On 2 × 2 MIMO Gaussian Channels with a Small Discrete-Time Peak-Power Constraint

2024/01/30 by Alex Dytso, Dytso, Alex, Luca Barletta +3 · 1 citation
Engineering · #Wireless Communication Security Techniques #Wireless Body Area Networks #Advanced MIMO Systems Optimization

paper · pdf · doi:10.48550/arxiv.2401.17084

Abstract

A multi-input multi-output (MIMO) Gaussian channel with two transmit antennas and two receive antennas is studied that is subject to an input peak-power constraint. The capacity and the capacity-achieving input distribution are unknown in general. The problem is shown to be equivalent to a channel with an identity matrix but where the input lies inside and on an ellipse with principal axis length r_p and minor axis length r_m. If r_p ≤ √(2), then the capacity-achieving input has support on the ellipse. A sufficient condition is derived under which a two-point distribution is optimal. Finally, if r_m < r_p ≤ √(2), then the capacity-achieving distribution is discrete.

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