Method and apparatus for setup of a circuit switched call during circuit switched fallback
A method, at a user equipment (‘UE’), the method: sending a request to a first network for Circuit Switched Fallback (‘CSFB’); receiving, responsive to the request, redirection information; acquiring a second network based on the redirection information; initiating establishment of Circuit Switched (‘CS’) voice radio bearers with the second network; waiting for a predetermined event to occur; after the predetermined event has occurred, establishing a Packet Switched (‘PS’) connection with the second network. Further, a method, at a network element, the method receiving a request for Circuit Switched Fallback (‘CSFB’) from a user equipment (‘UE’); sending, to the UE, redirection information; receiving a Routing Area Update (‘RAU’) message from the UE; waiting for a predetermined event to occur; upon the predetermined event occurring, responding to the RAU message.
1. A method, at a user equipment (‘UE’), comprising:
sending a request to a first network for Circuit Switched Fallback (‘CSFB’) while connected to the first network;
receiving, responsive to the request, redirection information to a second network;
initiating the establishment of radio bearers for a circuit switched (CS) connection with the second network based on the redirection information;
starting a timer;
waiting for a first of the CS voice radio bearers being established and the expiration of the timer;
initiating Packet Switched (‘PS’) signaling with the second network in response to the first of the CS voice radio bearers being established and the expiration of the timer;
wherein an initial value of the timer is configured based on a message from one of the first network and the second network; and
wherein CS voice radio bearers are determined to be established when the UE sends a radioBearerSetupComplete message for the CS domain.
2. The method of claim 1 , wherein the UE waits for a predetermined event to occur before said initiating if the UE does not have a pending data session request on the second network.
3. The method of claim 1 , wherein the UE waits for a predetermined event to occur before said initiating if the UE does not have a pending data transmission on the second network.
4. A user equipment comprising:
a processor;
a communications subsystem;
wherein the processor and communications subsystem cooperate to:
send a request to a first network for Circuit Switched Fallback (‘CSFB’) while connected to the first network;
receive, responsive to the request, redirection information to a second network;
initiate the establishment of radio bearers for a circuit switched (CS) connection with the second network based on the redirection information;
start a timer;
wait for a first of the CS voice radio bearers being established and the expiration of the timer;
initiate Packet Switched (‘PS’) signaling with the second network in response to the first of the CS voice radio bearers being established and the expiration of the timer;
wherein an initial value of the timer is configured based on a message from one of the first network and the second network; and
wherein CS voice radio bearers are determined to be established when the UE sends a radioBearerSetupComplete message for the CS domain.
5. The user equipment of claim 4 , wherein the UE waits for a predetermined event to occur before the initiating if the UE does not have a pending data session request on the second network.
6. The user equipment of claim 4 , wherein the UE waits for a predetermined event to occur before the initiating if the UE does not have a pending data transmission on the second network.
7. A method, at a network element, comprising:
receiving a request for Circuit Switched Fallback (‘CSFB’) from a user equipment (‘UE’), the UE having a connection to a first network;
sending, to the UE, redirection information for transfer of the connection to a second network;
receiving a Routing Area Update (‘RAU’) message from the UE to initiate the transfer of the connection to the second network;
start a timer;
wait for a first of the CS voice radio bearers being established and the expiration of the timer;
initiating Packet Switched (‘PS’) signaling with the second network in response to the first of the CS voice radio bearers being established and the expiration of the timer;
wherein an initial value of the timer is configured based on a message from one of the first network and the second network; and
wherein CS voice radio bearers are determined to be established when the UE sends a radioBearerSetupComplete message for the CS domain.
8. A network element, comprising:
a processor;
a communications subsystem;
wherein the processor and communications subsystem cooperate to:
send a request to a first network for Circuit Switched Fallback (‘CSFB’) while connected to the first network;
receive, responsive to the request, redirection information to a second network;
acquire the second network based on the redirection information;
start a timer;
wait for a first of the CS voice radio bearers being established and the expiration of the timer;
initiate Packet Switched (‘PS’) signaling with the second network in response to the first of the CS voice radio bearers being established and the expiration of the timer;
wherein an initial value of the timer is configured based on a message from one of the first network and the second network; and
wherein CS voice radio bearers are determined to be established when the UE sends a radioBearerSetupComplete message for the CS domain.