Optimize Research On Multi-user MIMO-OFDM Resource Allocation

OFDM is a powerful technique employed in mobile communication systems. Combined with MIMO multiple antennas as well as adaptive modulation, it is proven to be robust against frequency selectivity fading and multi- path delay spread. In MIMO- OFDM system over mobile fading channels, each sub- channel has different channel capacity because of individual attenuation. Therefore, it is important for a MIMO- OFDM system to adaptively allocate resources (bits, power, etc) according to each sub- channel's features. This thesis's main work is studying on adaptive resource allocation algorithm in MIMO- OFDM system.The thesis is considered in two stages. The first stage involves the application of bits and power allocation in MIMO- OFDM system without antenna selection. By using the SVD to separate the MIMO channel into parallel sub- channels, the MIMO-OFDM system can be simplified in to SISO- OFDM system. On the bases of the current greedy algorithm for changeable BER based on Margin Adaptive principle, an efficient resource allocation algorithm is proposed for antenna array OFDM system aiming at minimizing the bit error rate under a constraint of the total transmits power and date rate. By introducing proportional resource allocation constraints to the traditional margin adaptive algorithm, the suggested approach can fairly allocate the sub- carriers, the powers, and the data bits among all the users. The second stage discusses the adaptive allocation in MIMO- OFDM systems by introducing antenna selection on the side of receiver. Taking the power approached from channel estimation as the judgment, choose L out of M_r antennas for signal processing can reduce the complexity. The simulation shows the proposed scheme in this thesis is feasible.