On the Capacity of Nonlinear Massive MIMO-OFDM Systems

The use of massive multiple input multiple output (MIMO) techniques combined with orthogonal frequency division multiplexing (OFDM) modulations is being proposed for future broadband wireless systems such as 5G cellular networks. However, although these combination brings large capacity gains, it also suffers from two important drawbacks: the high implementation complexity inherent to the large number of antenna elements and the high sensitivity to nonlinear distortion effects due to the large peak-to-average power ratio (PAPR) of OFDM signals. In this paper, we study the capacity of massive MIMO-OFDM systems with strong nonlinear distortion effects. We derive theoretical expressions for the channel capacity considering different downlink scenarios where a base station with T nonlinear transmitting branches communicate with R receive antennas. It is shown that, although nonlinear distortion effects can reduce substantially the system capacity, this capacity loss can be reduced by increasing the number of transmit antennas (i.e., by using T≫ R).
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