Efficient barrier synchronization on wireless computing systems

This work deals with efficient barrier synchronization for wireless cluster computing where nodes communicate with each other wirelessly in one or multiple hops. Such a computing system is referred to as a wireless computing system (WCS). Given t nodes participating in barrier synchronization on such a WCS of size n (≥ t), a backbone structure (BBS) is constructed and maintained to cover all the t participants throughout the course of barrier synchronization necessary for correct execution of an assigned task cooperatively. Two mechanisms for BBS construction, dubbed RAD_Expansion and G_Search, have been developed and evaluated empirically, and RAD_Expansion is found to be more desirable. Our transport-layer barrier primitive is then implemented on the BBS constructed using RAD_Expansion, with AODV as its underlying network protocol, for evaluation using NS-2. It arrives at faster barrier synchronization than a naive approach, which lets every participant send its check-in messages directly to the barrier controller. The barrier time gap widens as the number of participants increases under given mobility.