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In this paper, a unified analytical model is established to analyze the performance of backoff schemes in IEEE 802.11 DCF networks under saturation condition. It is shown that BEB suffers from deteriorated queueing performance due to a large second moment of access delay, and a key to reduce the second moment lies in the growth rate of the backoff window size. Quadratic Backoff (QB) is further proposed,...
We introduce a 3-dimensional Markov chain that integrates the IEEE 802.11 DCF contention resolution and queueing processes into one model. Important QoS measures, delay and loss, plus throughput and queue length, can be obtained for a realistic systems with finite buffer under finite load. We present an efficient method for solving the steady state probabilities of the Markov chain. Simulations confirm...
This paper introduces two important enhancements to the IEEE 802.11 medium access control (MAC) protocols which are not considered in the current IEEE 802.11 MAC protocol: the channel state between the transmitter and the receiver and the node queue state. Our objective is to characterize the impact of these parameters on medium access regulation, and ultimately rely on them in order to enhance the...
The wide usage of IEEE 802.11 based wireless LANs have led to lots of interest in providing quality of service (QoS) guarantees in such networks. 802.11e is the QoS variant of the 802.11 family of protocols. But it has a twofold drawback. First, QoS requirements relevant to a given application are always fulfilled by the "statically" associated priority. Second, resource requests of the...
DQCA is a near-optimum medium access control (MAC) protocol designed for wireless local access networks (WLANs). The protocol operates as a random access scheme under low traffic load and switches smoothly and automatically to a reservation scheme as the traffic grows. The inherent feedback mechanism of DQCA facilitates the implementation of a link adaptation algorithm that properly selects the best...
Performance of multi-hop ad hoc networks is highly affected by the hidden and exposed node problems. The RTS/CTS handshaking protocol used in the IEEE 802.11 standard was designed to solve the hidden node problem; however it was not successful in thoroughly eradicating the problem. We claim that it is sometimes possible to earn more throughput by controlling or even wisely creating this phenomenon...
The Distributed Coordination Function (DCF) in the IEEE 802.11 protocol is a random access scheme based on the carrier sense multiple access with collision avoidance (CSMA/CA). In recent years, there have been numerous research on the performance analysis and model of DCF under the assumption that the transmission queue is always nonempty (i.e. saturation state). In this paper, we propose a dynamic...
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