中文摘要：

为解决移动通信系统过载传输,在稀疏图多址接入基础上,将低密度扩频技术拓展至多载波传输系统,设计了基于多载波码分多址（MC-CDMA）的多进制联合稀疏图.该多进制联合稀疏图通过变量节点和置换节点,将低密度扩频矩阵和多进制低密度奇偶校验码（LDPC）校验矩阵结合起来,使得系统的接收端能够在整幅稀疏图上同时完成多用户检测和信道译码.多进制联合稀疏图融合了扩频、多载波调制和信道编码等技术,包含多维信号的综合协作处理.计算机仿真表明,多进制联合稀疏图MC-CDMA在系统严重过载情况下,仍然能达到理想的通信性能.

英文摘要：

Idea of the low density spreading to multicarrier transmission systems was extended,and nonbinary united low density graph for MC-CDMA（multi-carrier code division multiple access）was designed.Such graph linked low density spreading matrix and low density parity check（LDPC）matrix through variable nodes and transform nodes.On the receiver,united detection and decoding could be implemented.Spreading,multiuser access and channel coding were combined and processed jointly.Computer simulations show that compared with similar systems,the nonbinary united low density graph MC-CDMA can achieve better performance even when user′s number severely surpasses the system capacity.