A novel kind of multidimension symbol/sequence trellis coded modulation (TCM) based on TCM of lower coding rate has been constructed. The redundancy of this new kind of TCM is provided not only by the modulated symbo...A novel kind of multidimension symbol/sequence trellis coded modulation (TCM) based on TCM of lower coding rate has been constructed. The redundancy of this new kind of TCM is provided not only by the modulated symbol sequence but also by the PN sequences for spreading spectrum as well. The performance of direct sequence spread spectrum multiple access (DS/SSMA) system with this symbol/sequence TCM over flat Rayleigh fading channel has been investigated by theoretical analysis and numerical simulation. The results obtained in this research demonstrate the performance improvements of this system in comparison with that of the DS/SSMA system with conventional TCM under the same conditions.展开更多
In an Approximately Synchronized Code Division Multiple Access (AS-CDMA) commu-nication system,a family with large number of Zero Correlation Zone (ZCZ) sequences is desired,which can satisfy the rapid increase of use...In an Approximately Synchronized Code Division Multiple Access (AS-CDMA) commu-nication system,a family with large number of Zero Correlation Zone (ZCZ) sequences is desired,which can satisfy the rapid increase of users. This paper presents a method to generate a (2L ,2M ,Zc' z )-ZCZsequence family from an original (L ,M ,Z cz)-ZCZsequence family,where Z c' z =Zcz if Z czis even and Z c' z = Zcz 1if Z czis odd. This method can also recursively act on a ZCZ sequence family to construct a series of ZCZ sequence families with large sequence number and zero correlation zone length identical to or one less than that of original ZCZ sequences.展开更多
由于长短码直扩码分多址(LSC-DS-CDMA)信号包含了多个用户的长码和短码,已有的直扩码分多址信号的盲伪码估计方法不再适用。为此该文提出一种基于矩阵填充和三阶相关的伪码估计方法。首先从理论上将结构复杂的LSC-DS-CDMA信号构建为多...由于长短码直扩码分多址(LSC-DS-CDMA)信号包含了多个用户的长码和短码,已有的直扩码分多址信号的盲伪码估计方法不再适用。为此该文提出一种基于矩阵填充和三阶相关的伪码估计方法。首先从理论上将结构复杂的LSC-DS-CDMA信号构建为多用户短码扩频的缺失矩阵模型,将复合码矩阵估计建模为盲源信号分离问题;然后将矩阵填充理论应用于复合码矩阵估计,提出基于奇异值阈值算法和快速独立成分分析算法的各用户复合码序列估计方法;最后利用m序列的移位相加性特性,提出延迟三阶相关算法,从各用户复合码序列中估计其包含的长短伪码序列。仿真表明,当信噪比高于-2 d B时,该文算法的长短伪码估计平均误码率低于0.1%。展开更多
直序码分多址系统(DS-CDMA)与多载波码分多址系统(MC-CDMA)是高速率无线通信中两个重要的CDMA技术。文章将一种改进的每个用户最小均方差(PU-MMSE)检测技术应用于频域均衡的DS-CDMA系统中,并通过计算机仿真分别对传统的每个载波最小均方...直序码分多址系统(DS-CDMA)与多载波码分多址系统(MC-CDMA)是高速率无线通信中两个重要的CDMA技术。文章将一种改进的每个用户最小均方差(PU-MMSE)检测技术应用于频域均衡的DS-CDMA系统中,并通过计算机仿真分别对传统的每个载波最小均方差(PC-MMSE)与PU-MMSE两种检测技术应用于Wi MAX SUI信道下的DS-CDMA和MC-CDMA系统进行了性能比较。实验结果表明:使用了PU-MMSE检测技术的DS-CDMA系统能够更好地消除串行干扰,且与使用相同检测技术的MC-CDMA系统的性能几乎没有差别,但是却大大降低了峰值平均功率比(PAPR)。展开更多
文摘A novel kind of multidimension symbol/sequence trellis coded modulation (TCM) based on TCM of lower coding rate has been constructed. The redundancy of this new kind of TCM is provided not only by the modulated symbol sequence but also by the PN sequences for spreading spectrum as well. The performance of direct sequence spread spectrum multiple access (DS/SSMA) system with this symbol/sequence TCM over flat Rayleigh fading channel has been investigated by theoretical analysis and numerical simulation. The results obtained in this research demonstrate the performance improvements of this system in comparison with that of the DS/SSMA system with conventional TCM under the same conditions.
基金the National Natural Science Foundation of China (No.60673081)the National "863" Project (No.2006AA01Z417).
文摘In an Approximately Synchronized Code Division Multiple Access (AS-CDMA) commu-nication system,a family with large number of Zero Correlation Zone (ZCZ) sequences is desired,which can satisfy the rapid increase of users. This paper presents a method to generate a (2L ,2M ,Zc' z )-ZCZsequence family from an original (L ,M ,Z cz)-ZCZsequence family,where Z c' z =Zcz if Z czis even and Z c' z = Zcz 1if Z czis odd. This method can also recursively act on a ZCZ sequence family to construct a series of ZCZ sequence families with large sequence number and zero correlation zone length identical to or one less than that of original ZCZ sequences.
文摘由于长短码直扩码分多址(LSC-DS-CDMA)信号包含了多个用户的长码和短码,已有的直扩码分多址信号的盲伪码估计方法不再适用。为此该文提出一种基于矩阵填充和三阶相关的伪码估计方法。首先从理论上将结构复杂的LSC-DS-CDMA信号构建为多用户短码扩频的缺失矩阵模型,将复合码矩阵估计建模为盲源信号分离问题;然后将矩阵填充理论应用于复合码矩阵估计,提出基于奇异值阈值算法和快速独立成分分析算法的各用户复合码序列估计方法;最后利用m序列的移位相加性特性,提出延迟三阶相关算法,从各用户复合码序列中估计其包含的长短伪码序列。仿真表明,当信噪比高于-2 d B时,该文算法的长短伪码估计平均误码率低于0.1%。
文摘直序码分多址系统(DS-CDMA)与多载波码分多址系统(MC-CDMA)是高速率无线通信中两个重要的CDMA技术。文章将一种改进的每个用户最小均方差(PU-MMSE)检测技术应用于频域均衡的DS-CDMA系统中,并通过计算机仿真分别对传统的每个载波最小均方差(PC-MMSE)与PU-MMSE两种检测技术应用于Wi MAX SUI信道下的DS-CDMA和MC-CDMA系统进行了性能比较。实验结果表明:使用了PU-MMSE检测技术的DS-CDMA系统能够更好地消除串行干扰,且与使用相同检测技术的MC-CDMA系统的性能几乎没有差别,但是却大大降低了峰值平均功率比(PAPR)。
