Abstract:
A method for a Portable Subscriber Station (PSS) to be provided with a service in a communication system where heterogeneous networks interwork with each other. The method includes receiving a first message including an authorization token that is bearer resource authorization information, generating a flow identifier for distinguishing between at least one service flows by referring to Session Description Protocol information of the PSS, and transmitting a second message including the authorization token and the flow ID.

Description:
PRIORITY 
       [0001]    This application claims priority under 35 U.S.C. § 119(a) to a Korean Patent Application filed in the Korean Intellectual Property Office on Apr. 26, 2006 and assigned Serial No. 2006-37690 and a Korean Patent Application filed in the Korean Intellectual Property Office on Jul. 7, 2006 and assigned Serial No. 2006-63871, the disclosures of each of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to a method for providing a service between heterogeneous networks, and in particular, to a method for providing a service in interworking between an Internet Protocol (IP) Multimedia Subsystem (IMS) network and another type of network. 
         [0004]    2. Description of the Related Art 
         [0005]    An IMS network is intended to provide an IP-based packet communication system. The IMS network is based on a Session Initiation Protocol (SIP) that is a text-based application layer control protocol. The SIP is based on a client/server structure in which a server responds as clients start calling. The SIP has a function in which one or more participants can make, modify, and terminate a session. 
         [0006]    Thus, the IMS network is expected to serve as an infra network for providing a Voice over IP (VoIP) service and a multimedia service in an integrated wired/wireless network. However, a scheme for providing various services in interworking between the IMS network and another type of network has not yet been defined. 
       SUMMARY OF THE INVENTION 
       [0007]    An aspect of the present invention is to address at least the above problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a method for providing a service in interworking between an IMS network and another type of network. 
         [0008]    According to one aspect of the present invention, there is provided a method for a Portable Subscriber Station (PSS) to be provided with a service in a communication system where heterogeneous networks interwork with each other. The method includes receiving a first message including an authorization token that is bearer resource authorization information, generating a flow identifier (ID) for distinguishing between at least one service flows by referring to Session Description Protocol (SDP) information of the PSS, and transmitting a second message including the authorization token and the flow ID. 
         [0009]    According to another aspect of the present invention, there is provided a method for a Base Station (BS) to provide a service in a communication system where heterogeneous networks interwork with each other. The method includes receiving a first message including a flow ID for distinguishing at least one service flows and an authorization token that is bearer resource authorization information from a PSS, transmitting a second message including binding information, i.e., combined information of the flow ID and the authorization token, generating a Service Flow ID (SFID) that logically corresponds to the flow ID, and mapping the generated SFID and the flow ID to each other. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The above and other features and advantages of exemplary embodiments of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0011]      FIG. 1  illustrates a system where an IMS network and a portable Internet network interwork with each other according to the present invention; 
           [0012]      FIG. 2  illustrates mapping for providing a Quality of Service (QoS) in a system where an IMS network and a portable Internet network interwork with each other according to the present invention; 
           [0013]      FIG. 3  is a signal flow diagram illustrating a call connection procedure according to a first embodiment of the present invention; 
           [0014]      FIG. 4  is a signal flow diagram illustrating a call connection procedure according to a second embodiment of the present invention; 
           [0015]      FIG. 5  is a flowchart illustrating a process in which a Portable Subscriber Station (PSS) is provided with a service according to the present invention; 
           [0016]      FIG. 6  is a flowchart illustrating a process in which a BS is provided with a service according to the present invention; and 
           [0017]      FIG. 7  illustrates a process in which a BS maps a flow ID and an SFID to each other according to the present invention. 
       
    
    
