MIMO-OFDM系统中自适应技术研究

Adaptive Modulation Analysis of MIMO-OFDM System

针对MIMO-OFDM系统的自适应调制技术进行分析,利用奇异值分解把MIMO-OFDM信道转化成一系列并行的子信道,然后将这些子信道按照信道增益从大到小的顺序排列。通过研究排序后信道增益的统计特性,提出了一种低复杂度的自适应传输方法来优化系统的发射功率。该方法通过固定排序后的子信道的功率和比特分配方案大大降低了复杂度。

In this paper, the adaptive modulation techniques for MIMO-OFDM systems are first studied. The MIMO-OFDM channel can be decomposed into a group of parallel subchannels by Singular Value Decomposition （SVD）. A low-complexity bit and power allocation algorithm is proposed based on this structure. To minimize the overall transmit power, we carry out a fixed bit and power allo- cation over these subchannels by exploring the characteristics of the ordered subchannels gains. The fixed bit and power assignment can be determined by greedy algorithm at the initial stage and utilized without change throughout the data transmission process. Simu lation results show that the proposed algorithm has less than ldB performance loss relative to the optimal algorithm when the number of OFDM subcarriers is large, but the complexity is drastically reduced.