CAJ | 학술논문

由于水声环境时变特性，在水声信道中进行正交频分复用（orthogonal frequency division multi-plexing，OFDM）信号传输，子载波间的正交性易受到破坏，从而产生载波间干扰，使得水声通信的误码率性能变差。针对这个问题，提出一种适用于水下时变信道的自适应 OFDM 均衡算法，该算法采用滑动窗口进行子块短时傅里叶变换获得接收信号的二维时频谱，进而对该二维时频谱进行自适应时－频域联合合并均衡。该自适应均衡算法中采用最小均方误差算法跟踪信道时变特性，并通过自适应判决反馈均衡更新二维时频谱的加权合并系数，提高了 OFDM 系统抗载波间干扰的性能。仿真分析表明，所提出的 OFDM 均衡算法可在时变信道下，有效降低水声通信的误码率。
유우수성배경시변특성，재수성신도중진행정교빈분복용（orthogonal frequency division multi-plexing，OFDM）신호전수，자재파간적정교성역수도파배，종이산생재파간간우，사득수성통신적오마솔성능변차。침대저개문제，제출일충괄용우수하시변신도적자괄응 OFDM 균형산법，해산법채용활동창구진행자괴단시부리협변환획득접수신호적이유시빈보，진이대해이유시빈보진행자괄응시－빈역연합합병균형。해자괄응균형산법중채용최소균방오차산법근종신도시변특성，병통과자괄응판결반궤균형경신이유시빈보적가권합병계수，제고료 OFDM 계통항재파간간우적성능。방진분석표명，소제출적 OFDM 균형산법가재시변신도하，유효강저수성통신적오마솔。
For orthogonal frequency division multiplexing (OFDM)signal transmission over underwater acoustic channel,the subcarrier orthogonality is quite easily destroyed by the time varying characteristic of un-derwater environment,which will cause great inter-carrier interference,and increase the bit error ratio of the underwater acoustic communication system.An adaptive underwater acoustic OFDM equalization algorithm is proposed,which adopts adaptive joint time-frequency combination of the two-dimension spectrum of the received signal obtained by a sliding window based sub-block short time Fourier transform (STFT).The adaptive equali-zation algorithm is implemented by adaptively tracking the time varying channel characteristic by least mean square (LMS)method,then adaptively combine the time-frequency sequences with the coefficients updated by adaptive decision feedback equalization.Simulation results show that the proposed OFDM equalization method over time varying channel can decrease the bit error ratio of the underwater acoustic communication effectively.