Content for TR 26.916 Word version: 14.2.0
2 References
3 Definitions, symbols and abbreviations
4 eSRVCC Reference Architecture
5 eSRVCC Reference Procedure
6 Selected example scenarios for eSRVCC
7 Identified Problems with current eSRVCC
8 Speech Quality and Media Handling Aspects
9 Codec Mode Control before, during and after SRVCC
10 SDP Offer-Answer between MSC and ATCF
11 Codec Compatibility
12 Enhancements for media and quality aspects
13 Proposals for Stage 2 and Stage 3
$ Change history
2 References p. 8
3 Definitions, symbols and abbreviations p. 8
4 eSRVCC Reference Architecture p. 10
5 eSRVCC Reference Procedure p. 12
5.1 General p. 12
5.2 Codec Selection during eSRVCC p. 14
5.3 Voice Path Switching during eSRVCC p. 15
5.4 Possibilities to adjust codecs after eSRVCC without standards extensions p. 16
6 Selected example scenarios for eSRVCC p. 17
6.1 General p. 17
6.2 eSRVCC AMR(...) to AMR(...) p. 18
6.3 eSRVCC AMR(...) to AMR-WB(...) p. 19
6.4 eSRVCC AMR(...) to UMTS_EVS(...) p. 19
6.5 eSRVCC AMR-WB(...) to AMR(...) p. 20
6.6 eSRVCC EVS (br=5.9-128; bw=nb-fb) to UMTS_EVS (Set1) p. 20
6.7 eSRVCC EVS (br=16.4-128; bw=fb) to UMTS_EVS (Set1) p. 21
6.8 eSRVCC EVS (br=9.6-24.4; bw=swb) to UMTS_EVS (Set1) p. 23
6.9 eSRVCC EVS (...) to AMR-WB (...) p. 23
6.10 eSRVCC EVS (...) to AMR (...) p. 23
6.11 eSRVCC EVS (br=5.9-128; bw=nb-fb) to UMTS_EVS (Set 1) and subsequent Handover to AMR-WB(0,1,2) p. 24
6.12 eSRVCC and Handover in speech pauses p. 24
7 Identified Problems with current eSRVCC p. 25
7.1 General p. 25
7.2 IMS Selected Codec not known in Target RAN p. 25
7.2.0 General p. 25
7.2.1 Remote Access Network supports only lower quality codecs than Target RAN p. 25
7.2.2 Remote Access Network supports higher quality codecs than Target RAN p. 26
7.2.3 Assemble the remote IMS Preferred Codec List p. 26
7.3 Late Information about the Target RAN Codec p. 27
7.4 Access Transfer and Handover Command p. 28
7.5 Target MGW is blocked in Uplink p. 29
7.6 The remote UE does not follow CMR commands p. 29
8 Speech Quality and Media Handling Aspects p. 30
8.1 General p. 30
8.2 Blind Selection of the Target RAN Codec p. 30
8.3 Unnecessary speech break by missing Rate Control p. 30
8.4 Unsynchronized, early Handover switching by ATGW p. 30
8.5 Synchronized hard Handover p. 32
8.6 Ideal eSRVCC Handover p. 32
9 Codec Mode Control before, during and after SRVCC p. 34
9.1 General p. 34
9.2 Mode Control commands in the User Plane p. 36
9.3 Mode Control Rules for AMR and AMR-WB p. 36
9.4 Mode Control Rules for EVS p. 36
9.5 Call Setup and Initial Codec Mode p. 37
9.6 Mode Control before eSRVCC p. 39
9.7 Mode Control during eSRVCC p. 39
9.8 Mode Control after eSRVCC p. 41
10 SDP Offer-Answer between MSC and ATCF p. 41
10.1 General p. 41
10.2 Message and Information from MSC to ATCF p. 42
10.3 Information in ATCF and ATGW and actions p. 42
10.4 Message from ATCF to MSC, MGW actions p. 42
10.5 Message from MSC to MME and LTE UE p. 43
11 Codec Compatibility p. 43
11.1 Digital Mobile Communication p. 43
11.2 Transcoding p. 44
11.3 EVS configurations p. 44
11.3.1 General p. 44
11.3.2 The EVS Bottom-up Configurations p. 45
11.3.3 The EVS Punctured Configurations p. 46
11.4 Transcoding Less Operation p. 48
11.4.1 General p. 48
11.4.2 GSM_EFR and AMR (mode-set=7) p. 49
11.4.3 AMR p. 49
11.4.4 AMR-WB and EVS-IO p. 51
11.4.4.1 General p. 51
11.4.4.2 Additional Conditions for TLCI-Compatibility for AMR-WB and EVS-IO p. 52
11.4.5 EVS p. 52
11.5 Transcoding Less Operation at call setup p. 53
11.6 Transcoding Less Operation after Handover p. 53
12 Enhancements for media and quality aspects p. 53
12.1 General p. 53
12.2 Early Information exchange between MSC and ATCF p. 53
12.2.1 Proposed Requirement p. 53
12.2.2 Proposed Solution 1: CS/IMS Bi-directional Codec List Exchange p. 54
12.2.2.1 Overview p. 54
12.2.2.2 Information in Handover Preparation Response p. 55
12.2.2.3 Information in Handover Preparation Request p. 55
12.2.3 Proposed Solution 2: MSS initiated codec inquiry p. 56
12.3 Access Transfer and Handover Command p. 58
12.4 Unblock the Target MGW in Uplink p. 59
12.5 Clarify that it is indispensable to follow CMR commands p. 59
12.6 Updated Message flow according to proposed solution 1 p. 60
13 Proposals for Stage 2 and Stage 3 p. 61
$ Change history p. 62
