A Cross-Layer Modification to the DSR Routing Protocol in Wireless Mesh Networks

A cross-layer modification to the DSR routing protocol that finds high throughput paths in WMNs has been introduced in this work. The Access Efficiency Factor (AEF) has been introduced in this modification as a local congestion avoidance metric for the DSR routing mechanism as an alternative to the hop count (Hc) metric. In this modification, the selected path is identified by finding a path with the highest minimum AEF (max_min_AEF) value. The basis of this study is to compare the performance of the Hc and max_min_AEF as routing metrics for the DSR protocol in WMNs using the OPNET modeler. Performance comparisons between max_min_AEF, Metric Path (MP), and the well known ETT metrics are also carried out in this work. The results of this modification suggest that employing the max_min_AEF as a routing metric outperforms the Hc, ETT, and MP within the DSR protocol in WMNs in terms of throughput. This is because the max_min_AEF is based upon avoiding directing traffic through congested nodes where significant packet loss is likely to occur. This throughput improvement is associated with an increment in the delay time due to the long paths taken to avoid congested regions. To overcome this drawback, a further modification to the routing discovery mechanism has been made by imposing a hop count limit (HCL) on the discovered paths. Tuning the HCL allows the network manager to tradeoff throughput against delay. The choice of congestion avoidance metric exhibits another shortcoming owing to its dependency on the packet size. It penalises the smaller packets over large ones in terms of path lengths. This has been corrected for by introducing a ModAEF metric that explicitly considers the size of the packet. The ModAEF metric includes a tuning factor that allows the operator determine the level of the weighting that should be applied to the packet size to correct for this dependence

A new routing metric for wireless mesh networks

In Wireless Mesh Networks the main goal is to achieve the best possible quality and efficiency of data transmission between source and destination nodes. To achieve such transmission, a routing algorithm should select better paths by taking the quality of wireless links into account. Simple path selection based on minimal hop count often leads to poor performance due to the fact that paths with low hop count often have higher packet loss rates. Better paths can be obtained by characterizing the actual quality of wireless link. A number of link quality aware routing metrics such as Expected Transmission Count (ETX), Expected Transmission Time (ETT), Weighted Cumulative Expected Transmission Time (WCETT), Metric of Interference and Channel Switching (MIC), Interference Aware Metric (iAWARE) etc have been explored. This study highlights some shortcomings of these routing metrics and proposes the design of a novel metric called ETX- 3 hop, which addresses the discussed weaknesses and works more efficiently under various link quality conditions. ETX-3hop consists of a more accurate method to measure the link quality and a path metric that better captures the quality of a path. The performance of the ETX-3hop metric is compared against the original ETX with different path metrics. In extensive simulations, ETX-3hop metric outperforms the original ETX metric in terms of network throughput

A Review of the Energy Efficient and Secure Multicast Routing Protocols for Mobile Ad hoc Networks

This paper presents a thorough survey of recent work addressing energy efficient multicast routing protocols and secure multicast routing protocols in Mobile Ad hoc Networks (MANETs). There are so many issues and solutions which witness the need of energy management and security in ad hoc wireless networks. The objective of a multicast routing protocol for MANETs is to support the propagation of data from a sender to all the receivers of a multicast group while trying to use the available bandwidth efficiently in the presence of frequent topology changes. Multicasting can improve the efficiency of the wireless link when sending multiple copies of messages by exploiting the inherent broadcast property of wireless transmission. Secure multicast routing plays a significant role in MANETs. However, offering energy efficient and secure multicast routing is a difficult and challenging task. In recent years, various multicast routing protocols have been proposed for MANETs. These protocols have distinguishing features and use different mechanismsComment: 15 page

Channel Allocation in An Overlaid Mesh Network

In spite of recent advancement of Wireless Mesh Technology, a lot of research challenges remained to be solved to extract the full capacity of this modern technology. As 802.11a/b/g standards make available the use of multi radio multi channel in a wireless node, a lot of research activities are going on to efficiently allocate the channel of a Mesh Network to boost its overall performances. In this research, the prospect of dividing the total network area into two non-overlapping channels of a given Mesh Network is investigated and analyzed numerically. It is found that the throughput is doubled as well as the fairness improves considerably if we deploy two channels instead of single channel backbone. An extensive simulation study has been carried out to find the optimum coverage area between two channels. The study shows that at a particular point of allocation, the network gives the optimum response.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format