Location dependent data multicasting in intelligent transportation system and its evaluation

摘要

A number of mobile hosts might be densely distributed in an area caused by traffic congestions. The greater part of the mobile hosts will require commonly useful information, such as traffic information, parking information and other driving related information in such environment. It will be very effective to provide such information by using a common communication channel. In fixed networks, IP multicast is a well-known mechanism providing efficient point-to-multipoint data delivery, however it does not mention how to handle mobile hosts as a member of a multicast group. In this paper, we introduce a "BS multicast group" that is the set of base stations under which the mobile hosts belong to the same multicast group in a given area. Furthermore, we define new messages to control the BS multicast group based on the group management messages in IP multicast. Advanced Join mechanism, that manages the base stations in the BS multicast group by the control messages according to the movement of mobile hosts, eliminates lost packets during the movement of mobile hosts between the base stations. Evaluation results via the road model simulator show that the average rate of data reception of mobile hosts using the proposed mechanism is improved more than 17% and the time until a mobile host completes data reception is also improved more than 33%. Moreover, we recognize that it is indispensable to provide a data retransmission method to achieve more reliable data delivery to moving mobile hosts via the simulation results, and propose a simple data retransmission method called TOA (The order of arrival). By applying the TOA method to Advanced Join mechanism, the number of mobile hosts which complete the data reception is increased 6.9 times by the maximum.