/14BME0133/MEE499R01V007
Radio waves and infrared have been studied to give medium support to IVCs. The radio waves include micro, millimeter and VHF waves. The communication with millimeter waves and infrared are usually directional, while VHF is used for broadcast. The typical radio bandwidth used in IVC is 5.9 GHz in US, 5.8 GHz in Japan and 5.8 GHz in Europe. The FleetNet project chose ULTRA TDD due to the availability of the unlicensed frequency band 2010-2020 MHz in Europe. Most projects, however, have adopted the use of infrared (CarTALK, COOPER, JSK, PATH…).
There are two approaches in developing MAC for IVCs. One is using IEEE 802.11 as a radio interface, while the other consists on extended 3G technology, such as CDMA for distributed access.
Both of them have to be modified and adapted to provide an efficient solution for IVCs.
The advantage of using IEEE 802.11 is the inherited support for distributed coordination in ad hoc mode. On the other hand, 3G extensions present high granularity for data transmission.
Almost all routing protocols used by the different IVC projects are position-based. In addition, existing MAC ad hoc protocols could be directly applied. But if an optimal performance is desired taking into account the linear nature of the networks seen in section III, modification of the existing routing protocols must be performed. In addition, the features most of vehicles offer nowadays makes possible to get position information via GPS or GIS, very useful for routing. The protocol uses a forwarding scheme which avoids beacons for impactful transmission and effective sensing.