Cellular Network Infrastructure

h1. Installing a [[OsmoTRX:]] based GSM network from scratch

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{{include(Disclaimer-user-content)}}

*This document is outdated by now and only applies if you would like to use hardware based on [[OsmoTRX:]]!*

*THE CONFIG FILES ON THIS PAGE ARE PROBABLY OUTDATED. You may try the examples found in git, e.g. "here":https://git.osmocom.org/openbsc/tree/openbsc/doc/examples/osmo-nitb/sysmobts/openbsc.cfg and "here":https://git.osmocom.org/osmo-bts/tree/doc/examples/trx/osmo-bts.cfg.*

This document describes how to install, configure and run [[OsmoTRX:]], [[OsmoBTS:]], [[OsmoNITB:]] and LCR.

In order to use this quick howto, you must have basic knowledge about GIT and be familiar with compiling packages from source.

h2. Prerequisite

These packages may be available from you distribution. If not, install them by hand as follows.

h3. opencore-amr (optional, for LCR only)

This package installs GSM adaptive multirate codecs and the EFR codec. The Full-Rate codec is included in LCR's repository.

<pre>

tar xvzf opencore-amr-x.x.x.tar.gz

cd opencore-amr-x.x.x

./configure

make

make install

ldconfig

cd ..

</pre>

h3. Sip-Sofia (optional, for LCR only)

This package installs the open source SIP stack of Nokia Research Center.

It can be downloaded at http://sourceforge.net/projects/sofia-sip/files/sofia-sip/":http://sourceforge.net/projects/opencore-amr/files/opencore-amr/

<pre>

tar xvzf sofia-sip-x.xx.xx.tar.gz

cd sofia-sip-x.xx.xx

./configure

make

make install

ldconfig

cd ..

</pre>

h3. oRTP

This package installs the open source RTP protocol required for libosmo-abis.

<pre>

tar xvzf ortp-x.xx.x.tar.gz

cd ortp-x.xx.x

./configure

make

make install

ldconfig

cd ..

</pre>

h3. others

sqlite3, libdbi, dbd-sqlite3 (driver) should should be available from your distribution.

h2. Building and installing 

Build the following projects according to [[Build from source]]:

* libosmocore

* libosmo-abis

* openbsc

* osmobts with @./configure --enable-trx@

* osmotrx

Additional information related to OsmoTRX is available at [[OsmoTRX:]].

h3. Linux-Call-Router (LCR) (optional)

This package installs the open source PBX software to bridge ISDN (DSS1) / SIP / GSM (MNCC protocol)

The latest version can downloaded via git:

<pre>

git clone http://git.eversberg.eu/lcr.git

</pre>

Now configure, as described here:

<pre>

cd lcr

autoreconf -i

./configure --with-sip --with-gsm-bs --with-gsm-ms

</pre>

I strongly suggest not to use the Half-Rate codec (--enable-gsmhr) except for testing, because this codec is so slow, that only one or two calls may occupy CPU completely.

Sometimes it is necessary to point to different pkgconfig path, because your distribution may use other pkgconfig path than the default path of the packages above. Use the following prefix:

<pre>

PKG_CONFIG_PATH=/usr/local/lib/pkgconfig/ ./configure .....

</pre>

The configure result should include:

<pre>

configure: Compiled with GSM network side support

configure: Compiled with GSM mobile side support

configure: Compiled with GSM half rate codec support

configure: Compiled with GSM AMR codec support

configure: Compiled with SIP support

</pre>

Finish the installation:

<pre>

make

make install

ldconfig

cd ..

</pre>

h2. Configuration examples

h3. [[OsmoBTS:]]

<pre>

mkdir ~/.osmocom

edit ~/.osmocom/osmo-bts.cfg

</pre>

<pre>

bts 0

 band DCS1800

 ipa unit-id 1801 0

 oml remote-ip 127.0.0.1

 rtp bind-ip 127.0.0.1

 rtp jitter-buffer 0

 paging lifetime 0

 gsmtap-sapi bcch

 gsmtap-sapi ccch

 gsmtap-sapi rach

 gsmtap-sapi agch

 gsmtap-sapi pch

 gsmtap-sapi sdcch

 gsmtap-sapi pacch

 gsmtap-sapi pdtch

 gsmtap-sapi sacch

 fn-advance 20

 ms-power-loop -10

 timing-advance-loop

 trx 0

  rxgain 0

  power 0

</pre>

h3. [[OpenBSC:]]

