MIMO-OFDM系统无线衰落信道容量分析

推导了MIMO-OFDM系统在衰落信道下的各态历经容量、最优发送策略、使用等功率分配时的容量上界以及相对于单天线OFDM系统的容量增益。结果表明：天线数和平均接收信噪比是决定MIMO-OFDM系统信道容量的关键因素。天线数越多或者接收信噪比越大,信道的容量越大,信道容量几乎不受多径时延扩展的影响。慢衰落信道下的最大信道容量可以使用空-频两维注水算法得到,当接收信噪比足够大时,最大信道容量也可以用平均分配发送功率的方法逼近。

Analysis on Capacity of Broadband MIMO - OFDM Systems in Wireless Fading Channels

The ergodic capacity and optimal power allocation policy of broadband MIMO-OFDM systems in wireless fading channels is derived based on the system model.Then,the upper bound of capacity and its gain over single antenna OFDM are calculated for the slow fading channel with equal-power policy.The results indicate that the channel capacity of MIMO-OFDM system grows with the number of antennas and average received signal noise ratio(SNR),which are significant parameters determining the capacity;the impact of the time delay spread on capacity is negligible;the maximal channel capacity of MIMO-OFDM in slow fading channel can be achieved by two-dimensional space- frequency water-filling policy,and it can be approached by the scheme allocating equal-power for each sub-channel when the received SNR is enough high.