Upward bit allocation algorithm for transmit power in MIMO-OFDM systems

Orthogonal frequency division multiplexing (OFDM) systems in combination with multiple-input multiple-output (MIMO) transmission are potential candidates for next generation wireless local area networks (WLAN). In this paper, we propose a novel algorithm for bit allocation, called upward bit allocation algorithm (UBAA), to minimize transmit power while maintaining bit error rate (BER) in MIMO-OFDM systems with fixed throughput. Since the optimal discrete bit allocation is of high complexity, UBAA with efficient logarithmic search is proposed as a sub-optimal approach. Performance of UBAA is evaluated by computer simulation and compared to that of optimal algorithm and existing sub-optimal schemes.