Many types of mobile computers such as personal computers and cellular phones have recently come into wide use in the mobile wireless environment according to the growth of the Internet, intranet and wireless networks. Users in mobile environment hope to get various types of information closely related to their life from anywhere and at anytime, while they change their locations. ITS (Intelligent Transport Systems) is one real example of the network system matching the wireless mobile environment. In ITS networks, there are various kinds of data that is suitable for point-to-point or point-to-multipoint communication. The point-to-point communication is indispensable for accessing to individual data. However, if a number of mobile hosts move into a crowded location, the limited communication capacity in cells is not sufficient for some mobile hosts. For example, if an accident occurs, the road around the area will be congested in a short time. Traffic congestion shows a state of distribution type of mobile hosts, called dense-mode, that is a number of mobile hosts are densely distributed in an area. It is expected that the greater part of the mobile hosts will require commonly useful information, such as traffic information, parking information and other driving related information. It will be very effective to provide such information by using a common communication channel. Multicasting communication in mobile networks recently became a hot research area. In this paper, the authors propose a BS multicast group that consists of base stations accessed by mobile hosts that belong to a multicast group. Base stations in a BS multicast group become proxy nodes corresponding to a multicast group, which is subscribed by mobile hosts. Then, they define additional messages to control a BS multicast group based on the group management messages in IP multicast. By controlling the members group according to the movement of mobile hosts, it is expected to reduce message traffic for multicast group management and to eliminate packet loss during mobile hosts' movement between base stations, as a result the data receiving ratio on mobile hosts will be improved as well. They show the effectiveness of their proposal by the simulation results that are the rate of average data reception in mobile terminals at the time of making generation interval seconds.
Abstract