IEEE 802.11 is often considered as the underlying wireless technology of multihop wireless networks. But the use of 802.11 in such networks raises issues, like efficiency and/or fairness issues. Different kinds of solutions have been proposed to overcome these problems. One approach is to design new MAC protocols that provide alternatives to the IEEE 802.11 MAC protocol. Although these solutions are of some interest, it should probably take some time before new wireless network interface cards based on one of these solutions are developed and released. Another approach is to consider that 802.11 will remain the underlying wireless technology and to design solutions above it. Several solutions based on rate allocation have been proposed so far. The main drawback of the proposed solutions is that they rely on a radio medium sharing model that is difficult to compute in a wireless, distributed and mobile environment. Indeed, very few of these solutions have been derived into a network protocol.In this article, we propose a distributed and dynamic rate allocation solution that is based on a simple sharing model. Due to its simplicity, we can derive a network protocol that can be practically used in multihop wireless networks. This protocol provides a fair bandwidth sharing between end-to-end flows while maintaining an efficient overall throughput in the network. This solution has been implemented in NS2 and evaluated by simulations. † Key-words: Distributed algorithms, protocols, evaluation, IEEE 802.11 * ENS Lyon -46, allée d'Italie 69364 Lyon Cedex 07 -FRANCE {remi.vannier,isabelle.guerin-lassous}@ens-lyon.fr † This work was partially supported by the european integrated project AEOLUS.Vers un protocole de répartition de débit équitable et réaliste pour les réseaux sans fil multi-sauts basé sur un modèle par noeuds Résumé : On considère souvent IEEE 802.11 comme la technologie sous-jacente aux réseaux sans fil multisauts. Pourtant, dans de tels résaux, 802.11 s'avére dans de nombreuses situations inefficace et/ou inéquitable. Pour faire face à ces problèmes, de nombreuses solutions ont déjà été proposées. Une première approche consiste à fournir une alternative à la couche MAC de 802.11. Cependant, il faudra du temps avant que de nouvelles cartes réseau s'appuyant sur l'une de ces solutions voient le jour. Une autre approche consiste à considérer que 802.11 restera durablement, et donc à développer des solutions reposant sur 802.11. Des solutions de ce type, basées sur la régulation de débit, ont été proposées, mais elles reposent sur un modèle de partage du medium radio complexe, et difficile à utiliser dans un contexte sans fil, distribué et mobile. Dans cet article, nous proposons un algorithme d'allocation de débit dynamique et distribué, reposant sur un modèle de partage simple. Grâce à sa simplicité, nous avons obtenu un protocole simple et réaliste pour les réseaux radio multi-sauts. Ce protocole permet de garantir un partage équitable de la bande passante entre flux, tout en assurant une utilisat...

Fairness in multihop ad hoc networks has received considerable attention in the literature. Many schemes have been proposed, which attempt to compute the "optimal" bit rates of the transmitting mobile nodes so that a certain fairness criterion is met. As the related literature indicates, there is a trade-off between fairness and efficiency, since fairness schemes typically reduce the channel utilization. Also, it is questionable whether certain fairness schemes have a positive or negative impact on the QoS of certain user services. So far, there has been limited research on the impact of the varying short-term allocations of these protocols, due to their inherent features and also nodes mobility, on the user-perceived QoS (and social welfare) for services of long duration. In this paper, we introduce an assessment framework, based on history-dependent utility functions that can be used as a holistic performance evaluation tool of these fairness schemes. These functions quantify the satisfaction that the ad hoc users obtain from the way their long-lived service sessions are allocated bandwidth, due to the behavior of the MANETs fair schemes. This way we can unambiguously compare the performance of various fair solutions whose maximization goals are inherently different (max-min fairness, proportional fairness, etc.). Finally, we demonstrate the usefulness of this framework by applying it on different protocols. 1

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