【摘要】 为解决基于理想互补码的CDMA系统用户容量受互补码子码个数限制的问题,提出了偶位移互补码及其平衡四相扩频调制传输方案,使得基于偶位移互补码的CDMA系统用户容量突破了子码个数的限制,达到了子码个数的2倍。先将一个哈达玛矩阵按列分成列数相等的一组子矩阵,再对每一个子矩阵通过克罗内克算子进行扩展后,与另外一个哈达玛矩阵每一个行向量形成的三角矩阵相乘生成偶位移互补码。相关函数的分析结果表明,偶位移互补码不具有理想相关特性,采用平衡四相扩频调制方案可以解决这一问题。仿真结果验证了基于偶位移互补码的CDMA系统能有效地抑制系统中的多径干扰和多址干扰。更多还原

【Abstract】 The number of supportable users of complementary coded CDMA systems using perfect complementary codes is limited by the number of element codes. To break through the limit,a kind of even-shift complementary codes,along with a transmitting scheme based on balanced quaternary spreading and modulation,was proposed. The number of supportable users of even-shift complementary codes based on CDMA system reaches to double the number of element codes. For the construction of even-shift complementary codes,a Hadamard matrix was divided to a group of submatrices with equal number of columns. Then,each submatrix was spread by Kronecker operator. Last,another Hadamard matrix was selected. From each row of the Hadamard matrix,a diagonal matrix was constructed and used to multiply each aforementioned spread submatrix to generate even-shift complementary codes. Analysis results showed that even-shift complementary codes would not possess ideal correlation properties,which could be resolved by balanced quaternary spreading and modulation. Simulation results verified that the proposed system using even-shift complementary codes could significantly cancel the multipath and multiple access interferences.更多还原