Change in osmo-bsc[master]: manual: describe LCS and Lb interface

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neels gerrit-no-reply at lists.osmocom.org
Wed Oct 28 14:26:41 UTC 2020 

neels has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bsc/+/20944 )

Change subject: manual: describe LCS and Lb interface
......................................................................

manual: describe LCS and Lb interface

Change-Id: I7ba432706759433987fabbc674bfc8cd55f2ce62
---
M doc/manuals/chapters/running.adoc
A doc/manuals/chapters/smlc.adoc
A doc/manuals/message-sequences/location_services_ta.msc
M doc/manuals/osmobsc-usermanual.adoc
4 files changed, 136 insertions(+), 0 deletions(-)

Approvals:
  Jenkins Builder: Verified
  fixeria: Looks good to me, approved



diff --git a/doc/manuals/chapters/running.adoc b/doc/manuals/chapters/running.adoc
index ae45afc..ae177a9 100644
--- a/doc/manuals/chapters/running.adoc
+++ b/doc/manuals/chapters/running.adoc
@@ -140,3 +140,15 @@
  mgw remote-ip 10.9.8.7
  mgw remote-port 2427
 ----
+
+==== Configure Lb to connect to an SMLC
+
+Enable the Lb interface. OsmoBSC will then use the default point-codes to
+establish a connection to the SMLC.
+
+----
+smlc
+ enable
+----
+
+More detailed configuration is described in <<smlc-config>>.
diff --git a/doc/manuals/chapters/smlc.adoc b/doc/manuals/chapters/smlc.adoc
new file mode 100644
index 0000000..7fd3e12
--- /dev/null
+++ b/doc/manuals/chapters/smlc.adoc
@@ -0,0 +1,73 @@
+== Location Services: Lb interface to SMLC
+
+OsmoBSC and OsmoSMLC support positioning by Timing-Advance (TA), since October
+2020.
+
+A Perform Location Request is initiated by the MSC via BSSMAP on the
+A-interface, for a specific subscriber. The request is typically passed on via
+BSSMAP-LE on the Lb-interface to the SMLC. If required, the SMLC may request the
+subscriber's Timing Advance (a.k.a. Access Delay) from the BSC via BSSLAP
+(encapsulated BSSLAP APDU in a BSSMAP-LE Connection Oriented Information
+message). The SMLC may combine several location and velocity estimate methods to
+form a GAD PDU containing the resulting geographic location information. In
+TA-based positioning, the Timing-Advance information from the BSC is combined
+with the preconfigured latitude and longitude of the serving cell to form a
+location estimate. This is returned to the BSC via the Lb-interface, and in turn
+to the MSC via the A-interface.
+
+[mscgen]
+----
+include::{srcdir}/message-sequences/location_services_ta.msc[]
+----
+
+Location Services (LCS) are described in 3GPP TS 43.059 <<3gpp-ts-43-059>>.
+Messages for LCS on the A-interface (BSSMAP, between BSC and MSC) are described
+in 3GPP TS 48.008 <<3gpp-ts-48-008>>, on the Lb-interface (BSSMAP-LE between BSC
+and SMLC) in 3GPP TS 49.031 <<3gpp-ts-49-031>>. The resulting geographic
+location and possibly velocity information is encoded in GAD, described in 3GPP
+TS 23.032 <<3gpp-ts-23-032>>.
+
+[[smlc-config]]
+=== Configure Lb-interface
+
+All Lb-interface related configuration is found in the `smlc` section of
+OsmoBSC's configuration.
+
+By default, the Lb-interface is disabled in OsmoBSC. It is started by `enable`.
+
+----
+smlc
+ enable
+----
+
+On the Lb-interface, OsmoBSC always uses SSN "BSC (BSSMAP-LE)" (SSN code 250)
+and contacts the remote SMLC on SSN "SMLC (BSSMAP-LE)" (SSN code 252).
+
+The point-codes are configurable, and default to OsmoBSC's local point-code
+0.23.3 (187), and remote SMLC point-code 0.23.6 (190).
+
+To configure a different remote SMLC point-code, first configure an arbitrarily
