Abstract:
Methods and apparatus for enabling short message service (SMS) and supplementary services (SS) in a long term evolution (LTE) network via evolved packet system (EPS) mobility management (EMM) over the LTE control plane are described. In one embodiment, the radio resource control (RRC) connection signaling radio bearer (SRB) is used for SMS and SS transport over the LTE control plane between a wireless transmit/receive unit (WTRU) and a mobility management entity (MME). EMM interfaces and primitives are defined for actions towards SMS and SS entities for enabling SMS and SS services in LTE via the LTE control plane media. Message formats for SMS and SS message transport are also disclosed for sending SMS and SS messages within EMM uplink (UL) non-access stratum (NAS) transport and downlink (DL) NAS transport messages.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/549,804, filed Jul. 16, 2012, which is a continuation of U.S. patent application Ser. No. 13/236,819, filed Sep. 20, 2011, which issued as U.S. Pat. No. 8,224,363 on Jul. 17, 2012, which is a continuation of U.S. patent application Ser. No. 12/552,779, filed Sep. 2, 2009, which issued as U.S. Pat. No. 8,032,164 on Oct. 4, 2011, which claims the benefit of U.S. Provisional Application No. 61/099,097 filed Sep. 22, 2008, all of which are hereby incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    This application is related to wireless communications. 
       BACKGROUND 
       [0003]    Current efforts in the third generation partnership project (3GPP) long term evolution (LTE) program aim to bring new technology, new architecture, and new methods to provide improved spectral efficiency, reduced latency, and better utilization of radio resource to bring faster user experiences and richer applications and services with lower cost. Enabling the traditional commercially viable wireless services, especially the short message service (SMS), would greatly enhance the acceptance of the LTE technology in the wireless service product market. 
         [0004]    In the current LTE specification, the SMS service is either not fully defined or it depends on the Internet protocol (IP) multimedia service (IMS) based SMS service or the circuit switched (CS) fallback methodology, such that the overhead of development cost is large, the network service interactions are complex and the transport efficiency is low. For supplementary services (SS) in LTE, the supportability has yet to be defined and enabled. 
         [0005]    It would be desired to provide methods and apparatus that enable SMS and SS in LTE with implementation and backbone routing simplicity, while achieving overall data transport efficiency. 
       SUMMARY 
       [0006]    Methods and apparatus for communicating SMS and SS messages in an LTE network via evolved packet system (EPS) mobility management (EMM) over the LTE control plane are described. A radio resource control (RRC) connection signaling radio bearer (SRB)-2 may be used for SMS and SS transport over the LTE control plane between a wireless transmit/receive unit (WTRU) and a mobility management entity (MME). EMM interfaces and primitives are defined for actions towards SMS and SS entities for enabling SMS and SS services in LTE via the LTE control plane media. Message formats for SMS and SS message transport are also disclosed for sending SMS and SS messages within EMM uplink (UL) non-access stratum (NAS) transport and downlink (DL) NAS transport messages. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein: 
           [0008]      FIG. 1  shows a wireless communication system including a WTRU having a protocol entity architecture; 
           [0009]      FIG. 2  shows a wireless communication system with a WTRU having an alternate protocol entity architecture; 
           [0010]      FIG. 3  shows a procedure for supporting an outgoing SMS; 
           [0011]      FIG. 4  shows a procedure for supporting an incoming SMS; 
           [0012]      FIG. 5  shows call independent supplementary services supported using the systems of  FIGS. 1 and 2 ; 
           [0013]      FIG. 6  shows an overall NAS message header format for EMM; 
           [0014]      FIG. 7  shows an EMM message UL/DL transport format; 
           [0015]      FIG. 8  shows an SMS and SS message header plus payload format; 
           [0016]      FIG. 9  shows an EMM message format supporting SMS and SS in LTE; 
           [0017]      FIG. 10  is a signaling diagram for a mobile terminated (MT) SMS procedure; and 
           [0018]      FIG. 11  is a signaling diagram for an MT SS procedure. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    When referred to hereafter, the terminology “wireless transmit/receive unit (WTRU)” includes but is not limited to a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of user device capable of operating in a wireless environment. 
