In the context of the IEEE 802.11e standard for WLANs, we provide an analytical model for obtaining the maximum number of VoIP calls that can be supported on HCCA, such that the delay QoS constraint of the accepted calls is met, when TCP downloads are coexistent on EDCA. In this scenario, we derive the TCP download throughput by using an analytical model for the case where only TCP sessions are...

In this paper the unfairness problems in wireless 802.11 LAN are researched and studied via simulation. The contributions are twofold. First of all, the intra-class fairness of the EDCA queues for downlink streams, in the presence of bidirectional traffic is investigated. Secondly, Active Queue Management schemes are evaluated as an possible improvement for the intra-class fairness. The simulat...

Recently, the 802.11e Working Group (WG) has proposed the Hybrid Coordination Function (HCF), which has a HCF Controlled Channel Access (HCCA) and an Enhanced Distributed Coordination Access (EDCA), in order to provide QoS in WLANs. In this paper an innovative HCCA-based algorithm, which will be referred to as Power Save Feedback Based Dynamic Scheduler (PS FBDS) providing bounded delays while ...

One of the main challenges in Wireless Sensor and Actuator Networks (WSAN) is the delay caused by shared and nondeterministic behavior of wireless communication medium. The Retry-Limit parameter of IEEE 802.11 standard can be used to control packet reliability, whereas other parameters mostly effect on the packet delay. In this paper, at first the delay-reliability trade-off in WSANs based on M...

In this paper, we are interested to enhance the QoS in sensor networks. First, we study the MMSPEED routing protocol (Multi path Multi SPEED) [1] conceived to ensure the quality of real-time services in sensor networks. We present, then, a second approach which takes advantage of the standard 802.11e EDCA protocol [16] that ensures effective end to end delay and good quality of traffic. Finally...

The next deployments of IEEE 802.11 WLAN will involve the coexistence of the legacy best effort stations and the new recently standardised QoS-aware stations in QoS Basic Service Set (QBSS). However, if no control is applied to the legacy stations, this coexistence may deteriorate QoS support provided by the new IEEE 802.11e standard. In this paper the influence of IEEE 802.11b DCF stations on ...

This paper proposes a set of performance enhancements techniques aiming to improve the perceived performance of video transmission across the IEEE 802.11e network. The proposed mechanism preserves the video Quality of Experience (QoE) by protecting the I-Frames transmitted as part of the Group of Pictures (GoP) during queue congestion. The method is evaluated using the NS-3 simulator with the E...

We propose in this paper a Markov chain model that describes the behavior of an EDCA (Enhanced Distributed Channel Access) access category under saturation. Compared to previous work [1], [2], [3], the model explicitly integrates the behavior of an access category when submitted to a virtual collision. We give in this paper two views of the model : a general one explicitly representing the diff...