In this tutorial, we will describe how to connect a commercial off-the-shelf UE (i.e. smartphone and LTE dongle) with the C-RAN version of the OAI eNB. The OAI C-RAN architecture is described in detailed on this whitepaper.
Specifically, this tutorial describes how to deploy and run OAI as RCC and RRU on different hosts as depicted in the following figure:
The tutorial set up is depicted once more in the following figure, this time containing interconnection information (i.e. IP addresses and Ethernet interface names) that will be used in certain configuration files.
Figure 2: OAI RRU, OAI RCC and OAI EPC+HSS on different hosts (interface information included)
1.1 Choice of configuration files
At the time of writing this tutorial, OAI architecture supports IF4.5 and IF5 functional splits (note: IF5 and IF4p5/RAW Ethernet are broken and not tested with CI/CD for the moment, so test only IF4p5/UDP). The different splits can be run by using the appropriate configuration files from below.
NGFI IF4p5 (10 MHz)
2. Installation and Configuration of OAI RRU
Step 1: Check out the develop branch
Download the source code from the appropriate Git repository (see Get the Sources). We assume that you have following directory:
openairinterface5g: The location of openairinterface5g repository.
Step 2: Run automated script for OAI RRU/RCC (for software installation->TO BE RUN ONLY ONCE))
cd ~/openairinterface5gsource oaienvcd cmake_targets./build_oai -I--eNB-w USRP #for USRP
You can print out the help message to see what these options mean using the command "./build_oai -h". A short summary is as follows.
-I: installs required packages.
-w: adds the hardware support, which is USRP in our case
You can skip this if you've already installed the packages (including the RF hardware you are using) or do not wish to update the packages.
2.2 Configuration and execution
Step 1: Edit the RRU configuration file (start from ~/openairinterface5g/targets/PROJECTS/GENERIC-LTE-EPC/CONF/rru_oaisim.conf)
Under the following configuration parameters:
IP address of RCC towards RRU is 10.10.10.1 and RRU Ethernet interface name is eth0
IP address of RRU is 10.10.10.2
RRU will have a USRPB210 attached to it
-27 dBm/RE RS EPRE (maximum level for USRP B2x0 with 10 MHz carrier bandwidth)
115 dB RX gain (a reasonable choice for USRP B2x0)
The contents of the RU section in the RRU .conf file should look like :
If you have previously build OAI on your host, please use -c or -C to remove existing compiled files.
Step 2: Compile & Run the RCC
cd ~/openairinterface5gsource oaienvcmake_targets/build_oai -t ETHERNET -c--eNBcd cmake_targets/lte_build_oai/buildsudo-E ./lte-softmodem -O$OPENAIR_DIR/targets/PROJECTS/GENERIC-LTE-EPC/CONF/**rcc_file**# replace based on choice of functional split
4. UE Configuration and User Registration on HSS Database
At this point we have an operating base station and core network, so it is time to configure the COTS UE and use it (see Stage 2 of HowToConnectCOTSUEwithOAIeNBNew tutorial).