Performance Analysis of OFDM over Multi-Scale Multi-Lag Channels

摘要

Due to the low speed of sound in water, the underwater acoustic (UWA) signal suffers obvious time scaling when relative motion exists between the transceivers. In general, given a single scale, the scaling-induced distortion can be rectified by a resampling operation. However, the scaling coefficients of the channel paths may be different from each other, especially in shallow water. In recent years, a multi-scale multi-lag (MSML) model has been used to describe the high speed mobile UWA channels in the literature. In this paper, we analyze the performance of OFDM system under this model. Considering the resalmper as a part of the channel, we get a an equivalent MSML channel. We first derive the sub-channel gains in closed form, and then get the analytical expression of the average channel gains and inter-carrier interference (ICI) under given statistics of the channel paths. Finally, we discuss the average achievable rate of the system and get a lower bound of that in closed form.