The effect of packet loss on redundancy elimination in cellular wireless networks

Network-level redundancy elimination (RE) algorithms reduce traffic volume on bandwidth-constrained network paths by avoiding the transmission of repeated byte sequences. Previous work shows that RE can suppress the transmission of 20-50% bytes when deployed at ISP access links or between routers. In this paper, we focus on the challenges of deploying RE in cellular networks. The potential benefifit is substantial, since cellular networks have a growing subscriber base and network links, including wired backhaul, are often oversubscribed. Using three large traces captured at two North American and one European wireless network providers, we show that RE can reduce the bandwidth consumption of the majority of mobile users by at least 10%. However, cellular links have much higher packet loss rates than their wired counterparts, which makes applying RE much more difficult. Our experiments also show that the loss of only a few packets can disrupt RE and eliminate the bandwidth savings. We propose informed marking, a lightweight scheme that detects lost packets and prevents RE algorithms from using them for future encodings. We implement RE with informed marking and deploy it in a real-world cellular network. Our results show that with informed marking, more than 60% of the bandwidth savings of RE are preserved, even when packet loss rates are high.