In the past decades, cooperative communications schemes have gained significant attention in wireless networks. The cooperative scheme leads to longer transmission time which can considerably degrade the system performance. We evaluate the saturation throughput and saturation delay of the Markov chain model with direct/cooperative schemes to support QoS in WLANs. Simulation results show that di...

This paper proposes a new backoff algorithm for a CSMA/CA protocol and an analytical model computing the saturation throughput and delay of the scheme. The scheme differs from the standard backoff schemes in that the backoff time is not uniformly chosen in the contention window interval which results in reduced collision probability under high loads. Numerical analysis shows that saturation thr...

A fuzzy logic controlled protocol that enables each station to tune its contention window based on the online channel sensing results is proposed for the wireless local area networks. Extensive simulations are provided to compare the performance of the proposed protocol with that of the distributed protocol employed in the IEEE 802.11 standard. Simulation results show that the proposed protocol...

In this short communication we focus on the Contention Window mechanism of 802.11e EDCA. We first show that existing analyses for this mechanism rely on a system of equations that does not always have a unique solution. Next, we present an alternative analysis for which we prove mathematically the existence of a unique solution. Finally, we validate the accuracy of our analysis by means of simu...

This paper proposes new data control (best effort rate control) algorithm which changes minimum contention window (CWmin) of best effort traffic with respect to traffic load. By applying new traffic load indication parameter, CWmin of best effort is adaptively controlled. In the result of C++ based network simulation, throughput and drop rate of QoS traffic are guaranteed when proposed algorith...

This paper describes a scheme, AEDCF-CW/PF, that allows stations implementing IEEE 802.11e to have varying maximum contention window sizes and persistence factors. The values of these parameters are adjusted using knowledge of the station’s collision probability. Our research indicates that stations implementing this scheme experience much lower frame delays and frame dropping probabilities und...

The tremendous number of devices involved in the Internet Things is bringing new challenges to wireless networking. more that transmit a network, higher contention for channel. novel Wi-Fi HaLow standard introduces channel access mechanism called Periodic Restricted Access Window (PRAW), which aims reduce this contention. With mechanism, an point can define series time intervals during only pre...

Performance of existing TCP implementations over Optical Burst Switched (OBS) networks is not satisfactory, as they suffer from false congestion detection. As the contention induced losses are more common than congestion induced losses in OBS, the TCP reduces the congestion window even when there is no congestion. This effect, in turn unnecessarily reduces the TCP throughput. So it is crucial t...

In Multihop Wireless Networks, traffic forwarding capability of each node varies according to its level of contention. Each node can yield its channel access opportunity to its neighbouring nodes, so that all the nodes can evenly share the channel and have similar forwarding capability. In this manner the wireless channel is utilized effectively, which is achieved using Contention Window Adapta...

IEEE 802.11e standard has been specified to support differentiated quality of service (QoS), one of the critical issues on the conventional IEEE 802.11 wireless local area networks (WLANs). Enhanced Distributed Channel Access (EDCA) is the fundamental and mandatory contention-based channel access method of IEEE 802.11e, and delivers traffic based on differentiated Access Categories (ACs). A gen...