Research Of Handover Technique In Mobile System

Handover is the indispensable method which makes sure the mobile user can enjoy the mobility in the mobile communication system. Since the concept of cell came into the mobile communication system area, the handover technology has appeared and became the very important concept of the mobile communication system. Handover is the particular function of the cell system, and also is the key character of the mobile communication system, it influents the capability of the mobile system directly.The hard-handover is the typical handover technology of the traditional mobile system. In this handover process, MS cut off the connection of the former BS before make a new connection of the target BS. It is a "Cut off and then Connect" process. Along with the development of the 3G system, the soft-handover has appeared. The soft-handover means MS handover between the channels which have the same frequency, it is a "Connect and then Cut off' process. The soft-handover can subdivide into soft-handover and softer-handover. Softer-handover means MS handover between the different channels in the sectors of the same cell. It was named softer-handover because the process don't need MSC, it only under the Node B. The soft-handover can add gain and reduce system interference. The TD-SCDMA introduce the relay handover technology which need the precise localize for the precondition. Compares to the hard-handover, the soft-handover technology make the UE handover more rapidly and reduce the disconnection rate. In the B3G system, the handover technology which need to achieve in the different sub network become more and more complicated, considering about the requirements of the customers and the characters of the network.This thesis have research the handover algorithm with their particular measure method and handover mechanism between the GSM, CDMA, WCDMA and TD-SCDMA system. This thesis also discussed the different influences of the system capability which the these different handover strategies bring into, and discussed the different advantages as well as the disadvantages. And research how to extract signaling and signals of handover from the GSM air interface, research the working process of extracting signaling and signals also.