面向中频的短码直扩信号数字盲解扩算法

doi:10.3969/j.issn.1001-506X.2020.10.27

摘要/Abstract

摘要：

针对直接序列扩频(direct sequence spread spectrum, DSSS)信号盲解扩问题,现有的方法大多基于矩阵分解理论,抽取主特征向量进行解调进而恢复伪码波形。非合作接收条件下,由于伪码波形未知且信噪比极低,载波频率、相位信息往往难以精确估计。考虑非合作接收条件,伪码未同步且含有随机载波频偏,现有方法常对两倍长度的复基带分段相关矩阵进行分解,带来了极大的计算资源消耗,并且存在性能退化等问题。本文提出了一种面向中频的短码DSSS信号数字盲解扩算法,分析了载波残余对伪码波形同步的影响,并通过中频实矩阵分解重构了伪码波形,最后针对含任意载波残余的DSSS二进制相移键控(DSSS-binary phase shifted keying, DSSS-BPSK)信号,设计了完整的从波形到比特的低复杂度盲解调解扩流程。仿真结果表明,所提算法拥有更好的误码率性能以及良好的载波参数鲁棒性。

关键词: 短码直扩信号, 中频盲解扩, 伪码波形估计

Abstract:

Aiming at the problem of the blind despreading for direct sequence spread spectrum (DSSS) signal, existing works are mostly based on matrix decomposition theory, and the principal eigenvectors are extracted and demodulated to recover the pseudo-noise (PN) code waveform. Under the non-cooperative reception occasion, the carrier frequency and phase information are almost impossible to estimate accurately due to the unknown PN code waveform and extremely low signal to noise ratio (SNR). Considering the non-cooperative reception occasion with unsynchronized PN code and stochastic carrier frequency offset, current methods usually decompose the complex baseband piecewise correlation matrix with twice the length. It brings problems such as huge computing resource consumption and performance degradation. A digital blind despreading algorithm for intermediate frequency (IF) short code DSSS signal is proposed. The influence of residual carrier to PN synchronization is evaluated and the PN waveform is reconstructed by decomposing the IF real matrix. Finally, the low complexity blind despreading and demodulating process from waveform to bit for DSSS-binary phase shifted keying (DSSS-BPSK) signal with any residual carrier is designed. Simulation results verify the better bit error rate (BER) performance and robustness to carrier parameter of the proposed algorithm.

Key words: short code direct sequence spread spectrum (DSSS) signal, intermediate frequency (IF) blind despreading, pseudo-noise (PN) code waveform estimation

中图分类号:

TN975

邱钊洋, 李天昀. 面向中频的短码直扩信号数字盲解扩算法[J]. 系统工程与电子技术, 2020, 42(10): 2366-2373.

Zhaoyang QIU, Tianyun LI. Digital blind despreading algorithm for IF short code DSSS signal[J]. Systems Engineering and Electronics, 2020, 42(10): 2366-2373.

