Abstract:
A system and method adapted to support a satellite component as generic access in the terrestrial mobile networks. The present invention uses the Third Generation Partnership Project (3GPP) baseline standard, 3GPP Generic Access Network (GAN) to support a Mobile Satellite Service (MSS) satellite component at the physical, Radio Link Control (RLC) and Medium Access Control (MAC) layers, with the terrestrial standards based in the Generic Access Protocol architecture framework.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to satellite communications. More particularly, and not by way of limitation, the present invention is directed to a system and method for facilitating mobile satellite service via a Third Generation Partnership Project (3GPP) generic radio access network. As used herein, the abbreviations used herein shall have the following meanings: 
         [0002]    AAA Authentication, Authorization and Accounting 
         [0003]    AP Access Point 
         [0004]    ATC Ancillary Terrestrial Component 
         [0005]    BER Bit Error Rate 
         [0006]    BSC Base Station Controller 
         [0007]    BTS Base Transceiver Station 
         [0008]    CC Call Control 
         [0009]    CS Circuit Switched 
         [0010]    EGPRS Enhanced General Packet Radio Service 
         [0011]    FCC Federal Communications Commission 
         [0012]    GAN Generic Access Network 
         [0013]    GANC Generic Access Network Controller 
         [0014]    GMR Geo Mobile Radio 
         [0015]    GMR 3G Geo Mobile Radio with 3G (evolution of GMR1 or GMR2 protocols to support packet access support) 
         [0016]    Gb Interface between BSC and SGSN 
         [0017]    GPRS General Packet Radio Service 
         [0018]    GSM Global System for Mobile Communication 
         [0019]    HBS Home Base Station 
         [0020]    HBSC Home Base Station Controller 
         [0021]    HLR Home Location Register 
         [0022]    HSPA High Speed Packet Access 
         [0023]    IGW IP Gateway 
         [0024]    IP Internet Protocol 
         [0025]    IETF Internet Engineering Task Force 
         [0026]    LTE Long Term Evolution 
         [0027]    MAC Medium Access Control 
         [0028]    MIPv6 Mobile IP version 6 
         [0029]    MM Mobility Management 
         [0030]    MME Mobility Management Entity 
         [0031]    MMS Multimedia Messaging Services 
         [0032]    MS Mobile Station 
         [0033]    MSS Mobile Satellite Service 
         [0034]    PCU Packet Channel Unit 
         [0035]    RLC Radio Link Control 
         [0036]    RFC Request for Comments 
         [0037]    RTP Real Time Protocol 
         [0038]    SAE System Architecture Evolution 
         [0039]    SGSN Serving GPRS Support Node 
         [0040]    SGW Security Gateway 
         [0041]    SMS Short Messaging Services 
         [0042]    UT User Terminal 
         [0043]    UMA Unlicensed Mobile Access 
         [0044]    WCDMA Wideband Code Division Multiple Access 
         [0045]    XCP Explicit Control Protocol 
         [0046]    The US Federal Communications Commission (FCC) permits MSS spectrum to be used nationwide on the ground for terrestrial networks (under the ATC), provided that Satellite services are also offered. MSS operators are thus able to offer terrestrial mobile telecommunication services using a hybrid satellite/terrestrial UT. 
         [0047]    In order to be successful, MSS/ATC operators must be able to leverage the economies of scale of the existing UTs and also the existing mobile communication network infrastructure. While it is possible to implement a system using ETSI GMR1 or GMR2 standards, as derivative of mainstream 3GPP GSM/EGPRS standards, it will likely be cost prohibitive to sustain the satellite component in an integrated UT or mobile communication infrastructure when terrestrial standards continue evolve to later generations. 
         [0048]    The 3GPP GAN enables end users to use alternative air interface technologies, such as Bluetooth and WiFi, to access mobile services that otherwise are commonly accessed using WCDMA/GSM/EGPRS networks. One system that illustrates the 3GPP GAN reference architecture is Ericsson&#39;s Mobile@Home system as seen in  FIG. 1 . A 3GPP GAN system enables GSM and GPRS services over the IP backbone and short-range unlicensed radio access technology, such as Bluetooth or WiFi. The end user hence will be able to use the “public” cellular network or the UMA Bluetooth/NiFi pico-cell to access the same voice, GPRS, MMS and/or SMS services. 
