This paper proposes and investigates a simple selfadaptive contention window adjustment algorithm for 802.11 WLAN. We present simulation and analytical results showing 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 both when ...

The random backoff contention window algorithm implemented in the IEEE 802.11 Distributed Coordination Function (DCF) provides a certain degree of collision mitigation. However, the issue of high collision rates within the IEEE 802.11 contention mode in a wireless local area network (WLAN) with high number of nodes is still not resolved. High packet collision rates result in throughput degradat...

The Assured Forwarding (AF) service in a differentiated services network offers different levels of forwarding assurance for IP packets. In the wired Internet, the AF service is implemented as a queue management scheme associated with a drop policy in each router. In multi-hop wireless networks, however, queue management in each node is not enough to provide service differentiation globally sin...

Some frame components, such as SYNC (frame synchronization) and RTS/CTS (Ready to Send/Clear to Send), are not taken into consideration when the traditional setting strategies conduct the optimization of SMAC (Sensor MAC) contention window size. This paper proposes mathematical models that allow the analysis of data packets forwarding delay within one SMAC virtual cluster. Simulation results in...

Leader election and initialization are two fundamental problems in mobile ad hoc networks (MANETs). The leader can serve as a coordinator in the MANETs and the initialization protocol can assign each host a sequential, unique, and short IDž. Q1 As we know, nož research on initialization for IEEE Q2 802.11-based MANETs has been done. Here, we propose two contention-based leader election and init...

According to the latest version of the IEEE 802.16 standard, the mandatory contention resolution method is the truncated binary exponential backoff, with the initial window size and the maximum window size controlled by the base station. However, the problem of choosing the right set of backoff parameters for the current network level remains unsolved and left as an open issue since this strate...

In this paper, we propose two mechanisms, differentiation by backoff exponent and differentiation by the size of contention window, for IEEE 802.15.4 sensor networks to provide multi-level differentiated services in beacon-enabled mode with slotted CSMA/CA algorithm under non-saturation condition. Mathematical model based on discrete-time Markov chain is presented and analyzed to measure the pe...

We analytically prove that the error in the channel idle time-based collision probability estimation in face of non-saturated stations is bounded by 2/(CWmin+1) in the IEEE 802.11 wireless LANs (WLANs). This work explicitly quantifies the impact of non-saturation, and the result vindicates the use of the estimation technique in real-life IEEE 802.11 WLANs, in such applications as the acknowledg...

The focus of this thesis lies in investigating possible abuse of the standardized medium access protocol 802.11a within Wireless Local Area Networks (WLAN). By modifying the Contention Window (CW), a network can capture more traffic in expense of its rivals. The competing network scenarios are modeled by the use of Game Theory, applying simple and repeated form games. We argue that by modifying...