Research On Handover Algorithms In Satellite Mobile Communication System

Satellite communication system, as an important part of wireless communication, is favored in emergency rescue and navigation positioning for its large message capacity and long transmission distance. As the complement of terrestrial mobile communication, satellite communication technology has become an important means of modem communication and has broad application prospects in the future. In satellite communication system, handover between beams happens frequently when users cross the boundary of spot beam because of the high speed movement of satellite and terrestrial users. The service of handover affects the quality of handover call, reliable handover algorithm in satellite communication system is particularly important. So the following three aspects based on handover is researched in this paper.Firstly, this paper analyzes the causes of handover trigger, the classification of handover and notes the importance of the parameters in the process of handover. After this, it summarizes the handover types in satellite mobile communication system and analyzes the close contact of handover and channel allocation and then notes the importance of good handover algorithm to ensure the continuity of users.Secondly, based on the difference between terrestrial mobile communication system and the satellite communication system, the paper notes the inapplicability of terrestrial handover algorithm to high-speed users in satellite mobile communication system. After analyzing that too early or to late handover will bring a great waste of resourceand will reduce the service quality of uers, this paper proposes a beam-handover algorithm which is applicable to satellite mobile communication system. In this algorithm, the current signal strength is used to control the hysteresis parameter, and different Time To Trigger is set for terrestrial users of different speeds, thereby performing reasonable handover decision.Finally, this paper researches on the satellite mobile communication technology and channel allocation strategy. After analyzing several typical channel allocation methods such as reservation channel and handover queue and so on, this paper proposes that combine channel reservation strategy and handover queue strategy to ensure the service of the handover call. On this basis, proposes that the new call users can access reservation channel as a certain probability. The strategy considers the service quality of both the handover users and new users, reduces the rate of new call blocking and the handover failure rate, thus improvingthe performance of the overall system.