scholarly journals Adaptive and Fuzzy Approaches for Nodes Affinity Management in Wireless Ad-Hoc Networks

2008 ◽  
Vol 4 (4) ◽  
pp. 273-295 ◽  
Author(s):  
Essam Natsheh ◽  
Tat-Chee Wan

In most of the ad-hoc routing protocols, a static link lifetime (LL) is used for a newly discovered neighbors. Though this works well for networks with fixed infrastructures, it is inadequate for ad-hoc networks due to nodes mobility and frequent breaks of links. To overcome this problem, routing protocols with estimated LL using nodes affinity were introduced. However, these protocols also used the static estimated LL during the connection time. In contrast to that, in this paper two methods are presented to estimate LL based on nodes affinity and then continually update those values depending on changes of the affinity. In the first method, linear function is used to map the relationship between the signal strength fluctuation and LL. In the second method, fuzzy logic system is used to map this relationship in a nonlinear fashion. Significance of the proposed methods is validated using simulation. Results indicate that fuzzy method provides the most efficient and robust LL values for routing protocols.

2022 ◽  
Vol 14 (1) ◽  
pp. 28
Author(s):  
Yelena Trofimova ◽  
Pavel Tvrdík

In wireless ad hoc networks, security and communication challenges are frequently addressed by deploying a trust mechanism. A number of approaches for evaluating trust of ad hoc network nodes have been proposed, including the one that uses neural networks. We proposed to use packet delivery ratios as input to the neural network. In this article, we present a new method, called TARA (Trust-Aware Reactive Ad Hoc routing), to incorporate node trusts into reactive ad hoc routing protocols. The novelty of the TARA method is that it does not require changes to the routing protocol itself. Instead, it influences the routing choice from outside by delaying the route request messages of untrusted nodes. The performance of the method was evaluated on the use case of sensor nodes sending data to a sink node. The experiments showed that the method improves the packet delivery ratio in the network by about 70%. Performance analysis of the TARA method provided recommendations for its application in a particular ad hoc network.


Author(s):  
Chi-Kin Chau ◽  
Jon Crowcroft ◽  
Kang-Won Lee ◽  
Starsky H.Y. Wong

Because of the increasing number of diverse routing protocols proposed to deal with the network dynamics in mobile ad hoc networks (MANETs), the heterogeneity of MANETs has increased dramatically. While many of these extant proposals only concern enhancing routing in a single domain, little attention has been given to the interoperations among heterogeneous MANETs. Moreover, the existing inter-domain routing protocols (i.e., BGP) that have been designed for the Internet cannot cope with the new challenges derived from the MANETs, such as (1) the rapid dynamic changes of network topology due to mobility, and (2) the larger diversity in intra-domain ad hoc routing protocols. In this chapter, the authors address some of the major challenges and identify new directions to the development of seamless inter-domain routing for enabling end-to-end communications over heterogeneous MANET domains.


Author(s):  
Pramita Mitra ◽  
Christian Poellabauer

The presence of asymmetric links is a common and non-negligible phenomenon in many ad-hoc networks, including MANETs and sensor networks. Asymmetry is caused by node mobility, heterogeneous radio technologies, and irregularities in radio ranges and packet loss patterns. Most existing ad-hoc routing protocols either assume fully symmetric networks or simply ignore any asymmetric links. In the first case, route discovery can fail when the symmetry assumption does not hold true, e.g., many reactive routing protocols rely on a two-phase communication process, where the same path is used to communicate between a sender and a receiver. If a single link on this path is asymmetric, the route establishment may fail. In the second case, asymmetric links are identified and explicitly ignored in the route establishment phase. This can lead to route discovery failure if there is no symmetric path between a sender and a receiver or it can lead to less than optimal routes. This document provides an overview of routing protocols that explicitly consider asymmetric links in the route discovery phase and introduces robust mechanisms that bypass asymmetric links to ensure successful route establishment.


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