Patent Publication Number: US-2009239567-A1

Title: Poc server automatic search method, quality adjustment method, and communication system using these methods

Description:
TECHNICAL FIELD 
     The present invention relates to a communication technology for communicating media information such as text data, voice data, and moving image data through a server using a network. 
     BACKGROUND ART 
     In recent years, due to the spread of the Internet and the progress in wireless communication networks, communication providers of cell phone and the Like have begun to provide services for communicating various media on IP networks. 
     These services include chat services based primarily on text data and PoC services based primarily on voice data. In either case, services that include a method for offering a convenience to the user are provided in which connection destination information (a group list or the like) is listed through a server, the user selects a connection destination, and the communication is started. 
       FIG. 4  is a functional block diagram showing a general service system configuration example. As shown in  FIG. 4 , terminal devices  1 -( 1 ),  1 -( 2 ), . . .  3 -( 2 ) ( 6 A( 1 ),  6 A( 2 ), . . .  6 C( 2 )) are terminals connected to networks using wireless networks provided by communication providers. As shown in  FIG. 4 , as for the wireless networks, networks  3 A,  3 B, and  3 C provided by the communication providers are often different, such as a W-CDMA network, a GPRS network, and a W-LAN network, depending on the communication providers. 
     The communication providers permit access to communication provider networks ( 1  to  3 )  3 A to  3 C provided by communication enterprises through wireless base station devices ( 1  to  3 )  5 A to  5 C and network connection devices ( 1  to  3 )  4 A to  4 C. 
     A PoC server and a GL server are installed on each of the communication provider networks ( 1  to  3 )  3 A to  3 C, and each terminal device receives services by accessing the PoC server and the GL server, acquiring a group list, and performing a connection process for starting the PoC services. 
       FIG. 5  is a sequence diagram of a connection destination acquisition process in the system shown in  FIG. 4 . As shown in  FIG. 5 , in a sequence example when the connection is possible, a terminal device  6  requests acquisition of a group list to a GL server  3 A- 2 , and the GL server  3 A- 2  queries a PoC server  3 A- 1  for free space. When the connection is possible, the PoC server  3 A- 1  responds to the GL server  3 A- 2  that there is a free space, and the GL server  3 A- 2  transmits connection destination information to the terminal device  6 . The connection is made based on this. When the connection is not possible, a response indicative of no free space is returned.  FIG. 5(B)  is a group list example when the connection is possible, and since the number of currently connected users is 3 while the number of maximum users is 5, there is a free space.  FIG. 5(C)  is a group list example when the connection is not possible, and since the number of currently connected users is 3 while the number of maximum users is 3, there is no free space. 
       FIG. 6  is a diagram showing a sequence example of PoC connection. Hereinafter, when a plurality of terminal devices  6  exist, the terminal devices  6  are denoted as terminal devices ( 1 )  6 A- 1 , ( 2 )  6 A- 2 , and so forth. With reference to  FIG. 6 , a PoC connection sequence example between the terminal device ( 1 )  6 A- 1 , the PoC server  3 A- 1 , and the terminal device ( 2 )  6 A- 2  in the above configuration will be described. However, the description in relation to a message transmitted and received between the terminal devices and the PoC server is omitted, and only a message related to the quality or the like will be focused and described. 
     As shown in  FIG. 6 , an INVITE signal transmitted from the terminal device ( 1 )  6 A- 1  reaches the terminal device ( 2 )  6 A- 2  through the PoC server  3 A- 1 . At this point, SDP (Session Description Protocol) information including parameters, such as Ptime, that defines the length of voice data is provided. Subsequently, an OK signal is returned from the terminal device ( 2 )  6 A- 2  to the terminal device ( 1 )  6 A- 1  through the PoC server  3 A- 1 . The SDP information is also included at this point. 
     The PoC server  3 A- 1  changes the values of the information related to the quality, such as Ptime of the SDP information transmitted from the terminal device ( 1 )  6 A- 1  and the SDP information transmitted from the terminal device ( 2 )  6 A- 2 , in accordance with optimal values within the same communication provider network and the voice data conversion capability of the PoC server  3 A- 1 . 
     The terminal device ( 1 )  6 A- 1  transmits voice data  1  in accordance with parameter values included in the SDP information, and the PoC server  3 A- 1  converts part of the voice data and transmits the voice data to the terminal device ( 2 )  6 A- 2 , thereby enabling to maintain a certain quality. Although an example has been described herein in which the signal is transmitted in the order of terminal device ( 1 )  6 A- 1 →PoC server  3 A- 1 →terminal device ( 2 )  6 A- 2 , voice data transmitted in the order of, for example, terminal device ( 2 )  6 A- 2 →PoC server  3 A- 1 →terminal device ( 1 )  6 A- 1  can be considered in a similar way. Non-Patent Document 1: OMA Push to talk over Cellular (PoC) Architecture Candidate Version 1.0 (OMA-AD_PoC-V1 — 0-20051006-C), URL: http://www.openmobilealliance.org/releaseprogram/poc-v1 — 0.html 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     In conventional services for communicating various media, there are limits to the number of users, the number of group lists, and the like that the servers provided by communication providers can handle. The user cannot receive services when users beyond the capability of the servers simultaneously try to communicate. 
