中圖分類(lèi)號(hào)： TN914.42 文獻(xiàn)標(biāo)識(shí)碼： A DOI：10.16157/j.issn.0258-7998.212094 中文引用格式： 潘微宇，趙知?jiǎng)? 帶殘余頻偏的LSC-DS-CDMA信號(hào)偽碼估計(jì)[J].電子技術(shù)應(yīng)用，2022，48(6)：58-63. 英文引用格式： Pan Weiyu，Zhao Zhijin. Pseudo code estimation of LSC-DS-CDMA signal with residual frequency offset[J]. Application of Electronic Technique，2022，48(6)：58-63.
Pseudo code estimation of LSC-DS-CDMA signal with residual frequency offset
Pan Weiyu1，Zhao Zhijin1，2
1.School of Communication Engineering，Hangzhou Dianzi University，Hangzhou 310018，China； 2.State Key Lab of Information Control Technology in Communication System of No.36 Research Institute， China Electronic Technology Corporation，Jiaxing 314001，China
Abstract： Aiming at the problem of estimation of long and short code direct spread code division multiple access signal with residual frequency offset, firstly, the signal matrix is constructed by using the periodic piecewise received signals of short code and long code. Secondly, the eigenvalue decomposition method is used to obtain the user eigenvector sub-space with residual carrier, and the digital phase-locked loop is used to track and eliminate the residual frequency offset. Then, the Givens matrix is used to rotate the load matrix composed of eigenvectors, and a whale optimization algorithm combined with random difference and simulated annealing is proposed to find the best rotation angle to minimize variance, so as to estimate the composite code segments of each user and splice them in turn. Finally, Berlekamp-Messay algorithm and correlation operation are used to estimate the long code and short code of each user. Simulation results verify the effectiveness of the proposed algorithm for pseudo code estimation of LSC-DS-CDMA signals with residual frequency offset.
Key words : long and short code direct spread code division multiple access；digital phase locked loop；Givens rotation；whale optimization algorithm；Berlekamp-Massey algorithm
0 引言
直接擴(kuò)頻序列碼分多址(Direct Sequence Code Division Multiple Access，DS-CDMA)采用高速率的偽碼對(duì)信息碼進(jìn)行擴(kuò)頻調(diào)制，具有較強(qiáng)的隱蔽性和抗干擾能力[1]。DS-CDMA信號(hào)可根據(jù)擴(kuò)頻方式分為短碼(Short Code，SC)DS-CDMA和長(zhǎng)碼(Long Code，LC)DS-CDMA兩種信號(hào)，為了進(jìn)一步提高保密性，利用長(zhǎng)碼對(duì)短碼擴(kuò)頻信號(hào)做加擾處理，得到長(zhǎng)短碼(Long and Short Code，LSC)DS-CDMA信號(hào)。SC-DS-CDMA信號(hào)用一周期擴(kuò)頻碼調(diào)制一個(gè)信息碼，文獻(xiàn)[2]-[3]分別采用多重信號(hào)分類(lèi)法[2]和平行因子法[3]實(shí)現(xiàn)了各用戶(hù)偽碼盲估計(jì)；文獻(xiàn)[4]利用特征值分解法和Givens矩陣旋轉(zhuǎn)法來(lái)估計(jì)SC-DS-CDMA信號(hào)各用戶(hù)的偽碼，但在尋找Givens矩陣旋轉(zhuǎn)角度時(shí)采用極值法，難以得到最佳旋轉(zhuǎn)角度，估計(jì)性能不佳；LC-DS-CDMA信號(hào)用一周期擴(kuò)頻碼調(diào)制多個(gè)信息碼，文獻(xiàn)[5-6]通過(guò)構(gòu)建張量模型，分別利用TUCKER分解[5]和CP分解[6]估計(jì)LC-DS-CDMA信號(hào)的偽碼；文獻(xiàn)[7]采用迭代最小二乘投影算法和庫(kù)搜索估計(jì)異步LC-DS-CDMA信號(hào)各用戶(hù)的偽碼；文獻(xiàn)[8]采用矩陣填充理論、奇異值分解和FastICA算法估計(jì)LSC-DS-CDMA信號(hào)各用戶(hù)復(fù)合碼，并利用m序列三階相關(guān)特性估計(jì)出各用戶(hù)長(zhǎng)短碼；文獻(xiàn)[9]利用FastICA算法分離LSC-DS-CDMA信號(hào)各用戶(hù)復(fù)合碼，并基于分圓陪集理論和三階相關(guān)特性估計(jì)長(zhǎng)短碼。上述研究都只針對(duì)理想信號(hào)，實(shí)際接收信號(hào)總會(huì)帶有小的殘余頻偏[10]，使得上述方法無(wú)法直接使用。文獻(xiàn)[11]-[12]分別利用線(xiàn)性調(diào)頻Z變換法和無(wú)跡卡爾曼濾波法估計(jì)殘余頻偏，但無(wú)法完全消除頻偏；文獻(xiàn)[13]利用特征值分解法得到帶殘余頻偏的偽碼，并通過(guò)全數(shù)字鎖相環(huán)(Digital Phase Locked Loop，DPLL)對(duì)頻偏進(jìn)行跟蹤消除，實(shí)現(xiàn)了長(zhǎng)碼直擴(kuò)信號(hào)的偽碼估計(jì)，但并未對(duì)LSC-DS-CDMA信號(hào)進(jìn)行研究。
