Research On Scheduling Methods For Video Streaming In Long Term Evolution System

LTE system is designed to support multi data service including video streaming. To take advantage of the bursty characteristics of the data traffic and obtain the statistical multiplexing gain, LTE system abolishes the circuit switch domain and carries all traffic through the packet switch domain. The fallibility and bandwidth variation of wireless channel makes it a challenge to meet the high bandwidth and low latency requirement of video streaming traffic in LTE system. LTE uses more complex modulation and coding scheme and larger bandwidth than the earlier cellular system, increasing the power consumption of UE radio transceiver circuit. Meanwhile video streaming applications increases the power consumption of the UE's displayer. As a result, saving UE's power consumption becomes another problem faced by video applications in LTE system. Radio resource management is essential for the full utilization of wireless resources, and packet scheduling is at the core of wireless resource management. Wireless packet scheduling plays the key role in meeting the needs of users'QoS requirement and improving the system throughput and reducing the power consumption of UE's wireless transceiver circuit.A scheduling algorithm for pre-coded video streaming based on SVC codec is proposed in this paper first. This algorithm considers the scalability of SVC video sequence and the QoS requirement of video streaming traffic. Moreover, the difference of users'channel quality is also considered. We normalized the instantaneous data rate of a user by the average data rate the user obtained, so that users with different channel conditions can get the same transmission opportunity. Meanwhile, we use larger waiting time function for packets belonging to base layer than those belonging to enhancement layer, so that the transmission of packets belong to the base layer can be guaranteed better and the decoded video quality can be improved. The simulation results show that, the proposed algorithm can improve the perceived video quality of users with bad channel quality significantly, so the fairness of the system can be improved;Although the throughput from the physical layer'view is reduced, but the average video quality can be improved when the system is congested due to the fact that the transmission of packets belonging to base layer can be guarantee better and the contribution for video quality per bit of the base layer is far larger than that of enhancement layer. DRX is adopted by LTE in the link level for power saving. The basic idea of DRX is to allow a UE to turn off the wireless transceiver and enter the sleep mode when there is no data to be transmitted or received, avoiding unnecessary power consumption. Although a UE's power consumption can be reduced using DRX, wake-up delay is introduced inevitably. The wake-up delay challenges how to guarantee the delay requirement of video streaming. A scheduling method for saving UE's power by using DRX for the video streaming is proposed in this paper. This method jointly considers the remaining time and the remaining active time of a packet. The times of starting/restarting I-Timer can be reduced while guaranteeing the delay requirement of a packet. Simulation results show that the proposed method can reduce the power consumption of a UE significantly with the same packet loss rate, compare with the existing scheduling method for delay-sensitive traffic under DRX.