Research On The Channel Allocation And Handover Management Scheme Of Leo Satellite Mobile System

As the primary choice for the communication solution of areas that terrestrial cellular systems have difficulties covering, satellite mobile communication system plays an important role in achieving global seamless coverage. And one recent hot point of research is LEO satellite mobile network, which receives much attention for its advantages such as global coverage, low propagation delay and low power requirement. Because the resources on-board satellites are very limited and the communication environment, compared with terrestrial network, is so complicated, radio resource management, which focuses on managing and allocating bandwidth reasonably for mobile users, becomes a crucial problem in constructing a successful satellite network.As the satellite orbit is low, LEO satellites circulate the earth at a very high speed, which leads to the problem that for a connected user on earth, to maintain the connection, the user has to switch from one satellite to another. To make it worse, the coverage area of a satellite is divided into adjacent overlapping spotbeams, i.e., cells, for the sake of frequency reuse. So, LEO satellite mobile network is characterized by frequent spotbeam handovers experienced by users, which means that the lack of available bandwidth in the cell the user is entering may cause the users to experience the disruption of the connection. To solve this problem, novel channel (bandwidth) allocation schemes are proposed for LEO mobile satellite networks. The proposed schemes aim at allocating bandwidth precisely and adaptively, trading-off the share of bandwidth between different mobile users belonging to different traffic, providing them with satisfactory Quality of Service (QoS) while maintaining bandwidth utilization high.Firstly a mobility model based on reasonable premises of LEO satellite mobile networks was developed, in which QoS parameters used to evaluate the system and other related mobility parameters were defined. By analyzing the mobility model, solid foundation were laid for subsequent algorithm research and simulation.Then the Adaptive Probability based Reservation Strategy (APRS) was developed for LEO satellite mobile network that supports only voice traffic. Based on the predictable and deterministic feature of mobile users'movement, APRS takes user location and connection characteristics into consideration, thus reserving resources more accurately and maximizing the number of connections admitted into the system while providing users with satisfactory Quality of Service (QoS).As the wireless communication network is developing to be a network that supports not only voice traffic but also multimedia and data traffic, a Utility Fair Bandwidth Allocation Strategy (UFBAS) was proposed for multimedia LEO satellite mobile networks. Based on the considerations that excessive reservation and deficient fairness are major drawbacks in existing bandwidth allocation algorithms networks, a novel bandwidth allocation algorithm based on fair QoS is presented. As the algorithm introduces adaptive bandwidth reservation strategy and fair utility bandwidth allocation rule, it maintains effectiveness of user's connection, keeps high utilization of bandwidth while guaranting fairness of QoS among multiple users.