Adaptive HARQ and scheduling for video over LTE

This paper proposes a cross-layer approach to the delivery of real-time video streams over LTE cellular systems. The objective is to maximally improve video quality by adapting the wireless system (specifically, HARQ retransmission and scheduling rules) to video packet importance. Complying with the LTE framework, video packets are given priorities and assigned to different radio bearers or logical channels based on their importance. Applicable to both uplink (UL) and downlink (DL), the adaptive HARQ minimizes the effect of transmission errors by performing potentially more HARQ retransmissions for high-priority video packets while the scheduling algorithm deals with congestion by giving high priority to important packets to minimize their transmission timeout. We show that the combination of adaptive HARQ and priority-based scheduling offers significant gains in video quality by enabling the wireless system to handle congestion and transmission errors, two of the main challenges to cellular delivery of real-time video.