<pre>

mkdir ~/.osmocom

edit ~/.osmocom/open-bsc.cfg

</pre>

*Be sure to change 'arfcn' to a frequency you have license for!*

<pre>

e1_input

 e1_line 0 driver ipa

 e1_line 0 port 0

network

 network country code 262

 mobile network code 42

 short name [[OpenBSC]]

 long name [[OpenBSC]]

 auth policy accept-all

 location updating reject cause 13

 encryption a5 0

 neci 1

 paging any use tch 0

 rrlp mode ms-based

 mm info 1

 handover 0

 handover window rxlev averaging 10

 handover window rxqual averaging 1

 handover window rxlev neighbor averaging 10

 handover power budget interval 6

 handover power budget hysteresis 3

 handover maximum distance 9999

 timer t3101 10

 timer t3113 60

 timer t3122 10

 dtx-used 0

 subscriber-keep-in-ram 0

 bts 0

  type sysmobts

  band DCS1800

  cell_identity 0

  location_area_code 1

  training_sequence_code 7

  base_station_id_code 63

  ms max power 0

  cell reselection hysteresis 4

  rxlev access min 0

  periodic location update 30

  channel allocator descending

  rach tx integer 9

  rach max transmission 7

  channel-descrption attach 1

  channel-descrption bs-pa-mfrms 5

  channel-descrption bs-ag-blks-res 1

  ip.access unit_id 1801 0

  oml ip.access stream_id 255 line 0

  neighbor-list mode automatic

  trx 0

   rf_locked 0

   arfcn 869

   nominal power 0

   max_power_red 0

   rsl e1 tei 0

    timeslot 0

     phys_chan_config CCCH+SDCCH4

     hopping enabled 0

    timeslot 1

     phys_chan_config TCH/F

     hopping enabled 0

    timeslot 2

     phys_chan_config TCH/F

     hopping enabled 0

    timeslot 3

     phys_chan_config TCH/F

     hopping enabled 0

    timeslot 4

     phys_chan_config TCH/F

     hopping enabled 0

    timeslot 5

     phys_chan_config TCH/F

     hopping enabled 0

    timeslot 6

     phys_chan_config TCH/F

     hopping enabled 0

    timeslot 7

     phys_chan_config TCH/F

     hopping enabled 0

</pre>

h3. Linux-Call-Router (LCR) (optional)

h4. options.conf

<pre>

edit /usr/local/etc/lcr/options.conf

</pre>

Add a line to show logging to the console:

<pre>

debug 0x100000

</pre>

h4. interface.conf

The simplest configuration uses only the GSM interface. It allows LCR to forward calls from GSM to GSM or from GSM to a call test feature.

<pre>

edit /usr/local/etc/lcr/interface.conf

</pre>

You can remove (or comment out) everything and just add this interface:

<pre>

[gsm]

gsm-bs

tones yes

earlyb no

extern

</pre>

h4. routing.conf

<pre>

edit /usr/local/etc/lcr/routing.conf

</pre>

You can remove (or comment out) everything and just add these rulesets:

<pre>

[main]

interface=gsm                           : goto ruleset=gsm

                                        : disconnect cause=31

[gsm]

dialing=99                              : test

                                        : extern interfaces=gsm

</pre>

Look at the main rule set. All calls from interface 'gsm' are forwarded to rule set 'gsm'.

Look at the gsm rule set. All calls that dial '99' prefix, will be test calls. All other calls will be forwarded back to 'gsm' interface.

h2. Running

I suggest to have one shell for every process to run, rather than stating all processes as damon from one shell. Not starting as deamon allows to easily see the debugging output.

h3. [[OpenBSC:]]

Open a shell and start [[OpenBSC:]]:

<pre>

osmo-nitb -c ~/.osmocom/open-bsc.cfg -l ~/.osmocom/hlr.sqlite3 -P -C --debug=DRLL:DCC:DMM:DRR:DRSL:DNM

</pre>

[[OpenBSC:]] runs as a stand-alone network with given config file and data base. In order to use LCR, add '-m' option. In this case the LCR replaces the built-in call control.

<pre>

osmo-nitb -c ~/.osmocom/open-bsc.cfg -l ~/.osmocom/hlr.sqlite3 -P -m -C --debug=DRLL:DCC:DMM:DRR:DRSL:DNM

</pre>

Very important is the option '-C'. On certain machines, osmo-nitb will halt from time to time while writing counters to database. This Without this option, audio might interrupt several seconds from time to time.

The debugging is usefull for early tests, because you will quickly see what happens if a mobile requests something.

<pre>

<0005> bsc_init.c:422 

WARNING: You are running an 'accept-all' network on a BTS that is not barred.

This configuration is likely to interfere with production GSM networks and

should only be used in a RF shielded environment such as a faraday cage!

<0019> input/ipaccess.c:925 enabling ipaccess BSC mode

DB: Database initialized.

DB: Database prepared.

<001d> sms_queue.c:220 Attempting to send 20 SMS

</pre>

h3. [[OsmoBTS:]]

Open a shell and start [[OsmoBTS:]]:

<pre>

osmobts-trx -c ~/.osmocom/osmo-bts.cfg

</pre>

<pre>

((*))

  |

 / \ [[OsmoBTS]]

Using MAC address of eth0: 'xx:xx:xx:xx:xx:xx'

...