+named SCCP address in the `cs7` address book, and then apply that to the
+`smlc-addr` configuration:
+
+----
+cs7 instance 0
+ sccp-address my-smlc
+  point-code 0.42.6
+smlc
+ smlc-addr my-smlc
+----
+
+Similarly, OsmoBSC's local point-code on the Lb-interface is configured by the
+`bsc-addr` configuration:
+
+----
+cs7 instance 0
+ sccp-address my-bsc-on-lb
+  point-code 0.42.3
+smlc
+ bsc-addr my-bsc-on-lb
+----
+
+The geographic locations of individual cells are configured at the SMLC. See
+for example OsmoSMLC's user manual <<userman-osmosmlc>>.
diff --git a/doc/manuals/message-sequences/location_services_ta.msc b/doc/manuals/message-sequences/location_services_ta.msc
new file mode 100644
index 0000000..e6bef38
--- /dev/null
+++ b/doc/manuals/message-sequences/location_services_ta.msc
@@ -0,0 +1,49 @@
+msc {
+  hscale="2";
+
+  ms[label="MS/BTS"],bsc[label="BSC"],smlc[label="SMLC"],__msc[label="MSC"];
+
+  ||| [label="Location Services (LCS): Perform Location Request using TA"];
+
+  |||;
+  --- [label="MS in DEDICATED MODE (currently active)"];
+
+  ms =>> bsc [label="earlier Measurement Report provides Timing Advance"];
+
+  bsc <<= __msc [label="PERFORM LOCATION REQUEST\n3GPP TS 48.008 3.2.1.71"];
+
+  bsc =>> smlc [label="BSSMAP-LE PERFORM LOCATION REQUEST\n3GPP TS 49.031 9.1\nwith BSSLAP APDU = TA Layer3\n3GPP TS 48.071 4.2.8"];
+
+  smlc rbox smlc [label="SMLC uses TA included in TA Layer3"];
+
+  bsc <<= smlc [label="BSSMAP-LE PERFORM LOCATION RESPONSE\n3GPP TS 49.031 9.2"];
+
+  bsc =>> __msc [label="PERFORM LOCATION RESPONSE\n3GPP TS 48.008 3.2.1.72"];
+
+  ...;
+  ...;
+  --- [label="MS in IDLE MODE (not connected)"];
+
+  bsc <<= __msc [label="PERFORM LOCATION REQUEST\n3GPP TS 48.008 3.2.1.71"];
+
+  bsc =>> smlc [label="BSSMAP-LE PERFORM LOCATION REQUEST\n3GPP TS 49.031 9.1"];
+
+  smlc rbox smlc [label="SMLC needs TA information,\nasks BSC via BSSLAP"];
+
+  bsc <<= smlc [label="BSSMAP-LE CONNECTION ORIENTED INFORMATION\n3GPP TS 49.031 9.12\nwith BSSLAP APDU = TA Request\n3GPP TS 48.071 4.2.1"];
+
+
+  ms <<= bsc [label="RR Paging Request\n3GPP TS 48.018 9.1.22-24"];
+
+  ms =>> bsc [label="RSL CHANNEL REQUIRED\n3GPP TS 48.058 8.5.3\nincludes Access Delay (9.3.17) == Timing Advance"];
+
+  ms =>> bsc [label="RR Paging Response\n3GPP TS 48.018 9.1.25"];
+
+  ms <<= bsc [label="RF CHANNEL RELEASE\n3GPP TS 48.058 8.4.14"];
+
+  bsc =>> smlc [label="BSSMAP-LE CONNECTION ORIENTED INFORMATION\n3GPP TS 49.031 9.12\nwith BSSLAP APDU = TA Response\n3GPP TS 48.071 4.2.2"];
+
+  bsc <<= smlc [label="BSSMAP-LE PERFORM LOCATION RESPONSE\n3GPP TS 49.031 9.2"];
+
+  bsc =>> __msc [label="PERFORM LOCATION RESPONSE\n3GPP TS 48.008 3.2.1.72"];
+}
diff --git a/doc/manuals/osmobsc-usermanual.adoc b/doc/manuals/osmobsc-usermanual.adoc
index a34d3d4..3c80cee 100644
--- a/doc/manuals/osmobsc-usermanual.adoc
+++ b/doc/manuals/osmobsc-usermanual.adoc
@@ -30,6 +30,8 @@
 
 include::{srcdir}/chapters/mscpool.adoc[]
 
+include::{srcdir}/chapters/smlc.adoc[]
+
 include::./common/chapters/counters-overview.adoc[]
 
 include::{srcdir}/chapters/counters.adoc[]

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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Change-Id: I7ba432706759433987fabbc674bfc8cd55f2ce62
Gerrit-Change-Number: 20944
Gerrit-PatchSet: 1
Gerrit-Owner: neels <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria <vyanitskiy at sysmocom.de>
Gerrit-Reviewer: neels <nhofmeyr at sysmocom.de>
Gerrit-MessageType: merged
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