Supporting real-time multiple data items query in multi-RSU vehicular ad hoc networks (VANETs)

There has been increasing interest in the issue of multi-item queries in wireless broadcasting systems recently. Query starvation and bandwidth utilization have been identified as key issues for improved performance. In this paper, we examine this problem in the context of VANETs with multiple cooperating Road Side Units (RSUs). We characterize a query with two deadlines: Query Total Deadline (QTD) which is the actual deadline of a query and Query Local Deadline (QLD) which is the duration a query is valid for serving in an RSU. By considering these two deadlines together with vehicle speed, RSU range and inter-RSU distance, we formulate a Cooperative Query Serving (CQS) scheme which allows multiple RSUs to share residual bandwidth and effectively address the query starvation as well as the bandwidth utilization problems, hence maximizing the chance of serving multiple items queries. Extensive simulation results confirm that CQS outperforms other existing scheduling algorithms. © 2013 Elsevier Inc. All rights reserved.