Response Time Analysis in a Data Broadcast System with User Cache

Abstract

Data broadcast has been considered a promising way of information dissemination to a massive number of users in a wireless communication environment. Reducing user-waiting time is a major problem in developing a data broadcast system. There are two approaches for this problem; One is to design a broadcast schedule at the server side which reduces the mean response time, and the other is to utilize a local cache at the user side which may respond to a user request instantly. Though these two approaches were addressed separately in the literature, they may be taken jointly for better performance. The performance of system with joint approach depends on several factors such as broadcast schedule, cache size, cache management strategy, etc. In this paper we analyze response time in a data broadcast system with joint approach in which information items are structurally related with each other as in WWW. Based on the worst-case assumption, we derive a lower bound on the system performance for a given set of broadcast schedule, cache size, and cache management strategy. This result will be of help for designing and developing a data broadcast system. We support our analysis by carrying out an extensive simulation on some interesting proposed broadcast schedules and cache management strategies.