The proliferation of wireless devices calls for a suitable network infrastructure for supporting communication among them. Medium Access Control(MAC), the most crucial part of the protocol stack, is discussed in the thesis. The design of wireless MAC protocols is signi cantly di erent from wired MAC protocols because of distinctive features of wireless medium, such as high error rates, limited ...

In wireless sensor network (WSN) studies, the main objective is minimizing the energy consumption so that the lifetime is maximized under the limited battery capacity constraints. Additionally, in most event-driven WSN applications, the end-to-end delay, and hence, the medium access delay should be minimized. Majority of the WSN MAC protocols are contention-based wherein contention window size ...

SIFS DIFS SIFS PIFS Contention window

We propose here an extended linear feedback model, taking the binary exponential backoff mechanism adopted in IEEE 802.15.4 CSMA/CA and analyze the energy consumption issues of the one hop sensor nodes. Numerical results show that the energy consumption in Wireless Sensor Networks (WSNs) can be reduced by applying CSMA protocol with fixed contention window size. Besides, an optimal contention w...

In this paper, a simple self-adaptive contention window adjustment algorithm for 802.11 wireless local area networks (WLAN) is proposed and analyzed. Numerical results show that the new algorithm outperforms the standard 802.11 window adjustment algorithm. Compared with the standard and previously proposed enhancement algorithms, a salient feature of our algorithm is that it performs well in bo...

Wireless Sensor Networks (WSNs) have emerged to meet the multimedia requirements in new emerging applications. So it’s important for WSN to have an adaptive and energy-efficient TDMA-CSMA based MAC protocol which significantly reduces energy consumption of the network. Here, this study proposes an Adaptive MAC protocol with effective TDMA time-slot assignment and CSMA contention window adaptati...

In the IEEE 802.11, an exponential backoff has been adopted, which means whenever a collision occurs, the contention window (CW) of the station is doubled until it reaches the maximum value. The purpose of increasing CW is to reduce the collision probability by distributing the traffic into a larger time space. In this paper, we use a fixed contention window (FCW) scheme and then evaluate the p...

In the wireless network, TCP performs poorly because it was originally designed for wired networks and does not take into consideration wireless characteristics such as mobility, high-loss probability, and hidden-terminal problems. In particular, in the wireless multi-hop networks, a large congestion window increases the probability of contention and packet losses, and TCP performance is degrad...

The quality-of-service (QoS) support for wireless LANs has been a hot research topic during the past few years. In this paper, two QoS provisioning mechanisms are proposed for the employment in 802.11e EDCA MAC scheme. First, the proposed call admission control mechanism can not only guarantee the QoS for the higher priority existing connections but also provide the minimum reserved bandwidth f...