Research On Handover In WCDMA

WCDMA has been widely adopted as the 3rd Generation air interface. Handover is one of the most important aspects in mobile management, and efficient soft handover algorithm can greatly improve system performance. This paper focuses on the handover technology in WCDMA.In WCDMA system, handover is an important aspect of wireless resource management. Soft Handover is the most widely used in WCDMA, which has many advantages, for example, enhance the capacity of system, decrease the cutoff rate, and eliminate the Ping Pong effect and so on. So it not only increases the capacity of WCDMA system, but also maintains the integrity of the call. However, soft handover also has its disadvantage .It will cause extra burden to the system and consume system's resource. So it is vital to control the ratio of handover rate for the system. This paper focused on the core of soft handover, which is soft handover algorithm. Because the classic soft handover algorithm is not sensitive to load balance of the system, this paper introduces an improved algorithm for balance load of the system.To guarantee the quality of communication and assure the system capacity, the improved algorithm not only considers the ratio of receipt signal power in CPICH to the noise but also cell load. To compare the performance of the improved soft handover algorithm and the classic one, we firstly analyze the effect of the parameter of the algorithms to the system performance, give the relationship of them and optimize the parameters in each algorithm, and then compare the performance of the two optimized algorithm in simulation. From the result, it shows that the improved soft handover algorithm has better performance in soft handover capacity gain and blocking probability, so the improved ones enhance the performance of the system.