In this paper we propose a modified EDCF scheme, M-EDCF, to improve the Quality of Service (QoS) of the IEEE 802.11e wireless network. The IEEE 802.11e standard is presented to support QoS at medium access control level using a priority scheme by differentiating the inter-frame space and the initial window size. In addition to providing relative priorities by adjusting the size of the Contentio...

In IEEE 802.11 Power Saving (PS) mode specified for Independent Basic Service Set (IBSS), mobile stations announce their pending data packets within Announcement Traffic Indication Message (ATIM) window immediately after the reception of Time Synchronization Function (TSF) beacon. This paper proposed modifications to the PS mode by transmitting the TSF beacon at the end of each ATIM window. Upo...

This paper presents an analysis of MAC layer misbehaviour in 802.11 mobile ad-hoc networks. Such misbehaviour can be performed, e.g., to achieve greater throughput or extended battery life. Focus is put on actions which are both easy to perform and give substantial benefits to the misbehaving node. In particular, the new IEEE 802.11e standard, which defines QoS enhancements, is taken into accou...

In this paper we present a new scheme which is mend to increase the efficacy of the present EDCA, and also make EDCA more robust in a high noise environment, where high packet loss is characteristic. This paper provides a brief account of EDCA mode; it also informs about limitations of present EDCA scheme. Nex t , paper postulates a more robust scheme; this newly proposed scheme exploits alread...

window, collision, IEEE 802.11e, EDCF. Abstract—The Enhanced Distributed Channel Access (EDCA) is introduced to provide QoS on the basis of Distributed Coordination Function (DCF) in IEEE802.11. The access mechanism of IEEE802.11e, referred to as EDCA, assigns different access categories (AC) with different types of data traffic based on priorities. Each priority uses a different set of medium ...

Predictive p-persistent CSMA protocol is an important MAC solution developed for networked sensor/control applications and used in Local Operating Networks (LonWorks) technology. The protocol uses a built-in network load prediction to support collision avoidance. The paper presents an analytical study of prediction efficiency for a channel with collision detection. The approach based on Markov ...

Wireless communication technology has gained widespread acceptance in recent years. Wireless Local Area Networks (WLANs) are becoming more and more popular and widely used, since they provide high data rates. The main characteristics of this technology are simplicity, flexibility and cost effectiveness. Recent applications include media streaming, interactive collaboration, videoconferencing an...

IEEE 802.11 MAC protocol for medium access control in wireless Local Area Networks (LANs) is the de facto standard for wireless ad hoc networks, but it does not necessarily satisfy QoS requirement by users such as fairness among flows or throughput of flows. In this paper, we propose a new scheme aiming to solve per-flow fairness problem and achieves good throughput performance in IEEE 802.11 m...

Most of analytical models proposed so far for the IEEE 802.11 distributed coordination function (DCF) focus on saturation performance. In this paper, we develop an analytic model for unsaturation performance evaluation of the IEEE 802.11 DCF with and without slow contention window decrease (SCWD). The model explicitly takes into account the carrier sensing mechanism and an additional backoff in...