Maximizing transfer opportunities in bluetooth DTNs

Devices in disruption tolerant networks (DTNs) must be able to communicate robustly in the face of short and infrequent connection opportunities. Unfortunately, one of the most inexpensive, energy-efficient and widely deployed peer-to-peer capable radios, Bluetooth, is not well-suited for use in a DTN. Bluetooth's half-duplex process of neighbor discovery can take tens of seconds to complete between two mutually undiscovered radios. This delay can be larger than the time that mobile nodes can be expected to remain in range, resulting in a missed opportunity and lower overall performance in a DTN. This paper proposes a simple, cost effective, and high performance modification to mobile nodes to dramatically reduce this delay: the addition of a second Bluetooth radio. We showed through analysis and simulation that this dual radio technique improves both connection frequency and duration. Moreover, despite powering two radios simultaneously, nodes using dual radios are more energy efficient, spending less energy on average per second of data transfered.