       [0018]    Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features and structures. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    The matters defined in the description, such as construction, elements, etc., are provided to assist in a comprehensive understanding of preferred embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
         [0020]    The present invention provides a method for providing a service between heterogeneous networks. The heterogeneous networks may be an Internet Protocol (IP) Multimedia Subsystem (IMS) network and a portable Internet network. Although a method for providing a service in interworking between the IMS network and the portable Internet network will be described, the present invention can also be applied to provide a service between the IMS network and any type of network capable of interworking with the IMS network. 
         [0021]      FIG. 1  shows a system in which an IMS network and a portable Internet network interwork with each other according to the present invention. The system includes an IMS core network  100 , an Access Control Router (ACR)  110 , a Radio Access Station (RAS)  120 , a Portable Subscriber Station (PSS)  130 , a Correspondent Node (CN)  140 , and a policy server  150 . The system may further include an Authentication, Authorization, and Accounting (AAA) server (not shown). 
         [0022]    The IMS core network  100  may include an IMS server, a Home Subscriber Server (HSS), and a multimedia content providing server, and has a Session Initiation Protocol (SIP) interface with the PSS  130 . 
         [0023]    The ACR  110  manages connection and mobility of a user and provides interfaces with the RAS  120  and the IMS core network  100 . The ACR  110  also exchanges functions related to an IP Convergence Sublayer (CS) with the RAS  120 . The interface with the IMS core network  100  may be a Common Open Policy Server (COPS) interface. The ACR  110  may use a diameter interface with the AAA server (not shown). The ACR  110  allocates a unique service flow to each service connection. 
         [0024]    The RAS  120  is positioned between the ACR  110  and the PSS  130  in order to provide a communication service to the PSS  130  or perform scheduling based on Medium Access Control (MAC) Quality of Service (QoS) information. 
         [0025]    The PSS  130  can be provided with various services such as a VoIP service and supports the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard. 
         [0026]    Once the PSS  130  sets up a call through SIP signaling, the policy server  150  is notified of call generation from the IMS server. The policy server  150  then generates an identifier for each flow of a session, i.e., a flow identifier (ID), and QoS profile information. The generated information is transmitted to the ACR  110  and the ACR  110  applies a QoS for each service flow based on the received information. 
         [0027]      FIG. 2  illustrates mapping for providing a QoS in a system where an IMS network and a portable Internet network interwork with each other according to the present invention. The system may include a portable Internet network including a PSS  200  and a Base Station (BS)  210  and an IMS network including an IMS server  220  and a policy server  230 . The BS  210  includes an RAS and an ACR. 
         [0028]    The PSS  200 , the BS  210 , the IMS server  220 , and the policy server  230  include units that operate in terms of hardware and/or software in order to provide a QoS and the units maintain and manage profile information for application QoS  201 ,  209 , and  211 ,  16  MAC QoS  203 ,  207 , and  215  and IP QoS  205  and  213 . 
         [0029]    Profile information for each QoS can be configured as follows.
       Application QoS       
 
         [0031]    Connection information 
         [0032]    Media format information 
         [0033]    Bandwidth information
       IP QoS       
 
         [0035]    Packet classification (5 tuples): Source IP address, Destination IP address, Protocol, Source port number, and Destination port number. 
         [0036]    QoS service class: DSCP (Diffserv Code Point) 
         [0037]    QoS data rate
       16 MAC QoS       
 
