The Interference Channel Revisited: Eliminating Interference with a Two Antenna Receiver
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It is shown that a receiver equipped with two antennas may null an arbitrary large number of spatial directions to any desired accuracy, while maintaining the interference-free signal-to-noise ratio, by judiciously adjusting the distance between the antenna elements. The main theoretical result builds on ergodic theory. The practicality of the scheme in moderate signal-to-noise systems is demonstrated for a scenario where each transmitter is equipped with a single antenna and each receiver has two receive chains where the desired spacing between antenna elements is achieved by selecting the appropriate antennas from a large linear antenna array. We then extend the proposed scheme to show that interference can be eliminated also in specular multipath channels as well as multiple-input multiple-output interference channels. To demonstrate the performance of the scheme, we show significant gains at low and moderate signal-to-noise ratios (0-20 dB) with 4 and 6 users scenarios. The robustness of the proposed technique to small direction estimation errors is also explored.
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