Cross-layer routing metrics for mesh networks: Current status and research directions

A number of routing metrics have been proposed to select a path with better performance in wireless mesh networks. Most of them partially rely on link loss rates when evaluating the paths’ performance. Thus it is essential to accurately measure the link loss rate. Currently, a broadcast based probe mechanism is commonly used by routing metrics to estimate the link loss rates. However, this mechanism often yields inaccurate link loss rates. Based on our extensive simulations, we find out that the limitations of this mechanism are due to: 1) the use of basic (lowest) data rates to probe the loss rate while the link might be used with a higher data rate; 2) the assumption that links are symmetric, which is not true in real case; 3) the low number of packet probes used to measure the link loss rate. This work proposes appropriate solutions to the above weaknesses. Our experimental results indicate that the proposed modifications are able to measure the link loss rate with more accuracy.

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Accurate Assessment of Link Loss Rate in Wireless Mesh Networks

Routing is an essential mechanism for proper functioning of large networks, and routing protocols make use of routing metrics to determine optimal paths. The design of routing metrics is critical for achieving high throughput and we begin this chapter by proposing the design principles for routing metrics. These design principles are for ensuring the proper functioning of the network and achieving high throughput. We continue by giving a detail analysis of the existing routing metrics. We also look at the pitfalls of the existing routing metrics. We conclude the chapter by outlining the future research directions. DOI: 10.4018/978-1-61520-680-3.ch024

Towards Designing High-Throughput Routing Metrics for Wireless Mesh Networks:

A dissertation submitted to the Department of Computer Science in the Faculty of Science and Agriculture, in fulfilment of the requirements for the degree of Master of Science in Computer Science at the University of Zululand, South Africa, 2011.

Performance evaluation of routing metrics for wireless mesh networks

Avec le succes des communications sans fil, il devient possible d'acceder au reseau partout et a tout moment sans avoir recours a connecter physiquement les appareils communicants a une infrastructure. Les nœuds (ordinateurs portables, smartphones, etc) peuvent analyser les differents canaux radio afin de pouvoir s'associer a un reseau sans fil disponible (station de base, point d'acces, etc.). Un avantage indeniable de ses technologies sans fil est la possibilite d'etre mobile tout en restant connecte. Cependant, la mobilite est une tâche difficile a gerer car elle doit etre abordee a differentes couches pour etre transparente aux utilisateurs. Dans les MANET (Mobile Ad hoc Network), les protocoles de routage utilisent des metriques pour selectionner les meilleures routes. Les metriques peuvent refleter la qualite de la liaison sans fil et aider a gerer la mobilite.Mais, un retard important entre l'estimation des metriques et leur inclusion dans le processus de routage rend cette approche inefficace.Les travaux de cette these s'interessent a la proposition de nouvelles methodes de calcul des metriques de routage pour gerer le probleme de la mobilite dans les reseaux ad hoc. Les nouvelles metriques doivent refleter la qualite du lien et etre sensibles a la mobilite en meme temps. Nous considerons les metriques classiques, en particulier ETX (Expected Transmission Count) et ETT (Expected Transmission Time). Nous introduisons de nouvelles methodes pour anticiper les valeurs de ces metriques en utilisant des algorithmes de prediction. Nous utilisons une approche Cross layer, qui permet l'utilisation conjointe de l'information a partir des couches 1, 2 et 3. La validation de nouvelles methodes de calcul des metriques de routage necessite une evaluation au travers d'un veritable banc d'essai. Nous avons donc egalement mis en œuvre les nouvelles metriques de routage dans un testbed afin d'evaluer et de comparer leurs performances avec les metriques classiques.

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Gestion de la mobilité dans les réseaux Ad Hoc par anticipation des métriques de routage

Routing metrics are critical to select a path that yields a high throughput in multi-rate multi-hop wireless networks. This paper illustrates the weaknesses of existing routing metrics and proposes a new routing metric called Improved Expected Transmission Time (iETT). iETT addresses two key characteristics of a routing path that other routing metrics ignored: 1) a high discrepancy in packet loss rates of links and 2) the position of the links with different packet loss rates. By capturing these two characteristics, the iETT metric is able to choose a route with a better performance than shortest path, Expected Transmission Count (ETX) and Expected Transmission Time (ETT) metrics.

Bing Qi

Papers

iETT: A Quality Routing Metric for Multi-Rate Multi-Hop Networks