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Abstract-WiMAX networks have received wide attention as they support high data rate access and amazing ubiquitous connectivity with great quality-of-service (QoS) capabilities. In order to support QoS, bandwidth request (BW-REQ) mechanisms are suggested in the WiMAX standard for resource reservation, in which subscriber stations send BW-REQs to a base station which can grant or reject the requests according to the available radio resources. In this paper we propose a new analytical model for the performance analysis of various contention based bandwidth request mechanisms, including grouping and no-grouping schemes, as suggested in the WiMAX standard. Our analytical model covers both unsaturated and saturated traffic load conditions in both error-free and error-prone wireless channels. The accuracy of this model is verified by various simulation results. Our results show that the grouping mechanism outperforms the no-grouping mechanism when the system load is high, but it is not preferable when the system load is light. The channel noise degrades the performance of both throughput and delay.Index Terms-Bandwidth request (BW-REQ), broadband wireless access (BWA), IEEE 802.16, Markov chain, medium access control (MAC), performance analysis, quality-of-service (QoS), WiMAX.

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This paper focuses on the design and implementation of an Emergency TeleOrthoPaedics System (ETOPS). The proposed system, which integrates state-of-the-art devices with Internet and wireless telecommunication networks, is a useful tool for doctors, when they require a second opinion during the confrontation of mainly emergency orthopaedics incidents. Doctors can exchange securely medical images and video as well as other important data, and thus perform remote consultations, fast and accurately using a user friendly interface, via a reliable and secure telemedicine system of low cost. The quality of the transmitted compressed (JPEG2000) images was measured using different metrics. The results have shown that all metrics were within acceptable limits. The performance of the system was evaluated successfully under different wireless communication links based on real data.

Abstract. Systems that convert the sunlight into electrical energy like photovoltaics (PV) have been becoming widespread worldwide. The prospect of using the promising technology of wireless sensor networks (WSN) in the field of PV plant supervising and monitoring is studied here. The knowledge of the status and good working condition of each PV module separately as well as of any PV system component will lead in a more efficient way for power management. The nature of the wireless sensor networks (WSN) offers several advantages on monitoring and controlling applications over other traditional technologies including self-healing, self-organization and flexibility. The versatility, ease of use and reliability of a mesh network topology offered by the ZigBee technology that is based on the IEEE 802.15.4 standard, is used here to offer its maximum advantages on a system that is capable for real time measurements and event alerts.