Full-Duplex Wireless Communications Using Off-The-Shelf Radios: Feasibility and First Results

Submitted to The Asilomar Conference on Signals, Systems, and Computers 2010.

Authors: Melissa Duarte and Ashutosh Sabharwal

Abstract

We study full-duplex wireless communication systems where same band simultaneous bidirectional communication is achieved via cancellation of the self interfering signal. We present an analysis of the self interference cancellation mechanism and derive expressions for the average power of the self interfering signal after RF and baseband cancellation. We present experimental results that show that the equations we have derived are a good fit for the measured data and the average percentage error is less than 4.1\% for all the scenarios considered. Perfect self interference cancellation is not possible in real systems due to noise in the estimates of the signals required for cancellation. We show that self interference can be suppressed sufficiently such that the resulting full-duplex system capacity lies between the capacity of a half-duplex Multiple Input Multiple Output (MIMO) system using diversity techniques and the capacity of a half-duplex spatial multiplexing MIMO system. This result opens the possibility for the design of new systems and network protocols based on FD radios.