     Furthermore, in order to communicate information, such as a group list, between different communication providers, a roaming agreement needs to be signed in advance between the different communication providers, address information of a GroupList server, a PoC server, or the like needs to be exchanged in advance, and the sequential establishment of environments allowing mutual operations of services is needed. 
     Moreover, when the PoC services are provided using PoC servers installed on different communication provider networks, data jitters or the like are changed because the distances between the terminal devices and PoC servers in networks are changed. Therefore, in the case of voice data, there was a problem that voice discontinuity or noise was generated, thereby degrading the service quality. 
     The object of the present invention is to solve the problems caused by differences between communication providers. 
     Means for Solving the Problems 
     One aspect of the present invention provides a communication system characterized by comprising a plurality of communication provider network systems, each of the communication provider network systems including: a GroupList server (GL server) that provides a group list related to terminal devices belonging to the communication provider network system; and a PoC server that exchanges information related to registration of the group list and existence of free space for terminal devices, the plurality of the communication provider network systems connected through a network, the communication system further comprising a PoC domain server connected to the network and performing communications across the GL servers belonging to the plurality of communication provider network systems, the communications including registration of group list information and querying. 
     This allows the user to receive services of PoC and the like from a terminal device by automatically searching another server when users beyond the capability of a server simultaneously try to communicate. 
     Also provided is a PoC domain server used for a communication system comprising a plurality of communication provider network systems, each of the communication provider network systems including: a GL server that provides a group list related to terminal devices belonging to the communication provider network system; and a PoC server that exchanges information related to registration of the group list and existence of free space for the terminal devices, the plurality of communication provider network systems connected through a network, the PoC domain server connected to the network and performing communications across the GL servers belonging to the plurality of communication provider networks, the communications including registration of group list information and querying. 
     Another aspect of the present invention provides a communication method in a communication system, the communication system comprising a plurality of communication provider network systems, each of the communication provider network systems including: a GL server that provides a group list related to terminal devices belonging to the communication provider network system; and a PoC server that exchanges information related to registration of the group list and existence of free space for the terminal devices, the plurality of communication provider network systems connected through a network, the communication method characterized by comprising: a step of the GL server in each communication provider network system registering in advance as a GL server with a PoC domain server installed on the network; and a step of querying another PoC server for a free space in response to a request for acquiring a group list from the terminal device to the GL server, acquiring a response, requesting the PoC domain server to acquire a domain when the connection to the another PoC server is not possible, and the PoC domain server receiving domain information of a selected GL server based on the registration. 
     Preferably, the communication method comprises a step of returning the group list from the another GL server to the terminal device with reference to connection destination information generated based on the domain name of the PoC server that has performed querying and based on existing user information registered in the group list, when, in response to the query of free space to the another GL server based on the acquired domain information, the query is relayed from the another CL server to the PoC server in the communication provider network system to which the CL server belongs and the response indicative of free space is returned. 
     ADVANTAGES OF THE INVENTION 
     The present invention facilitates the user to receive services of PoC and the like from a terminal device by automatically searching another server when users beyond the capability of a server simultaneously try to communicate. 
     The present invention also enables to exchange in advance address information of GroupList servers, PoC servers, and the like through the PoC domain server for execution between different communication providers and enables to receive services from different communication providers and server providers without undergoing the procedure of roaming agreement and the like. 
     Furthermore, the present invention adjusts information of jitter amount and the like between PoC servers in advance, thereby enabling to minimize the quality degradation when PoC servers of different communication providers and server providers are used. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing one configuration example of a communication system according to one embodiment of the present invention; 
         FIG. 2  is a diagram showing a sequence example of connection destination acquisition according to the present embodiment; 
         FIG. 3  is a diagram showing a sequence example of PoC connection according to the present embodiment; 
         FIG. 4  is a diagram showing a general system configuration example; 
         FIG. 5  is a diagram showing a sequence example of general connection destination acquisition; and 
         FIG. 6  is a diagram showing a general PoC connection sequence example. 
     
