GNURadio CFO Estimation tutorial

Description

This tutorial illustrates the use of GNURadio flowgraphs to estimate the Carrier Frequency offset between a pair of USRPs in COSMOS, ORBIT testbeds.

Prerequisites

In order to access the test bed, create a reservation 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 USRPs in COSMOS or ORBIT testbed, 2 host nodes, and 2 mmWave devices(if using mmWave) are required. This page uses the 28GHz IBM mmWave devices in ​sb1.cosmos-lab.org. As shown in the ​basic tutorial for IBM 28GHz devices, the current connections in SB1 are as shown in this ​diagram

• sdr1-in1 RF2 TX/RX — rfdev4-in1 all ICs/TX/H, sdr1-in1 RF2 RX2 — rfdev4-in1 all ICs/RX/H
• sdr1-in1 RF3 TX/RX — rfdev4-in1 all ICs/TX/V, sdr1-in1 RF3 RX2 — rfdev4-in1 all ICs/RX/V
• sdr1-in2 RF2 TX/RX — rfdev4-in2 all ICs/TX/H, sdr1-in2 RF2 RX2 — rfdev4-in2 all ICs/RX/H
• sdr1-in2 RF3 TX/RX — rfdev4-in2 all ICs/TX/V, sdr1-in2 RF2 RX2 — rfdev4-in2 all ICs/RX/V

Hence, the resources required to execute this tutorial are rfdev4-in1, rfdev4-in2 (IBM PAAMs), sdr1-in1, sdr1-in2 (USRP N310s), srv1-lg1, srv2-lg1 in sb1.cosmos-lab.org.

Tutorial Setup

Follow the steps below to gain access to the sandbox 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 SB1
3. Login into sandbox console (console.sb1.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 sdr1-in1,sdr1-in2,rfdev4-in1,rfdev4-in2,srv1-lg1,srv2-lg1
   

5. Use the gnuradio_ofdm.ndz node image with Ubuntu 20.04, UHD 4.4, gnuradio 3.9, and a grc example used in this tutorial. Load gnuradio_ofdm.ndz on the servers.

   omf load -i gnuradio_ofdm.ndz -t srv1-lg1,srv2-lg1
   

6. Turn all the required resources on and check the status of all the resources. Use the following commands .

   omf tell -a on -t sdr1-in1,sdr1-in2,rfdev4-in1,rfdev4-in2,srv1-lg1,srv2-lg1
   

   omf stat -t all
   

7. ssh to the server with option -Y for using GUI with gnuradio.

   ssh -Y root@srv1-lg1
   

Experiment Execution

Find and prepare USRPs

• Upon logging into the server, run eth_config.sh script. This sets up the 10G data interfaces eno1, eno2. After running the script, you should see that the data interfaces have the appropriate IP addresses assigned, as per the tables for ​SB1 and ​SB2.

SB1 root@srv1-lg1:~# ./eth_config.sh root@srv1-lg1:~# ifconfig eno1 eno1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 9000 inet 10.38.1.1 netmask 255.255.0.0 broadcast 10.38.255.255 inet6 fe80::1e34:daff:fe42:c3c prefixlen 64 scopeid 0x20<link> ether 1c:34:da:42:0c:3c txqueuelen 1000 (Ethernet) RX packets 712 bytes 74814 (74.8 KB) RX errors 0 dropped 595 overruns 0 frame 0 TX packets 42 bytes 9132 (9.1 KB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 root@srv1-lg1:~# ifconfig eno2 eno2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 9000 inet 10.39.1.1 netmask 255.255.0.0 broadcast 10.39.255.255 inet6 fe80::1e34:daff:fe42:c3d prefixlen 64 scopeid 0x20<link> ether 1c:34:da:42:0c:3d txqueuelen 1000 (Ethernet) RX packets 643 bytes 51548 (51.5 KB) RX errors 0 dropped 599 overruns 0 frame 0 TX packets 42 bytes 9132 (9.1 KB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

• Run und_find_devices to make sure that both USRP N310s can be reached:

SB1 root@srv1-lg1:~# uhd_find_devices [INFO] [UHD] linux; GNU C++ version 7.5.0; Boost_106501; UHD_3.15.0.0-release -------------------------------------------------- -- UHD Device 0 -------------------------------------------------- Device Address: serial: 3176DF5 addr: 10.38.2.1 claimed: False mgmt_addr: 10.37.2.1 mgmt_addr: 10.38.2.1 mgmt_addr: 10.39.2.1 product: n310 type: n3xx -------------------------------------------------- -- UHD Device 1 -------------------------------------------------- Device Address: serial: 3196937 addr: 10.38.3.1 claimed: False mgmt_addr: 10.37.3.1 mgmt_addr: 10.38.3.1 mgmt_addr: 10.39.3.1 product: n310 type: n3xx

Configure IBM 28GHz PAAM

COSMOS uses a RESTful ​service for IBM PAAM management The service can be used for

• Dynamic array management - where the user connects to the antenna using connect command, dynamically steers the antenna during the experiment using steer command, and disconnects once the experiment is done.
• Static array management - where the user can connect, steer and disconnect using a single command, configure

Details and examples for the above are provided at the ​array management page. For this experiment, we use static array management commands as shown below. First, start PAAM #1 (rfdev4-in1) in RX mode with V-polarization using 16 antenna elements on all the ICs, and configure the RX beamforming direction to be in the broadside (0,0). Check the current consumption on 2v7_0,1,2,3 to make sure all the ICs have been successfully initialized.