         [0049]      FIG. 1  illustrates a conventional 3GPP GAN system  100 . The protocol stacks in the 3GPP GAN standards support end user applications and services transparently across the underlying radio access  101  which are unlicensed lower layers between the MS  102  and AP  103 , shown here as a HBS. 
         [0050]      FIG. 2  illustrates the 3GPP GAN Protocol Stack  200  for a CS domain. The unlicensed lower layers  201  supported by 3GPP GAN are Bluetooth and WiFi.  FIG. 3  further illustrates the 3GPP GAN unlicensed lower layers for Bluetooth  301  and an 802.11 based wireless network  302 . 
         [0051]    Conventional MSS systems are based on several air interface standards, including: GMR1, GMR2, Globalstar air interface, Iridium air interface and Inmarsat  14  air interface. Each of these standards is unique, and hence they are non-interoperable. As a result, the MSS is fragmented, making it difficult to leverage economies of scale in the MSS market for UT and the network infrastructure. As a result, the MSS has seen limited market success. 
         [0052]    It would thus be advantageous to have a system and method for simpler reference network architecture to support a satellite component as generic access in the terrestrial mobile networks and UTs that overcomes the disadvantages of the prior art. The present invention provides such a system and method. 
       BRIEF SUMMARY OF THE INVENTION 
       [0053]    The present invention comprises a system and method for simpler reference network architecture to support a satellite component as generic access in the terrestrial mobile networks. The present invention uses the 3GPP baseline standard, 3GPP GAN, to support a MSS satellite component at the physical, RLC and MAC layers, with the terrestrial standards based in the Generic Access Protocol architecture framework. The present invention seamlessly incorporates satellite component lower layers into the GAN protocol architecture, leveraging the flexibility of the IP transport protocols between the UT or MS and the GAN Radio Access Network to slide in satellite protocol lower layers in the GAN protocol architecture framework. To support this mobility management system across the IP domain, the present invention uses the IETF RFC 4423 protocol for Host Identity protocol and multi-homing support. These additions are transparent to the GAN infrastructure, particularly the UMA GANC. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0054]    In the following section, the invention will be described with reference to exemplary embodiments illustrated in the Figures, in which: 
           [0055]      FIG. 1  illustrates a conventional 3GPP GAN system; 
           [0056]      FIG. 2  illustrates the conventional 3GPP GAN protocol stack for the CS domain; 
           [0057]      FIG. 3  illustrates the 3GPP GAN—unlicensed lower layers: 
           [0058]      FIG. 4  illustrates the 3GPP GAN CS domain protocol layers with satellite access; and 
           [0059]      FIGS. 5A and 5B  illustrate the 3GPP GAN protocol architecture operable to support satellite enabled handsets with a GAN/MSS inter-working unit. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0060]    In the present invention, the 3GPP GAN protocol stack is used to provide access by satellite instead of by Bluetooth or WiFi. This enables the MSS component to be incorporated into the existing terrestrial UT or MS and network that supports the 3GPP GAN reference architecture. This is seen in  FIG. 4 . As seen therein, the 3GPP GAN CS domain protocol layers with satellite access  400  of the present invention is shown. This provides an example of a protocol instance illustrating how the satellite protocol layers  401  can be introduced in the 3GPP GAN protocol architecture.  FIG. 4  can be generalized to include other GAN protocol architectures, such as Up interface CS Voice bearer protocol, Up interface GPRS signaling and user plane protocols. In addition, other mechanisms existing in the 3GPP GAN for roving, GAN cell identification and the like can be leveraged for the satellite access as well 
         [0061]    Referring now to the satellite protocol lower layers, the present invention provides that the satellite protocol architecture in the 3GPP GAN framework will be comprised of the physical, RLC, MAC and IP transport layers. These will comprise peer to peer protocol layers between the UT or MS and a satellite RBS. The satellite physical, RLC and MAC layers comprise an adaptation of the terrestrial EGPRS standards for physical, RLC and MAC layers. The adaptation of the physical, RLC and MAC layers are based on the Ericsson satellite cellular backhaul solutions for Abis over satellite. 
