Resouuce Scheduling Algorithms For VoIP And Multi-Services In High-Speed Train Wireless Communications

LTE-A(Long Term Evolution-Advanced) system has faster transmission rate, shorter delay and more abundant types of services than the other cellular communication systems. In order to meet the urgent needs of large capacity multimedia services for high-speed train users, it is necessary to bring LTE-A into high-speed train communication system. For LTE-A system, in order to make full use of the limited resources to improve the system capacity, it is necessary to investigate efficient scheduling algorithms of radio resource under high-speed train scenario.In LTE-A system, there is no circuit domain but only the packet domain. Voice service is loaded by the VoIP(Voice over Internet Protocol). So, it is a fundamental requirement for LTE-A to have an efficient VoIP support. In order to improve the performance of wireless communication system in high speed train, a two- hop radio link based on an on-vehicle station is normally employed. By using this network architecture, the ground eNBs do not directly communicate with users on-train but through the on-vehicle station. Therefore, the existing resource scheduling algorithms for VoIP used in traditional cellular network is not suitable and may even degrade the system performance. In this thesis, we proposed a resource scheduling algorithm for VoIP service based on adaptive MCS(Modulation and Coding Scheme) with packet-bundling for high speed train scenarios. In order to verify the performance of the proposed algorithm, we add a resource scheduling module and a calculation of outage probability module to the existing system-level platform which is based on IT++and Visual Studio 2005. System-level simulation results show that the proposed scheme has a better performance in terms of the outage probability and VoIP capacity.With the rapid development of multimedia services, high-speed train users require more services such as webpage browsing, file downloads, video conferencing and so on, i.e. simple voice service cannot meet the demand of passengers. LTE-A is a communication system supporting multiple service, each of which has their own characteristics and QoS(Quality of service) requirements. When multi-services coexist in LTE-A network, LTE scheduler schedules radio resources according to the priority of QoS of different services, which may waste valuable resource. In this thesis, by considering the special network architecture of high-speed train scenario, together with the characteristics of VoIP service and FTP(File Transfer Protocol) service, a resource scheduling algorithm based on the idea of SINR sorting is proposed. System level simulation results show that, although there is a small increase of the VoIP delay (but tolerable), the proposed algorithm can improve the system throughputs.