OTFS分阶段权重调控的MRC检测算法

doi:10.19665/j.issn1001-2400.20250109

摘要/Abstract

摘要：

正交时频空调制技术是近年来提出的一种新型信号调制方式,旨在解决高移动性多径传输场景下,由多普勒频移引起的通信质量下降问题。为了克服在传输过程中产生的符号块间干扰,采用补零填充正交时频空调制结构,重点分析了在时延-时间域重调制加权输出的最大比合并检测算法中权重系数与迭代次数、信噪比以及调制阶数对系统收敛性与误码率性能的影响。针对高阶调制方式下因固定最佳权重系数导致迭代次数较高的问题,提出了一种基于分阶段权重系数调控的最大比合并检测算法,通过在不同迭代阶段合理设置权重系数,使每个迭代阶段的权重选择更加符合当前系统状态的需求,从而逐步优化现有最大比合并检测的过程,提升整体检测性能。实验结果表明,改进后的最大比合并检测算法显著加快了收敛速度,并在保持相同迭代次数的情况下,进一步改善了系统的误码率性能。此外,改进算法在多种信道条件下均表现出较强的适应性和鲁棒性,可以有效对抗高速移动场景下的快时变信道。

关键词: 正交时频空, 最大比合并, 低复杂度, 信号检测

Abstract:

Orthogonal time frequency space (OTFS) modulation is a novel signal modulation technique proposed in recent years,specifically designed to address the degradation in communication quality caused by Doppler shifts in high-mobility multipath transmission scenarios.To overcome the inter-symbol interference (ISI) generated during transmission process,a Zero-Padded OTFS modulation structure is employed,with a focus on analyzing the impact of weight coefficients,iteration number,signal-to-noise ratio (SNR),and modulation order on system convergence and bit error rate (BER) performance in the Maximal Ratio Combining (MRC) detection algorithm with the remodulation weighted output in the delay-time domain.To address the issue of a high iteration number caused by fixed optimal weight coefficients under high-order modulation schemes,an MRC detection algorithm based on staged weight coefficient control is proposed.By appropriately setting weight coefficients at different iterative stages,the weight selection at each stage can better align with the needs of the current system state,thereby gradually optimizing the traditional MRC detection process and improving overall detection performance.Experimental results show that the improved MRC detection algorithm significantly accelerates convergence and further enhances the system BER performance while maintaining the same number of iterations.Moreover,the improved algorithm exhibits a strong adaptability and robustness across various channel conditions,effectively combating rapidly time-varying channels in high-mobility scenarios.

Key words: orthogonal time frequency space, maximal ratio combining, low complexity, signal detection

中图分类号:

TN92

党柯, 孙锦华, 吴小钧. OTFS分阶段权重调控的MRC检测算法[J]. 西安电子科技大学学报, 2025, 52(3): 61-72.

DANG Ke, SUN Jinhua, WU Xiaojun. Staged weight-controlled MRC detection algorithm for the OTFS system[J]. Journal of Xidian University, 2025, 52(3): 61-72.

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参考文献 17

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参数名称	参数值
子载波个数(M)	64
符号个数(N)	16
载波频率/GHz	4
调制方式	4QAM/16QAM/64QAM
最大移动速度/(km·h^-1)	500
子载波间隔/kHz	15
信道模型	EVA
路径数(L)	9
最大迭代次数(ite)	10/20/50
权重系数(ω)	0~1

分阶段权重系数(ω₁、ω₂)	16QAM	64QAM
	ω₁=0.2,ω₂=1.0	ω₁=0.1,ω₂=1.0
最大迭代次数(ite)	14(ω_opt=0.2在30 dB下的收敛次数)	35(ω_opt=0.1在37.5 dB下的收敛次数)
	11(ω_opt=0.2在27.5 dB下即将收敛次数)	24(ω_opt=0.1在35.0 dB下即将收敛次数)
	10(ω_opt=0.2未收敛状态)	20(ω_opt=0.1未收敛状态)

算法	复杂度	数值分析
LMMSE^[5]	O(M³N³)	1.0×10⁹
MP^[7]	O(iteMNQP)	1.1×10⁶
AMP^[8]	O(iteMNQP)	1.1×10⁶
MRC^[10-11]	O(iteMNL)	1.3×10⁵
文中改进算法	O(iteMNL)	1.3×10⁵

算法	参数	复杂度	性能增益/dB
现有MRC算法^[10-11]	ite为14,ω_opt=0.2	1.3×10⁵
文中改进算法	ite为14,ω₁=0.2 ω₂=1.0 mid-ite为12	1.3×10⁵	0.3
现有MRC算法^[10-11]	ite为14,ω_opt=0.2	1.3×10⁵
文中改进算法	ite为11,ω₁=0.2 ω₂=1.0 mid-ite为9	1.0×10⁵	0
现有MRC算法^[10-11]	ite为11,ω_opt=0.2	1.0×10⁵
文中改进算法	ite为11,ω₁=0.2 ω₂=1.0 mid-ite为9	1.0×10⁵	0.6
现有MRC算法^[10-11]	ite为10,ω_opt=0.2	9.2×10⁴
文中改进算法	ite为10,ω₁=0.2 ω₂=1.0 mid-ite为8	9.2×10⁴	0.9