Lane Based Backbone Synthesis Protocols for Vehicular Ad Hoc Networks

Vehicular ad hoc networks (VANETs) are configured to provide for communications with highway vehicles. We have recently introduced a network architecture to support such communications through the dynamic synthesis of a backbone network, identified as a Vehicular Backbone Network (VBN). Nominal positions across each road are optimally selected and announced as best locations to use for packet forwarding purposes. During each election period, within each designated sub-segment situated in the vicinity of these nominal locations, a vehicle whose location is relatively close to the nominal position is elected to temporarily act as a relay node (RN). Through cross-layer settings, the relay nodes interconnect, forming a VANET backbone network. Vehicles inter-communicate through access to or from the backbone relay network. In this paper, we present distributed protocols that are employed by highway vehicles, in parallel in each segment, to elect relay nodes. Vehicles can have the capability to sense the lane in which they travel, and to gather statistics concerning the distance spacing between vehicles. We present a highly effective Lane Based Election (LBE) algorithm for the election of relay nodes. The protocol is implemented at a forwarding layer that is located above the MAC layer and is thus independent of the latter. We present mathematical analyses, confirmed by simulations, that assess the probability that a successful relay node election process will take place within a very brief period of time. For systems that do not make use of vehicular knowledge of their lane residency, we present a Group Based Election (GBE) algorithm and characterize its delay-throughput performance. We show both classes of algorithms to operate in a highly effective manner, serving to construct and update the layout of a backbone in a timely manner with high probability of success.