Access methods for handling the updates of broadcast data in wireless mobile computing

Abstract

In a ubiquitous information environment, a large number of users carrying their low-powered portable computers can retrieve information anywhere and anytime by a wireless mobile computing technology. Wireless data broadcasting, as a way of disseminating information to the large number of clients, has an inherent advantage. It provides all types of users global access to information. Lo and Chen [IEEE Trans. Knowl. Data Eng. 12 (4) (2000) 609] have proposed a method known as adaptive access method. This method works in an error-prone mobile environment and tolerates the access failure in which the occurrence of access failures is due to disconnections, handoffs, and communication noises. However, the influence of version bits to deal with the updates of the broadcast data has not been exploited for the broadcast with modified (but the same size and structure) update. In this paper, we identify the types of updates and investigate the access methods. The basic idea is to distinguish the type of update that does not influence the change in the size and structure of the broadcast. To deal with the types of updates, we classified the users in mobile computing environment into the users in-system and the new users. In the proposed continuous algorithms, the users in-system record the previous result and use it efficiently to access the desired records with less number of additional probes in the broadcast, which is updated by a stream of same size and structure bits. In the performance analysis, the experimental results show that our proposed modified progression method has the best performance, as it requires the minimum cost to access the broadcast data.