A Reliable Multicast Mechanism for Location Dependent Data in DSRC-Based ITS Networks

Tatsuji MUNAKA  Tatsushi YAMAMOTO  Masahiro KURODA  Tadanori MIZUNO  Takashi WATANABE  

IEICE TRANSACTIONS on Information and Systems   Vol.E85-D   No.11   pp.1809-1821
Publication Date: 2002/11/01
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Issue on Information System Technologies for ITS)
ITS,  DSRC access network,  host mobility,  multicast,  retransmission method,  

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A number of mobile hosts might be densely staying in an area caused by traffic congestions. The greater part of the mobile hosts will require commonly useful data, such as traffic information, parking information and other driving related information in such environment. Simultaneous data transmission broadcasts using a common link are regarded as a suitable means to distribute this location-dependent information. However, there is no guarantee that mobile hosts can finish receiving the information completely within a limited time. In this paper, we propose a data retransmission method for communications between a base station and mobile hosts and a data recovery processing method for use between base stations. The data retransmission method called "TOA" (The Order of Arrival) schedules retransmission data specified in the first NACK request received after retransmission processing. We have proposed "Advanced" Join system in which a base station makes consolidated join requests to a multicast group on behalf of mobile hosts. Applying the TOA method to resending in the Advanced Join system, data-receiving efficiency is higher than with the simple Advanced Join system and the absolute number of completed mobile host data reception is higher. Using the TOA method, even with the base station disposition rate of 50% the number of completed reception is higher than with the Advanced Join system at 80%. The proposed reliable multicasting system to the DSRC-based ITS network can realize an efficient base station arrangement in the ITS network infrastructure and contribute to the deployment of a superior ITS.