Knowledge-based replica deletion scheme using directional anti-packets for vehicular delay-tolerant networks

As stable end-to-end paths seldom exist in vehicular delay-tolerant networks, replication-based opportunistic routing protocols are often utilised to improve the data delivery ratio and decrease the transfer delay. However, the network load increases heavily because of numerous data replicas. In this paper, we propose a knowledge-based replica deletion Scheme using Directional Anti-packets (SuDAs), in order to reduce the transmission of anti-packets by considering vehicle contact statistics. We firstly use the contact judgment algorithm to avoid invalid anti-packet transmissions and select better forwarder for the anti-packets to reach each relay node, which has redundant data replica. Then, in the directional anti-packet transmission algorithm, we set different anti-packet transmission thresholds according to different requirements for the quality of replica deletion in the network. Formal validations and extensive simulations evaluate the performance of our scheme, which show that SuDA has a distinct advantage over others in striking a balance between the replica deletion delay and the anti-packet overhead. Copyright (c) 2013 John Wiley & Sons, Ltd.