****OFDM水声通信自适应调制算法研究

分析预估信道长度对信道估计算法的影响规律,提出了利用水声通信均衡恢复信号统计量对信道估计质量实时评估的方法,通过信道长度自适应修正机制,实现了对未知水声信道高精度、快速估计；针对水声信道造成的OFDM子载波特性差异,基于信道估计结果,提出了在码元总速率、能量约束条件下,各个OFDM子载波局部速率、功率优化分配的自适应调制算法,相比于传统的等功率、速率分配算法,新算法能够显著提升水声通信系统的误码率性能,通过仿真和实地试验,验证了本文研究内容的有效性。

Self-adjusting modulation algorithm for OFDM underwater acoustic communication based on channel estimations

Regulations between pre-estimated channel length and estimation precision were analyzed in this paper. The estimation quality was evaluated in time using statistics of the equalized signals which helped to adjust the length of channel estimation algorithm automatically. Aimed at the differences among subcarriers caused by underwater acoustic channels, a new algorithm which realized optimum rate and power assignments based on channel estimating results was brought forward. Compared to traditional algorithm which assigned rate and power equally to each subcarrier, the new algorithm achieved better property of BER.. Correctness and validity of the researching contents were validated by simulations and experiments.