Research On The Key Technologies Of Handover Based On The Heterogeneous Cooperative Satellite Communication Network

Low earth orbit satellite(LEO)communication system is main component of building a global seamless communication system,it will occupy the important position in military and personal communication in the future due to characteristics of a wide range covering,low propagation delay and low energy.In satellite communication systems,velocity of satellites move relatively users is higher than middle earth orbit(MEO)and geostationary orbit(GEO),this will lead to that users need frequent cell handover to maintain the current communication service.At the same time,channel assignment is especially important in handover process,this is directly related to system channel utilization,so how to optimum channel assignment is of great importance.This paper discuss and analysis various kinds of handover and channel assignment strategies,taking an overall consideration of the relationship of handover and channel assignment,resource reservation and user queuing strategy,utilizing mingled algorithm to reduce the probability of new call blocking and handover call blocking to improve the utilization of system resource.Firstly,this paper introduce the research statue and development tendency of satellite mobile communication.And current channel assignments of satellite communication system,assessments and handover control technologies are described.Then the main work,contribution and research significance are introduced.Then,the application of modified channel reservation strategy in spot-beam handover of LEO satellite communication system is researched.The new strategy proposes a dynamic channel reservation strategy taking full advantage of the characteristics of users and combining the characteristics of LEO satellite communication system itself.The strategy forecast the arrival rate of new calls and handover calls by a priori information,dynamically reserving channels according to the arrival rate of new calls and handover calls.Simulations show that the strategy can obvious reduce the handover call blocking probability in guaranteeing low new call blocking probability.After that,this paper proposed a reservation channel strategy based on new call queuing combining queuing theory and handover strategy.That is,when reserving channels for handover calls,adopting first in first out(FIFO)to queue for new calls.So the handover calls have high jurisdiction to use channel,at the same time,queuing for new calls to reduce the new call blocking probability.Results indicate that,new call blocking probability have a greatly improved under the precondition of maintaining a low handover call blocking probability.The dissertation is summarized in the last chapter and the future research work is pointed out.