This chapter analyzes two prominent technologies, IEEE 802.11g (WiFi) and IEEE 802.16e (WiMAX), for single-hop inter-vehicular communication (SIVC). We begin our analysis by comparing the physical and MAC layers of both standards. Following this, we simulate two scenarios, one with IEEE 802.11g and the other with IEEE 802.16e, in a single-hop inter-vehicular communication network. In both scenarios, the Location-Based Routing Algorithm with Cluster-Based Flooding (LORA-CBF) was employed to create a hierarchical vehicular organization that acts as a cluster-head with its corresponding member nodes. The simulation scenarios consist of five different node sizes of 20, 40, 60, 80 and 100 vehicles, respectively. We propose a novel simulation model that is suitable for mesh topologies in WiMAX networks and provide preliminary results in terms of delay, load and throughput for single-hop inter-vehicle communication.
TopIntroduction
Interest in inter-vehicular communication (IVC) and vehicle-to-roadside communication (VRC) has significantly increased over the last decade, in part, because of the proliferation of wireless networks. Most research in this area has concentrated on vehicle-to-roadside communication, also called beacon-vehicle communication (BVC) in which vehicles share the medium by accessing different time slots.
Some applications for vehicle-to-roadside communication, including Automatic Payment, Route Guidance, Cooperative Driving, and Parking Management have been developed to function within limited communication zones of less than 60 meters. However, the IEEE 802.11 Standard has led to increased research in the areas of wireless ad hoc networks and location-based routing algorithms, (Morris et. al., 2000), (Da Chen, Kung, & Vlah, 2001), (Füßler, et. al., 2003), (Lochert, et. al., 2003), (Kosh, Schwingenschlögl, & Ai, 2002). Applications for inter-vehicular communication include Intelligent Cruise Control, Intelligent Maneuvering Control, Lane Access, and Emergency Warning, among others. In (Morris et. al., 2000), the authors propose using Grid (Li, et. al., 2000), a geographic forwarding and scalable distributed location service, to route packets from car to car without flooding the network. The authors in (Da Chen, Kung, & Vlah, 2001) propose relaying messages in low traffic densities, based on a microscopic traffic simulator that produces accurate movement traces of vehicles traveling on a highway, and a network simulator to model the exchange of messages among the vehicles. Da Chen et. al., employ a straight bidirectional highway segment of one or more lanes. The messages are propagated greedily each time step by hopping to the neighbor closest to the destination. The authors in (Füßler, et. al., 2003) compare a topology-based approach and a location-based routing scheme. The authors chose Greedy Perimeter Stateless Routing (GPSR) (Karp & Kung, 2000) as the location-based routing scheme and Dynamic Source Routing (DSR) (Johnson, Maltz, & Hu, 2007) as the topology-based approach. The simulator used in (Füßler, et. al., 2003) is called FARSI, which is a macroscopic traffic model. In (Lochert, et. al., 2003), the authors compare two topology-based routing approaches, DSR and Ad Hoc On-Demand Distance Vector (AODV) (Perkins, Belding-Royer & Das, 2003), versus one position-based routing scheme, GPSR, in an urban environment. Finally, in (Kosh, Schwingenschlögl, & Ai, 2002), the authors employ a geocast routing protocol that is based on AODV.
In inter-vehicular communication, vehicles are equipped with on-board computers that function as nodes in a wireless network, allowing them to contact other similarity equipped vehicles in their vicinity. By exchanging information, vehicles can obtain information about local traffic conditions, which improves traffic control, lowers contamination caused by traffic jams and provides greater driver safety and comfort.
Future developments in automobile manufacturing will also include new communication, educational and entertainment technologies. The major goals are to provide increased automotive safety, achieve smoother traffic flow, and improve passenger convenience by providing information and entertainment. In order to avoid communication costs and guarantee the low delays required to exchange safety-related data between cars, inter-vehicular communication (IVC) systems, based on wireless ad hoc networks, represents a promising solution for future road communication scenarios. IVC allows vehicles to organize themselves locally in wireless ad hoc networks without any pre-installed infrastructure. Communication in future IVC systems will not be restricted to neighboring vehicles traveling within a specific radio transmission range. As in typical wireless scenarios, the IVC system will provide multi-hop communication capabilities by using “relay” vehicles that are traveling between the sender and receiver. Vehicles between the source-destination act as intermediate vehicles, relaying data to the receiver. As a result, the multi-hop capability of the IVC system significantly increases the virtual communication range, as it enables communication with more distant vehicles.