         [0039]    Service flow scheduling type 
         [0040]    Tolerated jitter 
         [0041]    Maximum latency 
         [0042]    Maximum sustained traffic rate 
         [0043]    Maximum traffic burst 
         [0044]    Maximum reserved traffic rate 
         [0045]    Maximum tolerable traffic rate 
         [0046]      FIG. 3  shows an example of a call connection procedure according to the present invention. A PSS 1   300  as a source terminal transmits a Session Initiation Protocol INVITE (SIP_INVITE) message to an IMS server  330  in order to set up connection of a call, e.g., a VoIP call, destined to a destination terminal, i.e., a PSS 2   340  in step  301 . The SIP_INVITE message includes Session Description Protocol (SDP) information of the PSS 1   300 . The SDP information includes QoS information and bearer related information of the PSS 1   300 . 
         [0047]    The IMS server  330  transmits the SIP_INVITE message to the PSS 2   340  in step  303 . The PSS 2   340  transmits an SIP  183  message to the IMS server  330  in step  305 . The SIP  183  message includes SDP information of the PSS 2   340 . 
         [0048]    The IMS server  330  transmits an authorization request message including SDP information including bearer information for a session to a policy server  320  in step  307 . The policy server  320  generates an authorization identifier, i.e., an authorization token, and a flow ID and transmits an ACKnowledge (ACK) message including the generated authorization token and flow ID to the IMS server  330  in step  311 . The authorization token includes information about a policy server that manages a QoS profile of a session and QoS authorization information. 
         [0049]    The IMS server  330  transmits an SIP  183  message including the authorization token to the PSS 1   300  in step  313 . The PSS 1   300  generates a flow ID in step  315  and encapsulates the QoS information of the PSS 1   300  and the authorization token received from the IMS server  330  into a Dynamic Service Addition-REQuest (DSA-REQ) message and transmits the DSA-REQ message to a BS  310  in step  317 . The DSA-REQ message is a message requesting connection setup for a session. 
         [0050]    The BS  310  transmits a Common Open Policy Server-DECision (COPS-DEC) message including binding information to the policy server  320  in step  319 . The binding information means combined information of the authorization token and the flow ID. 
         [0051]    The policy server  320  transmits the COPS-DEC message to the BS  310 . The COPS-DEC message may include information indicating whether or not service connection is successful. Subsequent processes are not associated with the subject matter of the present invention and thus will not be described. 
         [0052]      FIG. 4  shows another example of a call connection procedure according to the present invention. A PSS 1   400  as a source terminal transmits an SIP_INVITE message to an IMS server  430  in order to set up connection of a call, e.g., a VoIP call, destined to a destination terminal, i.e., a PSS 2   440  in step  401 . The SIP_INVITE message includes SDP information of the PSS 1   400 . The SDP information includes QoS information and bearer related information of the PSS 1   400 . 
         [0053]    The IMS server  430  transmits the SIP_INVITE message to the PSS 2   440  in step  403 . The PSS 2   440  transmits an SIP  183  message to the IMS server  430  in step  405 . The SIP  183  message includes SDP information of the PSS 2   440 . 
         [0054]    The IMS server  430  transmits an authorization request message including SDP information including bearer information for a session to a policy server  420  in step  407 . The policy server  420  generates an authorization identifier, i.e., an authorization token, and a flow ID and transmits an ACKnowledge (ACK) message including the generated authorization token and flow ID to the IMS server  430  in step  411 . 
         [0055]    The IMS server  430  transmits the SIP  183  message including the authorization token to the PSS 1   400  in step  413 . The PSS 1   400  generates a flow ID for identifying a flow for each medium using its own SDP information in step  415  and transmits a DSA-REQ message including the authorization token received from the IMS server  430  and the generated flow ID in step  417 . 
         [0056]    The BS  410  transmits a COPS-REQ message including binding information, i.e., combined information of the authorization token and the flow ID, to the policy server  420  in step  419 . The BS  410  then maps the flow ID and a Service Flow IDentifier (SFID) to each other in step  412 . The SFID is generated by the BS  410  and the BS  410  logically maps the flow ID and the SFID to each other. The flow ID is used to identify a flow for each medium based on SDP information and the SFID means an identifier for unidirectional connection having a particular QoS. 
         [0057]    The flow ID is flow information of an application layer, whereas the SFID is flow information of an MAC layer. The flow ID included in the DSA-REQ message received from a PSS is identical in a downlink and an uplink, whereas the SFID has to have a value for distinguishing between a downlink and an uplink. For this reason, the flow ID that is identical in the uplink and the downlink has to be mapped to the SFID that is different in the uplink and the downlink in step  421 . Step  421  will be described in more detail with reference to  FIG. 7 . 
         [0058]    The mapped information will serve as binding information for mapping the SFID using QoS profile information provided from the policy server  420  using the flow ID. 
         [0059]    The policy server  420  transmits a COPS-DEC message including QoS information and classifier information to the BS  410  in step  423 . The policy server  420  maps SDP information for a session to IP QoS information and encapsulates the mapped information into the COPS-DEC message. 
         [0060]    The BS  410  having received the COPS-DEC message allocates a bearer resource to a session, maps the received IP QoS information to MAC QoS information, and compares the received IP QoS information with MAC QoS information requested by the PSS 1   400  in order to determine a MAC QoS suitable for the PSS 1   400 . The BS  410  encapsulates the determined MAC QoS information into a Dynamic Service Addition-Response (DSA-RSP) message and transmits the DSA-RSP message to the PSS 1   400  in step  427 . 
         [0061]    The PSS 1   400  transmits a DSA-ACK message to the BS  410  in response to the DSA-RSP message in step  427 . The BS  410  transmits a COPSRPT message including information indicating that bearer resource allocation and MAC QoS determination are successful to the policy server  420  in step  429 . 
         [0062]    In step  439 , the PSS 1   400  can perform traffic exchange to which a QoS provided from the IMS network is applied with the PSS 2   440  through SIP message transmission/reception (steps  423  through  437 ) between the PSS 1   400 , the IMS server  430 , and the PSS 2   440 . 
         [0063]    A PSS generates a flow ID for each medium using SDP information. Table 1 illustrates an example in which a PSS allocates a flow ID for each medium (m) and each uplink (UL)/downlink (DL). In Table 1, “RTP” indicates a Real Time Protocol and “RTCP” indicates a Real Time Control Protocol. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Order of ‘m’ 
                 Type of IP 
                 Dest IP 
                   
                   
               
               
                 line 
                 Flow 
                 Address 
                 Port Number 
                 Flow ID 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 RTP(video) 
                 165.213.10.10 
                 91230 
                 &lt;1, 1&gt; 
               