         [0020]    When referred to hereafter, the terminology “evolved Node-B (eNodeB)” includes but is not limited to a base station, a site controller, an access point (AP), or any other type of interfacing device capable of operating in a wireless environment. 
       Enabling SMS and SS Over EMM 
       [0021]      FIG. 1  shows a wireless LTE communication system  100  including a WTRU  105 , an evolved universal terrestrial radio access network (E-UTRAN)  110 , an MME  115  and a mobile switching center (MSC)/visitor location register (VLR)  120 . The E-UTRAN includes a plurality of eNodeBs. The system  100  provides EMM functionality in the WTRU  105  and the MME  115 , and supports SMS and SS by accessing an EMM interface over an LTE C-plane media. The MSC/VLR  120  may be part of a global system for mobile communications (GSM) network or universal mobile telecommunications system (UMTS) network, and is considered to be in the CS domain. The E-UTRAN  110  and the MME  115  are part of an LTE network, which is considered to be in a packet switch (PS) domain. SMS traffic may be transferred over the control plane of the LTE network using a CS fallback mechanism. 
         [0022]    As shown in  FIG. 1 , the WTRU  105  includes an SMS protocol entity  125 , an SS protocol entity  130 , a mobility management (MM) protocol entity  135 , an EMM protocol entity  140  and an LTE RRC protocol entity  145 . The EPS EMM protocol entity  140  in the WTRU  105  will forward SMS and SS requests/messages towards the LTE network via the LTE RRC protocol entity  145  and SRB  150 . 
         [0023]    A corresponding functionality may exist on the LTE network side, (e.g., in a base station or a core network component). An LTE EMM protocol entity  155  in the MME  115  handles the forwarding and receiving of SMS and SS messages towards/from the traditional SMS or SS processing center, such as the MSC/VLR  120 , via a serving gateway (SG) interface between the MME  115  and the MSC/VLR  120 , and towards a service center (SC) (not shown) for SMS. 
         [0024]    Logically, the SG interface is defined between the MME and VLR functional entities. The interface defined herein is between the existing connection management (CM) protocol entities (SMS and SS) and the new MM protocol entity, EMM, for LTE. 
         [0025]      FIG. 2  shows a wireless LTE communication system  200  including a WTRU  205  with an alternate protocol entity architecture. The WTRU  205  includes an SMS protocol entity  225 , an SS protocol entity  230 , an MM protocol entity  235 , an EPS EMM protocol entity  240  and an LTE RRC protocol entity  245 . However, unlike the protocol entity architecture of the WTRU  105  shown in  FIG. 1 , the SMS protocol entity  225  and the SS protocol entity  230  do not communicate directly with the EMM protocol entity  240 , but instead only communicate with the MM protocol entity  235 . 
         [0026]    The protocol entity architecture of  FIG. 2  also differs from that of  FIG. 1  by the direct interface between the MM protocol entity  235  and the EMM protocol entity  240 . This direct interface provides SMS and SS in LTE and legacy access networks. When an SMS/SS message is created, it will be sent to the MM protocol entity  235  in order to be delivered. Upon reception of the SMS/SS message, the MM protocol entity  235  checks for the existing radio access technology (RAT) of the terminating WTRU. If the existing RAT is either GSM/enhanced data rates for GSM evolution (EDGE) radio access network (GERAN) or UTRAN, the MM protocol entity  235  continues according to known procedures. However, in case the existing RAT is E-UTRAN/LTE, the MM protocol entity  235  contacts the EMM protocol entity  240  and delivers the higher layer information (the SMS/SS message). From this point forward, the defined procedures for EMM SMS/SS delivery are then followed. 
