Research And Simulation Of Resource Allocation For Terrestial Relay Based Mobile Satellite System

Mobile satellite system has played an important role in the communication network since its appearance. In the sparsely populated areas that terrestrial networks can not cover, satellite communications become the most effective contact bridge between people and the outside world. Besides, when the terrestrial networks are damaged, satellite networks can also be stable to provide communication services, achieving a wide area seamless coverage. However, in the densely populated urban areas, the conditions for satellite communications are restricted. But with the appearance of the terrestrial relay technology, mobile satellite system can also provide communication services for dense urban and indoor users, which plays an effective role to implement a seamless coverage solution.With adding terrestrial relays to mobile satellite system, the problem of interference suppression and resource allocation becomes more complex. According to the chosen channel models for the satellite and terrestrial link and the schemes for resource allocation, this thesis considers and analyzes the existing scene, then establishes the system model for terrestrial relay based mobile satellite system. This thesis learns from the existing resource allocation algorithm, and then proposes a resource allocation scheme that applies to the terrestrial relay integrated mobile satellite system.An asymmetric resource allocation algorithm that divides different time slot proportion to satellite and terrestrial link for terrestrial relay based mobile satellite system is proposed. Due to the optimization problem involved is a mixed integer programming problem, and the rigor of GEO satellite power limit, as well as the complexity and effectiveness of resource allocation, the algorithm uses an asynchronous way to allocate the subcarrier resource to the satellite and terrestrial link and optimize power distribution, and then adjusts the time slot proportion to balance the capacity of two links. This algorithm can effectively avoid the frequency interference impact among the various terrestrial relays. Simulation results show that, compared with the symmetric proportion time slot divided resources allocation algorithms, asymmetric resource allocation algorithm can achieve higher bandwidth efficiency and the advantage is obvious.Moreover, this thesis uses NS-2simulation tool to build a simulation platform for terrestrial relay integrated mobile satellite system. The simulation platform firstly adds a control plane function in the original satellite communications module, and then improves the function of the user plane. To meet the needs of relaying communication, create a new type of nodes, terrestrial relay, and modify the MAC layer of the all types of nodes. To the terrestrial relay, in the first several time slots, it receives the packets from the gateway station (satellite node). In the second several time slots, it forwards the received packets according to the adopting relay pattern. In the resource management module, the simulation platform the simulation platform characterizes power, channel status in NS-2in a certain way, and implements the asymmetric resource allocation algorithm interface. The simulation results show that the simulation platform is designed reasonable and effective. It can achieve the purpose of simulation analysis and verification for resource allocation scheme to the terrestrial relay based mobile satellite systems, and then achieves its simulation analysis and performance evaluation.