CDMA系统呼叫接入控制方案及性能分析

On a Call Admission Control Scheme for CDMA System and Its Performance Analysis

呼叫允许控制是无线移动通信网络保障用户服务质量、提高无线资源利用率的一种重要机制。该文提出了一种适用于CDMA系统的呼叫允许控制方案。为了保障切换用户的服务质量,该方案为切换用户预留专用信道;并考虑了CDMA的软切换特性,为切换用户设置等待队列。切换请求到达时,若无可用信道,该切换请求不会被立即拒绝,而是进入队列等待。待有空闲信道时,队列中最前面的用户立即进行切换。理论分析表明,与已有的方案相比,该方案能显著降低GoS,提高无线资源利用率。

Call Admission Control(CAC)is a crucial mechanism adopted in wireless mobile communication networks to assure the Quality of Service(QoS)of subscribers and at the same time maximizes the utilization efficiency of radio resource.In this paper,a CAC scheme is proposed for Code Division Multiple Access(CDMA) system.In order to guarantee the QoS of handoff users,some dedicated guard channels arc reserved for handoff calls.Considering the unique soft handoff feature of CDMA system,a queue is adopted to accommodate handoff requests which cannot be admitted immediately.Upon handoff arrival,if all channels in the target cell arc busy,the handoff is allowed to queue.Once an occupied channel is released,the user in the front of the queue can get handoff.Theoretical analysis proves that,compared with existing scheme,significant improvement in overall performance,i.e.,Grade of Service(GoS)and radio resource utilization efficiency,can be achieved with the proposed scheme.