         [0027]    The interface between the MM protocol entity  235  and the EMM protocol entity  240  may have a set of control primitives and data carriage containers (i.e., data primitives). The control primitives may be used for translating SMS and MM primitives sent to the EMM protocol entity  240  for session/connection establishment and error indication. 
       Enhanced EMM (E-EMM) Interface for SMS 
       [0028]    The SMS protocol entities  125  and  225 , (also referred to herein as an enhanced SMS (E-SMS) since the underlying RAT is LTE), communicate with a corresponding peer entity, (in the WTRU and the MME), using an EMM interface over an LTE control plane. 
         [0029]    When an SMS message is to be sent and an EMM connection (through the LTE RRC connection) does not exist at the time, one must be established at the request of the E-SMS on the originating end. 
         [0030]    The primitives and interactions used for SMS/EMM state manipulation between the E-SMS and the EMM include: 
         [0031]    1) SMS-EMM-Conn-Est-Req (from E-SMS to EMM for requesting establishment of a connection for outgoing SMS if no connection currently exists); 
         [0032]    2) SMS-EMM-Conn-Est-Cnf (from EMM to E-SMS to confirm the connection establishment request); 
         [0033]    3) SMS-EMM-Conn-Est-Ind (from EMM to E-SMS for indicating incoming SMS message); and 
         [0034]    4) SMS-EMM-Conn-Est-Rsp (from E-SMS to EMM for responding to the incoming SMS message indication). 
         [0035]    Connection release primitives are also defined and include the following: 
         [0036]    1) SMS-EMM-Rel-Req (from E-SMS to EMM for requesting release of established connection); 
         [0037]    2) SMS-EMM-Rel-Cnf (from EMM to E-SMS for confirming the release request); 
         [0038]    3) SMS-EMM-Rel-Ind (from EMM to E-SMS for indicating a connection release); and 
         [0039]    4) SMS-EMM-Rel-Rsp (from E-SMS to EMM for responding to the connection release indication). 
         [0040]    The data primitives between the E-SMS and EMM are also defined and include the following: 
         [0041]    1) SMS-EMM-Data-Req (a primitive for carrying an SMS message from E-SMS to EMM); and 
         [0042]    2) SMS-EMM-Data-Ind (a primitive for carrying an SMS message from EMM to E-SMS). 
         [0043]    The following control protocol (CP) messages are used to transparently support the transportation of the SMS messages between the E-SMS and the EMM: CP-Data, CP-ACK and CP-Error messages. 
         [0044]      FIG. 3  shows signaling that occurs between an E-SMS protocol entity  305  and an EMM protocol entity  310  in a wireless communication system  300 . As shown in  FIG. 3 , when originating an SMS, the E-SMS  305  entity checks with the EMM  310  sending an SMS-EMM-Conn-Est-Req message  315  to the EMM protocol entity  310 . The EMM protocol entity  310  in turn checks to see if it already has an EMM-connection over the LTE RRC connection. If that is the case, the EMM protocol entity  310  responds with an SMS-EMM-Conn-Est-Cnf message  320  back to the E-SMS protocol entity  305 . If no EMM connection exists over the LTE RRC connection, the EMM protocol entity  310  triggers the LTE RRC to establish an RRC connection towards the currently attached E-UTRAN for “service request”. When the RRC connection is successfully established, the EMM protocol entity  310  will then send an SMS-EMM-Conn-Est-Cnf message  320  back to the E-SMS  305 . The outgoing SMS data activity may then proceed using Data-Req message  325  and Data-Ind message  330  to transport SMS messages. 
