DeltaCast: Efficient File Reconciliation in Wireless Broadcast Systems
ACM MOBYSIS |
Recently, there has been an increasing interest in wireless broadcast systems as a means to enable scalable content delivery to large numbers of mobile users. However, gracefully providing efﬁcient reconciliation of different versions of a ﬁle over such broadcast channels still remains a challenge. Such systems often lack a feedback channel and consequently updates cannot be easily tailored to a speciﬁc user. Moreover, given the potentially large number of possible versions of a ﬁle, it is impractical to send a tailored update for each particular user. In this paper we consider the problem of efﬁciently updating ﬁles in such wireless broadcast channels. To this extent, we present DeltaCast, a system that combines hierarchical hashes and erasure codes to minimise the amount of battery power and the amount of time needed to synchronise each mobile device. Based on our experimental results, we show that DeltaCast is able to efﬁciently identify the missing portions of a ﬁle and quickly updated each client.