R-ALOHA Protocol for SS Inter-Vehicle Communication Network Using Head Spacing Information

Young-an KIM  Masao NAKAGAWA  

IEICE TRANSACTIONS on Communications   Vol.E79-B   No.9   pp.1309-1315
Publication Date: 1996/09/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Personal Communications)
Category: CDMA and multiple access technologies
inter-vehicle communication network,  spread spectrum,  R-ALOHA protocol,  head spaing information,  

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Recently, there have been intensive studies on protocol methods and applications of short range inter-vehicle communication network (SR-IVCN) and systems. The purpose of the studies is to improve the safety of road traffic systems and the smooth control of the traffic flow by providing information to vehicles. Spread spectrum (SS) communication systems are able to simultaneously communicate and measure the distance between the terminals, thus it is advantageous to apply the spread spectrum technique to inter-vehicle communications. This paper assumes that the vehicles incidentally close to each other, form and manage a locally autonomous decentralized dynamic network. An R-ALOHA (Reservation-ALOHA) protocol for the spread spectrum inter-vehicle communication network using head spacing information is proposed which improve the conventional slot reservation methods. Since the near-far problem in SS communication is one reason for the degradation of system performance, this proposed scheme is shown to improve the efficiency of communication. The performance of the proposed system in the environment where the vehicles are assumed to run freely on a highway is verified by computer simulation. It is shown that inter-vehicle communication can be smoothly carried out between one vehicle and the surrounding vehicles using the propose method.