图/表 7

图1

图2

图3

表1

图4

图5

表2

参考文献 24

1	COOK C E , MARSH H S . An introduction to spread spectrum[J]. IEEE Communications Magazine, 1983, 21 (2): 8- 16. doi: 10.1109/MCOM.1983.1091346
2	QU F Z , QIN X Z , YANG L Q , et al. Spread-spectrum method using multiple sequences for underwater acoustic communications[J]. IEEE Journal of Oceanic Engineering, 2018, 43 (4): 1215- 1226. doi: 10.1109/JOE.2017.2750298
3	HASAN A, AOWLAD H. Simultaneous transmission of biomedical signals using DS-CDMA[C]//Proc.of the International Conference on Innovation in Engineering and Technology, 2018.
4	MIRONOV A S, BURDINSKIY I N, KARABANOV I V. The method of defining the threshold value of the symbolic correlation function for detecting DSSS hydroacoustic signal[C]//Proc.of the International Multi-Conference on Industrial Engineering and Modern Technologies, 2018.
5	MUNIR M A, MAUD A R M. Direct-sequence spread spectrum with variable spreading sequence for jamming immunity[C]//Proc.of the 16th International Bhurban Conference on Applied Sciences and Technology, 2019: 933-937.
6	BUREL G, BOUDER C. Blind estimation of the pseudo-random sequence of a direct sequence spread spectrum signal[C]//Proc.of the Milcom Century Military Communications Conference, 2000: 967-970.
7	ZHANG T Q , DAI S S , MA G N . Approach to blind estimation of the PN sequence in DSSS signals with residual carrier[J]. Journal of Systems Engineering and Electronics, 2010, 21 (1): 1- 8.
8	DOMINIQUE F , REED J H . Simple PN code sequence estimation and synchronisation technique using the constrained Hebbian rule[J]. Electronics Letters, 1997, 33 (1): 37- 38.
9	DOMINIQUE F , REED J H . Subspace based PN code sequence estimation for direct sequence signals using a simplified Hebb rule[J]. Electronics Letters, 1997, 33 (13): 1119- 1120. doi: 10.1049/el:19970778
10	BOUDER C, BUREL G. Spread spectrum codes identification by neural networks[C]//Proc.of the 4th World Multiconfe-rence on Circuits, Systems, Communications & Computers, 2000: 257-262.
11	ZHANG T Q , DAI S S , ZHANG W . Blind estimation of the PN sequence in lower SNR DSSS signals[J]. IEICE Trans.on Communications, 2005, 88 (7): 3087- 3089.
12	张红波, 吕明. 基于子空间跟踪的扩频码盲估计算法[J]. 系统工程与电子技术, 2006, 28 (10): 1470- 1472.
	ZHANG H B , LYU M . Blind estimation of pn spreading sequence based on subspace tracking[J]. Systems Engineering and Electronics, 2006, 28 (10): 1470- 1472.
13	ZHANG T Q , DAI S S , ZHANG W , et al. Blind estimation of the PN sequence in lower SNR DSSS signals with residual car-rier[J]. Digital Signal Processing, 2012, 22 (1): 106- 113.
14	宫二玲, 王跃科, 杨俊. 直序扩频系统中频信号的同时解扩解调方法[J]. 国防科技大学学报, 2004, 26 (6): 65- 68.
	GONG E L , WANG Y K , YANG J . Simutaneous despreading and demodulating method of IF signal in DSSS system[J]. Journal of National University of Defense Technology, 2004, 26 (6): 65- 68.
15	LUISE M , REGGIANNINI R . Carrier frequency recovery in all-digital modems for burst-mode transmissions[J]. IEEE Trans.on Communications, 1995, 43 (2): 1169- 1178.
16	NASIR A A , DURRANI S , KENNEDY R A . Particle filters for joint timing and carrier estimation: improved resampling guidelines and weighted Bayesian Cramer-Rao bounds[J]. IEEE Trans.on Communications, 2012, 60 (5): 1407- 1419. doi: 10.1109/TCOMM.2012.022912.100559
17	BUREL G, BOUDER C, BERDER O. Detection of direct sequence spread spectrum transmissions without prior knowledge[C]//Proc.of the IEEE Global Telecommunications Conference, 2001.
18	张天骐, 张传武, 林孝康, 等. 直扩信号伪码周期及序列的估计算法[J]. 系统工程与电子技术, 2005, 27 (8): 1365- 1368.
	ZHANG T Q , ZHANG C W , LIN X K , et al. Algorithm for period sequence estimation of the PN code in DSSS signals[J]. Systems Engineering and Electronics, 2005, 27 (8): 1365- 1368.
19	金艳, 孙玖玲, 姬红兵. 基于相关熵的扩频周期估计方法[J]. 系统工程与电子技术, 2018, 40 (1): 17- 22.
	JIN Y , SUN J L , JI H B . PN sequence period estimation method based on correntropy[J]. Systems Engineering and Electronics, 2018, 40 (1): 17- 22.
20	BOUDER C, AZOU S, BUREL G. A robust synchronization procedure for blind estimation of the symbol period and the timing offset in spread spectrum transmissions[C]//Proc.of the IEEE 7th International Symposium on Spread Spectrum Techniques and Applications, 2002.
21	吴利平. 极低信噪比条件下基于平均互相关和特征分解的DS伪码估计算法[J]. 中国科学:信息科学, 2011, 41 (3): 338- 348.
	WU L P . A PN sequence estimation algorithm for DS signal based on average cross-correlation and eigen-analysis in lower SNR conditions[J]. Science China: Information Sciences, 2011, 41 (3): 338- 348.
22	QIU Z Y , PENG H , LI T Y . A blind despreading and demodulation method for QPSK-DSSS signal with unknown carrier offset based on matrix subspace analysis[J]. IEEE Access, 2019, 7, 125700- 125710. doi: 10.1109/ACCESS.2019.2938785
23	刘少林. MPSK信号调制方式识别与参数估计[D].北京:北京邮电大学, 2015.
	LIU S L. Modulation recognition and parameter estimation of MPSK signals[D]. Beijing: Beijing University of Posts and Telecommunication, 2015.
24	GOLUB G H , LOAN V C F . Matrix computations[M]. 3rd ed Baltimore: Johns Hopkins University Press, 1996.

信号参数	仿真实验
信号参数	实验1、4	实验2、5	实验3、6
伪码波形长度N	63	63	63
伪码速率R_b/kBps	160	160	160
采样速率f_s/kHz	800	800	800
中频频率F_c/kHz	200	200	180~220
(E_s/N₀)/dB	0~10	5	5
符号数量	200	50~500	200

算法	自相关矩阵求解	矩阵分解
CB-SVD算法	O(64N²)	O(64N³)
本文算法	O(N²)	O(N³)

[1]	陈晓威, 杨文革. 基于时变白化滤波器的DSSS系统干扰盲检测[J]. 系统工程与电子技术, 2021, 43(7): 1981-1988.
[2]	赵凡, 金虎. 基于GAN的通信干扰波形生成技术[J]. 系统工程与电子技术, 2021, 43(4): 1080-1088.
[3]	史蕴豪, 许华, 郑万泽, 刘英辉. 基于集成学习与特征降维的小样本调制识别方法[J]. 系统工程与电子技术, 2021, 43(4): 1099-1109.
[4]	范新峰, 谭志良. 基于数字对消的跟踪干扰抑制方法[J]. 系统工程与电子技术, 2020, 42(6): 1235-1240.