Efficient service channel utilization in multichannel vehicular ad hoc networks

Abstract

The current IEEE 1609.4 standard defines multichannel operations to alternate control and service channel intervals during a period of 100ms. However, there is no mention of service channel selection for a service provider, which allows hidden service providers to select the same service channel (SCH). This limitation can cause the hidden terminal problem during the SCH intervals, leading to significant performance deterioration. Conforming to the existing standards, the proposed scheme enables hidden service providers to avoid selecting the same SCH by delivering their candidate service channel number in the optional field of the basic safety message (BSM). Unlike the CCH interval, during the SCH interval, the RTS/CTS/data/ACK handshake can be triggered to transmit large size of data without the hidden node problem. However, it can cause the exposed node problem that hinders concurrent transmissions, which is fatal in highly dynamic VANETs. The proposed scheme enables the exposed vehicles to avoid selecting the same SCH. Through extensive simulations, it is verified that the packet reception ratio can be increased in broadcast scenarios, and the average throughput can be improved in unicast scenarios. Finally, a novel protocol is designed to further improve spatial reuse by incorporating directional antennas with the IEEE 1609.4 multichannel vehicular ad hoc networks.