Wideband Channel Sounding with USRP X310s ¶

Description ¶

This tutorial shows how to use the RFNoC Correlator block(CE) for channel sounding. This experiment is conducted using USRP X310s on ORBIT grid.

Set Up ¶

Make a reservation on the ​Orbit Scheduler for using the grid.

Prepare Receive Node ¶

• Load rfnoc_channel_sounder.ndz on an ORBIT node.

  prasanthi@console.grid:~$ omf load -i rfnoc_channel_sounder.ndz -t node1-19
  

• Once imaging is done, turn the node on and log in

  prasanthi@console.grid:~$ omf tell -a on -t node1-19
  prasanthi@console.grid:~$ ssh root@node1-19
  

Prepare Receive USRPs ¶

• Pick USRP X310s from the MIMO racks 23-1…8, 23-11…18, 24-1…8, 24-11…18 and load correlator FPGA image on them. The USRPs are programmed one at a time.

  root@node1-19:~# uhd_image_loader --args="addr=10.10.24.12,type=x300" --fpga-path="/root/bit/corrmag63avg8k_v2_8_7.bit"
  

• Power cycle USRPs so that the new FPGA image is active

  prasanthi@console.grid:~$ omf tell -a offh -t node24-12,node24-13
  prasanthi@console.grid:~$ omf tell -a on -t node24-12,node24-13
  

• Running uhd_usrp_probe on the X310s with spectrum sensing FPGA image should give the following

  |   |    /
  |   |   |       RFNoC blocks on this device:
  |   |   |
  |   |   |   * DmaFIFO_0
  |   |   |   * Radio_0
  |   |   |   * Radio_1
  |   |   |   * DDC_0
  |   |   |   * DUC_0
  |   |   |   * Corrmag63avg8k_0
  |   |   |   * FIFO_0
  
  

Prepare Transmit Node ¶

A spectrum spreader RFNoC block is being used to generate wideband PN signal.

• Load prasanthi-channel-sounder.ndz on an ORBIT node.

  prasanthi@console.grid:~$ omf load -i prasanthi-channel-sounder.ndz -t node14-20
  

• Once imaging is done, turn the node on and log in

  prasanthi@console.grid:~$ omf tell -a on -t node14-20
  prasanthi@console.grid:~$ ssh root@node14-20
  

Prepare Transmit USRP ¶

• Pick a USRP X310 for transmitting, and load the spectrum spreader FPGA image

  root@node1-20:~# uhd_image_loader --args="addr=10.10.24.11" --fpga-path="/root/bit/x310_spreader_4_28.bit"
  

• Power cycle the USRP so that the new FPGA image is active

  prasanthi@console.grid:~$ omf tell -a offh -t node24-11
  prasanthi@console.grid:~$ omf tell -a on -t node24-11
  

• Running uhd_usrp_probe on the X310 with spectrum spreader FPGA image should give the following

  |   |     _____________________________________________________
  |   |    /
  |   |   |       RFNoC blocks on this device:
  |   |   |
  |   |   |   * DmaFIFO_0
  |   |   |   * Radio_0
  |   |   |   * Radio_1
  |   |   |   * DUC_0
  |   |   |   * Spreader_0
  |   |   |   * FIFO_0
  |   |   |   * FIFO_1
  

Set up SSH tunnel from your local port 5100 to grid.orbit-lab.org:5100 ¶

ssh -L 5100:grid.orbit-lab.org:5100 username@grid.orbit-lab.org

Set up a web proxy for the receive node ¶

Use run-websock command to set up the proxy (this is required for remote web based streaming)

prasanthi@console.grid:~$ run-websock 5100 10.10.1.19:5100 --daemon
WARNING: no 'numpy' module, HyBi protocol will be slower
WebSocket server settings:
  - Listen on :5100
  - Flash security policy server
  - No SSL/TLS support (no cert file)
  - Backgrounding (daemon)

Run the experiment ¶

• Run rfnoc_spec_sense_display on the receive node. The command below starts the application to receive spectrum sensing samples from 4 USRP X310s at 100MSPS.

  root@node1-19:~/uhd/host/build/examples# ./rfnoc_spec_sense_display --args="addr0=10.10.23.11,addr1=10.10.23.12,addr2=10.10.23.13,addr3=10.10.23.14,skip_ddc,skip_duc" --freq 5e9 --gain 15 --ddc-args="input_rate=200000000.0,output_rate=100000000.0" --num-usrp 4 --spec-sense-args="avg_size=256"
  

• Run rfnoc_spreader on the transmit node. The command below starts the application to send a 50MHz wide PN signal on node23-17.

  root@node14-20:~/uhd/host/build/examples# ./rfnoc_spreader_dmafifo --args="addr=10.10.24.11,skip_ddc,skip_duc" --freq 2e9 --gain 15 --duc-args="input_rate=100000000.0,output_rate=200000000.0"
  

• Download spec_sense_display.html and open it in your browser. Once you click the Start button, you should see power spectrum display as shown below.