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doc: add codec_resolution.msc 

Illustrate the various factors that influence picking a codec for a 2G
voice call in osmo-bsc.

Change-Id: I3d63a0d587a43fc18ea54b3982800b19b4d50a08
This commit is contained in:
Neels Hofmeyr 2022-09-12 03:19:55 +02:00 committed by neels
parent 220ef9a380
commit 071446d1b0
2 changed files with 49 additions and 0 deletions
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1
doc/Makefile.am
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@ -14,6 +14,7 @@ msc: \
$(builddir)/handover-inter-bsc-in.png \
$(builddir)/mgw-endpoint.png \
$(builddir)/location_services_ta.png \
$(builddir)/codec_resolution.png \
$(NULL)
dot: \

48
doc/codec_resolution.msc Normal file
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@ -0,0 +1,48 @@
msc {
hscale="1.7";
ms[label="MS/BTS"],cfg[label="osmo-bsc.cfg"],bsc[label="osmo-bsc"],__msc[label="MSC"],sip[label="SIP"];
ms => bsc [label="EST IND / Compl L3"];
cfg => bsc [label="'msc 0'\n'codec-list fr3 hr3 fr2 fr1 hr1'"];
bsc rbox bsc [label="build Speech Codec List\ngen_bss_supported_codec_list()"];
bsc => __msc [label="Compl L3"];
bsc note __msc [label="Speech Codec List (BSS Supported)\n{GSM0808_SCT_FR3 + AMR-cfg,\nGSM0808_SCT_HR3 + AMR-cfg,\nGSM0808_SCT_FR2,\nGSM0808_SCT_FR1,\nGSM0808_SCT_HR1}"];
--- [label="AMR-cfg:"];
bsc note __msc [label="S0-S15: 16bit flags\nS0 = 1: 4.75 ---- ---- ---- ---- ---- ---- ----\nS1 = 1: 4.75 ---- 5.90 ---- 7.40 ---- ---- 12.2\nS2 = 1: ---- ---- 5.90 ---- ---- ---- ---- ----\nS3 = 1: ---- ---- ---- 6.70 ---- ---- ---- ----\nS4 = 1: ---- ---- ---- ---- 7.40 ---- ---- ----\nS5 = 1: ---- ---- ---- ---- ---- 7.95 ---- ----\nS6 = 1: ---- ---- ---- ---- ---- ---- 10.2 ----\nS7 = 1: ---- ---- ---- ---- ---- ---- ---- 12.2\n\nS8 = 1: 4.75 ---- 5.90 ---- ---- ---- ---- ----\nS9 = 1: 4.75 ---- 5.90 6.70 ---- ---- ---- ----\nS10= 1: 4.75 ---- 5.90 6.70 7.40 ---- ---- ----\nS11= 1: ---- ---- ---- ---- ---- ---- ---- ----\nS12= 1: 4.75 ---- 5.90 6.70 ---- ---- 10.2 ----\nS13= 1: ---- ---- ---- ---- ---- ---- ---- ----\nS14= 1: 4.75 ---- 5.90 ---- ---- 7.95 ---- 12.2\nS15= 1: ---- ---- ---- ---- ---- ---- ---- ----\n\n3GPP TS 28.062 Table 7.11.3.1.3-2: \"Preferred Configurations\",\nsome removed as specified in 3GPP TS 48.008 3.2.2.103"];
cfg => bsc [label="'bts 0'\n'amr tch-x modes 0 2 4 7'"];
bsc rbox bsc [label="convert AMR modes to\nbts-S0-S15"];
cfg => bsc [label="'msc 0'\n'amr-config 4_75k allowed'"];
bsc rbox bsc [label="convert AMR modes to\nmsc-S0-S15"];
bsc => __msc [label="Compl L3 Speech Codec List:\nbitwise AND:\nbts-S0-S15 & msc-S0-S15"];
---;
ms => __msc [label="Bearer Capabilities"];
__msc <= sip [label="SDP"];
__msc note sip [label="m=audio 12345 RTP/AVP 112 3 111 110\na=rtpmap:112 AMR/8000\na=fmtp:112 mode-set=0,2,4,7\na=rtpmap:3 GSM/8000\na=rtpmap:111 GSM-HR-08/8000\na=rtpmap:110 GSM-EFR/8000"];
__msc rbox __msc [label="combine:\nBSC: Speech Codec List\nMS: Bearer Cap\nSIP: SDP"];
bsc <= __msc [label="BSSMAP Assignment Request\ncontains\nChannel Type\nSpeech Codec List (MSC Preferred)"];
bsc note __msc [label="Channel Type\nChannel Rate And Type:\n- [prefer] full rate\n- [prefer] half rate\n- indicated by Permitted Speech list\nPermitted Speech [1..9]:\n{GSM0808_PERM_FR3,\nGSM0808_PERM_HR3,\nGSM0808_PERM_FR2,\nGSM0808_PERM_FR1,\nGSM0808_PERM_HR1}"];
bsc note __msc [label="Speech Codec List (MSC Preferred)\n{GSM0808_SCT_FR3 + AMR-cfg,\nGSM0808_SCT_HR3 + AMR-cfg,\nGSM0808_SCT_FR2,\nGSM0808_SCT_FR1,\nGSM0808_SCT_HR1}"];
cfg => bsc [label="'msc 0'\n'codec-list fr3 hr3 fr2 fr1 hr1'"];
cfg => bsc [label="'bts 0'\n'phys_chan_cfg TCH/F'"];
cfg => bsc [label="'bts 0'\n'codec-support amr efr fr hr'"];
cfg rbox bsc [label="combine:\n'msc 0' 'codec-list fr3 hr3 fr2 fr1 hr1'\n'bts 0' 'phys_chan_cfg TCH/F'\n'bts 0' 'codec-support amr efr fr hr'\nMSC: Channel Type\nMSC: Speech Codec List (MSC Preferred)\n=>\n{GSM48_CMODE_SPEECH_AMR, FR, S0-S15},\n{GSM48_CMODE_SPEECH_AMR, HR, S0-S15}"];
cfg => bsc [label="'bts 0'\n'amr tch-x bts threshold'\n'amr tch-x bts hysteresis'"];
ms <= bsc [label="RSL CHANnel ACTIVation"];
ms note bsc [label="Channel Rate and Type: Full/Half rate\nSpeech Coding Algorithm Version: 3 (=AMR)\nMultiRate Configuration:\n- 4.75 | 5.90 | 7.40 | 12.2\n- Threshold / Hysteresis x 3"];
cfg => bsc [label="'bts 0'\n'amr tch-x ms threshold'\n'amr tch-x ms hysteresis'"];
ms <= bsc [label="RSL Assignment Command"];
ms note bsc [label="Channel Description: TCH/F\nSpeech Coding Algorithm Version: 3 (=AMR)\nMultiRate Configuration:\n- 4.75 | 5.90 | 7.40 | 12.2\n- Threshold / Hysteresis x 3"];
bsc => __msc [label="BSSMAP Assignment Complete"];
bsc note __msc [label="Chosen Channel: Speech, Full Rate\nSpeech Version (Chosen): FR3\nSpeech Codec (Chosen): FR AMR, S0-S15"];
__msc => sip [label="SDP (optional)"];
__msc note sip [label="m=audio 12345 RTP/AVP 112\na=rtpmap:112 AMR/8000\na=fmtp:112 mode-set=0,2,4,7"];
}