分布式残余频偏信道中的Alamouti STBC-OFDM功率分配

在具有不同残余频偏的分布发射天线多径瑞利衰落信道中，该文使用Cholesky判决反馈检测的Alamouti STBC-OFDM链路，提出了一种抑制残余频偏影响的发射功率分配方法:以最小化残余频偏下链路的平均误比特率下界为准则，为发射天线分配功率。首先推导了残余频偏下链路的平均误比特率下界，然后给出了发射天线间最优功率分配因子的闭合解。仿真结果表明，与传统的假设频率理想同步的功率分配方法相比，在残余频偏对性能影响占主导作用的场景中，该文方法提升了链路性能，提升程度随着两根发射天线到接收机间平均信道功率增益之比的增加而增大。

On Power Allocation for Alamouti STBC-OFDM Systems with Distributed Transmit Antennas in the Presence of Residual Frequency Offsets

In this paper, a transmit power allocation method is proposed for distributed transmit antenna Alamouti Space-Time Block Coded Orthogonal Frequency Division Multiplexing (STBC-OFDM) systems based on Cholesky-decision-feedback detector in multipath Rayleigh fading channels with multiple Residual Frequency Offsets (RFOs). The method is designed by minimizing the lower bound of the average Bit Error Ratio (BER) so as to reduce the influence of RFOs. Theoretical analysis of the lower bound on the average BER performance is presented and the closed-form expression of the optimal power allocation factor is derived. Simulation results show that in the scenario where the performance is dominated by the RFOs, the proposed method provides increasing performance gain compared with the conventional power allocation method ignoring the existence of RFOs as the ratio between the average channel gains from the two transmit antennas to receiver increasing.