevant tasks include forecasting demand for group calls that are expected to arrive in the future, and determining the topology of IP tunnels that must be set up to meet the projected demand.

【0092】

Forecasting demand depends on historical information in the form of group call logs. The history of group calls is divided into a series of windows. In this case, each window is defined by a length of time called the "window size". The window size can range from minutes to tens of minutes and is proportional to the average retention time of the group call. The actual window size used in the demand forecast will vary depending on the required accuracy of the forecast and the computational resources used to make the forecast. Generally, the smaller the window size, the more accurate the prediction, but the more computational resources are wasted when compared to the larger window size. Also, smaller window sizes tend to respond faster to burst traffic and less likely to average out deviations. Each window contains a large number of group call requests along with a parameter that describes the call, namely the number of GIR calls between any two multicast routers. In the following description, X (I, J, N) indicates the number of group calls between routers I and J in window N.

【0093】

The example below is a forecast of future demand for group calls. In the case of this example, the group call history is divided into four windows. In this case, window 1 is the earliest window in time and window 4 is the slowest window in time (ie, the current window). The following smoothing formula is used to calculate the demand in the next (future) window, namely window 5. X (I, J, 5) = (1-α)^*X (I, J, 4) + α^*(1-α)^*X (I, J, 3) + α^*α^*(1-α)^*X (I, J, 2) + α^*α^*α^*(1-α)^*In equation X (I, J, 1), α (alpha) is an empirically determined weighting factor with a value between 0 and 1. As shown in this equation, the traffic prediction for the next window of time is focused on the new window rather than the previous window. This emphasis becomes apparent when the formula is rewritten in a more general form of reproduction. X (I, J, N) = (1-α)^*X (I, J, N-1) + α^*X'(I, J, N-1) where X'(I, J, N-1) is a smoothed estimate that includes the past history up to N-1.

【0094】

In the formula, "current" means the newest window in the time series. Based on this equation and a given history of demand (windows 1-N), the values in rows I and column J represent the predicted number of group calls in the upcoming window between multicast routers I and J. Thus, a table of values T (I, J) (demand matrix) can be calculated for the next window, as shown by the values of parameter X (I, J, N) as an example.

【0095】

The following information is used as input regarding the determination of the tunnel topology to meet the demand. The information below is a two-point demand matrix for group calls between any two multicast routers, the cost structure of a tunnel by a service provider, that is, to establish a tunnel of a particular capacity between any two routers. Cost, service provider delay guarantee, that is, maximum delay in the IP forwarding network between any two specific multicast routers, and quality of service (QoS) limits that group calls must meet.

【0096】

In consideration of such an input, the topology of the tunnel between the multicast routers, that is, which tunnel of which capacity is connected to which multicast router is determined so that the topology satisfies the following restrictions. The following limits are that the tunnels exiting each multicast router do not exceed the total output capacity of the router (in bits per second) and that the number of tunnels exiting each multicast router does not exceed the internal limit on the number of tunnels in the router. That is.

【0097】

As described below, the mathematical optimization technique of Integer Linear Programming (ILP) is used to determine the minimum cost topology, taking into account the following points, as described below: .. The following points are the recognition that the case is "NP hard"; the formalization of the task as a degree constrained multi-commodity flow that can be solved by ILP technology.

【0098】

According to the theory of NP hardness, cases that can be shown to be NP hard cannot be expected to have an efficient N algorithm solution. For example, a given case, such as X, can be considered, for example, by considering a case that is already considered NP hardware, such as Y, and by proving that Y becomes X in a polynomial time conversion. It can be proved that it is NP hard. The case of tunnel topology design can be proved to be NP hard by observing that it is a generalization of the indivisible multiple commodity flow problem (1996 Computer Science Foundation 37th). See J. Kleinberg's "Single source unsplittable flow" in the minutes of the IEEE Symposium).

【0099】

Therefore, the tunnel topology case can be rewritten in the following form, which is suitable for applying ILP approximation techniques. &lt;Input&gt; N shall indicate the number of multicast routers in the network.

【0100】

Suppose D (max, I) indicates the maximum number of tunnels that Router I can set up. Let P (t, l) indicate the unit cost of tunnel l for a trunk of type t. Here, "l" is a pair of nodes l = (i, j) for multicast-enabled routers (MCR) i and j.

【0101】

Suppose τ (tau) indicates a set of trunks of all possible types (DS0, DS1, OC3, etc.). Let T (I, J) represent the demand matrix, i.e., the predicted group call traffic between Routers I and J for a given future period.