         [0045]      FIG. 4  shows signaling that occurs between an E-SMS protocol entity  405  and an EMM protocol entity  410  in a wireless communication system  400 . As shown in  FIG. 4 , in the case of an incoming SMS, the EMM protocol entity  410  will be paged if no EMM/RRC connection towards the E-UTRAN exists. As the EMM protocol entity  410  responds to the page for establishing an RRC connection, the EMM protocol entity  410  will indicate the SMS event to the E-SMS protocol entity  405  via an SMS-EMM-Conn-Est-Ind message  415  and the E-SMS protocol entity  405  will respond with an SMS-EMM-Conn-Est-Rsp message  420 . The incoming SMS data activity may then proceed using Data-Req message  425  and Data-Ind message  430  to transport SMS messages. 
       E-EMM Interface for SS 
       [0046]    The SS protocol entities  130  and  230 , (also referred to herein as an enhanced SS (E-SS) since the underlying RAT is LTE), communicate with a corresponding peer entity, (in the WTRU and the MME), using an EMM interface over an LTE control plane. 
         [0047]    When an SS message is to be sent and an EMM session (through the LTE RRC connection) does not exist at the time, one must be established at the request of the E-SS on the originating end. 
         [0048]    The primitives and interactions used for SS/EMM state manipulation between the E-SS and the EMM include: 
         [0049]    1) SS-EMM-Sess-Est-Req (from E-SS to EMM for requesting establishment of a session for outgoing SS if no session currently exists); 
         [0050]    2) SS-EMM-Sess-Est-Cnf (from EMM to E-SS to confirm of the session establishment request); 
         [0051]    3) SS-EMM-Sess-Est-Ind (from EMM to E-SS for indicating an incoming SS message); and 
         [0052]    4) SS-EMM-Sess-Est-Rsp (from E-SS to EMM for responding to the incoming SS message indication). 
         [0053]    Session release primitives are also defined and include the following: 
         [0054]    1) SS-EMM-Rel-Req (from E-SS to EMM for requesting release of established session); 
         [0055]    2) SS-EMM-Rel-Cnf (from EMM to E-SS for confirming the release request); 
         [0056]    3) SS-EMM-Rel-Ind (from EMM to E-SS for indicating a session release); and 
         [0057]    4) SS-EMM-Rel-Rsp (from E-SS to EMM for responding to the session release indication). 
         [0058]    The data primitives between the E-SS and the EMM are also defined and include the following: 
         [0059]    1) SS-EMM-Data-Req (a primitive for carrying a SS message from E-SS to EMM); and 
         [0060]    2) SS-EMM-Data-Ind (a primitive carrying a SS message from EMM to E-SS). 
         [0061]    For SS in LTE, only the call independent SS messages will be supported for the LTE standard, since CS call service is not supported in release-8 LTE. Currently, the following call independent SS are supported and shown in  FIG. 5 . 
         [0062]    Given that the SS message header construction is the same as those for SMS (see  FIG. 8 ), the above supported call independent SS messages will be inserted at the octet-9 (with the SS message header) in the EMM message shown in  FIG. 9 . 
       Encapsulation Mechanism for SMS and SS Transport with EMM 
     Base EMM Message Format for Encapsulation 
       [0063]    The EMM message for transporting the SMS or SS is generated by including the SMS message or the SS message (shown in  FIG. 8 ) in an information element (IE) of the EMM UL NAS transport message or DL NAS transport message (shown in  FIG. 7 ), which is then encapsulated into the NAS message header of the EMM message shown in  FIG. 6 . 
         [0064]    The NAS message shown in  FIG. 7  is either a UL NAS transport message or a DL NAS transport message that carries the SMS or SS message for the intended service. Additional details of the header and body of the NAS transport message are shown in  FIG. 9 . 
       SMS and SS Message Header 
       [0065]    The currently used CM level SMS messages, (CP-Data, CP-ACK and CP-Error), as well as the SS messages may have the header format shown in  FIG. 8 . 
         [0066]    In  FIG. 8 , the transaction-identifier field may be used for SMS and SS as a field for their original transaction identifiers. The protocol discriminator field may be used to identify the encapsulated SMS or SS or others. The message type field may be used to indicate a type of each individual SMS or SS messages. 
