+
+This page is valid on the following branches:
+
+- `master` starting from tag `v1.1.0`
+- `develop` starting from tag `2019.w11`
+
+# 1. Building the basic-simulator.
+
+After the build simplification, the basic simulator is available directly from the standard build.
+
+```bash
+$ source oaienv
+$ cd cmake_targets
+$ ./build_oai --eNB --UE
+```
+
+Both eNB (lte-softmodem) and UE (lte-uesoftmodem) are present on `cmake_targets/lte_build_oai/build` folder.
+
+More details are available on the [build page](BUILD.md).
+
+# 2. Running the basic simulator.
+
+The basic simulator is a oai device replacing the radio heads (for example the USRP device). It allows connecting the oai UE and the oai eNodeB through a network interface carrying the time-domain samples, getting rid of over the air unpredictable perturbations.
+
+This is the ideal tool to check signal processing algorithms and protocols implementation and having debug sessions without any HW radio equipment.
+
+The main limitations are:
+
+- A single OAI UE will connect to the OAI eNB
+- No channel noise
+
+## 2.1. Starting eNB
+
+The basic simulator is able to run with a connected EPC or without any (the so-called "noS1" mode).
+
+Example 1: running in FDD mode with EPC.
+
+```bash
+$ source oaienv
+$ cd cmake_targets/lte_build_oai/build
+$ ENODEB=1 sudo -E ./lte-softmodem -O $OPENAIR_HOME/ci-scripts/conf_files/lte-fdd-basic-sim.conf --basicsim
+```
+
+Edit previously the `ci-scripts/conf_files/lte-fdd-basic-sim.conf` file to modify:
+
+- `N_RB_DL` field to change the Bandwidth (25, 50, 100)
+- `CI_MME_IP_ADDR` with the EPC IP address
+- `CI_ENB_IP_ADDR` with the container (physical server, virtual machine, ...) on which you are executing the eNB soft-modem
+
+Example 2: running in TDD mode without any EPC.
+
+```bash
+$ source oaienv
+$ cd cmake_targets/lte_build_oai/build
+$ ENODEB=1 sudo -E ./lte-softmodem -O $OPENAIR_HOME/ci-scripts/conf_files/lte-tdd-basic-sim.conf --basicsim --noS1
+```
+
+## 2.2. Starting UE
+
+Before starting the UE, you may need to edit the SIM parameters to adapt to your eNB configuration and HSS database.
+
+The file to use for conf2uedate is `openair3/NAS/TOOLS/ue_eurecom_test_sfr.conf`
+
+You need to set the correct OPC, USIM_API_K, MSIN (this is the end par of the IMSI), HPLMN (the front part of IMSI) to match values from HSS.
+
+```bash
+$ source oaienv
+# Edit openair3/NAS/TOOLS/ue_eurecom_test_sfr.conf
+$ cd cmake_targets/lte_build_oai/build
+$ ../../nas_sim_tools/build/conf2uedata -c $OPENAIR_HOME/openair3/NAS/TOOLS/ue_eurecom_test_sfr.conf -o .
+$ sudo -E ./lte-uesoftmodem -C 2625000000 -r 25 --ue-rxgain 140 --basicsim [--noS1]
+```
+
+The `-r 25` is to use if in the conf file of the eNB you use N_RB_DL=25. Use 50 if you have N_RB_DL=50 and 100 if you have N_RB_DL=100.
+
+The `--noS1` is mandatory if you started the eNB in that mode.
+
+# 3. Testing the data plane
+
+# 3.1. In S1 mode
+
+First we need to retrieve the IP address allocated to the OAI UE.
+
+On the server that runs the UE:
+
+```bash
+$ ifconfig oaitun_ue1
+oaitun_ue1 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
+ inet addr:192.172.0.2 P-t-P:192.172.0.2 Mask:255.255.255.0
+...
+```
+
+`192.172.0.2` is the IP address that has been allocated by the SPGW in the EPC.
+
+On the server that runs the EPC:
+
+```bash
+$ ping -c 20 192.172.0.2
+ --- 192.172.0.2 ping statistics ---
+ 20 packets transmitted, 20 received, 0% packet loss, time 19020ms
+ rtt min/avg/max/mdev = 13.241/18.999/24.208/2.840 ms
+```
+
+You can ping the EPC from the UE:
+
+```bash
+$ ping -I oaitun_ue1 -c 20 192.172.0.1
+ --- 192.172.0.1 ping statistics ---
+...
+ 20 packets transmitted, 20 received, 0% packet loss, time 19019ms
+ rtt min/avg/max/mdev = 13.015/18.674/23.738/2.917 ms
+```
+
+For DL iperf testing:
+
+On the server that runs the UE.
+
+```bash
+$ iperf -B 192.172.0.2 -u -s -i 1 -fm -p 5001
+```
+
+On the server that runs the EPC.
+
+```bash
+$ iperf -c 192.172.0.2 -u -t 30 -b 10M -i 1 -fm -B 192.172.0.1 -p 5001
+```
+
+For UL iperf testing:
+
+On the server that runs the EPC.
+
+```bash
+$ iperf -B 192.172.0.1 -u -s -i 1 -fm -p 5001
+```
+
+On the server that runs the UE.
+
+```bash
+$ iperf -c 192.172.0.1 -u -t 30 -b 2M -i 1 -fm -B 192.172.0.2 -p 5001
+```
+
+# 3.2. In noS1 mode
+
+The IP addresses are fixed. But we can still retrieve them programmatically.
+
+For the UE it is quite the same:
+
+```bash
+$ ifconfig oaitun_ue1
+oaitun_ue1 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
+ inet addr:10.0.1.2 P-t-P:10.0.1.2 Mask:255.255.255.0
+...
+```
+
+For the eNB:
+
+```bash
+$ ifconfig oaitun_enb1
+oaitun_enb1 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
+ inet addr:10.0.1.1 P-t-P:10.0.1.1 Mask:255.255.255.0
+...
+```
+
+Pinging like this:
+
+```bash
+$ ping -I oaitun_ue1 -c 20 10.0.1.1
+$ ping -I oaitun_enb1 -c 20 10.0.1.2
+```
+
+And the same for iperf:
+
+```bash
+$ iperf -B 10.0.1.2 -u -s -i 1 -fm
+$ iperf -c 10.0.1.2 -u -b 1.00M -t 30 -i 1 -fm -B 10.0.1.1
+```
diff --git a/doc/RUNMODEM.md b/doc/RUNMODEM.md
index 314c2cc78b..bb89407f70 100644
--- a/doc/RUNMODEM.md
+++ b/doc/RUNMODEM.md
@@ -14,6 +14,10 @@
After you have [built the softmodem executables](BUILD.md) you can set your default directory to the build directory `cmake_targets/lte_build_oai/build/` and start testing some use cases. Below, the description of the different oai functionalities should help you choose the oai configuration that suits your need.
+# Basic Simulator
+
+See the [dedicated page](BASIC_SIM.md).
+
# RF Simulator
The rf simulator is a oai device replacing the radio heads (for example the USRP device). It allows connecting the oai UE and the oai eNodeB through a network interface carrying the time-domain samples, getting rid of over the air unpredictable perturbations. This is the ideal tool to check signal processing algorithms and protocols implementation.
+
+
+