LASP: Look-ahead spatial protocol for vehicular multi-hop communication

Vehicular multi-hop protocols typically employ distance-based metrics, which do not capture the complexity of vehicular connectivity. In this work we present LASP, a geographic protocol that uses a more accurate spatial connectivity-based metric. Spatial connectivity describes the historical probability of successfully delivering a packet from one geographic area to another. Analysis of data collected from a vehicular testbed showed that, unlike other metrics, spatial connectivity indirectly captures all major factors affecting wireless connectivity. Moreover, it is temporally stable, which makes it useful in estimating the quality of future co-located links. When forwarding, LASP uses spatial connectivity information to pick a well-connected geographic forwarding zone, inside which multiple nodes cooperate in relaying through a distributed prioritization scheme. Compared with other techniques where the sender picks a specific next hop relay, cooperative forwarding improves resilience to losses through vehicle diversity. We evaluated LASP on a 30-node testbed, where it achieved a 30% increase in packet delivery ratio over the benchmark GPSR protocol.