Andrzej R. Pach

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This paper presents a simulation analysis of the backoff mechanism presented in the IEEE 802.11 standard. The obtained simulations allow us to determine the efSective throughput and the mean packet delay versus offered load for different values of the Contention Window parameter and the number of contending stations, The choice of the CWmin and CWmax(More)
—This article presents a new MAC layer protocol for IEEE 802.11 EDCA-based ad-hoc networks with hidden nodes. The key idea of the proposed solution is based on an intelligent two-step reservation procedure which is combined with the advantages of EDCA service differentiation. The new protocol achieves significant performance improvement for high priority(More)
The paper presents the network provisioning proposed for the Future Internet solution called System IIP. The relation of the provisioning rule to the management strategy is described. The required input parameters as well as two proposed approaches to provisioning are given. The first approach formulates an optimization problem with the goal function(More)
We present a novel model of IEEE 802.11 EDCA with support for analysing networks with misbehaving nodes. In particular, we consider backoff misbehaviour. Firstly, we verify the model by extensive simulation analysis and by comparing it to three other IEEE 802.11 models. The results show that our model behaves satisfactorily and outperforms other widely(More)
This paper presents a work in progress which deals with the important and unresolved problem of node misbehavior. A realistic approach is used to determine the impact of contention window manipulation on IEEE 802.11e ad-hoc networks. It is explained why such networks are more prone to misbehavior. Novel results pertaining to the 802.11e standard are(More)
In this paper an innovative simulation study of five IEEE 802.11e network configurations is presented. The conducted analysis is crucial for understanding how a theoretically simple and, most of all, popular line topology network can be degraded by the presence of hidden and exposed nodes. The discussion of the obtained results helps to understand how and(More)
Studies indicate that HIV risk behaviors vary greatly among injection drug users (IDUs). The source of such variation is often ascribed to individual differences, but much of it is due to how IDUs are grouped into social networks. Nevertheless, given the turbulent and uncertain lives led by many IDUs, it would not be surprising if their social networks(More)
IEEE 802.11 is a wireless network standard that was completed in 1997. Unfortunately, the medium access protocol described in the standard meets some problems that arise from the presence of so-called hidden stations. This situation can cause degradation of the network performance. The paper describes a simulation analysis of influence of hidden stations on(More)