Study on Code-Division Multiple Access Scheme for Multimedia Mobile Communications

本研究的目的是探讨如何在多媒体移动的通信中获得可靠、高速和大容量的CDMA系统。在各种类型的干扰消除器中，已知连续多址干扰消除器具有良好的性能。它生成每个干扰信号的副本，并从接收信号中减去该副本。因此，可以通过使再生信号更精确来改善连续MAI消除器的性能。基于这一观察，我们提出了一个方案，集成了纠错码和多址干扰消除器和一个方案，集成了自适应阵列天线和多址干扰消除器。通过计算机模拟证实了这些方案的性能改进。在一些模拟中，我们假设接近系统容量的情况。针对这些情况，我们设计了适合于并行计算的模拟程序，并提出了两种改善DS-CDMA系统综合话音和数据传输性能的方案。一个是与两个数据包检测器相结合的干扰消除器。另一种是用于数据分组的功率控制方案，其避免语音信号质量的劣化。计算机仿真结果表明，在数据包传输延迟略有增加的情况下，系统的性能得到了改善。此外，我们还提出了一个可认证的密钥协商方案和一个具有身份和位置保密性的双向认证方案。我们证明了该计划是安全的，对主动攻击的基础上正式的安全定义。

The purpose of this study is to investigate the techniques that achieve reliable, high-speed and high-capacity CDMA systems for multimedia mobile communications.The performance of a DS-CDMA system is limited by multiple access interference (MAI). Among various types of interference cancellers, a successive MAI canceller is known to have good performance. It generates a replica of each interference signal and subtracts it from the received signal. Thus, the performance of a successive MAI canceller can be improved by making the regenerated signals more accurate. Based on this observation, we proposed a scheme that integrates an error correction code and an MAI canceller and a scheme that integrates an adaptive array antenna and an MAI canceller. The performance improvements are confirmed for these schemes by computer simulations. In some simulations, we assume the situation with near the system capacity. For these cases, we have implemented simulation programs suitable for parallel computation.We also proposed two schemes that improve the performance of integrated voice and data transmission in DS-CDMA systems. One is an interference canceller combined with two packet detectors. The other is a power control scheme for data packets that avoids the degradation of the voice signal quality. The performance improvements are confirmed at the cost of slight increase of transmission delay of data packets by computer simulations.Furthermore, we also proposed an authenticated key agreement scheme and a mutual authentication scheme with identity and location privacy. We proved that the schemes are secure against active attacks based on formal security definitions.