Design And Implementation Of A Novel Scheme Of Soft-handoff In CDMA System Based On Mobile Agent

The Code Division Multiple Access (CDMA) system is becoming a very promising communication system as rapid development of mobile communication and coming of multimedia. Soft-handoff is one of key technologies of CDMA which can realize mobile station's moving among difference cells. Fast soft-handoff could reduce rate of communication break, increase the system capacity and save bandwidth.Presently researches on soft-handoff include: algorithm of handoff and the influence of parameter of handoff on system. But all these researches are base on a kind of centralized management by Move Switch Center (MSC). By this way, when network becomes bigger and bigger, soft-handoff will cause"bottle-neck"problem to bandwidth using. It will also waste bandwidth and increase signal delay. Then it should not satisfy Quality of Service (QoS) of multimedia communication.A novel scheme of soft-handoff in CDMA system based on mobile agent is promoted in this thesis. Mobile agent which is a distributed management technology is used in our soft-handoff scheme. This scheme has applied for national invention patent. In this novel scheme, soft-handoff will be managed by each Base Station (BS) instead of MSC which could achieve distributed management. This can reduce communications among mobile stations and system resources of BS and MSC, solve the"bottle-neck"problem.By analysis and simulation on the novel method, the reliability of the scheme is verified. It could reduce the system delay to 55.2% when the network is busy. So this technology is very efficient in the centre of city or shopping center.Furthermore, queue model is studied deeply. A novel dynamic queue model satisfied the QoS (the type of operation, the aspect and speed of MS) is also proposed in this thesis which is very promising.The program of soft-handoff agent is designed and realized by JAVA, and is operated on aglet (IBM) flat roof. And the method is tested.Finally, some applications using mobile agent in 3G have shown which are next n step research.