On Reducing Broadcast Transmission Cost and Redundancy in Ad Hoc Wireless Networks Using Directional Antennas

Using directional antennas to conserve bandwidth and energy consumption in ad hoc wireless networks has attracted much attention from the research community in recent years. However, very little research has focused on applying directional antennas to broadcasting. In this paper, we propose a virtual link reduction (VLR)-based broadcasting protocol for ad hoc wireless networks using directional antennas. Based on two-hop neighborhood information, VLR relies on no location nor angle-of-arrival (AOA) information. VLR is a localized or distributed protocol, and it achieves full delivery. VLR operates on top of any existing broadcast routing protocols. In VLR, no node rebroadcasts a given packet more than once. No physical link is actually reduced, but if a packet has already been forwarded to the end node of the current link, the packet is no longer forwarded, that is, this link is virtually reduced. To evaluate the performance of the proposed VLR-based protocol, we conduct extensive simulation, for simplicity, assuming that there is no packet collision, no channel contention, and no mobility. Simulation results show that VLR outperforms most existing omnidirectional and directional broadcasting schemes in the sense that its normalized transmission cost and redundancy are significantly reduced. Based on the results, we conclude that VLR is more bandwidth and energy efficient

Development of an efficient Ad Hoc broadcasting scheme for critical networking environments

Mobile ad hoc network has been widely deployed in support of the communications in hostile environment without conventional networking infrastructure, especially in the environments with critical conditions such as emergency rescue activities in burning building or earth quick evacuation. However, most of the existing ad hoc based broadcasting schemes either rely on GPS location or topology information or angle-of-arrival (AoA) calculation or combination of some or all to achieve high reachability. Therefore, these broadcasting schemes cannot be directly used in critical environments such as battlefield, sensor networks and natural disasters due to lack of node location and topology information in such critical environments. This research work first begins by analyzing the broadcast coverage problem and node displacement form ideal locations problem in ad hoc networks using theoretical analysis. Then, this research work proposes an efficient broadcast relaying scheme, called Random Directional Broadcasting Relay (RDBR), which greatly reduces the number of retransmitting nodes and end-to-end delay while achieving high reachability. This is done by selecting a subset of neighboring nodes to relay the packet using directional antennas without relying on node location, network topology and complex angle-of-arrival (AoA) calculations. To further improve the performance of the RDBR scheme in complex environments with high node density, high node mobility and high traffic rate, an improved RDBR scheme is proposed. The improved RDBR scheme utilizes the concept of gaps between neighboring sectors to minimize the overlap between selected relaying nodes in high density environments. The concept of gaps greatly reduces both contention and collision and at the same time achieves high reachability. The performance of the proposed RDBR schemes has been evaluated by comparing them against flooding and Distance-based schemes. Simulation results show that both proposed RDBR schemes achieve high reachability while reducing the number of retransmitting nodes and end-to-end delay especially in high density environments. Furthermore, the improved RDBR scheme achieves better performance than RDBR in high density and high traffic environment in terms of reachability, end-to-end delay and the number of retransmitting nodes