Over the past few years, there has been growing research interests on vehicular ad hoc networks (VANETs) due to their ease of deployment and the potential support for wide range of applications that can greatly enhance our everyday driving experience. Multi-hop messaging is expected to be the primary mode of communication among vehicles in numerous VANET-based applications including road safety, traffic management and infotainment services. Proper selection of the next-hop relay nodes is an essential part in the design of multi-hop message dissemination schemes in VANETs, which highly governs the reception of the broadcasted messages, especially when evaluated over large coverage distances and high node density networks. Existing message dissemination schemes adopt only a single relay nodes selection criterion for choosing nodes in the group of next-hop relays. However, potential of the selected relay nodes can be restricted due to exploiting only a single selection criterion, hence limiting the performance outcomes. This research proposes a new class of hybrid relay nodes selection scheme that attempts to exploit the best features of existing message dissemination protocols, in terms of message reachability, communication delay and bandwidth utilization, while avoiding their shortcomings. The new hybrid scheme takes into account the spatial distribution of the next-hop relay nodes with reference to the current sending node. To the best of our knowledge, the present study is the first in literature to propose such a hybrid scheme that attempts to improve performance of VANETs over varying node densities, traffic load conditions and mobility speed scenarios. Over the most stringent communication scenario considered in this work, our performance analysis indicates that the new hybrid scheme improves reachability by up to 10% compared to the most competitive conventional versions. This improvement is obtained while having a marginal performance fall in terms of the end-to-end communication delays and messages saved rebroadcast ratios. (C) 2018 Elsevier B.V. All rights reserved.
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