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authorPau Espin Pedrol <pespin@sysmocom.de>2017-07-18 15:21:59 +0200
committerHarald Welte <laforge@gnumonks.org>2017-07-18 14:20:49 +0000
commitb052cb0499672bb86c97e764aa77d9eb8ff1d60f (patch)
treefa546092e33d0fd85233645ff21787c5ecfb6a03
parentbed4162c70f4a41c79c68af118d53bce4aa3405c (diff)
rtp-amr: Describe requirement to recieve all PH-DATA.ind events
-rw-r--r--OsmoBTS/rtp-amr-docinfo.xml8
-rw-r--r--OsmoBTS/rtp-amr.adoc86
2 files changed, 59 insertions, 35 deletions
diff --git a/OsmoBTS/rtp-amr-docinfo.xml b/OsmoBTS/rtp-amr-docinfo.xml
index fe5d681..3f4de8d 100644
--- a/OsmoBTS/rtp-amr-docinfo.xml
+++ b/OsmoBTS/rtp-amr-docinfo.xml
@@ -15,6 +15,14 @@
FSM added
</revremark>
</revision>
+ <revision>
+ <revnumber>3</revnumber>
+ <date>July 2017</date>
+ <authorinitials>PE</authorinitials>
+ <revremark>
+ Add section and update sequence charts to describe requirement to receive all PH-DATA.ind events
+ </revremark>
+ </revision>
</revhistory>
<authorgroup>
diff --git a/OsmoBTS/rtp-amr.adoc b/OsmoBTS/rtp-amr.adoc
index 982a5af..5f0f803 100644
--- a/OsmoBTS/rtp-amr.adoc
+++ b/OsmoBTS/rtp-amr.adoc
@@ -14,6 +14,22 @@ back-haul towards the MGW.
=== TCH/AFS Uplink (MS to Network)
+==== TCH/AFS Uplink: Initial Assumptions
+
+When a call is established, the BTS expects PH-DATA.ind (TCH) events to be
+triggered by BTS-PHY at regular intervals and none of them being lost, even if
+the MS is not transmitting at that time due to DTX. This requirement is
+important as upper layers rely on this timing to update the RTP source clock at
+a correct pace. Given an event from BTS-PHY is lost, the RTP source clock will
+drift and this may be seen as steady increase of delay over time from the
+receiver point of view.
+
+In the case of Nutaq GSM PHY and API, option fBFILevel is set to a ridiculously
+low value -200 to ensure all indications are notified to upper layers, even if
+no meaningful payload is available at that time. In this case, an empty payload
+is delivered from PHY-BTS to BTS, which updates the clock without sending any
+RTP packet.
+
==== TCH/AFS Uplink: During Talk-Spurt
During a talk-spurt, the system behaves identical to a system without
@@ -83,14 +99,14 @@ msc {
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 1+2 of SID_UPDATE)", id="ULSU2"];
ms => phy [label="L1 burst (sub-block 3+4 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 5+6 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 7+8 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
@@ -133,7 +149,7 @@ msc {
ms => phy [label="L1 burst (sub-block 3+4 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 5+6 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 7+8 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
@@ -147,49 +163,49 @@ msc {
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 1+2 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 3+4 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 5+6 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 7+8 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
@@ -242,14 +258,14 @@ msc {
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (block 1 of SID_ONSET + sub-block 1 of speech frame N)", id="ULSO2"];
ms => phy [label="L1 burst (block 2 of SID_ONSET + sub-block 2 of speech frame N)"];
ms => phy [label="L1 burst (block 3 of SID_ONSET + sub-block 3 of speech frame N)"];
ms => phy [label="L1 burst (block 4 of SID_ONSET + sub-block 4 of speech frame N)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 5 of speech frame N + sub-block 1 of speech frame N+1)"];
@@ -333,14 +349,14 @@ msc {
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (block 1 of SID_ONSET + sub-block 1 of FACCH frame)"];
ms => phy [label="L1 burst (block 2 of SID_ONSET + sub-block 2 of FACCH frame)"];
ms => phy [label="L1 burst (block 3 of SID_ONSET + sub-block 3 of FACCH frame)"];
ms => phy [label="L1 burst (block 4 of SID_ONSET + sub-block 4 of FACCH frame)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 5 of FACCH frame + sub-block 1 of SID First frame)"];
@@ -734,7 +750,7 @@ msc {
ms => phy [label="L1 burst (sub-block 5+6 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 7+8 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
@@ -772,11 +788,11 @@ msc {
ms => phy [label="L1 burst (sub-block 1+2 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 3+4 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 5+6 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 7+8 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
@@ -786,36 +802,36 @@ msc {
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 1+2 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 3+4 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 5+6 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 7+8 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];
@@ -864,17 +880,17 @@ msc {
ms -x phy [label="Suppressed L1 burst"];
ms -x phy [label="Suppressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (block 1 of SID_ONSET + sub-block 1 of speech frame N)"];
ms => phy [label="L1 burst (block 2 of SID_ONSET + sub-block 2 of speech frame N)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 3 of speech frame N + sub-block 1 of speech frame N+1)"];
ms => phy [label="L1 burst (sub-block 4 of speech frame N + sub-block 2 of speech frame N+1)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 3 of speech frame N+1 + sub-block 1 of speech frame N+2)"];
@@ -916,7 +932,7 @@ msc {
ms => phy [label="L1 burst (sub-block 3 of speech frame N+1 + sub-block 1 of speech frame N+2)"];
ms => phy [label="L1 burst (sub-block 4 of speech frame N+1 + sub-block 2 of speech frame N+2)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 3 of speech frame N+2 + sub-block 1 of speech frame N+3)"];
@@ -948,17 +964,17 @@ msc {
ms => phy [label="L1 burst (sub-block 1+2 of SID_UPDATE)"];
ms => phy [label="L1 burst (sub-block 3+4 of SID_UPDATE)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (block 1 of SID_UPD_INH + sub-block 1 of speech frame N)", id="SFU1"];
ms => phy [label="L1 burst (block 2 of SID_UPD_INH + sub-block 2 of speech frame N)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 3 of speech frame N + sub-block 1 of speech frame N+1)"];
ms => phy [label="L1 burst (sub-block 4 of speech frame N + sub-block 2 of speech frame N+1)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 3 of speech frame N+1 + sub-block 1 of speech frame N+2)"];
@@ -985,17 +1001,17 @@ msc {
ms -x phy [label="Supressed L1 burst"];
ms -x phy [label="Supressed L1 burst"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (block 1 of SID_ONSET + sub-block 1 of FACCH/H)"];
ms => phy [label="L1 burst (block 2 of SID_ONSET + sub-block 2 of FACCH/H)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 3+4 of FACCH/H)"];
ms => phy [label="L1 burst (sub-block 5+6 of FACCH/H)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms => phy [label="L1 burst (sub-block 7 of FACCH/H + sub-block 1 of SID_FIRST_P1)"];
@@ -1007,7 +1023,7 @@ msc {
ms => phy [label="L1 burst (sub-block 3 of SID_FIRST_P1 + block 1 of SID_FIRST_P2)"];
ms => phy [label="L1 burst (sub-block 4 of SID_FIRST_P1 + block 2 of SID_FIRST_P2)"];
- phy -x bts [label="No PH-DATA.ind sent[BFI]"];
+ phy => bts [label="PH-DATA.ind with empty payload"];
bts -x mgw [label="Suppressed RTP frame"];
ms -x phy [label="Supressed L1 burst"];