Cellular Network Infrastructure

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This page will describe how to install and configure [[OpenBSC]], Osmo-BTS, Osmo-TRX, Osmo-PCU and [[OpenGGSN]] to create an opensource 2G/GSM network with your Ettus USRP B200/B210 SDR hardware.

This page in under development, please stay tuned.

*Pre-Req:*

The following guide is created on Ubuntu 14.14.03 LTS 64bit with kernel 3.19.0-26-lowlatency

1. Installing the UHD driver stack for Ettus USRP SDRs:

http://files.ettus.com/manual/page_install.html#install_linux_ourbins

*2. Installing dependencies:*

<pre>

apt-get install libdbi0-dev libdbd-sqlite3 build-essential libtool autoconf automake git-core pkg-config libssl-dev libpcsclite-dev libusb-1.0 libncurses5-dev libgsm1-dev libpcap-dev libc-ares-dev libtalloc-dev libsctp-dev

</pre>

Create a folder, where all the projects files will be stored:

<pre>

mkdir osmocom

cd osmocom

</pre>

*Get Opencore AMR:*

<pre>

wget http://downloads.sourceforge.net/project/opencore-amr/opencore-amr/opencore-amr-0.1.3.tar.gz

tar xvzf opencore-amr-0.1.3.tar.gz

cd opencore-amr-0.1.3

./configure

make

make install

ldconfig

cd ..

</pre>

*Get ORTP:_

Note: 0.24.2 is not working with [[OpenBSC]]!

<pre>

wget http://download.savannah.gnu.org/releases/linphone/ortp/sources/ortp-0.22.0.tar.gz

tar xvzf ortp-0.22.0.tar.gz

cd ortp-0.22.0

./configure

make

make install

ldconfig

cd ..

</pre>

Please refer to [[Build_from_source]] to get, built and install source for the projects listed below.

* libosmocore

* libosmo-abis

* libosmo-netif

* openggsn

* libosmo-sccp

* openbsc       after command autoreconf -fi  enter @export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig

* osmo-pcu

* osmo-trx

* osmo-bts  

for osmo-bts use branch: 201509-fairwaves-rebase by issuing command bellow:

<pre> git checkout 201509-fairwaves-rebase

</pre> 

<pre>

./configure --enable-trx

</pre>

*Get mISDN kernel and user space:*

Note: if you see "configure: error: kernel build tree does not exist" then you need to install kernel headers.

<pre>

git clone git://git.misdn.eu/mISDN.git

cd mISDN

./configure 

cp mISDN.cfg.default standalone/mISDN.cfg

make modules

make modules_install

ldconfig

cd ..

</pre>

<pre>

git clone git://git.misdn.eu/mISDNuser.git

cd mISDNuser

make

./configure

make

sudo make install

ldconfig

cd ..

</pre>

<pre>

depmod –a

modprobe mISDN_core

modprobe mISDN_dsp

modprobe mISDN_l1loop nchannel=30 interfaces=2

</pre>

To auto-load the mISDN kernel modules do:

<pre>

cd /etc/modules-load.d/

 cat > misdn-modules.conf

 mISDN_core

 mISDN_dsp

 mISDN_l1loop nchannel=30 interfaces=2

</pre>

Hit Ctrl+C

<pre>

chmod 644 misdn-modules.conf

cd /

</pre>

*Install Asterisk (ver 1.8 !):*

On Ubuntu 14.04 there is no version 1.8 Asterisk anymore, to get it, do the following:

<pre>

wget http://launchpadlibrarian.net/153943558/asterisk-modules_1.8.13.1~dfsg-3ubuntu3_amd64.deb

wget http://launchpadlibrarian.net/153943773/asterisk-config_1.8.13.1~dfsg-3ubuntu3_all.deb

wget http://launchpadlibrarian.net/153943772/asterisk-dev_1.8.13.1~dfsg-3ubuntu3_all.deb

wget http://launchpadlibrarian.net/153943557/asterisk_1.8.13.1~dfsg-3ubuntu3_amd64.deb

wget http://launchpadlibrarian.net/107480639/asterisk-core-sounds-en-gsm_1.4.22-1_all.deb

wget http://launchpadlibrarian.net/58272892/asterisk-moh-opsound-gsm_2.03-1_all.deb

dpkg -i *.deb

apt-get -f install

</pre>

Otherwise the Asterisk channel driver (chan_lcr) will not compile.

*Get LCR (master):*

<pre>

git clone git://git.misdn.eu/lcr.git/

cd lcr

autoreconf -fi

./configure --with-gsm-bs --with-misdn --with-asterisk

make

make install

cp chan_lcr.so /usr/lib/asterisk/modules/

ldconfig

cd ..

</pre>

Configure the LCR interfaces:

<pre>

cat > /usr/etc/lcr/interface.conf 

[GSM]

gsm-bs

tones no

earlyb no

bridge ast

[ast]

remote asterisk

context from-lcr

earlyb no

tones yes

bridge GSM

</pre>

Hit Ctrl+C

Add the following two lines to the bottom of options.conf:

<pre>

nano /usr/etc/lcr/options.conf

socketuser asterisk

socketgroup asterisk

</pre>

*Configuration of Asterisk:*

You can find an attached configuration file called "extensions.conf". Please put that file and overwrite the original configuration at /etc/asterisk/exetensions.conf

Then restart asterisk:

<pre>

sudo service asterisk restart

</pre>

*Configuring the GGSN:*

Use the example configuration file called "ggsn.conf" and put it to /etc/ggsn.conf

The traffic from the UEs (mobiles, USB modems etc) are terminated on a TUN interface with the IP address: 10.0.0.1

The UEs are going to get an address from this range: 10.0.0.2 - 10.0.0.254

The GGSN will listen on 127.0.0.5. In this example all the services (BSC, GGSN, SGSN, PCU etc.) are running on the same computer.

*Configuring [[OpenBSC]], Osmo-SGSN, Osmo-PCU*

Please use the attached examle config files at the bottom fo this page.

*Starting the services*

Please note that in this example we are going to need quite a few terminals to be open, because except for LCR, GGSN and Asterisk, we are going to run the services in foreground.

*Start the GGSN:*

<pre>

ggsn

</pre>

Start LCR:

<pre>

lcr fork

</pre>

Open a new terminal and start the SGSN (with the sample config file provided):

<pre>

sudo osmo-sgsn -c sgsn.conf

</pre>

Open a new terminal and start the BSC (with the sample config file provided):

<pre>

sudo osmo-nitb -C -c openbsc.conf -T -P -m

</pre>

Open a new terminal and start Osmo-TRX:

<pre>

sudo osmo-trx

</pre>

Open a new terminal and start Osmo-BTS (with the sample config file provided):

<pre>

sudo osmobts-trx -c osmo-bts.cfg

</pre>

Open a new terminal and start Osmo-PCU (with the sample config file provided):

<pre>

sudo osmo-pcu -c osmo-pcu.cfg

</pre>

*Setting up NAT for GPRS:*

In order for the UEs to be able to "see" the internet, we need to enable network address translation (NAT).

First determine which network interface is connected to the internet with:

<pre>

ifconfig

</pre>

After you know the interface name (for example: eth0 or eth1 or em1 etc.), run the following commands.

Note that in the second command you need to use your interface name instead of "em1".

<pre>

sudo echo 1 > /proc/sys/net/ipv4/ip_forward

sudo iptables -A POSTROUTING -s 10.0.0.0/24 -t nat -o em1 -j MASQUERADE

</pre>