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Centralized Arbitrary Waveform Injection Subsystem (CAWIS)

This subsystem consists of arbitrary waveform generator (Agilent ESG) connected through distribution network to four multi-band antennas located in the four corners of the grid. The distribution network enables control over the attenuation of the individual antenna feed. Using CAWIS, users can inject (among other types of waveforms) AWGN signals into the main ORBIT grid and thus create different topologies.

Position of the noise antennas on the big grid

CAWIS usage

As most of the Orbit services, CAWIS is a web-based service accessible from main grid console through url: ​http://instrument1.orbit-lab.org:5012/interference. Accessing this url without any other arguments will show it's help page:

<serviceGroup name="interference">
  <info>Interference injection control service</info>
  <service name="awgn">
     <info>Configures interference injection singal type to AWGN</info>
     <args>
        <arg name="bandwidth" value="noise BW in MHz"/></args>
  </service>
  
  <service name="initialize">
     <info> Resets interference injection subsystem to default state </info>
  </service>

  <service name="set">
     <info>Set global interference injection parameters</info>
     <args><arg name="power" value="noise power in dBm"/>
           <arg name="channel" value="802.11 channel number"/>
           <arg name="frequency" value="interference center frequency"/>
           <arg name="antenna-atten-1" value="attenuation in db"/>
           <arg name="antenna-atten-2" value="attenuation in db"/>
           <arg name="antenna-atten-3" value="attenuation in db"/>
           <arg name="antenna-atten-4" value="attenuation in db"/>
     </args>
  </service>
  
  <service name="start">
       <info>Turn on interference injection</info>
  </service>
  
  <service name="status">
	<info>Show current status of the interference injection subsystem</info>
  </service>
  
  <service name="stop">
        <info>Turn off interference injection</info>
  </service>
  
  
</serviceGroup>

Example

To set AWGN on channel 36 at -30 dBm on all four antennas use the following sequence (either through a browser or wget). By default, the additional attenuation on all antennas is zero which means that the injected power is equally distributed. To create unequal distributions, users can use the antenna-atten-X option with the appropriate attenuation setting in dB to suppress noise in parts of the grid as desired

• Step 1: Initialize the "interference" mode of the service

        wget http://instrument1.orbit-lab.org:5012/interference/initialize
  

• Step 2: Select AWGN bandwidth (channel bw for 802.11a/b/g is 20 Mhz)

        wget http://instrument1.orbit-lab.org:5012/interference/awgn?bandwidth=20
  

• Step 3: Set power level to -30 dBm and channel number to 36 (PLEASE AVOID SETTING POWER OVER 0dBm)

        wget http://instrument1.orbit-lab.org:5012/interference/set?power=-30&channel=36
  

  • Step 4: Start RF injection

          wget http://instrument1.orbit-lab.org:5012/interference/start
    

At the end of the experiment,

• Step 5: Stop RF injection

        wget http://instrument1.orbit-lab.org:5012/interference/stop