An asynchronous transmission scenario for non-orthogonal multiple access(NOMA)user signals with arbitrary phase offset is investigated in this paper.To improve the system performance in the user power-balanced conditi...An asynchronous transmission scenario for non-orthogonal multiple access(NOMA)user signals with arbitrary phase offset is investigated in this paper.To improve the system performance in the user power-balanced conditions,we adopt a synthetic detection method at the receiver,i.e.,the jointly optimal maximal likelihood detection aided triangular successive interference cancellation(JO ML-TSIC)method.Analytical bit error rate(BER)solutions are obtained for a two-user case with the optimal,intentional onehalf symbol period time delay implemented between the user signals.Furthermore,closed-form BER solutions for the case using the triangular successive interference cancellation(TSIC)detection method are also derived for comparisons.Numerical results show that the JO ML-TSIC receiver for the asynchronous system outperforms the TSIC receiver as well as the synchronous successive interference cancellation(SIC)receiver in all the conditions concerned.The results also show that the superiority of the JO ML-TSIC receiver is strengthened when the signals experience flat Rayleigh fading channels compared to the TSIC and the synchronous SIC receivers.展开更多
针对水声信道多途信号引起的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)水声通信系统符号间干扰的问题,提出了无源时间反转均衡的方法,将发送的探测信号时间反转与OFDM信号做卷积,利用无源时间反转镜的时间聚焦原...针对水声信道多途信号引起的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)水声通信系统符号间干扰的问题,提出了无源时间反转均衡的方法,将发送的探测信号时间反转与OFDM信号做卷积,利用无源时间反转镜的时间聚焦原理减小信道多途带来的符号间干扰,在OFDM符号中不使用导频的情况下实现信道均衡,简化了均衡步骤并提高了OFDM符号频带利用率。分析比较了无源时反均衡方法与最小平方信道均衡在水声多途信道下的误码性能。仿真研究和湖上实验表明,无源时反信道均衡算法可以有效的减小多途信道对OFDM水声通信系统带来的影响。展开更多
超奈奎斯特（Faster Than Nyquist,FTN）信号是一种很有前途的无线通信技术,它能够在不影响频谱效率的情况下提高无线通信系统的数据传输速率。然而,FTN会存在符号间干扰（inter-symbol interference,ISI）,这样会使FTN的增益受损。为...超奈奎斯特（Faster Than Nyquist,FTN）信号是一种很有前途的无线通信技术,它能够在不影响频谱效率的情况下提高无线通信系统的数据传输速率。然而,FTN会存在符号间干扰（inter-symbol interference,ISI）,这样会使FTN的增益受损。为了抑制ISI带来的影响,本文使用一个鲁棒的带有Sphere Detector（SD）的判决反馈均衡器（Decision Feedback Equalizer,DFE）去处理FTN导致的ISI。它能大大降低系统的误码率并实现最大似然（Maximum Likelihood,ML）检测。通过仿真实验,结果表明,提出的算法性能更接近香农极限,相比传统的DFE,误码率会有1~2 d B的优势。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 62022019)
文摘An asynchronous transmission scenario for non-orthogonal multiple access(NOMA)user signals with arbitrary phase offset is investigated in this paper.To improve the system performance in the user power-balanced conditions,we adopt a synthetic detection method at the receiver,i.e.,the jointly optimal maximal likelihood detection aided triangular successive interference cancellation(JO ML-TSIC)method.Analytical bit error rate(BER)solutions are obtained for a two-user case with the optimal,intentional onehalf symbol period time delay implemented between the user signals.Furthermore,closed-form BER solutions for the case using the triangular successive interference cancellation(TSIC)detection method are also derived for comparisons.Numerical results show that the JO ML-TSIC receiver for the asynchronous system outperforms the TSIC receiver as well as the synchronous successive interference cancellation(SIC)receiver in all the conditions concerned.The results also show that the superiority of the JO ML-TSIC receiver is strengthened when the signals experience flat Rayleigh fading channels compared to the TSIC and the synchronous SIC receivers.
文摘针对水声信道多途信号引起的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)水声通信系统符号间干扰的问题,提出了无源时间反转均衡的方法,将发送的探测信号时间反转与OFDM信号做卷积,利用无源时间反转镜的时间聚焦原理减小信道多途带来的符号间干扰,在OFDM符号中不使用导频的情况下实现信道均衡,简化了均衡步骤并提高了OFDM符号频带利用率。分析比较了无源时反均衡方法与最小平方信道均衡在水声多途信道下的误码性能。仿真研究和湖上实验表明,无源时反信道均衡算法可以有效的减小多途信道对OFDM水声通信系统带来的影响。
文摘超奈奎斯特（Faster Than Nyquist,FTN）信号是一种很有前途的无线通信技术,它能够在不影响频谱效率的情况下提高无线通信系统的数据传输速率。然而,FTN会存在符号间干扰（inter-symbol interference,ISI）,这样会使FTN的增益受损。为了抑制ISI带来的影响,本文使用一个鲁棒的带有Sphere Detector（SD）的判决反馈均衡器（Decision Feedback Equalizer,DFE）去处理FTN导致的ISI。它能大大降低系统的误码率并实现最大似然（Maximum Likelihood,ML）检测。通过仿真实验,结果表明,提出的算法性能更接近香农极限,相比传统的DFE,误码率会有1~2 d B的优势。
