高铁场景下一种基于信噪比判决的双模切换信道估计算法

doi:10.11959/j.issn.1000-0801.2018199

摘要/Abstract

摘要：

为了提高信道在信噪比大范围变化环境下信道估计的精度，确保高速铁路通信系统的可靠性，提出高铁场景下一种基于信噪比判决的双模切换信道估计算法。该算法利用离散卡—洛基扩展模型（discrete Karhunen-Loeve basis expansion model，DKL-BEM）及线性最小均方误差（linear minimum mean square error， LMMSE）算法进行信道建模和不同速度环境下的信道估计。仿真发现，当信噪比增大至某值时，基于ICI消除的二次信道估计算法性能劣于传统的DKL-BEM算法（出现交叉点），且交叉点值随速度的提高左移（小信噪比方向）。通过对参数分析和两种算法交叉点值的提取，给出交叉点随速度变化的移动轨迹，自适应地实现两种算法的切换，提高信道估计算法的适应性和有效性。

关键词: 高铁场景, 双模切换, 自适应, 交叉点, 时变信道

Abstract:

A dual mode switching channel estimation algorithm based on SNR decision in high speed railway scenarios was proposed.The algorithm adopted DKL-BEM and LMMSE modelling the channel and estimating the channel under different speed conditions,respectively.The simulation results show that the SNR increased,the performance of the twice channel estimation algorithm based on ICI cancellation became worse than that of the traditional DKL-BEM algorithm,and a cross-point appeared,its value moved towards the small SNR as the speed increased.Through analyzing the parameters and extracting the cross-point values of the two algorithms,the moving trajectory of the cross-point with the speed changing was given.The proposed algorithm can adaptively achieve the switching between two algorithms and improve the applicability and effectiveness of the channel estimation algorithm.

Key words: high speed railway scenario, dual mode switching, adaptive, cross-point, time-varying channel

王传云,王敏,赵军辉,尹燕. 高铁场景下一种基于信噪比判决的双模切换信道估计算法[J]. 电信科学, 2018, 34(7): 72-79.

Chuanyun WANG,Min WANG,Junhui ZHAO,Yan YIN. A dual mode switching channel estimation algorithm based on SNR decision in high speed railway scenarios[J]. Telecommunications Science, 2018, 34(7): 72-79.

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参数	设置值
子载波个数N	256
调制方式	QPSK
信道多径数L	6
各径时延/μs	0，1，2，3，4，5
采样时间间隔t_s/μs	1
循环前缀长度	32
BEM阶数Q	4
梳状导频簇数M	8
每簇中的非零导频个数a	1
非零导频两侧保护导频数（单侧）b	4
导频簇之间的间隔载波个数	23

交叉点	A4	A5	A6
实际信噪比值/dB	23.197	18.065	14.883
理论计算值y_snr/dB	22.370	18.260	15.170
相对误差	3.57%	1.08%	1.93%