Content for TR 23.750 Word version: 14.0.0
5 Key Issues p. 7
5.1 Key Issue 1 - How to improve VoLTE call setup success rate and minimize the negative impact on user experience for VoLTE subscriber in LTE with bad coverage overlaid with 2/3G CS coverage p. 7
5.1.1 Description p. 7
6 Solutions p. 8
6.1 Solution #1 to key issue 1: VoLTE→(e)CSFB p. 8
6.1.1 Description p. 8
6.1.2 Mobile Originating call flows p. 9
6.1.3 Mobile Terminated call flows p. 12
6.1.4 Impacts on existing nodes and functionality p. 13
6.1.5 Solution Evaluation p. 14
6.1a Solution #1a to key issue 1a: VoLTE→CSFB p. 15
6.1a.1 Description p. 15
6.1a.2 Mobile Originating call flows p. 15
6.1a.3 Mobile Terminated call flows p. 16
6.1a.4 Impacts on existing nodes and functionality p. 16
6.1a.5 Solution Evaluation p. 17
6.2 Solution #2 to key issue 1: SRVCC temporary rejection p. 17
6.2.1 Description p. 17
6.2.2 Temporary SRVCC reject in originating phase p. 17
6.2.3 Temporary SRVCC reject in terminating phase p. 18
6.2.4 Impacts on existing nodes and functionality p. 19
6.2.5 Solution Evaluation p. 19
6.3 Solution #3: Optimised CSFB Procedure p. 19
6.3.1 Solution Description p. 19
6.3.2 Impacts on existing nodes and functionality p. 19
6.3.3 Solution Evaluation p. 20
6.4 Solution #4: UE radio capabilities consideration during PLMN and RAT p. 20
6.4.1 Solution Description p. 20
6.4.2 Impacts on existing nodes and functionality p. 21
6.4.3 Solution evaluation p. 21
6.5 Solution #5: Enabling provisioning of target cell(s) system information p. 21
6.5.1 Solution Description p. 21
6.5.2 Impacts on existing nodes and functionality p. 21
6.5.3 Solution evaluation p. 22
6.6 Solution #6 to key issue 1: Retry in CS domain p. 22
7 Overall Evaluation p. 26
8 Conclusions p. 29
$ Change History p. 30
