DENSITY-AWARE ZONE-BASED PACKET FORWARDING IN VEHICULAR NETWORKS

摘要

A method for multi-hop forwarding of data packets in vehicular ad-hoc networks is disclosed. Each node knows both its own and the destination's geographical coordinates. The coordinates of the one-hop neighbors are obtained from periodically broadcast Cooperative-Awareness Messages (CAMs). The method comprises the following distributed coordination scheme, executed by each node upon receiving a packet: i) computing the set of candidate forwarders; ii) ranking the candidate forwarders according to an utility metric; iii) forwarding the packet after a period of time proportional to its rank if top-ranked, dropping the packet otherwise. The base utility metric used for ranking forwarders is the inverse of the distance to the destination. Moreover, an extension is disclosed where this metric is replaced by the inverse of the expected number of packet transmissions to reach the destination. The latter metric is calculated based on spatial connectivity information cooperatively collected by nodes in the network.

主权项

1. Method for distributed multi-hop packet forwarding based on geographic coordinates for vehicular communications between nodes, each node having its own geographical coordinates and the geographical coordinates of the destination node of one said vehicular communication being known, said method comprising each node obtaining its one-hop neighbor nodes' coordinates from periodically broadcast beacons from said neighbor nodes and said method comprising the steps for each node, at each hop, upon receiving a packet:
based on the current node's position and the packet header information, verifying if the current node is closer to the destination than the previous hop; if not, dropping the packet; ranking the utility of the current node as a forwarder against the utility of the potential forwarder nodes which are the said one-hop neighbor nodes that are closer to the destination than the previous hop; if the current node is one of a predetermined number of best utility ranked forwarder nodes, then considering the current node as being in the forwarding zone; if not, dropping the packet; if the current node is in the forwarding zone, waiting a period of time inversely proportional to the current node utility rank before forwarding the packet; if, while waiting, the current node overhears another node forwarding the same packet, cancelling the forwarding of the packet;wherein the packet header comprises three node addresses: original packet source, packet destination, and packet previous hop, wherein each address includes both the respective node identifier and geographic coordinates,and wherein said nodes are vehicle nodes or a mix of vehicle nodes and fixed nodes.