论文部分内容阅读
水声单载波通信技术是一种频谱利用率较高的通信调制方式。基于自适应判决反馈均衡(Decision Feedback Equalizer,简记为DFE)技术的单载波接收机在水声单载波通信中取得了较大的成功。常规的基于递归最小二乘(Recursive Least Squares,简记为RLS)算法的DFE接收机在严重时变的水声多途扩展信道条件下面临着以下问题:(1)在常规RLS算法中,采用固定遗忘因子难以适应快变的水声信道;(2)在常规RLS算法中,未对水声信道的稀疏性加以利用导致常规RLS算法性能的下降。针对以上问题,本文提出一种结合信道短化技术和基于l1范数宽线性变遗忘因子RLS自适应均衡技术的DFE接收机算法。与传统的DFE接收机算法相比,该算法具有以下优势:(1)采用信道短化技术(被动时间反转(passive Time Reversal,简记为p TR)信道短化技术或最小均方误差(Minimum Mean Square Error,简记为MMSE)信道短化技术)对多途扩展严重的水声信道进行短化,通过减小信道多途扩展长度降低了DFE均衡算法的计算复杂度;(2)采用基于l1范数宽线性变遗忘因子RLS自适应均衡算法增强DFE接收机对时变稀疏的水声信道的跟踪能力和适应性。仿真及试验结果均表明相比于传统的DFE接收机算法,本文提出的基于l1范数宽线性变遗忘因子RLS自适应均衡算法和信道短化技术(p TR或MMSE信道短化技术)的判决反馈接收机在具有较低的计算复杂度的同时在稳态最小均方误差(Mean Square Error,简记为MSE)和误符号率(Symbol Error Rate,简记为SER)方面也具有较大的性能提升。
Acoustic single carrier communication technology is a high frequency spectrum utilization of communication modulation. The single carrier receiver based on the adaptive decision feedback equalizer (DFE) has achieved great success in underwater single carrier communication. The conventional DFE receiver based on Recursive Least Squares (RLS) algorithm faces the following problems under the severe time-varying underwater acoustic multi-channel extension channel: (1) In the conventional RLS algorithm, The fixed forgetting factor is hard to adapt to the fast changing acoustics channel. (2) In the conventional RLS algorithm, the sparseness of the underwater acoustic channel is not utilized and the performance of the conventional RLS algorithm is degraded. In view of the above problems, this paper proposes a DFE receiver algorithm which combines the channel shortening technique with an adaptive equalization technique based on the l1 norm wide linear forgetting factor RLS. Compared with the traditional DFE receiver algorithm, this algorithm has the following advantages: (1) Adopt the channel shortening technology (Passive Time Reversal (abbreviated as p TR) channel shortening technique or minimum mean square error Minimum Mean Square Error (MMSE) channel shortening technique) to shorten the multipath spreading severe water channel, and reduce the computational complexity of DFE equalization algorithm by reducing the channel multipath spreading length. (2) Based on the l1 norm wide linear forgetting factor RLS adaptive equalization algorithm to enhance DFE receiver tracking ability and adaptability to time-varying sparse underwater acoustic channel. Simulation and experimental results show that compared with the traditional DFE receiver algorithm, the proposed lll-norm-based linear variable forgetting factor RLS adaptive equalization algorithm and channel shortening technique (pTR or MMSE channel shortening technique) The feedback receiver also has a relatively large mean square error (Mean Square Error, abbreviated as MSE) and Symbol Error Rate (SER) with lower computational complexity Performance improvement.