MIMO Channel Sounding

Description

In this tutorial, we demonstrate the TDD 2x2 MIMO channel sounding procedure using the USRP-2974s in the ​COSMOS Sandbox2 (sb2) and the ​RENEW Sounder software

• The instructions of the RENEW Platform Sounder software can be found ​here under ​RENEW license.
• The COSMOS team contributes to adding the UHD support for the Sounder software under the ​UHD license.

Author: Tingjun Chen, Columbia University (tc2668[at]columbia.edu)

Last updated: Sept. 21, 2020

Prerequisites

In order to access sb2, create a reservation in sb2 and have it approved by the reservation service. Access to the resources is granted after the reservation is confirmed. Please follow the process shown on the COSMOS getting ​started page to get started.

Resources Required

• 2 USRP-2974 (sdr2-s1-lg1 and sdr2-md1)
• 1 Server (srv2-lg1)

Tutorial Setup

Follow the steps below to gain access to the sb2 console and set up nodes with appropriate images.

1. If you don't have one already, sign up for a ​COSMOS account
2. Create a resource reservation on COSMOS sb2
3. Login into sb2 console (console.sb2.cosmos-lab.org) with two SSH sessions.
4. Make sure all the nodes and devices used in the experiment are turned off:

   omf tell -a offh -t sdr2-s1-lg1,sdr2-md1,srv2-lg1
   

5. Use the baseline_gr.ndz node image (see ​here for the list of pre-defined images) with Ubuntu 18.04, UHD 3.15, and gnuradio 3.8. Load baseline_gr.ndz on on the server.

   omf load -i baseline_gr.ndz -t srv2-lg1
   

6. Turn all the required resources on and check the status

   omf tell -a on -t sdr2-s1-lg1,sdr2-md1,srv2-lg1
   

   omf stat -t system:topo:allres
   

7. ssh to the the same server from two terminals, use option -Y for using GUI.

   [Terminal 1] ssh -Y root@srv2-lg1,
   [Terminal 2] ssh -Y root@srv2-lg1
   

Experiment Execution

Find and prepare USRPs

• The IP addresses for Ethernet Port 1(10G) on sdr2-s1-lg1 and sdr2-md1 were hard-coded to 10.118.2.2 and 10.118.3.2 respectively. To access them from srv2-lg1, configure the network interface eno2 as follows:

  root@srv2-lg1:~# ifconfig eno2 10.118.1.2 netmask 255.255.0.0 mtu 9000 up
  root@srv2-lg1:~# sudo sysctl -w net.core.wmem_max=24862979
  net.core.wmem_max = 24862979
  root@srv2-lg1:~# sudo sysctl -w net.core.rmem_max=24862979
  net.core.rmem_max = 24862979
  root@srv2-lg1:~# ifconfig 
  eno2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9000
          inet 10.118.1.2  netmask 255.255.0.0  broadcast 10.118.255.255
          inet6 fe80::9a03:9bff:fe61:9609  prefixlen 64  scopeid 0x20<link>
          ether 98:03:9b:61:96:09  txqueuelen 1000  (Ethernet)
          RX packets 4053772  bytes 17770502341 (17.7 GB)
          RX errors 0  dropped 0  overruns 0  frame 0
          TX packets 1727950  bytes 2972166223 (2.9 GB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
  
  

• Run und_find_devicec to make sure that the USRP-2974s can be reached:

  root@srv2-lg1:~# uhd_find_devices --args="addr=10.118.2.2"
  [INFO] [UHD] linux; GNU C++ version 7.5.0; Boost_106501; UHD_3.15.0.HEAD-0-gaea0e2de
  --------------------------------------------------
  -- UHD Device 0
  --------------------------------------------------
  Device Address:
      serial: 318F20F
      addr: 10.118.2.2
      fpga: XG
      name: 
      product: NI-2974
      type: x300
  
  root@srv2-lg1:~# uhd_find_devices --args="addr=10.118.3.2"
  [INFO] [UHD] linux; GNU C++ version 7.5.0; Boost_106501; UHD_3.15.0.HEAD-0-gaea0e2de
  --------------------------------------------------
  -- UHD Device 0
  --------------------------------------------------
  Device Address:
      serial: 3165747
      addr: 10.118.3.2
      fpga: XG
      name: 
      product: X310
      type: x300
  

• Download and build the RENEW Sounder software on the develop branch at ​here and follow the ​instructions to build it. Note that the master branch does not have UHD support.