Qos Performance Analysis Of Wireless Network In High-Speed Mobile Environment

Recently, the rapid development of high-speed mobile environment has brought new challenge to communications industry. From the trend of development in communication industry and the increasing needs of the national high-speed mobile communications, the research in the high-speed mobile environment communication is in a fledging period and of great significance. Quality of Service (QoS) provides standardized objective indicators to the design of communication systems. Therefore, the exploration of QoS performance analysis in high-speed mobile communications is a significant issue for both research and application.In this paper, the main concerned issue is how to build proper analytical model and derive QoS performance of high-speed mobile communications, based on stochastic network calculus. The definitions and theorems of network calculus have been introduced. Two kinds of technical QoS factors in wireless networks, backlog and delay have been discussed. In this paper, research is carried out in two schemes. Performance analysis is studied in both high speed railway and high speed motorway.In high speed railway scheme, the communication delay of train control services has great impact on the track utilization and speed profile of high-speed trains. This paper focuses on stochastic delay analysis of train control services over fading channel of the high speed railway, which is based on stochastic network calculus. In high speed railway communication systems, the mobility of the train is modeled by a semi-Markov process, and the instantaneous data rate of the wireless fading channel is formulated by a semi-Markov modulated process. Given the effects induced by both large-scale fading and small-scale fading, the stochastic service curve of the high speed railway communication system can be derived based on the semi-Markov modulated process. With the help of stochastic network calculus, the stochastic delay upper bounds of train control services are obtained with two methods called the Moment Generating Function (MGF) method and the Complementary Cumulative Distribution Function (CCDF) method. Compared with the simulation results, analytical results show that the proposed model of high speed railway communication system in this paper can analyze the QoS performance effectively, which can provide theoretical support to the evolution of LTE-R system in the further.In high speed motorway scheme, this paper proposes a novel architecture that integrates LTE networks with IEEE802.11based Vehicle Ad Hoc Networks (VANETs), due to the complex network topology. Stochastic delay over the wireless channel in the proposed architecture can be analyzed based on stochastic network calculus. Since the highly variation of vehicular speed in the highway, the duration of each state in semi-Markov process is geometrically distributed, so the mobility model of vehicles in LTE networks reduces to a Markov process. Among the clusters using the IEEE802.11protocol, access delay of per packet has been taken consideration into this thesis to derive stochastic service curve. Based on the tandem principle of stochastic network calculus, the proposed architecture can be modeled as two dynamic servers in tandem, and the MGF of the equivalent single server can be exploited by them. The end-to-end delay upper bounds of highway communication systems are obtained according to the analytical principle of network calculus. Analytical and simulation results are utilized to validate the accuracy of QoS performance in the proposed model, which can meet the demands of the future vehicular networks.