Umts Radio Access Network Handover Self-Optimization Mechanism

In recent years, the size of cellular network has increased a lot. There is a trend that the network is going to be more dynamic, more heterogeneous and more complex. In order to realize effective management of network and to ensure that the system works efficiently, the concept of automatic management arises at the moment. It can make the network become self-perception, self-configuration, self-optimization, self-healing and self-protection.Quality of Handover (QoH) is a crucially important performance indicator for cellular networks. With the increasing requirement of users, the velocity of users should be highly valued, because it has great effect on handover process and user experience. In this paper, we propose Handover Self-optimization Mechanism based on Velocity (HSMV), a novel handover mechanism which can improve the performance:firstly, some original data should be extracted from the mobile devices and a mathematic model will be proposed to estimate the velocity of users using Received Signal Strength (RSS); secondly, the relation between handover margin (HM) and the estimated velocity is concluded based on the model, then the value of HM will be adjusted accordingly; finally, the assessment method to estimate velocity as well as tackle with some handover problems will be validated. Simulation results show that it can not only gain relatively accurate velocity but also decrease the call drop rate.The algorithm that judge whether the user should launch switch by only one factor is easy to realize, but it makes a relatively low switch success rate and ignore factors on the influence of switch. Therefore, it is necessary to make the switching algorithm more reasonable. This paper is based on this requirement. The author consider the factor of user’s movement speed as well as some other factors such as amount of users, the distance between user and the base station, bandwidth, making these factors as input to control switching parameters by fuzzy logic algorithm. By using genetic algorithm to optimize fuzzy logic membership function, the improved fuzzy logic switching mechanism can not only balance the bandwidth of the system, but also can reduce call drop rate.