CDMA TDD系统动态信道分配技术

【作者】 李彬；

【导师】 吴诗其；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2003， 硕士

【摘要】 随着无线多媒体业务的迅速扩展，业务上下行不对称的特点日益明显。TDD CDMA系统具备时隙分配的灵活性和对多媒体业务良好的适应性，使得对TDD 模式下CDMA系统的DCA算法以及性能的研究成了近几年的一个热点。要充分发挥TDD模式的优势，关键就在于动态信道分配算法的有效性。为了增加系统的容量，同时尽可能的减少系统的干扰，大量的信道分配算法和策略被提出并被研究。本文对于CDMA TDD 系统无线资源管理策略之一的动态信道分配技术进行了分析和研究，涉及到如何有效、合理的在上下行和小区间安排信道。在我们提出的CDMA/TDD系统中，上下行使用不同数目的时隙，而且，每个方向的时隙数目可以根据业务结构调整。本文所作的分析就是针对TDD CDMA系统中帧结构的时隙分配进行的。着重分析了话音、数据多业务混合情况下的不同时隙安排对系统总容量的影响，并分别考虑了在单小区和多小区环境下的不同分配策略。对每种信道分配算法都给出了计算或仿真结果。在选择信道分配方案时，总体目标是：获得较高的信道利用率；较令人满意的系统服务质量；尽可能短的搜寻时间以及采用尽可能简单的算法。因为在系统的通信服务质量和信道分配算法执行的复杂性之间存在矛盾，而且它与信道搜寻时间和信道利用率也有关系，所以任何一种解决方案的提出总是不同矛盾折中的结果。因此在实际的组网中，要根据具体情况采用合理﹑可行的方案。本文的研究成果对于CDMA TDD系统的性能分析和小区规划具有一定的参考意义。更多还原

【Abstract】 With the rapid development of the wireless multimedia services, the traffic asymmetry between uplink and downlink is more and more obvious. TDD CDMA system has both the flexibility of timeslot allocation and good adaptability to the multimedia services. The research on the DCA (dynamic channel assignment) algorithm and its performance in the TDD CDMA system has been a hotspot in these years. The validity of DCA algorithm has been vital to utilize the advantages of TDD model and a lot of algorithms have been proposed to increase the system capability and decrease the interference in the system as possible.This paper discusses the DCA technique, which is one of the strategies in the wireless resources management. It is about how to arrange the channels among the uplink, downlink and cells effectively. In our CDMA/TDD system, different numbers of time slot are applied and they can be adjusted according to the traffic patterns.Our analysis is aiming at the slot allocation in the TDD CDMA system. We put the emphasis on the effects of different slot allocation on the capability of the system with the heterogeneous traffic such as voice and data. We also consider different assignment strategies in the single cell and multi-cells environment. The algorithms and simulation results of each strategy are provided.The selection of the channel assignment strategies is always aiming at achieving higher channel efficiency, better Qos, shorter channel search time and simpler application of the algorithm. There exits contradiction between the Qos guarantee and complexity of channel assignment algorithms. And the channel search time is correlated with the channel utilizing efficiency. So each solution plan is the compromise among these factors.To select a DCA strategy, we should consider whether it is feasible in the practical network construction.The conclusions in this paper will be valuable for the performance analysis and cells plan in the CDMA TDD system.更多还原