Performance evaluation of a file repair procedure based on a combination of MBMS and unicast bearers

With the booming of multimedia services, the 3/sup rd/ generation partnership project (3GPP) has introduced the multimedia multicast/broadcast service (MBMS) feature for UMTS systems. The main objective of MBMS is to introduce real broadcast distribution capabilities into 3G systems. The MBMS service layer toolbox supports two distinct delivery methods: download and streaming. This paper focuses on the MBMS download delivery method. We have a particular focus on the file repair procedure, because the distribution of binary data via MBMS must result in 100% transmission error free downloaded files. In order to achieve this goal, MBMS offers a forward error correction (FEC) mechanism to protect the actual MBMS transmission and an extra file repair procedure to be used after the actual MBMS transmission. This paper discusses the trade-off between FEC protection and successive file repair, and then proposed a novel file repair scheme. The new scheme combines point-to-multipoint (PTM) file repair transmission with a point-to-point (PTP) file repair procedure. Using only a point-to-multipoint file repair scheme is not efficient, since the sender does not know the amount of needed repair data. Our simulations and analysis show that the new scheme achieves better performance than a PTP-only file repair procedure. Further, the two schemes are compared with respect to the radio resource consumption.