Link Adaptation Strategies for Multi-Antenna Assisted WiMAX-like System

In this work, we have studied bit and power allocation strategies for multi-antenna assisted orthogonal frequency division multiplexing (OFDM) systems. Popularly it is believed that simultaneous bit and power allocation at the same rate is not very much useful in terms of system throughput. Contrary to this popular belief, we have found that in some scenarios and in some system conditions, bit and power allocations across OFDM subchannels are required together for efficient system performance. We have studied a novel link adaptation algorithm in different multi-antenna systems. We have found that, if we cannot find the exact signal to noise ratio (SNR) thresholds due to different reasons, such as reduced link adaptation (LA) rate, channel state information (CSI) error, feedback delay etc., it is better to fix the transmit power across all sub-channels to guarantee the target frame error rate (FER). Otherwise, we can use adaptive power distribution to save power, which can be used for other purposes.