Energy efficient precoding for MIMO cyclic prefixed single carrier communications

This paper addresses the design of energy efficient precoding/decoding strategies for multiple-input multiple-output cyclic prefixed single carrier (MIMO CP-SC) systems with frequency-domain equalization. We opt for eigenbeamforming in the frequency domain for spatial precoding and decoding. We show that eigenbeamforming leads to a simple yet effective maximization of the energy efficiency (EE) of the MIMO CP-SC link. Moreover, the associated power allocation relies on the combination of waterfilling among the spatial streams and a proper distribution of the per-stream allocated power among subcarriers. Numerical results show that, if we account for the efficiency of the high power amplifier (HPA) associated with the peak-to-average power ratio (PAPR), CP-SC can be more energy efficient than orthogonal frequency division multiplexing (OFDM) for moderate to high signal-to-noise (SNR) values.