【0102】

Let C (I) indicate the capacity of Router I in bits per second. Suppose R (I, J) is a set of all viable routes for routing traffic between routers I and J. (This is the pre-processing step that produces all the viable quality of the service path between MCRI and J.) &lt;Output determinant&gt; Y (t, l): Type t trunk assigned on link 1. Number of units X (p): Amount of traffic flow on path p z_l: A binary variable with a value of 1 if the link "l" is assigned to a non-zero capacity; otherwise its value is zero &lt;ILP formulation&gt; minimized.

【0103】

[Number 1]<img file="JP2005506728A_D0001.tif" />The conditions are as follows. -Demand Satisfaction (Tunnel Topology Satisfies Demand Matrix): [0104]

[Number 2]<img file="JP2005506728A_D0002.tif" />-Sufficient tunnel capacity (all flows on all routes can be processed with the capacity of the selected trunk): [0105]

[Number 3]<img file="JP2005506728A_D0003.tif" />-Port restriction (the number of tunnels entering and exiting the router does not exceed the maximum internal setting of the router): [0106]

[Number 4]<img file="JP2005506728A_D0004.tif" />The above analysis is formulated as follows.<u style="single">input</u>N: Number of routers D_i^max: Maximum number of tunnels that Router i can set up p_l^t:type<u style="single">t</u>Tunnel to the trunk<u style="single">l</u>Unit cost τ: Set of trunks of all possible types T_{(I, J)}: Demand Matrix T (I, J) C_i: Router i capacity (bits per second) R_ij: A set of all viable routes for routing traffic between routers i and j<u style="single">Output decision variable</u>y_l^t:Link<u style="single">l</u>Number of units of type t trunk assigned to x_p: Amount of flow (traffic amount) on path p z_l: = 1 (if link l is allocated to non-zero capacity) = 0 (if not)<u style="single">ILP formulation</u>Minimize.

【0107】

[Number 5]<img file="JP2005506728A_D0005.tif" />The conditions are as follows. Satisfaction of demand [0108]

[Number 6]<img file="JP2005506728A_D0006.tif" /> Sufficient tunnel capacity [0109]

[Number 7]<img file="JP2005506728A_D0007.tif" /> Port restriction [0110]

[Number 8]<img file="JP2005506728A_D0008.tif" /> Tunnel existence restriction [0111]

[Number 9]<img file="JP2005506728A_D0009.tif" />Here, the damping coefficient ε is a user-given parameter having a value greater than zero.

【0112】

Further, to the extent of the embodiments described in the context of specific radio technologies such as the TDMA protocol or the CDMA protocol, the embodiments also include TDMA, CDMA, GSM, IS-136 and other second generation and first generations. It can be modified to work with radio technologies that include one or more of the three generations of protocols.

【0113】

Although the embodiments have been described as examples, it is clear that those skilled in the art can make various modifications to the embodiments without departing from the spirit and scope of the present invention.

[Simple explanation of drawings]

【0114】

FIG. 1 is a conceptual diagram showing a mobile communication network system according to a conventional technique.

FIG. 2 is a block diagram showing a conventional interface between a BS and a mobile exchange in a conventional mobile communication network.

FIG. 3 is a block diagram of a system including group call logic.

FIG. 4 is a block diagram showing a proxy exchange and some installed devices in a mobile communication network.

FIG. 5 is a block diagram showing a proxy exchange and some installed devices in a mobile communication network.

FIG. 6 is a block diagram of a data surface illustrating a proxy switch according to a preferred embodiment of the present invention.

FIG. 7 is a block diagram showing an architecture of a group communication system.

FIG. 8A is a calling flowchart of how to use the group communication system.

FIG. 8B is a calling flowchart of how to use the group communication system.

FIG. 8C is a calling flowchart of how to use the group communication system.

FIG. 9 is a block diagram showing an architecture of a group communication system.

FIG. 10 is a flowchart of a group call logic.

FIG. 11 is a calling flowchart of how to use the group communication system.

FIG. 12 is a calling flowchart of how to use the group communication system.

FIG. 13 is a calling flowchart of how to use the group communication system.

FIG. 14 is a calling flowchart of how to use the group communication system.

FIG. 15 is a calling flowchart of how to use the group communication system.

FIG. 16 is a block diagram showing an architecture of a group communication system.

FIG. 17 is a block diagram showing an architecture of a group communication system.