Massive MIMO Channel Sounding

Description

In this tutorial, we demonstrate the TDD 16x1 Massive MIMO channel sounding procedure using 1 Massive MIMO rack (8 USRP-X310s) and 1 USRP-B210 in the ​ORBIT grid 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: Zhenzhou (Tom) Qi, Duke University (zhenzhou.qi [at] duke [dot] edu)

Last updated: Jul. 07, 2022

Prerequisites

In order to access grid, create a reservation in grid 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

• 1 Massive MIMO Rack (node23-1 to node23-8)
• 1 USRP-B210 (node8-7)
• 1 Server (node21-1)

Tutorial Setup

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

1. If you don't have one already, sign up for a ​ORBIT account
2. Create a resource reservation on ORBIT grid
3. Login into grid console (grid.orbit-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 node21-1,node8-7
   

   omf tell -a offh -t [23,1..8]
   

5. Use the ubuntu2004-uhd4.1-gr3.9.ndz node image with Ubuntu 20.04, UHD 4.10, and gnuradio 3.9. Load ubuntu2004-uhd4.1-gr3.9.ndz on both the server and (node8-7).

   omf load -i ubuntu2004-uhd4.1-gr3.9.ndz -t node21-1
   

   omf load -i ubuntu2004-uhd4.1-gr3.9.ndz -t node8-7
   

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

   omf tell -a on -t node21-1,node8-7
   

   omf tell -a on -t [23,1..8]
   

   omf stat -t all
   

7. ssh to the server and (node8-7) from two terminals, use option -Y for using GUI.

   [Terminal 1] ssh -Y root@node21-1,
   [Terminal 2] ssh -Y root@node8-7
   

Experiment Execution

Find and prepare USRPs and the Sounder software

• The IP addresses for Ethernet Port 1(10G) on node23-1 to node23-8 were hard-coded to 10.10.23.1 to 10.10.23.8 respectively. To access them from the server node21-1, no configure of the network interface is needed, however, for better performance, we suggest the following operations:

  root@node21-1:~# ifconfig CTRL mtu 9000 up
  root@node21-1:~# sudo sysctl -w net.core.wmem_max=24862979
  net.core.wmem_max = 24862979
  root@node21-1:~# sudo sysctl -w net.core.rmem_max=24862979
  net.core.rmem_max = 24862979
  root@srv2-lg1:~# ifconfig 
  root@node21-1:~# ifconfig CTRL
  CTRL: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9000
          inet 10.10.21.1  netmask 255.255.0.0  broadcast 10.10.255.255
          inet6 fe80::9a03:9bff:fe3b:81e3  prefixlen 64  scopeid 0x20<link>
          ether 98:03:9b:3b:81:e3  txqueuelen 1000  (Ethernet)
          RX packets 28985875  bytes 107820952173 (107.8 GB)
          RX errors 121  dropped 0  overruns 0  frame 121
          TX packets 12711747  bytes 14132140459 (14.1 GB)
          TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
  

• Similarly for node8-7, USRP-B210 is connected via a USB-3 port, and no further configuration of the network interface is needed.

• Run uhd_find_device to make sure that the USRP-X310s and USRP-B210s can be reached respectively by node21-1 and node8-7:

  root@node21-1:~# uhd_find_devices --args="addr0=10.10.23.1"
  [INFO] [UHD] linux; GNU C++ version 9.3.0; Boost_107100; UHD_4.1.0.4-release
  --------------------------------------------------
  -- UHD Device 0
  --------------------------------------------------
  Device Address:
      serial: 30A3570
      addr: 10.10.23.1
      fpga: XG
      name: Mercury
      product: X310
      type: x300
  
  root@node8-7:~# uhd_find_devices --args="serial=30AD2E0"
  [INFO] [UHD] linux; GNU C++ version 9.3.0; Boost_107100; UHD_4.1.0.4-release
  --------------------------------------------------
  -- UHD Device 0
  --------------------------------------------------
  Device Address:
      serial: 30AD2E0
      name: MyB210
      product: B210
      type: b200
  

• In the server node21-1, download and build the RENEW Sounder software on the Pure-UHD-Multi-USRP branch at ​here and follow the ​instructions to build it.
• In node8-7, download and build the RENEW Sounder software on the USRP-B210 branch at ​here and follow the ​instructions to build it. Note that the master branch does not have UHD support and the Pure-UHD-Multi-USRP branch does not support USRP-B210.

