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On the Capacity of the AWGN Channel with Additive Radar Interference



  1. NSF award 1443967 : Let’s share CommRad — spectrum sharing between communications and radar systems

Problem Statement and Motivation 

  • Shortage of spectrum resources, specially with the ever increasing demand for commercial services, necessitates a more sensible bandwidth allocation policy.
  • Portions of radar-only spectrum is now open for commercial wireless services hence the radar and communication systems have to share the spectrum with one another.
  • We investigate the problem from the communication system perspective and seek to find the capacity of a communications channel that, in addition to additive white Gaussian noise, also suffers the interference from a co-existing radar transmission.
  • We find the structural properties of capacity achieving input distribution.

Technical Approach


  • We take an information theoretic approach to find the capacity of a communication system in presence of radar interference.
  • We model the radar interference as an additive term whose amplitude is known and constant, but whose phase is uniformly i.i.d at each channel use.
  • We find the structure of the capacity achieving input distribution, under the average power constraint.
  • We find the capacity achieving input for the large interference to noise ratios.

Key Achievements and Future Goals

  • S. Shahi, D. Tuninetti, N. Devroye, “On the Capacity of the AWGN Channel with Additive Radar Interference ,’’ Allerton 2016.
  • Future goals:
    • Extensions to MIMO/OFDM channels.
    • Finding the location and probabilities of the mass points of the optimal input.

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