= OAI Remote Radio Head (RRH)

This tutorial assumes that you have an ORBIT account, and a reservation for grid.orbit-lab.org

In this tutorial, we demonstrate the operation of a split eNB, with one node managing a RF device, and sending I/Q samples to another node fro processing.


== Basic Setup
We will use the following resources:
* node18-2.grid.orbit-lab.org as the RRH
* node18-1.grid.orbit-lab.org as the eNB
* node1-7.grid.orbit.lab.org as a client


1. Execute the following commands on the grid console, from separate ssh sessions (They can be done at the same time)
 1. {{{ omf load -t node18-2,node18-1 -i oai-rrh.ndz }}}
 1. {{{ omf load -t node19-3 }}}
1. After they are imaged, turn the nodes on
 1. {{{ omf tell -a on -t node18-2,node18-1,node19-3 }}}
1. Open a ssh session to each device
 1. {{{ ssh root@node18-2.grid.orbit-lab.org }}}
 1. {{{ ssh root@node18-1.grid.orbit-lab.org }}}
 1. {{{ ssh root@node19-3.grid.orbit-lab.org }}}
1. On node18-2
 1. Run script {{{ ./quickbuild_rrh.sh }}}
 1. Run script {{{ ./run_rrh.sh }}}
1. On node18-1
 1. Run script {{{ ./quickbuild_enb.sh }}}
 1. Run script {{{ ./run_enb.sh }}}
1. After executing both run scripts, you should see the RRH node load a USRP image, and the eNB node start printing log messages.
1. On node19-3
 1. Follow the instructions from the [wiki:Tutorials/g0WmLTE/Tutorial5 amarisoft tutorial] to connect.

== Modify Transport
We will use node18-3 as a bridge between the eNB and the RRH to experiment with fronthaul transport requirements.

1. Image and configure node
 1. {{{ omf load -t node18-3 }}}
 1. {{{ ssh root@node18-3.grid.orbit-lab.org }}}
 1. {{{ apt-get update }}}
 1. {{{ apt-get install vlan bridge-utils }}}
 1. Modify the file {{{ /etc/network/interfaces }}}
  1. Add the lines 
{{{ 
auto br0
iface br0 inet manual
bridge_ports eth0.1001 eth0.1002
bridge_stp off
bridge_waitport 0
bridge_fd 0
}}}
 1. run the command {{{ ifup br0 }}}
1. Configure vlans
 1. ?

Delay without bridge ~ 0.168ms
Delay with bridge ~ 0.66ms 


== Generalizing
To run this on other machines, you will need 3 devices.
* One with a USRP B210
* One with sufficient processing power
* And one to act as client.

To run this on nodes 1-1,1-2, and 2-1 on Sandbox 1, you would need to make the following changes:
1. Load the rrh image onto nodes 1-1 and 1-2.
1. execute the rrh scripts on node1-1
1. on node1-2, edit the file ~/conf/enb.band25.tm1.rrh.usrpb210.conf
 1. change the lines {{{ENB_IPV4_ADDRESS_FOR_S1_MME}}} and {{{ ENB_IPV4_ADDRESS_FOR_S1U}}} to {{{10.11.1.2}}}, or the interface that will send traffic to the MME
1. If you want to change the RRH interface or IP, you must change it in both run scripts, as well as the lines {{{local_if_name}}}, {{{remote_address}}}, and {{{local_address}}} in the eNB config.

Further instructions are available at the OAI wiki at https://gitlab.eurecom.fr/oai/openairinterface5g/wikis/HowtoconnectCOTSUEtoOAIeNBviaRRHGW