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

本研究的目的是探讨实现可靠、高速和高容量的多媒体移动通信CDMA系统的技术。多址干扰（multi - access interference， MAI）限制了DS-CDMA系统的性能。在各种类型的干扰消除器中，连续的MAI消除器具有良好的性能。它生成每个干扰信号的副本，并从接收到的信号中减去它。因此，可以通过提高再生信号的精度来提高连续MAI消去器的性能。基于这一观察，我们提出了一种集成纠错码和MAI消除器的方案，以及一种集成自适应阵列天线和MAI消除器的方案。通过计算机仿真验证了这些方案的性能改进。在一些模拟中，我们假设系统容量接近。针对这些情况，我们实现了适合并行计算的仿真程序。我们还提出了两种改进DS-CDMA系统话音和数据综合传输性能的方案。一种是与两个数据包检测器相结合的干扰消除器。另一种是避免语音信号质量下降的数据包功率控制方案。通过计算机仿真，以数据包传输延迟的轻微增加为代价，证实了性能的提高。此外，我们还提出了一种具有身份和位置隐私的认证密钥协议方案和一种相互认证方案。我们根据正式的安全定义证明了这些方案对主动攻击是安全的。

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.