DONC: Delay-based Opportunistic Network Coding Protocol

Generally vehicular ad hoc networks (VANETs) carry information public in nature, which benefits most of the vehicular nodes involved. Therefore broadcasting data becomes a natural choice for disseminating data in VANETs. Broadcasting also offers advantages of simplicity and flexibility, by virtue of not requiring knowledge of the actual network topology. Further-more, so-called delay-based vehicular broadcast mechanisms have been proven efficient in reducing redundant packet transmissions in dense networks. However, packet losses due to the imperfect wireless medium, medium access, and high mobility decrease this efficiency dramatically, re-introducing needless transmissions. In this paper, we propose a Delay-based Opportunistic Network Coding protocol called `DONC´, which combines delay-based techniques with opportunistic network coding, in order to successfully cancel this detrimental effect of losses: DONC improves dissemination of broadcast data in loss-prone VANETs and reduces packet retransmissions. We simulate DONC protocol in ns2 and compare it with classical delay-based VANET broadcast mechanisms. Results prove that DONC protocol outperforms other delay-based mechanisms, specially in the scenario of lossy VANETs.