GeOpps-N: Opportunistic Routing for VANET in a Public Transit System

GeOpps-N, a new hybrid routing protocol for communications between buses and operation control centers in a Public Transportation System (PTS) is proposed. Bus location must be updated each 30 seconds. We model the system as a Vehicular Ad-Hoc Network (VANET), which includes buses and Road Side Units (RSU). The network has a low density and is usually clustered, thus requiring relaying of the data. Topology-based routing protocols have proven to be well suited for these low node density scenarios, as compared with other protocols such as geographic-based routing or flooding-based routing. In these protocols, instead of looking for the destination inside the source cluster, the best candidate to transport the message to its destination is found. GeOpps-N searches for relaying nodes which can efficiently transport or relay the data to the closest RSU. GeOpps-N brings together aspects from reactive network topology-based routing and geographic-based routing protocols for delay tolerant networks. In our simulations, it improves the packet delivery ratio by up to 159% over the results of reactive protocols, such as DYMO-UM and DYMO-FAU and up to 59% over GeOpps. GeOpps-N also improves the mean end-to-end delay by up to 36% as compared to GeOpps.