[MERGED] osmo-gsm-manuals[master]: Add chapter on Cell Broadcast Support in Osmocom (to BSC+NIT...

historical

Harald Welte has submitted this change and it was merged.

Change subject: Add chapter on Cell Broadcast Support in Osmocom (to BSC+NITB manual)
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Add chapter on Cell Broadcast Support in Osmocom (to BSC+NITB manual)

Change-Id: I2c621def499dc0564d31eb9440e22e79948a5466
---
M OsmoBSC/osmobsc-usermanual.adoc
M OsmoNITB/osmonitb-usermanual.adoc
A common/chapters/cell-broadcast.adoc
A common/chapters/osmocom-cbs.msc
4 files changed, 91 insertions(+), 0 deletions(-)

Approvals:
  Harald Welte: Looks good to me, approved
  Jenkins Builder: Verified

diff --git a/OsmoBSC/osmobsc-usermanual.adoc b/OsmoBSC/osmobsc-usermanual.adoc
index 25bd35b..9323373 100644
--- a/OsmoBSC/osmobsc-usermanual.adoc
+++ b/OsmoBSC/osmobsc-usermanual.adoc
@@ -27,6 +27,8 @@
 
 include::../common/chapters/control_if.adoc[]
 
+include::../common/chapters/cell-broadcast.adoc[]
+
 include::../common/chapters/port_numbers.adoc[]
 
 include::../common/chapters/bibliography.adoc[]
diff --git a/OsmoNITB/osmonitb-usermanual.adoc b/OsmoNITB/osmonitb-usermanual.adoc
index ec219d9..73166fa 100644
--- a/OsmoNITB/osmonitb-usermanual.adoc
+++ b/OsmoNITB/osmonitb-usermanual.adoc
@@ -31,6 +31,8 @@
 
 include::../common/chapters/control_if.adoc[]
 
+include::../common/chapters/cell-broadcast.adoc[]
+
 include::../common/chapters/abis.adoc[]
 
 include::../common/chapters/port_numbers.adoc[]
diff --git a/common/chapters/cell-broadcast.adoc b/common/chapters/cell-broadcast.adoc
new file mode 100644
index 0000000..d439128
--- /dev/null
+++ b/common/chapters/cell-broadcast.adoc
@@ -0,0 +1,75 @@
+[[cell_broadcast]]
+== Cell Broadcast
+
+Normally, all user plane data in GSM/GPRS networks are sent in
+point-to-point channels from the network to the user. Those are called
+"dedicated" radio channels which exist between the network and one
+given phone/subscriber at a time.
+
+Cell Broadcast is an exception to that rule. It permits user data
+(so-called SMS-CB data) to be broadcast by the network in a way that
+can be received by all phones in the coverage area of the given BTS
+simultaneously.
+
+More high-level information can be found at
+https://en.wikipedia.org/wiki/Cell_Broadcast and the related
+specification is <<3gpp-ts-23-041>>.
+
+=== Use Cases
+
+Cell Broadcast was used for various different use cases primarily in
+the 1990ies and early 2000s, including
+
+* advertisement of the GPS position of the cell tower you're currently camping on
+* advertisement of the calling codes of your current "home zone", i.e. a
+ "lower cost short distance" call zone travelling with you as you roam around.
+
+More recently, SMS-CB is seeing some uptake by various disaster
+warning systems, such as
+
+* CMAS (Commercial Mobile Alert System), later renamed to WEA (Wireless Emergency Alerts) in the US.
+* EU-Alert in the European union
+* Messer Ishi (Rocket Alert) in Israel
+* ETWS (Earthquake and Tsunami Warning System) in Japan
+* KPAS (Korean Public Alert System)
+
+=== Osmocom Cell Broadcast support
+
+* OsmoBTS implements the "SMS BROADCAST COMMAND" Message in RSL
+  according to Section 8.5.8 of 3GPP TS 08.58
+* OsmoNITB and OsmoBSC implement a VTY command
+  `bts <0-255> smscb-command <1-4> HEXSTRING` to send a given hex-formatted cell
+  broadcast message to a specified BTS
+
+[mscgen]
+----
+include::osmocom-cbs.msc[]
+----
+
+==== What'a miaaing
+
+What's missing (for production operation in larger networks)
+
+* mechanism to broadcast one (set of) cell broadcast messages from the
+  BSC to multiple/all BTSs, rather than one BTS individually
+* OsmoBTS reporting of current CBCH load
+* BSC scheduler scheduling multiple alternating sets of CBCH messages
+  based on the current CBCH load reported by BTS
+* external interface from BSC to a Cell Broadcast Center (CBC), e.g.
+  according to 3GPP TS 48.049
+* an Osmocom implementation of the Cell Broadcast Center (OsmoCBC)
+  which can manage and distribute messages to multiple BSCs and which
+  has an external interface by which cell-broadcast can be entered
+  into the network
+
+If you would like to contribute in any of those areas (by means of
+code or funding), please reach out to us any time.
+
+=== Message Structure
+
+* Each message has a meximum of 15 pages
+* Each page is 82 bytes of data, resulting in 93 characters in GSM
+  7-bit default alphabet
+* Messages are broadcast on logical channels (more like an address)
+* Subscribers can activate/deactivate selective addresses
+
diff --git a/common/chapters/osmocom-cbs.msc b/common/chapters/osmocom-cbs.msc
new file mode 100644
index 0000000..f4fd297
--- /dev/null
+++ b/common/chapters/osmocom-cbs.msc
@@ -0,0 +1,12 @@
+msc {
+  hscale="2";
+  ms [label="MS"], bts [label="BTS"], bsc [label="BSC"], user [label="User"];
+
+  user -> bsc [label="Establish VTY connection"];
+  user -> bsc [label="VTY command"];
+  bsc -> bts [label="08.58 RSL SMS BROADCAST CMD"];
+  bts -> ms [label="04.12 SMS BC REQ (1st block)"];
+  bts -> ms [label="04.12 SMS BC REQ (2nd block)"];
+  bts -> ms [label="04.12 SMS BC REQ (3rd block)"];
+  bts -> ms [label="04.12 SMS BC REQ (4th block)"];
+}

-- 
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Gerrit-MessageType: merged
Gerrit-Change-Id: I2c621def499dc0564d31eb9440e22e79948a5466
Gerrit-PatchSet: 1
Gerrit-Project: osmo-gsm-manuals
Gerrit-Branch: master
Gerrit-Owner: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Harald Welte <laforge at gnumonks.org>
Gerrit-Reviewer: Jenkins Builder