    
    
     DESCRIPTION OF SYMBOLS 
     
         
           1  . . . Internet 
           2  . . . PoC domain server 
           3 A/ 3 B/ 3 C/ 3 D . . . communication provider networks  1  to  3 , and server provider network  4  (including PoC server and GL server) 
           4 A/ 4 B/ 4 C . . . network connection devices  1  to  3   
           5 A/ 5 B/ 5 C . . . wireless base station devices  1  to  3   
           6 A( 1 )/ 6 A( 2 ) . . . terminal devices  1 -( 1 ) and  1 -( 2 ) 
           6 B( 1 )/ 6 B( 2 ) . . . terminal devices  2 -( 1 ) and  2 -( 2 ) 
           6 C( 1 )/ 6 C( 2 ) . . . terminal devices  3 -( 1 ) and  3 -( 2 ) 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     A service system according to one embodiment of the present invention will now be described with reference to the drawings. One configuration example of the service system according to one embodiment of the present invention is shown in  FIG. 1 . Similar components as in  FIG. 4  are designated with the same reference numerals. As shown in  FIG. 1 , the configuration of the service system according to the present embodiment is different from the configuration shown in  FIG. 4  in that the service system includes a server provider network  4  in addition to the communication provider networks  1  to  3 , and that the communication provider networks  1  to  3  and the server provider network  4  are configured to be able to communicate with the PoC domain server  2  through the Internet  1 . While the communication provider networks  1  to  3  are connected to the terminals  6 A to  6 C through the network connection devices  1  to  3  and the wireless base stations  5 A to  5 C, the server provider network  4  is connected to the communication provider networks  1  to  3  through the Internet  1  and connected to the terminals  6 A to  6 C through the communication provider networks  1  to  3 . A server provider network ( 4 )  3 D having a PoC server  3 D- 1  and a GL server  3 D- 2  is also added. 
       FIG. 2  is a diagram showing a connection destination acquisition sequence example in the service system according to the present embodiment. The GL servers ( 1  and  2 )  3 A- 2  and  3 B- 2  in the communication providers are registered in advance as GroupList servers to the PoC domain server  2  installed on the Internet  1  ( 11 ). In  FIG. 2 , the GL server ( 1 )  3 A- 2  is first registered, and then the GL server ( 2 )  3 B- 2  is registered ( 12 ). 
     Subsequently, the terminal device  6 A transmits a GroupList acquisition request to the GL server ( 1 )  3 A- 2  ( 13 ). In response, the GL server ( 1 )  3 A- 2  first queries the PoC server ( 1 )  3 A- 1  for free space ( 14 ), and then the PoC server ( 1 )  13 A- 1  returns a response indicative of no free space ( 15 ). 
     Subsequently, recognizing that no connection to the PoC server ( 1 )  13 A- 1  is possible, the GL server ( 1 )  3 A- 2  transmits a domain acquisition request to the PoC domain server  2  ( 16 ). The PoC domain server  2  selects a pre-registered GL server and returns domain information ( 17 ) (domain information for accessing the GL server ( 2 )  3 B- 2 , herein). 
     The GL server ( 1 )  3 A- 2  queries, for example, the GL server ( 2 )  3 B- 2  for free space based on the acquired domain information ( 18 ), and the query is relayed from the GL server ( 2 )  3 B- 2  to the PoC server ( 2 )  3 B- 1  ( 19 ). 
     When there is a free space in the PoC server ( 2 )  3 B- 1 , a response indicative of free space in the CL server ( 2 )  3 B- 2  is returned from the PoC server ( 2 )  3 B- 1  ( 20 ) and relayed to the GL server ( 1 )  3 A- 2  ( 21 ). 
     The GL server ( 2 )  3 B- 2  generates connection destination information based on the domain name of the PoC server that has queried and existing user information registered in the group list and then returns the GroupList information to the terminal device  6 A ( 22 ). 
     Based on this, INVITE of connection is performed to the PoC server ( 1 )  3 A- 1  ( 23 ), and INVITE of connection is further performed to the PoC server ( 2 )  3 B- 1  ( 24 ). Although an example has been shown above in which the numbers of the GL servers and the PoC servers registered in the PoC domain server  2  are two, the numbers may be more than two. Furthermore, a server provider that provides only the GL servers and the PoC servers can also communicate in a similar procedure because the PoC domain server is installed on the Internet. Similarly, a GroupList server (GL server)  3 D- 1  that provides a group list related to the terminal devices and a PoC server  3 D- 2  that exchanges information related to the registration of the group list as well as the existence of free space for the terminal devices can be functioned. 
     A PoC connection sequence example according to the present embodiment will be described with reference to  FIG. 3 . 
     First, a quality adjustment sequence denoted with ( 1 ) will be described. Having acquired the group list, the GL server ( 1 )  3 A- 2  transmits in advance an adjustment request  31  to the PoC server ( 1 )  3 A- 1 , and the adjustment request is relayed to the PoC server ( 2 )  3 B- 1 . The PoC server ( 2 )  3 B- 1  transmits and receives adjustment data between the PoC server ( 1 )  3 A- 1  ( 32  and  33 ) to thereby measure characteristics (characteristics such as voice data size and jitter) between the PoC server ( 1 )  3 A- 1  and the PoC server ( 2 )  3 B- 1  and store the adjusted values ( 34 ). 
     The PoC server ( 2 )  3 B- 1  changes values of information related to the quality, such as Ptime of SDP information transmitted from the terminal device ( 1 )  6 A( 1 ) and SDP information transmitted from the terminal device ( 2 )  6 B( 1 ), in accordance with optimal values in the communication provider network, voice data conversion capability of the PoC servers, and the present adjusted values. 
     For example, the optimal value of Ptime in the communication provider network that the PoC server ( 1 )  3 A- 1  belongs to is assumed to be 200 ms, the jitter amount is assumed to be 100 ms, the optimal value of Ptime in the communication provider network that the PoC server ( 2 )  3 B- 1  belongs to is assumed to be 160 ms, the jitter amount is assumed to be 80 ms, and the jitter amount as an adjusted value between the PoC server ( 1 )  3 A- 1  and the Poe server ( 2 )  3 B- 1  is assumed to be 120 ms. 
     Ptime is changed so as to always have a maximum value, while the value of the jitter amount is changed by adding received values. 
     SDP of terminal device ( 1 )  6 A( 1 )→PoC server ( 1 )  3 A- 1   
     Ptime=100 ms, jitter amount=50 ms 
     SDP of PoC server ( 1 )  3 A- 1 →PoC server ( 2 )  3 B- 1   
     Ptime=200 ms, jitter amount=50 ms+100 ms (* 1 )=150 ms
         *1: jitter value in the communication provider that the PoC server ( 1 )  3 A- 1  belongs to       

