Robust adaptive modulation for MIMO systems

This paper investigates adaptive modulation (AM) algorithm to maximize transmission rate under bit error rate (BER) and transmit power constraints for multiple-input multiple-output (MIMO) systems with imperfect channel state information (CSI). The continuous results for the optimization problem are derived by Lagrange method and adjusted into even integers for practical use by two proposed schemes. Different from conventional AM algorithms, the proposed robust algorithm can satisfy system BER requirement even when CSI is subject to significant imperfection. Simulation results show this algorithm provides not only the more robust BER performance to CSI imperfection, but also higher spectral efficiency than the AM algorithm based on perfect CSI assumption.