Low-Complexity Link Adaptation for Energy Efficiency Maximization in MIMO-OFDM Systems

We present a low-complexity link adaptation algorithm for maximizing the energy efficiency (EE) of MIMO-OFDM systems. We prove that the EE is a single-peaked quasi-concave function of the transmit power and develop an iterative algorithm to find near-optimal transmit power. We further prune the search space by analyzing the singular values of the channel. The resulting link adaptation protocol achieves orders of magnitude reduction in complexity compared with the brute force search method without noticeably sacrificing the performance.