Procedures for 3GPP Circuit Switched Fallback

Patent metadata

Field	Value
Publication number	US-2016007240-A1
Application number	US-201514791687-A
Country	US
Kind code	A1
Filing date	Jul 6, 2015
Priority date	Jul 7, 2014
Publication date	Jan 7, 2016
Grant date	—

Abstract

Mobile devices, base stations, and/or relay stations may implement CSFB (circuit switched fallback) operations by using RRC (radio resource control) connection release and/or handover procedures. If the CSFB RAT (radio access technology) target is not well configured, the UE may be informed and provisioned by the NW during a CSFB procedure with the information to return to LTE. Having this information, the UE may perform an autonomous search of LTE cells after the CSFB call release, speeding up return to LTE. To minimize potential call failures during CSFB, the UE may autonomously perform an additional cell search, in particular a search for cells on a RAT different from the initial target RAT. This creates an opportunity to prevent call failure of CSFB calls that would otherwise fail. The UE may be provisioned during the CSFB procedure with information to perform the additional cell search, should such a search be necessary.

First claim

1 . A method for a wireless user equipment (UE) device to transition between communicating on a network (NW) operating according to a first radio access technology (RAT) and communicating on a NW operating according to a second RAT, the method comprising:
receiving, by the UE, an indication of whether the UE is to perform, subsequent to call release of a first voice call conducted by the UE in a first NW operating according to the first RAT, an autonomous network search for a network operating according to the second RAT; performing, by the UE, one of:
the autonomous network search, responsive to the indication instructing the UE to perform the autonomous network search, for a network operating according to the second RAT; and
remaining idle, responsive to the indication instructing the UE to not perform the autonomous network search.

2 . The method of claim 1 , further comprising:
receiving, by the UE, along with the indication, a priority list of radio frequency channels usable by the UE, upon the call release, to perform the autonomous network search for a network operating according to the second RAT, responsive to the indication instructing the UE to perform the autonomous network search.

3 . The method of claim 1 , wherein receiving the indication comprises receiving the indication while the UE is communicating in a network operating according to the second RAT, and further comprises receiving the indication in one of:
a radio resource control (RRC) connection release message; or a mobility from Evolved Universal Mobile Telecommunications System Terrestrial Radio Access (E-UTRA) command message.

4 . The method of claim 1 , further comprising:
receiving, by the UE, an alternate list containing alternate RAT and cell information usable by the UE to automatically and autonomously perform additional cell search in case a first cell search performed by the UE according to an original list containing original RAT and cell information is unsuccessful; wherein the first cell search and the second cell search are both for the purpose of establishing a second voice call in a network operating according to a RAT different from the second RAT.

5 . The method of claim 1 , further comprising:
establishing, by the UE, communications in a network operating according to the second RAT, responsive to the autonomous network search performed by the UE being successful.

6 . The method of claim 1 , further comprising:
receiving, by the UE, an indication of whether the UE is to autonomously perform additional cell search in case a first cell search performed by the UE according to an original list containing original RAT and cell information is unsuccessful; wherein the first cell search and the second cell search are both for the purpose of establishing a second voice call in a network operating according to a RAT different from the second RAT.

7 . The method of claim 1 , wherein the network operating according to the first RAT is a circuit switched network, and wherein the network operating according to the second RAT is a packet switched network.

8 . A wireless user equipment (UE) device comprising:
a radio, comprising one or more antennas for performing wireless communications; a processor; and a non-volatile memory device storing program instructions executable by the processor to cause the UE to:
receive an indication of whether the UE is to perform, subsequent to the UE completing a voice call conducted in a circuit switched network, an autonomous network search for a data packet network; and
receive a priority list of radio frequency channels usable by the UE when performing the autonomous network search for the data packet network responsive to the indication instructing the UE to perform the autonomous network search.

9 . The UE device of claim 8 , wherein the program instructions are further executable by the processor to cause the UE to:
perform the autonomous network search for a data packet network according to the priority list subsequent to the UE completing the voice call, responsive to the indication instructing the UE to perform the autonomous network search.

10 . The UE device of claim 9 , wherein the program instructions are further executable by the processor to cause the UE to:
establish communications with the data packet network, responsive to the UE successfully completing the autonomous network search.

11 . The UE device of claim 8 , wherein the program instructions are further executable by the processor to cause the UE to:
remain idle, responsive to the indication instructing the UE to not perform the autonomous network search.

12 . The UE device of claim 8 , wherein the program instructions are further executable by the processor to cause the UE to:
receive the indication while the UE is operating in a packed switched network prior to the UE conducting the voice call; and receive the indication in a message instructing the UE to sever connection with the packet switched network.

13 . The UE device of claim 8 , wherein the program instructions are further executable by the processor to cause the UE to:
receive an indication of whether the UE is to autonomously perform additional cell search in case a first cell search performed by the UE according to an original list containing original RAT and cell information is unsuccessful; wherein the first cell search and the second cell search are for the purpose of establishing a second voice call in a circuit switched network.

14 . The UE device of claim 13 , wherein the program instructions are further executable by the processor to cause the UE to:
receive an alternate list containing alternate RAT and cell information usable by the UE when performing the additional cell search.

15 . The UE device of claim 13 , wherein the program instructions are further executable by the processor to cause the UE to:
perform the additional cell search responsive to the indication instructing the UE to perform the additional cell search in case the first cell search performed by the UE is unsuccessful.

16 . A base station, comprising:
a radio, comprising one or more antennas for the base station to perform wireless communications according to a first radio access technology (RAT); a processor; and a non-volatile memory device storing program instructions executable by the processor to cause the base station to:
transmit, to a UE device, an indication of whether the UE is to perform, subsequent to a circuit switched fallback (CSFB) call release, an autonomous network search for a network operating according to the first RAT;
wherein, the indication is configured to assist the UE in determining whether to perform the autonomous network search upon completion of the CSFB call.

17 . The base station of claim 16 , wherein the program instructions are further executable by the processor to cause the base station to:
transmit, along with the indication, a priority list of radio frequency channels, wherein the priority list is configured to assist the UE in identifying which radio frequency channels to search for when performing the autonomous search upon completion of the CSFB call, responsive to the indication instructing the UE device to perform the autonomous search.

18 . The base station of claim 17 , wherein the program instructions are further executable by the processor to cause the base station to transmit the indication and the priority list in one of:
a radio resource control (RRC) connection release message; or a mobility from Evolved Uni

Assignees

• Apple Inc

Inventors

• Belghoul Farouk
• Boettger David
• Kiss Krisztian
• Zhang Dawei
• Tabet Tarik
• Rivera-Barreto Rafael L
• Liang Huarui

Classifications

• H04W88/06

  adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals · CPC title

• H04W76/27

  Transitions between radio resource control [RRC] states · CPC title

• H04W48/18

  Selecting a network or a communication service · CPC title

• H04W48/16

  Discovering, processing access restriction or access information · CPC title

• H04W36/0022 Primary

  for transferring data sessions between adjacent core network technologies · CPC title