自适应发送MIMO-OFDM超宽带系统

基于发送端已知信道状态信息假设，提出了一种多人多出正交频分复用（MIMO-OFDM）系统优化功率加载方案．给出了MIMO-OFDMUWB系统模型及其相应的空时编码方法，提出基于OFDM子载波分组的功率加载机制及其代价函数．通过引入Karush—Kuhn—Tucker（KKT）伸缩因子及条件的拉格朗日乘子法求得功率加载的优化解，并给出了迭代过程．实验结果表明：其性能和复杂度介于经典满注水机制和分组平均信道信息有限反馈功率加载机制之间．此外，多天线分集增益明显改善了系统性能．

Adaptive transmissions in MIMO-OFDM UWB systems with frequency-selecting fade

Assuming that the channel state information(CSI) at the transmission side was known,the optimal power allocation scheme was proposed for the multi-input multi-output(MIMO) orthogonal frequency-division multiplexing(OFDM) ultra wideband(UWB).The MIMO-OFDM UWB system model and the correspondent space-time code were given.A novel power load scheme and its cost function based on grouped sub-carrier were presented.The optimal solution to the power loads was obtained by Lagrangian multiplexer method introduced Karush-Kuhn-Tucker(KKT) scalar factor and conditions,and its iterative process was given.Compared with the classical full water-filling scheme and limited group CSI feedback scheme,the performance and complexity of the proposed scheme is between their ones.Ii is also seen that the performance of the system is significantly improved by the multi-antenna diversity gain.