Efficient Streaming Delivery in eMBMS with HARQ and Raptor

Enhanced Multimedia Broadcast/Multicast Service (eMBMS) is a new function defined in 3GPP specification to support PTMP (point to multiple points) transmission in LTE networks. In eMBMS, streaming delivery and file delivery are both supported. In order to guarantee the high reliability in single-cell eMBMS, only applying application-layer FEC at eBMSC (enhanced broadcast/multicast service center) is not enough. HARQ mechanism at eNB is an additional scheme to further improve the reliability. However, the coexistence of HARQ and Raptor FEC may cause unnecessary retransmission and excessive redundancy, which will decrease the transmission efficiency especially for streaming delivery. To resolve this issue, several theoretical schemes have been proposed recently. However, these schemes cannot be implemented in eMBMS system due to the long delay in the link between eNB and eBMSC as well as the backward compatibility. In this paper, a novel and practical coordination scheme for eMBMS system is proposed, which controls the HARQ feedback according to the current packet loss and the pre-set QoS requirement. The throughput improvement with QoS guarantees is shown by simulation results using Matlab and OPNET.