• Include in iles/special_conf/usrp_16qam.json the IP address 10.10.23.1 to 10.10.23.8 under BaseStations as the base station (BS);

• Similarly, set 30AD2E0 under Clients as the user

Execution

Run the experiment

• A file needed to be generated first as:

  root@node8-7:~/RENEWLab/CC/Sounder# ./build/sounder --conf files/special_conf/usrp-16QAM.json --gen_data_bits
  ...
  ...
  INFOR: Allocating 1 cores to receive threads ... 
  INFOR: Allocating 1 cores to record threads ... 
  INFOR: Allocating 1 cores to read threads ... 
  INFOR: Allocating 1 cores to client threads ... 
  Config: 1 BS, 1 BS radios (total), 1 UE antennas, 1 pilot symbols per frame,
      1 uplink data symbols per frame, 0 downlink data symbols per frame,
      64 OFDM subcarriers (52 data subcarriers), modulation 16QAM, frame time 18360.000 usec 
  Thread Config: 1 BS receive threads, 1 Client receive threads, 1 recording threads, 1 reading thread
  Saving UL data bits for radio 0 to logs/ul_data_b_16QAM_52_64_10_1_1_A_0.bin
  Saving UL frequency-domain data for radio 0 to logs/ul_data_f_16QAM_52_64_10_1_1_A_0.bin
  Saving UL time-domain data for radio 0 to logs/ul_data_t_16QAM_52_64_10_1_1_A_0.bin
  

• In order to have the correct Error Vector Magnitude(EVM) and Symbol Error Rate(SER) calculated in post-processing, the exact binary file needs to be used in both the Client and Base Station terminals:

  root@node21-1:~# scp root@node8-7:~/RENEWLab/CC/Sounder/logs/ul_data_f_16QAM_52_64_10_1_1_A_0.bin /root/RENEWLab/CC/Sounder/logs
  

• In the USRP-B210 node8-7 terminal [Terminal 1], start the client:

  root@node8-7:~/RENEWLab/CC/Sounder# ./build/sounder --conf files/special_conf/usrp-16QAM.json --client_only
  ...
  ...
  INFOR: ClientRadioSetUHD done!
  INFOR: Successfully pinned main scheduler thread to core 0finish start client threads
  INFOR: Launching reader task thread with id: 1 and core 1
  INFOR: Pinning reading thread 1 to core 1
  Opening time-domain data for radio 0 to logs/ul_data_t_16QAM_52_64_10_1_1_A_0.bin
  INFOR: Pinning client synctxrx thread 0 to core 2
  INFOR: Scheduling TX: 2 Frames (48.576000 ms) in the future!
  INFOR: Beacon detected at Time 197069085, sync_index: 106001
  Client 0 Estimated CFO (Hz): -213.117
  INFOR: Start main client txrx loop... tid=0
  Using resync period of 82
  

• In the server node21-1 [Terminal 2], start the BS:

  root@node21-1:~/RENEWLab/CC/Sounder# ./build/sounder --conf files/special_conf/usrp-16QAM.json --bs_only
  ...
  ...
  INFOR: Successfully pinned main scheduler thread to core 073:082345 INFOR: Creating recorder thread: 0, with antennas 0:7 total 8
  INFOR: Creating output HD5F file: logs/trace-uplink-2022-7-8-7-43-59_1_8x1_0_7.hdf5
  INFOR: Launching recorder task thread with id: 0 and core 1
  INFOR: Pinning rx thread 0 to core 2
  INFOR: Pinning recording thread 0 to core 1
  INFOR: Recv Thread 0: waiting for release
  INFOR: Recording thread 0 has 8 antennas starting at 0
  num channels are: 8
  INFOR: Receiver thread 0 has 1 radios
  INFOR: Sync BS host and FPGA timestamp for thread 0
  INFOR: Start BS main recv loop in thread 0
  INFOR: Saving HD5F: 2000 frames saved on CPU 1
  ...
  ...
  

Analyze the results

• Since we run Client and Base Stations in separate terminals, a minor modification in hdf5_lib.py is needed to specify the binary reference in the post-processing script: replace line 916 tx_file_names = metadata['TX_FD_DATA_FILENAMES'].astype(str) with manual_file = ['ul_data_f_16QAM_52_64_10_1_1_A_0.bin']; manual_file = np.array(manual_file); tx_file_names = manual_file;

• Once the hdf5 file is recorded (in this case, logs/trace-uplink-2022-7-8-7-43-59_1_8x1_0_7.hdf5), follow the Analyze the HDF5 dataset step ​here to analyze the results. For example, we can show the pilot and uplink IQ waveforms, Uplink User Constealltion along with its Error Vector Magnitude(EVM) and Symbol Error Rate(SER) values (in this case: EVM is 0.93%; SER is 5.63%]):

  root@node21-1:~/RENEWLab/PYTHON/IrisUtils# python3 plot_hdf5.py ../../CC/Sounder/logs/trace-uplink-2022-7-8-7-43-59_1_8x1_0_7.hdf5 --ref-frame=250 --signal-offset=1775 --demodulate zf
  

where --ref-frame=250 represents the reference frame to look at, and --signal-offset=1775 represents the signal offset where this value might be different under different senerios.