协同OFDM系统中继节点发送训练序列的功率分配算法

Power Allocation of Training Sequences for Cooperative OFDM Systems at the Relay

考虑到在复杂街区环境中由于距离太远或者障碍物阻挡等原因,造成源节点和目的节点之间没有直接链路,而是利用多个中继进行协同传输的情景,本文针对空间相关信道下的协同OFDM系统,提出了一种中继节点发送训练序列的功率分配算法,从窄带协同信道模型矩阵表示出发,推导得到了宽带协同OFDM信道模型。在已知信道协方差信息情况下,利用LMMSE(Linear Minimum Mean Square Error)准则对中继节点发送的训练序列进行了功率分配。仿真结果表明,该功率分配算法在空间相关信道下具有良好的均方误差性能;与末考虑空间相关性的功率分配算法相比,该算法的估计精度更接近于Cramer-Rao界(CRB)。

Considering the scene that in a street environment,there is no direct channel between the source node and the destination node because of distance or obstacles,and it needs some relay nodes to do the cooperative communications.In this paper,We propose a power allocation method for cooperative OFDM systems at the relay under spatial correlation circumstances.Based on the matrix formulation of narrowband cooperative channel,Broadband cooperative OFDM channel models was derived.Assuming that the relay has the knowledge of channel covariance,We allocate the power of training sequences that minimize the channel estimation Linear Minimum Mean Square Error（LMMSE）.Simulation results show that the power allocation method have good MSE（Mean Square Error） performance in spatial correlations of channels.Compared with less consideration of spatial correlation power allocation method,the precision of method is closer to the Cramer-Rao bound（CRB）.