Introducing Hierarchy in Energy Games

In this work we introduce hierarchy in wireless networks that can be modeled by a decentralized multiple access channel and for which energy-efficiency is the main performance index. In these networks users are free to choose their power control strategy to selfishly maximize their energy-efficiency. Specifically, we introduce hierarchy in two different ways: 1. Assuming single-user decoding at the receiver, we investigate a Stackelberg formulation of the game where one user is the leader whereas the other users are assumed to be able to react to the leader's decisions; 2. Assuming neither leader nor followers among the users, we introduce hierarchy by assuming successive interference cancellation at the receiver. It is shown that introducing a certain degree of hierarchy in non-cooperative power control games not only improves the individual energy efficiency of all the users but can also be a way of insuring the existence of a non-saturated equilibrium and reaching a desired trade-off between the global network performance at the equilibrium and the requested amount of signaling. In this respect, the way of measuring the global performance of an energy-efficient network is shown to be a critical issue.Comment: Accepted for publication in IEEE Trans. on Wireless Communication

Projet de développement de l’élevage camelin en Tunisie

Camel breeding is of great socio-economic importance in southern Tunisia. Although, the size of the national camel herd has decreased over the years from 120 000 to 56 000 heads in 2014. Illegal export, low breeding efficiency, social modernization and lack of investment are the major causes of this decline. To remedy this situation, the Tunisian government has established a national program for development and research on camel production. This program is based on grants to farmers to encourage rearing of replacement females and fattening camels; improvement of pastures and water infrastructure, promotion of applied research in specialized centers. Research efforts are centered on health, nutrition and improvement of rangelands, development of reproductive biotechnologies and genetic improvement. An attempt was carried out to genotype the local breeds of camels. Development of semen preservation and artificial insemination has met several challenges inherent to the peculiarities of reproduction in this species. Keywords: Husbandry, reproduction, biotechnologies, Camel, TunisiaL’élevage du dromadaire joue un rôle socio-économique important dans le sud tunisien mais le nombre de dromadaires a connu ces dernières années une diminution importante de 120 000 à 56 000 en 2014. L’exportation illégale, le rendement faible de l’élevage, la modernisation de la vie des personnes et le manque d’investissement dans ce domaine sont les principales causes de cette diminution. Pour remédier à ce problème, l’état tunisien a proposé un programme national de développement et de recherche dans le domaine du dromadaire basé sur (1) l’encouragement des éleveurs par la subvention de l’élevage des femelles de remplacement et l’engraissement des chamelons, (2) l’amélioration des infrastructures dans les pâturages; notamment l’aménagement des points d’eau pour les animaux et (3) la promotion de la recherche appliquée dans les centres spécialisés. Les principaux thèmes de recherche sont axés sur la santé animale, l’alimentation des dromadaires et l’amélioration des zones de parcours, l’insémination artificielle et le transfert d’embryon et la sélection génétique des animaux. Dans le domaine de la biotechnologie de la reproduction, des essais ont été réalisés dans le typage génétique des dromadaires, la conservation du liquide séminal et l’insémination artificielle pour surmonter les difficultés particulières de la reproduction chez le dromadaire. Mots-clés: Élevage, reproduction, biotechnologies, dromadaire, Tunisi

Design as/for Common(s): Decolonial Participatory Experiences for Post-Capitalist Resilient Future(s)

The catastrophic effects of the Anthropocene are evident. Manifestations of crisis are not only environmental, but also economic, social, political and ethical: combined with the dystopian imaginaries of the future, they suggest the need for a paradigm shift. The Commons are seen as an alternative for a transition to a post-capitalist economy. Yet, Design for social innovation is understood as a humanitarian action and remains linked to the logic of commodification; reason why some call for decolonizing Design from West- ern abstractions. The focus is on the relationship between Design and Commons, with particular attention to decolo- nial thinking. Following an action research approach that consisted in “inhabiting” the oasis of Chenini in Tunisia as a Commons in crisis, the idea was to understand the role of Design in the paradigm shift from an extractivist growth economy to a resource economy; Design as attached to situations rather than objects

Asymptotic Delay Analysis and Timeout-Based Admission Control for Ad Hoc Wireless Networks

International audienceIn this paper, we present an analytic model for evaluating average packet delay and achievable end-to-end goodput in a collision channel based multihop wireless ad hoc networks. We consider each node operates not only as a host but also as a router, i.e., the packets may have to be forwarded by several intermediate nodes before they reach their destinations. The end-to-end delay of a connection and through-put of this network depend on the number of nodes, the source traffic characteristics, the number of retransmissions at nodes, the forwarding cooperation level and the behavior of the MAC protocol. Our analysis gives expressions for the queue length and the delay in terms of probability generating functions. In addition to address routing and transmission scheduling, we adopt a cross-layer design that allows information sharing across different layers for efficient utilization of network resources, and meeting the end-to-end performance requirements of demanding applications. Furthermore, we propose a packet admission control scheme based on delay timeout mechanism. This guarantees quality of service for mul-timedia applications such as voice and video streaming. Afterward we conduct extensive simulations in order to verify our analytical results

Cooperative and Non-cooperative control for Slotted Aloha with random power level selections algorithms

International audienceIn this paper, we study the performance of Slotted Aloha under power differentiation schemes. We consider the up-link of a cellular system where m mobiles transmit over a common channel to a base station. In particular we analyze random sets possible transmission powers and further study the role of priorities given either to new arriving packet or to backlogged packets. We consider a general capture model where a mobile transmit successfully a packet if its instantaneous SINR is larger than the threshold. Under this capture model, we study both the cooperative team in which a common goal is jointly optimized as well as the noncooperative game problem in which mobiles try to optimize their own objectives. The performance metrics that we study are the throughput and the expected delay. Further we provide a stability analysis and show that schemes with power differentiation and power control can improve significantly the performance and could eliminate in some cases the bi-stable nature of Slotted Aloha