     SPD of PoC server ( 2 )  3 B- 1 →terminal device ( 2 )  6 B( 1 ) 
     Ptime 200 ms, jitter amount=150 ms+120 ms (adjusted value)+80 ms (*2)=350 ms
         *2: jitter value in the communication provider that the PoC server ( 2 )  3 B- 1  belongs to       

     The changes in the value of Ptime and the value of jitter amount can be handled by changing the reference method and the calculation method of the adjusted values in the PoC server ( 2 )  3 B- 1 . 
     As described above, the present embodiment allows the user to receive services of PoC and the like from a terminal device by automatically searching another server when users beyond the capability of a server simultaneously try to communicate. 
     The present embodiment also enables to exchange in advance address information of GroupList servers, PoC servers, and the like through the PoC domain server for execution between different communication providers and enables to receive services from different communication providers and server providers without undergoing the procedure of roaming agreement and the like. 
     Furthermore, the present embodiment adjusts information of jitter amount and the like between PoC servers in advance, thereby enabling to minimize the quality degradation when PoC servers of different communication providers and server providers are used. 
     In the above embodiment, although an example of PoC services has been described, the present invention is not limited only to the PoC services, but can be widely used for communication services such as chats and moving images. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be utilized as a communication technology for communicating media information such as text data, voice data, and moving image data through a server using a network.