root@console:~# curl "http://am1.orbit-lab.org:5054/array_mgmt/configure?dev_name=rfdev4-in1.sb1.cosmos-lab.org&ics=all&num_elements=16&txrx=rx&pol=v&theta=0&phi=0"

<?xml version="1.0" encoding="UTF-8"?>
<response status="OK">
  <action service="array_mgmt" name="configure" ipaddr="10.37.7.1">
    <step name="open" duration="3.599997"/>
    <step name="initializaition" duration="0.071123"/>
    <step name="enabling" duration="0.016817"/>
    <step name="steering" duration="0.007705"/>
    <state PAAM_ID="0x36" LO_switch="PLL" if_sw1="0x0" if_sw2="0x0" if_sw3="0x0" if_sw4="0x0"/>
    <adc>
      <conv index="0" name="1v2" tADC="120" tVolt="0.293" tCurr="0.147"/>
      <conv index="1" name="1v5" tADC="334" tVolt="0.816" tCurr="1.632"/>
      <conv index="2" name="1v8" tADC="24" tVolt="0.059" tCurr="0.029"/>
      <conv index="3" name="2v7_0" tADC="163" tVolt="0.398" tCurr="0.797"/>
      <conv index="4" name="2v7_1" tADC="206" tVolt="0.503" tCurr="1.007"/>
      <conv index="5" name="2v7_2" tADC="220" tVolt="0.538" tCurr="1.075"/>
      <conv index="6" name="2v7_3" tADC="180" tVolt="0.440" tCurr="0.880"/>
      <conv index="7" name="3v3_pll" tADC="408" tVolt="0.997" tCurr="0.499"/>
      <conv index="8" name="5v_uzed" tADC="206" tVolt="0.503" tCurr="0.503"/>
      <conv index="9" name="12v" tADC="244" tVolt="0.596" tCurr="1.988"/>
      <conv index="10" name="0V" tADC="0" tVolt="0.000"/>
      <conv index="11" name="1V8" tADC="737" tVolt="1.801"/>
    </adc>
    <step name="status" duration="0.020882"/>
    <step name="close" duration="0.100221"/>
  </action>
</response>

Similarly, start PAAM #2 (rfdev4-in2) in TX mode with V-polarization using 16 antenna elements on all the ICs, and configure the TX beamforming direction to be in the broadside (0,0). Check the current consumption to make sure the ICs have been successfully initialized.

root@console:~# curl "http://am1.orbit-lab.org:5054/array_mgmt/configure?dev_name=rfdev4-in2.sb1.cosmos-lab.org&ics=all&num_elements=16&txrx=tx&pol=v&theta=0&phi=0"

<?xml version="1.0" encoding="UTF-8"?>
<response status="OK">
  <action service="array_mgmt" name="configure" ipaddr="10.37.7.2">
    <step name="open" duration="3.558891"/>
    <step name="initializaition" duration="0.072244"/>
    <step name="enabling" duration="0.018709"/>
    <step name="steering" duration="0.008254"/>
    <state PAAM_ID="0x30" LO_switch="PLL" if_sw1="0x0" if_sw2="0x0" if_sw3="0x0" if_sw4="0x0"/>
    <adc>
      <conv index="0" name="1v2" tADC="125" tVolt="0.305" tCurr="0.153"/>
      <conv index="1" name="1v5" tADC="331" tVolt="0.809" tCurr="1.618"/>
      <conv index="2" name="1v8" tADC="22" tVolt="0.054" tCurr="0.027"/>
      <conv index="3" name="2v7_0" tADC="255" tVolt="0.623" tCurr="1.246"/>
      <conv index="4" name="2v7_1" tADC="250" tVolt="0.611" tCurr="1.222"/>
      <conv index="5" name="2v7_2" tADC="266" tVolt="0.650" tCurr="1.300"/>
      <conv index="6" name="2v7_3" tADC="264" tVolt="0.645" tCurr="1.290"/>
      <conv index="7" name="3v3_pll" tADC="410" tVolt="1.002" tCurr="0.501"/>
      <conv index="8" name="5v_uzed" tADC="215" tVolt="0.525" tCurr="0.525"/>
      <conv index="9" name="12v" tADC="300" tVolt="0.733" tCurr="2.444"/>
      <conv index="10" name="0V" tADC="0" tVolt="0.000"/>
      <conv index="11" name="1V8" tADC="734" tVolt="1.794"/>
    </adc>
    <step name="status" duration="0.021005"/>
    <step name="close" duration="0.100240"/>
  </action>
</response>

Run the experiment

• On srv1-lg1, start gnuradio companion and open the example experiment that establishes a single tone transmission. Use the file that is appropriate for the domain (SB1 or SB2).

  root@srv1-lg1:~# gnuradio-companion example_paam_tone_sb1.grc 
  

• For running the experiment on SB1, configure the USRP sink (TX) with sdr1-in2 ("mgmt_addr=10.37.6.2,addr=10.39.6.2") and the USRP source (RX) with sdr1-in1("mgmt_addr=10.37.6.1,addr=10.39.6.1"). For SB2, configure the USRP sink (TX) with sdr1-s1-lg1 ("mgmt_addr=10.116.2.1,addr=10.117.2.1") and the USRP source (RX) with sdr1-md1 ("mgmt_addr=10.116.3.1,addr=10.117.3.1"). Set the carrier frequency to 3GHz (3e9) and the subdev to be "B:1" (RF3) (For SB2, use "B:0", RF2) on both TX and RX. In this example flowgraph, the sampling rate and the tone frequency are set to be 2.5MHz (2.5e6) and 1MHz (1e6), respectively.