OFCDM based adaptive modulation with antenna array in fading channels

In this paper, a multilevel transmit power allocation (MTPA) for orthogonal frequency-code division multiplexing (OFCDM) based adaptive modulation system with antenna array is proposed in downlink slow fading channels. An efficient adaptive modulation scheme is proposed to guarantee a required quality of service (QoS) and to increase bandwidth efficiency with the total transmit power constraint. Regardless of channel and environment change, outer-loop control that can continuously maintain required QoS is also suggested. In the proposed system, modulation level and transmit power for each subcarrier is simultaneously controlled according to channel conditions to maximize transmitted bits per OFDM symbol while keeping both total transmit power and QoS constant. Computer simulation elucidates that our proposed system is effective in terms of throughput and QoS.