Determination of Appropriate Radio Resource to be Requested in Case of a Circuit-Switched (CS) Fallback Procedure

Abstract

A system and method for implementing fallback on a wireless device for circuit switched fallback from a first network that does not provide a circuit switched domain service is presented. A paging message is received from the first network. The paging message instructs the wireless device to implement circuit switched fallback to a circuit switched network. The paging message is inspected for information indicative of a service associated with the paging message, and a channel type suitable for the service is determined from the information indicative of the service. A request message for initiating the establishment of a radio connection is transmitted. The request message identifies the suitable channel type, and the service is used on the circuit switched network.

1 . A method for implementing fallback on a wireless device for circuit switched fallback from a first network that does not provide a circuit switched domain service, the method comprising:
 receiving a paging message from the first network, the paging message instructing the wireless device to implement circuit switched fallback to a circuit switched network;   inspecting the paging message for information indicative of a service associated with the paging message;   determining from the information indicative of the service a channel type suitable for the service;   transmitting a request message for initiating the establishment of a radio connection, the request message identifying the suitable channel type; and   using the service on the circuit switched network.   
     
     
         2 . The method of  claim 1 , wherein determining comprises identifying whether the service associated with the paging message is one of a first category of service, the first category of service including CS speech calls and CS services requiring a traffic channel or conversational resources, a second category of service, the second category of service including mobile terminated location requests or a third category of service, the third category of service including supplementary services. 
     
     
         3 . The method of  claim 2  wherein, if the service is in the first category of service, the channel type suitable for the service is at least one of a traffic channel (TCH)/half (H) or a TCH/full (F). 
     
     
         4 . The method of  claim 2  wherein, if the service is in at least one of the second or third categories of service, the channel type suitable for the service is a stand-alone dedicated control channel (SDCCH). 
     
     
         5 . The method of  claim 1 , wherein inspecting the paging message comprises detecting at least one of a supplementary service (SS) code information element, a location service (LCS) indicator information element, or an LCS client identity information element within the paging message; and wherein
 when the paging message includes the SS code information element, the channel type suitable for the service is suitable for a call independent supplementary service; or   when the paging message includes at least one of the LCS indicator information element and the LCS client identity information element, the channel type suitable for the service is suitable for a mobile terminated location request.   
     
     
         6 . The method of  claim 1 , wherein the paging message includes a CS SERVICE NOTIFICATION MESSAGE. 
     
     
         7 . The method of  claim 1 , wherein the paging message includes an E-UTRAN RRC protocol paging message received after a preliminary paging procedure implemented using an S1 interface. 
     
     
         8 . A wireless device configured to perform circuit switched fallback from a first network that does not provide a circuit switched domain service, the wireless device comprising:
 a processor, the processor being configured to:
 construct a service request message, the service request message identifying a cause for a circuit-switched (CS) service to be provided by a circuit switched network; 
 transmit the service request message to the first network, the service request message initiating a fallback procedure; 
 establish a connection to the circuit switched network; and 
 use the CS service on the circuit switched network. 
   
     
     
         9 . The wireless device of  claim 8 , wherein the cause for the service to be provided by the second network cell includes at least one of originating conversational call, originating high-priority signaling, or originating low-priority signaling. 
     
     
         10 . The wireless device of  claim 8 , wherein, when the cause for the service includes at least one of originating high-priority signaling, or originating low-priority signaling, the service request message includes at least one of a supplementary service (SS) code information element, a location service (LCS) indicator information element, or a LCS client identity information element. 
     
     
         11 . The wireless device of  claim 8 , wherein the service request message includes an EXTENDED SERVICE REQUEST message. 
     
     
         12 . The wireless device of  claim 8 , wherein the service request message includes a service type information element, and the service type information element identifies the circuit-switched (CS) service. 
     
     
         13 . The wireless device of  claim 8 , wherein the service request message includes an RRCConnectionRequest message. 
     
     
         14 . A wireless device configured to perform circuit switched fallback from a first network that does not provide a circuit switched domain service, the wireless device comprising:
 a processor, the processor being configured to:
 receive a paging message from the first network, the paging message instructing the wireless device to implement circuit switched fallback to a circuit switched network; 
 inspect the paging message for information indicative of a service associated with the paging message; 
 determine from the information indicative of the service a channel type suitable for the service; 
 transmit a request message for initiating the establishment of a radio connection, the request message identifying the suitable channel type; and 
 use the service on the circuit switched network. 
   
     
     
         15 . The wireless device of  claim 14 , wherein the processor is configured to identify whether the service associated with the paging message is one of a first category of service, the first category of service including CS speech calls and CS services requiring a traffic channel or conversational resources, a second category of service, the second category of service including mobile terminated location requests or a third category of service, the third category of service including supplementary services. 
     
     
         16 . The wireless device of  claim 15  wherein, if the service is in the first category of service, the channel type suitable for the service is at least one of a traffic channel (TCH)/half (H) or a TCH/full (F). 
     
     
         17 . The wireless device of  claim 15  wherein, if the service is in at least one of the second or third categories of service, the channel type suitable for the service is a stand-alone dedicated control channel (SDCCH). 
     
     
         18 . The wireless device of  claim 14 , wherein the processor is configured to detect at least one of a supplementary service (SS) code information element, a location service (LCS) indicator information element, or an LCS client identity information element within the paging message; and wherein
 when the paging message includes the SS code information element, the channel type suitable for the service is suitable for a call independent supplementary service; or   when the paging message includes at least one of the LCS indicator information element and the LCS client identity information element, the channel type suitable for the service is suitable for a mobile terminated location request.   
     
     
         19 . The wireless device of  claim 14 , wherein the paging message includes a CS SERVICE NOTIFICATION MESSAGE. 
     
     
         20 . The wireless device of  claim 14 , wherein the paging message includes an E-UTRAN RRC protocol paging message received after a preliminary paging procedure implemented using an S1 interface.