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Dynamic spectrum access has gained traction in wireless sensor networks (WSNs) because of the scarcity in spectrum caused by the proliferation of wireless devices and services, and it provides spectrum efficient communication for the WSNs. However, the communication between nodes in a cognitive radio sensor network (CRSN) is affected by the transmission power, fading, and interference with licensed...
Dynamic spectrum access in the form of cognitive radio (CR) has gained traction in wireless sensor networks (WSN) because of a) scarcity caused by the proliferation of wireless devices and service and b) it provides spectrum efficient communication for the resource constrained WSNs. However, proper means have to be devised to satisfy the requirements of both WSNs and CRs and to enjoy the benefits...
Dynamic spectrum access in the form of cognitive radio (CR) has gained traction in wireless sensor networks (WSN) because of a) scarcity caused by the proliferation of wireless devices and service and b) it provides spectrum efficient communication for the resource constrained WSNs. However, proper means have to be devised to satisfy the requirements of both WSNs and CRs and to enjoy the benefits...
The maximum throughput is limited by the slowest transmitting station in IEEE 802.11 distributed coordination function (DCF) medium access control (MAC), giving rise to the rate anomaly problem. This limitation is carried into a cognitive IEEE 802.11b DCF MAC. In our paper, we propose airtime fairness in a cognitive rate separation IEEE 802.11b MAC. Stations are grouped according to their transmission...
In our paper, we propose a Multi-Rate IEEE 802.11b MAC protocol with network coding. The standard X-OR operation is used in the network coding. Two topologies of paired topology and random topology are considered. The analytical framework is formulated for n stations. The state transition diagram is modeled by a two-dimensional discrete-time Markov chain. One dimension of the Markov chain is for the...
IEEE 802.11 distributed coordination function (DCF) medium access control (MAC) does not provide airtime fairness for all stations in a multi-rate scenario as it only provides max-min throughput fairness. This gives rise to the rate anomaly problem where the maximum throughput is limited by the slowest transmitting station. In our paper, we propose airtime fairness in a rate separation IEEE 802.11b...
CSMA/CA wireless MAC protocol is adopted in many standards. However, its performance at high contention level is less than desirable due to prolonged backoff period and collisions. We propose a novel cooperative MAC based on the Interweave Cognitive framework to combat high contention. In our setup, we incorporate a subset of self-organizing advanced nodes that opportunistically switch to a contention-free...
In cooperative wireless networks, the source node transmits the packets to its destination with the help from the cooperative nodes. However, existing routing metrics in the literature do not take into account the cooperative gain in choosing the next hop in a multi-hop network. In this paper, we propose a new routing metric that accounts for the potential cooperative gain a candidate next hop may...
Cooperative medium access control (MAC) protocols make use of the multi-rate capabilities of IEEE 802.11 to achieve higher throughput and shorter delay. This is achieved through transmitting a packet via a helper node by means of a faster two-hop links rather than a slower direct one-hop link. The cooperative MAC protocol transmits only one packet from the source node for each successful transmission...
Ultra-wideband (UWB) is a physical (PHY) layer technology that promises high transmission rates, as well as high resistance to noise and multipath effects. However, the impulse-based nature of UWB, coupled with its low transmission power, makes it difficult to enable efficient detection of the signals. Consequently, conventional carrier-sensing based MAC protocols cannot be used with a UWB PHY. In...
The inherent near-far effect in wireless networks causes nodes that are further away from the receiver to suffer from throughput degradation, as packets from nodes that are nearer are typically received with greater signal strengths. This unfair situation is traditionally overcome by power control. However, when power control is not feasible, for example in tiny sensor nodes with power-limited batteries,...
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