       EMM Message Format for Encapsulating SMS and SS Messages 
       [0067]    The combined header on EMM to support SMS or SS plus the message body, (i.e., the payload), is illustrated in  FIG. 9 . With this message format, the LTE access stratum control plane bearers are used to carry the SMS or the SS traffic between the WTRU and the network. In a first scenario, a direct interface between the SMS/SS entities and the EMM entity at the WTRU exist. Once the EMM session/connection is established with the E-UTRAN and MME via the LTE RRC connection, the WTRU may use the EMM and RRC interface through to the LTE SRB-2 as the SMS/SS transporting media. The SRB-2 (signal radio bearer 2) is mapped over the bidirectional logical channel DCCH (dedicated control channel), which is over the UL/DL transport channel UL-SCH (uplink shared channel)/DL-SCH (downlink shared channel), which is then mapped over the physical channel PUSCH (physical uplink shared channel)/PDSCH (physical downlink shared channel) in LTE. If an RRC connection does not exist in a mobile originated (MO) SMS scenario, the EMM protocol entity triggers the RRC protocol entity to establish an RRC connection. 
         [0068]    In one scenario, the SMS protocol entity  125  in the WTRU  105  shown in  FIG. 1  generates an SMS message using the header and payload shown in  FIG. 8 , and sends the SMS message to the EMM protocol entity  140 . The EMM protocol entity  140  then formats a UL/DL NAS transport message using the header format shown in  FIG. 7 , whereby the SMS message is inserted in the NAS message body IE of the UL/DL NAS transport message. The UL/DL NAS transport message is then encapsulated in the NAS message field of the EMM message shown in  FIG. 6 , and is forwarded to the RRC protocol entity  145 . The RRC protocol entity  145  then formats an UL/DL information transfer message to include the EMM message, and transmits the UL/DL information transfer message over the SRB  150 . 
         [0069]    In another scenario, the SS protocol entity  130  in the WTRU  105  shown in  FIG. 1  generates an SS message using the header and payload shown in  FIG. 8 , and sends the SS message to the EMM protocol entity  140 . The EMM protocol entity  140  then formats a UL/DL NAS transport message using the header format shown in  FIG. 7 , whereby the SS message is inserted in the NAS message body IE of the UL/DL NAS transport message. The UL/DL NAS transport message is then encapsulated in the NAS message field of the EMM message shown in  FIG. 6 , and is forwarded to the RRC protocol entity  145 . The RRC protocol entity  145  then formats an UL/DL information transfer message to include the EMM message, and transmits the UL/DL information transfer message over the SRB  150 . 
         [0070]      FIG. 10  shows a signaling diagram for an MT SMS procedure using the primitives defined above. As shown in  FIG. 10 , a WTRU  1000  includes an SMS protocol entity  1005 , an EMM protocol entity  1010  and an RRC protocol entity  1015 . A network  1020  is illustrated as a single entity for simplicity. 
         [0071]    In an MT SMS scenario, the network  1020  may send the WTRU  1000  a page  1025  while the WTRU  1000  is in an idle state, and the WTRU  1000  may respond with a service-request  1030  (with paging response) for establishing the RRC connection. The EMM protocol entity  1010  may then send and receive the SMS message using the EMM DL NAS transport message and UL NAS transport message. The RRC protocol entity  1015  uses an RRC DownlinkInformationTransfer message  1135  and an RRC UplinkInformationTransfer message  1140  for the transportation. 
         [0072]      FIG. 11  shows a signaling diagram for an MT SS procedure using the primitives defined above. As shown in  FIG. 11 , a WTRU  1100  includes an SS protocol entity  1105 , an EMM protocol entity  1110  and an RRC protocol entity  1115 . A network  1120  is illustrated as a single entity for simplicity. 
