Mário Macedo

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This article presents a scheduling algorithm for the IEEE 802.11e Hybrid Coordination Function under definition by the IEEE 802.11e task group. HCF can be used to provide IP quality of service guarantees in IEEE802.11e infrastructure WLANs. The Enhanced Distributed Coordination Function is mainly used for data transmission without QoS guarantees, but can(More)
This paper proposes MH-MAC, a new MAC protocol for wireless sensor networks capable of handling applications that generate infrequent huge peaks of traffic. Existing protocols are not adapted to this kind of applications. Asynchronous protocols are energy efficient for the long inactive periods, but fail to cope with the bandwidth and latency requirements(More)
This paper presents a distributed algorithm for efficient Time Division Multiple Access (TDMA) slot allocation in Wireless Sensor Networks. Unlike most of the existent proposals, which try to guarantee interference-free allocation based on the n-hop criterion (which can only work with regular topologies), the presented algorithm bases its decisions on the(More)
This paper presents a novel MAC protocol for Wireless Sensor Networks (WSN)s designated Tone-Propagated MAC (TP-MAC). This protocol is specially suited for early warning and tracking applications, where sensor nodes generate sporadic asynchronous traffic (mainly consisting of uplink alert messages and downlink control messages) with stringent latency(More)
This paper presents Tone-Propagated MAC (TP-MAC), a novel MAC protocol for Wireless Sensor Networks (WSN)s, specially suited for early warning and tracking applications, where the traffic generated by sensor nodes (mainly alert messages) is sporadic but has stringent latency requirements. This protocol aims to maximize energy-efficiency while minimizing(More)
Energy-efficiency and latency requirements in alarm-driven Wireless Sensor Networks often demand the use of TDMA protocols with special features such as cascading of timeslots, in a way that the sensor-to-sink delay bound can stay below the duration of a single frame. However, this single TDMA frame should be as small as possible. The results presented in(More)
This paper presents an analysis of the impact of shadow fading on the performance of TDMA slot allocation, with latter being measured in terms of the resultant in-network interference versus spatial reutilization. Simulations are presented which demonstrate that for Wireless Sensor Networks operating in shadow fading channels, protocols that feature TDMA(More)