Research On Handoff Algorithms In CDMA Mobile Communication System

The article makes a study of soft handoff technology in mobile communication system in particular. And the soft handoff is one of the key technologies in the CDMA system. It plays an important role in controlling and optimizing radio resources of the system.And the mobility is a typical characteristic of mobile communication. And implementing high efficient mobility managements for the mobiles not only can improve the use rate of system resources ,but also the system performances.Handoff is an important part of the mobility managements.The choice of soft handover algorithms diretly influences the capacity and the QoS of the system.At first, the article introduces key technologies in mobile communication systems,introducing the theory of handoff in particular. And then it researches into the rules of handoff in each mobile communication system.And in emphases analyzing the likely happening operations when the system adds, deletes or replaces pilots in Active Set in the talking process of the mobiles. Based on the handoff algorithms mentioned in references, in particular analyzing the influences that the soft handoff algorithms brings to the mobiles system with data services and voice services, then an improved scheme are raised.To meet the progressive importance of serving quality and system capacity, there are the analyses of the FIFO queuing algorithm and single-queue FIFO on HCA scheme which are the foundation of the new algorithm. The new scheme is based on dual-queue FIFO scheme and combined with HCA (Hybrid Channel Assignment) algorithm. It puts the handoff voice call queuing algorithm on prioritized handoff Reserved Channel Scheme, and then sets another FIFO queue for the residual calls.This article particularly analyses the new scheme on theory,and compared with the two basic schemes in numerical analyses.From the results, the conclusion is given that the new scheme not only reduces handoff failure probability and blocking probability but also improves resource utilization, and the capability of system is enhanced,too.Therefore the new scheme improves the system performances to a certainty.