Rasearch On Key Technologies For QoS Guarantees In Satellite Communication System

Satellite communication system has a feature of covering a wide range of area and geographical environment makes little impact on it. Because of this, satellite communication has become a research hotspot and it is a powerful way in modern information exchange. The next generation of satellite communication networks is turning for higher data rate and larger bandwidth. Satellite networks and ground communication networks can combine with each other to realize seamless global coverage. With the explosive development of space communication technology and the growth of user demand, the contradictions between the limited wireless resource and the continuously improvement of the quality of service requirement for the users are becoming increasingly acute. So the designing of resource management strategies that can support multimedia transmission with high speed and high quality has attracted more and more attention. At the same time, the satellite networking technology is the key to help the satellite system realize global coverage. Accordingly, routing protocol and link switching technology must be redesign according to the characteristics of satellite network. So the routing strategy is another research hotspot in satellite communication system.This paper studies some key technologies based on QoS guarantee in satellite communication system. The designing of the routing algorithm in LEO satellite system and the designing of the resource management algorithm in GEO satellite system are presented in this paper. The purpose is to meet the user’s QoS requirement as much as possible. The main innovative points and research works of this paper are described as follows:(1) Cross-layer design and ant-colony optimization based routing algorithm for LEO satellite networksIn order to improve the robustness of the LEO satellites networks and realize load balancing, a cross-layer design and ant-colony optimization based load-balancing routing algorithm for LEO satellite networks (CAL-LSN) is proposed in this paper. CAL-LSN can utilize the information of the physical layer to make routing decision during the route construction phase. In order to achieve load balancing, CAL-LSN makes use of a multi-objective optimization model. Meanwhile, how to take the value of pheromone evaporation coefficient is derived while designing the algorithm so as to improve the reliability. The performance of CAL-LSN is measured. Simulation results show that CAL-LSN performs well in balancing traffic load and increasing the packet delivery rate. Meanwhile, the end-to-end delay and delay jitter performance can meet the requirement of video transmission.(2) A multi-path routing algorithm of LEO satellite networks based on an improved ant colony systemIn this paper, a multi-path routing algorithm based on an improved ant colony system (MPRA-AC) is proposed according to the characteristic of LEO satellite networks. In order to improve the robustness of the network, the multi-objective optimization model proposed in this paper aims to minimize the number of the satellites contained in the main path and the alternate path. Meanwhile, this paper improves the original ant colony algorithm in order to find the optimal path more quickly. Simulation results show that MPRA-AC reduces the number of iterations to achieve a satisfactory solution. Compared with DSR-LSN, the packet delivery ratio is about7.9%higher when running MPRA-AC and MPRA-AC outperforms DSR-LSN in link utilization.(3) A cross-layer bandwidth request algorithm based on chaotic prediction model for broadband multimedia satellite communicationsA Cross-layer Bandwidth Request Algorithm Based on Chaotic Prediction Model (CBRA-CPM) is proposed in this paper. Cross-layer architecture is designed in CBRA-CPM to perceive the channel state. That is, it can change the quantity of resources requested from the Network Control Center according to the weather conditions. The objective is to guarantee a target QoS to internet traffic. Meanwhile, chaotic prediction model is introduced into CBRA-CPM according to the self similarity of network traffic. By adopting a method of co-simulation of OPNET and MATLAB, simulation platform is established. The performance of CBRA-CPM is compared with DAMA-CPM. Simulation results show that CBRA-CPM outperforms DAMA-CPM in packet delivery ratio and the end-to-end delay of the network.(4) Research on hardware in the loop simulation system of broadband multimedia satellite communication standard with OPNETHardware in loop simulation is a simulation method that integrates hardware and software. By replacing the virtual model with physical object, the simulation results can be closer to the actual situation. So the hardware in loop simulation method has important research value in modeling the broadband multimedia satellite communication system. Based on the deep investigation in the hardware in loop simulation method, this paper establishes hardware in loop simulation platform based on Digital Video Broadcasting and Return Channel via Satellite (DVB-RCS) standard. By analysis of various factors influencing the system, a relatively complex hardware in loop test environment is established in this paper.