【作者】 胡丹；

【导师】 段正华；

【作者基本信息】 湖南大学 ， 计算机应用技术， 2004， 硕士

【摘要】 基于CDMA技术的移动通信系统将支持语音，视频，数据等不同QoS要求的多类业务传输，如何设计有效的呼叫接入控制策略以保证各类业务的服务质量，同时最大限度地利用无线资源，支持尽可能多的用户，成为近年来移动通信领域研究的热点问题。 本文在充分总结前人研究成果的基础上，从自适应的角度，提出了有效的呼叫接入控制策略。 针对多类具有不同优先级的无线业务，已有的呼叫接入控制策略都是基于静态保护信道机制，无法适应系统业务量的实时变化，为此，本文提出了动态多门限呼叫接入控制策略。该策略根据优先级为各类业务设置相应的服务门限，服务门限能根据系统负荷的变化动态地调整。仿真表明，该策略与已有静态策略相比具有很好的业务量跟随能力。当系统负荷较低时，该策略在保证较高优先业务的阻塞率维持在门限值的同时，减少了较低优先业务的阻塞率；当系统负荷较高时，该策略总能做到尽量地保证较高优先业务的服务质量。 CDMA系统在区间业务不平衡的情况下会出现高的阻塞率，为了改善系统性能，本文提出了基于动态资源预留的呼叫接入控制策略，在各个小区中为邻区即将到来的呼叫预留部分资源，预留的大小随呼叫阻塞情况自适应地调整。仿真结果表明，这种策略能很好地解决区间业务不平衡的问题，而且与基于固定资源预留的呼叫接入控制策略相比，该策略能够跟随话务量的变化，保持良好性能。另外，本文还考虑了小区内移动台分布不均匀的情况，对于所提策略做了进一步的扩充，使得基于动态资源预留的呼叫接入控制策略更具有实际意义。更多还原

【Abstract】 The mobile communication systems based on CDMA technique are expected to support multi-traffic with different QoS requirements, such as voice, video, data, etc. The research on effective call admission control policies which can provide guaranteed QoS to as many users as possible, and maximizes resource utilization has become the hot spot in the mobile communication fields in recent years.In this paper, adaptive call admission control policies are proposed based on former research achievements.For multi-traffic with different priorities, the existing call admission control policies are built upon the concept of fixed guard channels, and can’t adapt to traffic changes. So the paper proposes a dynamic multi-threshold call admission control policy which sets service threshold for each traffic based priority, and dynamically adjusts service thresholds according to system load. Simulation results show that the policy outperforms the existing fixed policies in traffic load adaptation. When the system load is lower, the policy guarantees that the call blocking rate of higher-priority traffic is below its given threshold and at the same time, decreases the call blocking rate of lower-priority traffic. When the system load is higher, the policy does its utmost to guarantee the quality of higher-priority traffic.When the traffic are non-uniformly distributed among cells, the overall call blocking rate of CDMA system is very high. To improve the system performance, the paper presents a call admission control policy based on dynamic resource reservation. It reserves some portion of the system resource in each cell for upcoming calls occurring in neighbor cells. The proportion of reserved resource can be adaptively adjusted according to the call blocking situation. Simulation results show that the policy can resolve the inter-cell unbalanced traffic problem, and it can keep better performance under changing traffic conditions than the call admission control policy based on fixed resource reservation. In addition, the paper further extends the proposed policy to intra-cell unbalanced traffic environment, and makes it more practical.更多还原