Research on offloading delay-tolerant cellular traffic via Wi-Fi

Abstract

The explosive popularity of smartphones and mobile devices drives massive growth in the wide-area mobile data communication. Unfortunately, despite the continued efforts to increase the physical capacity, the current or near-future 3G/4G networks are deemed insufficient to meet the increasing data transfer demand. Recently, opportunistic offloading of cellular data traffic to a high-bandwidth wired Internet (e.g., Wi-Fi) via Delay-Tolerant Network (DTN) has been proposed to mitigate the capacity overload in the cellular network. Although an attractive option, practical system deployment would face a number of problems since existing Internet architecture lacks the support for handling network disruption and delay that arise from mobility in DTN environment. In this paper, we envision a practical cellular data offloading system, which provides scalable Internet access to mobile users by offloading the cellular traffic to Wi-Fi via DTN. We address two main challenges; network disruption from mobility causes the node to be disconnected due to the fundamental design of TCP, which binds a connection to the node’s network address; network delay causes the existing servers and mid-dle-boxes to explicitly close idle connections for bandwidth efficiency. We solve these problems by first pre-senting Disruption-tolerant Transmission Protocol (DTP), a reliable transport layer protocol that masks the failures of the preferred network from disruption. Unlike previous disruption/delay-tolerant protocols, DTP provides the same semantics as TCP on an IP packet level when the mobile device is connected to a network while providing the illusion of continued connection even if the underlying physical network becomes una-vailable. Next, we present a network-embedded protocol translation proxy, Disruption/Delay-tolerant Proxy (DProx), which masks the mobile device’s disruption and delay to the destination servers by relaying the data in a store-and-forward manner. We show that DTP...