               
                   
                 UL 
               
               
                 1 
                 RTP(video) 
                 165.213.10.20 
                 94560 
                 &lt;1, 1&gt; 
               
               
                   
                 DL 
               
               
                 1 
                 RTCP UL 
                 165.213.10.10 
                 91231 
                 &lt;1, 2&gt; 
               
               
                 1 
                 RTCP DL 
                 165.213.10.20 
                 94561 
                 &lt;1, 2&gt; 
               
               
                 2 
                 RTP(audio) 
                 165.213.10.10 
                 1230 
                 &lt;2, 1&gt; 
               
               
                   
                 UL 
               
               
                 2 
                 RTP(audio) 
                 165.213.10.20 
                 4560 
                 &lt;2, 1&gt; 
               
               
                   
                 DL 
               
               
                 2 
                 RTCP UL 
                 165.213.10.10 
                 1231 
                 &lt;2, 2&gt; 
               
               
                 2 
                 RTCP DL 
                 165.213.10.20 
                 4561 
                 &lt;2, 2&gt; 
               
               
                   
               
             
          
         
       
     
         [0064]    As mentioned above, the PSS has to encapsulate the flow ID into a DSA-REQ message and transmit the DSA-REQ message to a BS. The BS can apply a QoS profile for each flow using the received flow ID. Table 2 illustrates a DSA-REQ message format that is newly suggested in the present invention. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Type 
                 Length 
                 Value 
                 Scope 
               
               
                   
                   
               
             
             
               
                   
                 [145/146].xx 
                 Variable 
                 Flow ID that is 
                 DSA-REQ 
               
               
                   
                   
                   
                 used for enforcing 
                 DSA-RSP 
               
               
                   
                   
                   
                 the QoS for one or 
               
               
                   
                   
                   
                 service flows 
               
               
                   
                   
                   
                 generated by MS- 
               
               
                   
                   
                   
                 initiated higher- 
               
               
                   
                   
                   
                 level service flow 
               
               
                   
                   
                   
                 creation or 
               
               
                   
                   
                   
                 modification 
               
               
                   
                   
                   
                 procedures 
               
               
                   
                   
               
             
          
         
       
     
         [0065]    Although the flow ID generated by the PSS is transmitted through the DSA-REQ message herein, the flow ID can also be generated by a policy server. Thus, the PSS may receive the flow ID generated by the policy server and encapsulate the received flow ID into the DSA-REQ message for transmission to the BS. When the BS transmits the DSA-RSP message without receiving the DSA-REQ message from the PSS, it may encapsulate the flow ID into the DSA-RSP message for transmission. 
         [0066]      FIG. 5  shows a process in which a PSS is provided with a service according to the present invention. The PSS receives an SIP  183  message including authorization token information from an IMS server in step  502 . In step  504 , the PSS generates a flow ID. In step  506 , the PSS encapsulates the authorization token and the flow ID into a DSA-REQ message and transmits the DSA-REQ message to a BS, thereby requesting the BS to provide a service. 
         [0067]      FIG. 6  shows a process in which a BS is provided with a service according to the present invention. The BS receives a DSA-REQ message including an authorization token and a flow ID from a PSS in step  602 . In step  604 , the BS transmits a COPS-REQ message including binding information, i.e., combined information of the authorization token and the flow ID, to a policy server in step  604 . The BS generates an SFID in step  606 . The BS maps the flow ID and the SFID to each other in step  608 . 
         [0068]      FIG. 7  shows a process in which a BS maps a flow ID and an SFID to each other according to the present invention. A packet classifier  704  of the BS detects an Internet Protocol (IP) header from a signal  702  received from a PSS and reads 5-tuple information  706  from the detected header information. The 5-tuple information  706  is an SFID #1 for UL audio. The 5-tuple information  706  includes a source IP address, a destination IP address, a source port number, a destination port number, and a protocol type. 
         [0069]    The BS may acquire QoS information for each uplink and/or downlink traffic using the read 5-tuple information  706  and other information. The BS maps a flow ID and a newly generated SFID to each other based on the acquired QoS information. For example, the SFID #1 for UL audio may be mapped to a flow ID&lt;1,1&gt; transmitted from the PSS. 
         [0070]    As described above, according to the present invention, when an IMS network and another type of network interwork with each other, a PSS can be provided with an optimized QoS. In particular, in a system where a portable Internet network and the IMS network interwork with each other, the PSS can be provided with an optimized QoS. 
         [0071]    While the invention has been shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.