Research On Radio Resource Scheduling Techniques In LTE-based Satellite Mobile Communication System

Introducing standards and technologies of long term evolution(LTE) into satellite communications, LTE-based satellite mobile communication system can effectively utilize the mature technology, high data rate, low cost of LTE system and the wide coverage, strong survivability of satellite communications and have attracted the world's attention broadly in realizing global high-speed mobile communications. However, different from the wireless link environment experienced by terrestrial mobile communications, problems such as long transmission delay, high bit error rate and bandwidth asymmetry in satellite-ground link put forward great challenges to the radio resource scheduling in LTE-based satellite mobile communication system.This paper research radio resource scheduling techniques in LTE-based satellite mobile communication system. The main work is as follows:Firstly, we research the resource scheduling of voice services in LTE-based satellite mobile communication system. Based on the improvement to the existing semi-persistent scheduling, a voice services oriented semi-persistent scheduling approach(VoSPS) is proposed. We add an uplink channel quality based admission and cut-off mechanism in VoSPS to solve the problem of uplink resource waste when users' channel quality deteriorate. Furthermore, in order to use uplink resources effectively and increase the capacity of voice services, we introduce a voice service satisfaction based code rate adjustment algorithm(SCRA). Simulation results show that VoSPS can improve user satisfaction of the system and increase the capacity of voice services effectively.Secondly, we investigate the uplink resource scheduling of LTE-based satellite mobile communication system and present a buffer status prediction based scheduling approach(BSP). BSP includes a buffer status prediction and reporting mechanism(BSPR) and a buffer status based proportional fairness scheduling algorithm(BSPF). Aiming at the problem that the transmission delay of satellite-ground link is much longer than the scheduling period of LTE, BSPR mechanism predicts and reports the buffer status of user equipment(UE) according to the traffic characteristic of uplink services in order to enable the evolved Node B(eNB) to allocate radio resources more reasonably. BSPF scheduling algorithm adds buffer statuses of UEs as parameters of scheduling decision and considers the quality of service(QoS) level and data flow of service. The results of simulation show that BSP can increase resource utilization rate of the system effectively and satisfy the throughput requirement of services with a higher QoS level and larger data flow better.