<000a> trx_if.c:176 No response from tranceiver

<000a> trx_if.c:176 No response from tranceiver

<000a> trx_if.c:176 No response from tranceiver

</pre>

h3. [[OsmoTRX:]]

Refer to the [[OsmoTRX:]] page on how to run [[OsmoTRX:]].

h4. [[UmTRX:]]

The installation/setup/calibration of [[UmTRX:]] is beyond the scope of this document. Please refer to:

* https://github.com/fairwaves

* http://files.ettus.com/uhd_docs/manual/html/build.html

* http://wush.net/trac/rangepublic/wiki/BuildInstallRun

h4. calypso-BTS

Building Osmocom-BB with arm-elf toolchain is also beyond the scope of this document. If you managed to compile and run Osmocom-BB you should be able to run the transceiver too.

The latest version can downloaded via git:

<pre>

git clone https://gitea.osmocom.org/sdr/libosmo-dsp

git clone https://gitea.osmocom.org/phone-side/osmocom-bb

</pre>

In order to compile Osmocom-BB with transceiver support, do the following:

<pre>

cd libosmo-dsp

autoreconf -i

./configure

(sometimes it is necessary to point to different .../lib/pkgconfig/ path: PKG_CONFIG_PATH=/usr/local/lib/pkgconfig/ ./configure .....)

make

make install

cd ..

cd osmocom-bb

# change branch:

git checkout -b jolly/testing origin/jolly/testing

cd src

make

# after it compiles, just enable transceiver support

cd host/layer23

./configure --enable-transceiver

make

</pre>

*NOTE: "ms-power-loop" at osmo-bts.cfg should be set to -65, in order to prevent saturating the input. Also if the phone is only one or few meters away, "ms max power" should be set to 0. In case of long distance test it can be set to 30 (DCS) or 33 (GSM 900).*

Now you should start with a single phone for one timeslot only. If it works, you can try two phones to serve two timeslots. Since you have only one slot, you will only be able to transmit broadcast, do location updating and send/receive SMS. Here is the "osmo-bts.cfg" for a single timeslot:

<pre>

bts 0

 band DCS1800

 ipa unit-id 1801 0

 oml remote-ip 127.0.0.1

 rtp jitter-buffer 0

 paging queue-size 200

 paging lifetime 0

 fn-advance 30

 ms-power-loop -60

 timing-advance-loop

 settsc

 setbsic

 trx 0

  rxgain 0

  power 0

  slotmask 1 0 0 0 0 0 0 0

</pre>

Run osmocon and transceiver application in separate shells:

<pre>

# Please refer to Osmocom-BB wiki for compiling and running own firmware on compal phones...

osmocon -p /dev/ttyUSB0 -m c123xor -c path_to/trx.highram.bin -r 99

</pre>

<pre>

transceiver -e 5 -r 99

</pre>

When using two phones, two timeslots can be served. I suggest to configure second timeslot (TS 1) as TCH/H at openbsc.cnf. This way it is possible to allow two traffic channels on a single timeslot. If you do a call from one phone to another, you will need one channel for each phone. In order to use two phones, you need to change the alot map of osmo-bts.cnf:

<pre>

  slotmask 1 1 0 0 0 0 0 0

</pre>

Run two osmocon and transceiver application in separate shells:

<pre>

osmocon -p /dev/ttyUSB0 -m c123xor -c path_to/trx.highram.bin -r 99

</pre>

<pre>

# This osmocon connects to the serial interface of the second phone.

# Note: "/tmp/osmocom_l2.2" is the second socket to which the transceiver will connect.

osmocon -p /dev/ttyUSB1 -s /tmp/osmocom_l2.2 -m c123xor -c path_to/trx.highram.bin -r 99

</pre>

<pre>

transceiver -e 5 -r 99 -2

</pre>

h3. Linux-Call-Router (LCR) (optional)

Run LCR with debugging output.

<pre>

lcr start

</pre>

<pre>

** LCR  Version 1.14

LCR 1.14 started, waiting for calls...

</pre>

h2. Test

h3. Location Updating

Switch on the phone.

If you have a SIM card for your network 262 42, you can use it and do automatic network search. If not, do a manual network and select this network. You should see debugging output on [[OpenBSC:]] like this:

<pre>

...

 <0002> gsm_04_08.c:424 -> LOCATION UPDATE ACCEPT

...

</pre>

h3. Call the music (LCR required)

Now enter phone number 995 to select the test function 5 of LCR. This test function just plays the hold music.

h3. Echo and BFI test (LCR required)

Enter phone number 993 to select the test function 3 of LCR. This test function echoes back everything that is received. Note that it will re-transcode the speech data, so the audio from your voice is compressed and decompressed twice until you can hear a fraction of a second later.

You may experience short beeps. These beeps represent all bad frames that could not be decoded or got lost over the air. (Without this test, the missing frames will be extrapolated from previous frame, so some loss rate will not be recognized by the remote end.)

h2. See also

* [[openbsc:Multi-BTS with handover]] -- NITB plus two dual channel BTS (based on [[OsmoBTS:]]) with handover support