         [0073]    In an MT SMS scenario, the network  1120  may send the WTRU  1100  a page  1125  while the WTRU  1010  is in an idle state, and the WTRU  1100  may respond with a service request  1130  (with paging response) for establishing the RRC connection. The EMM protocol entity  1110  may then send and receive the SS message using the EMM DL NAS transport message in an RRC DownlinkInformationTransfer message  1135 , or an EMM UL NAS transport message in the RRC UplinkInformationTransfer message  1140 . 
         [0074]    The features described above will be now summarized by referring to  FIG. 1 . 
         [0075]    In one scenario, the WTRU  105  of  FIG. 1  communicates SMS messages by using the SMS protocol entity  125  to request the EMM protocol entity  140  to send an SMS message. The EMM protocol entity  140  then initiates a procedure to send a UL NAS transport message including an IE containing the SMS message. The SMS protocol entity  125  may send the SMS message to the EMM protocol entity  140 . The EMM protocol entity  140  formats the UL NAS transport message to include the SMS message, encapsulates the UL NAS transport message in an EMM message, and sends the EMM message to the LTE RRC protocol entity  145 . The LTE RRC protocol entity  145  formats a UL information transfer message to include the EMM message, and transmits the UL information transfer message over an SRB. The UL information transfer message may be transmitted to the MME  115 . 
         [0076]    In another scenario, the WTRU  105  of  FIG. 1  communicates SMS messages by using the EMM protocol entity  140  to receive a DL NAS transport message including an IE containing an SMS message. The EMM protocol entity  140  forwards the SMS message to the SMS protocol entity  125 . The RRC protocol entity  145  may receive a DL information transfer message, remove the DL NAS transport message from the DL information transfer message, and forward the DL NAS transport message to the EMM protocol entity  140 . The EMM protocol entity  140  then removes at least one NAS message header from the DL NAS transport message. The RRC protocol entity may receive the DL information transfer message from an MME. 
         [0077]    In yet another scenario, the WTRU  105  of  FIG. 1  communicates SS messages by using the SS protocol entity  130  to request the EMM protocol entity  140  to send an SS message. The EMM protocol entity  140  then initiates a procedure to send a UL NAS transport message including an IE containing the SS message. The SS protocol entity  130  may send the SS message to the EMM protocol entity  140 . The EMM protocol entity  140  formats the UL NAS transport message to include the SS message, encapsulates the UL NAS transport message in an EMM message, and sends the EMM message to the LTE RRC protocol entity  145 . The LTE RRC protocol entity  145  formats a UL information transfer message to include the EMM message, and transmits the UL information transfer message over an SRB. The UL information transfer message may be transmitted to the MME  115 . 
         [0078]    In yet another scenario, the WTRU  105  of  FIG. 1  communicates SS messages by using the EMM protocol entity  140  to receive a DL NAS transport message including an IE containing an SS message. The EMM protocol entity  140  forwards the SS message to the SS protocol entity  130 . The RRC protocol entity  145  may receive a DL information transfer message, remove the DL NAS transport message from the DL information transfer message, and forward the DL NAS transport message to the EMM protocol entity  140 . The EMM protocol entity  140  then removes at least one NAS message header from the DL NAS transport message. The RRC protocol entity may receive the DL information transfer message from an MME. 
         [0079]    Although features and elements are described above in particular combinations, each feature or element can be used alone without the other features and elements or in various combinations with or without other features and elements. The methods or flow charts provided herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). 
         [0080]    Suitable processors include, by way of example, a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), and/or a state machine. 
         [0081]    A processor in association with software may be used to implement a radio frequency transceiver for use in a wireless transmit receive unit (WTRU), user equipment (UE), terminal, base station, radio network controller (RNC), or any host computer. The WTRU may be used in conjunction with modules, implemented in hardware and/or software, such as a camera, a video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated (FM) radio unit, a liquid crystal display (LCD) display unit, an organic light-emitting diode (OLED) display unit, a digital music player, a media player, a video game player module, an Internet browser, and/or any wireless local area network (WLAN) or Ultra Wide Band (UWB) module.