         [0062]    Adapting the EGPRS satellite variants for the physical, RLC and MAC layers enables the reuse of the UT or MS EGPRS baseband and radio frequency electronics with minimal modification. Alternatively, the satellite physical, RLC, MAC layers can be based on proprietary VSAT IP modems technologies. 
         [0063]    In one embodiment of the present invention, the satellite link can be optimized for voice calls using a low data rate codec over the GAN user plane without IP overhead. The encapsulation of the codec payload into IP packets with RTP headers can be performed in the satellite BTS as transparent connectivity to the BSC, either the Home BSC or GAN. 
         [0064]    The satellite IP transport layer is an important aspect of the satellite RBS protocol stack of the present invention. The satellite IP transport layer contains performance enhancing proxies to combat satellite latencies and also provide a mechanism to appropriately map user locations, Identities to IP addresses and carrier frequencies in the lower layers for UT or MS mobility. 
         [0065]    Mobility refers to the ability of the network to provide support for handover to mobile devices such as UTs and MSs as they change point of access. Device mobility can either be addressed at layer  3  of the protocol stack, which means that the IP forwarding mechanism, which is based on IP addresses with implicit location information, either needs to be changed or the addressing scheme has be modified. In this way, mobility is hidden from higher layer protocols, and the host&#39;s IP address remains unchanged. 
         [0066]    This present invention is adapted to use the IETF RFC 4423, Host Identity Protocol, as an MME to implicitly map the end users locations for example to spot beam id and/or GPS positions and/or identities that are operable to determine end user locations. Alternatively MIPv6 can be used for mobility management to achieve similar results. 
         [0067]    The IP stack could also optionally support multi homing (using TCP or SCTP protocol) for the user to enable mobility management to ensure device mobility of the UTs or MSs. 
         [0068]    Several methods can be employed in concert with the present invention to determine the physical location of the UT or MS. These methods use information configured in the GAN and information received from the UT during location update typically via a GPS location. It is conventionally known that GANC is operable to allow an external database to map this data to the exact geographical location of the end user in relation to the spot beam id and/or GPS position. The UT or MS can also be adapted to report the geographic location to the GANC. 
         [0069]    There are several known techniques to improve transmission efficiency in the presence of long propagation delay. The present invention can be adapted to use such known techniques such as those available via commonly known TCP/IP accelerator products such as performance enhancing proxies and/or using XCP. In this manner, the present invention leverages the principles of 3GPP GAN network, is based on open standard interfaces, such as Up protocol stack, IP transport layers, and IETF RFC 4423 concerning Host Identity Protocol and uses conventional performance enhancing techniques to combat long propagation delay. In this manner, a BSC, either a Home BSC or GANC, can be used with minimum modifications or no changes. 
         [0070]    As seen in  FIGS. 5A and 5B , the MS platform  501  of a UT or MS  500  can be leveraged to incorporate satellite access in 3GPP GAN protocol domain. As seen in  FIG. 5B , the 3GPP GAN protocol architecture makes it feasible to support satellite enabled UTs or MSs with GAN/MSS internetworking unit  502 . The present invention comprises an MSS/ATC solution as an ancillary satellite component in WCDMA/HSPA/GSM/EGPRS mobile networks with minimal impact to these networks. The impacts are minimized due to the use of IP protocol stack at the lowest level of protocol stack granularity. 
         [0071]    As will be recognized by those skilled in the art, the innovative concepts described in the present application can be modified and varied over a wide range of applications. Accordingly, the scope of patented subject matter should not be limited to any of the specific exemplary teachings discussed above, but is instead defined by the following claims.