OFDMA系统存在定时偏移条件下的信干比分析

SIR analysis in uplink OFDMA with large timing offsets

在OFDMA(正交频分多址)系统的上行链路,单个用户的定时偏移也会导致多用户干扰(MUI)。实际的OFDMA标准利用接收机与发射机之间复杂的闭环修正来实现高精度定时,从而将多用户干扰控制在可接受的范围内。文中考虑并分析了OFDMA系统存在定时偏移的各种可能情况,以及每种情况下的信号与干扰的功率比(信干比)。Matlab仿真证实了理论分析结果的正确性。

In uplink OFDMA, timing offsets （TO） of other users with respect to a desired user can cause multiuser interference （MUI）. In practical OFDMA standards, the effect of this MUI is made acceptably small by requiring that timing alignment be achieved at the receiver with high precision, which is often realized using complex closed-loop correction between the transmitter and receiver. This letter first analytically characterizes the degradation in the average output signal-to-interference ratio（SIR） due to the combined effect of TOs in uplink OFDMA. The simulation results closely match with the analytical SIR.