Performance Analysis of Distributed Resource Reservation in IEEE 802.11e-Based Wireless Networks

Abstract-Guaranteeing quality of service is one of the most critical challenges in IEEE 802.11-based wireless networks. This paper proposes an analytical framework to evaluate hybrid MAC scheduling mechanisms with distributed resource reservation, that was proposed for the IEEE 802.11e enhanced distributed channel access protocol for guaranteeing quality of service. The hybrid MAC scheduling mechanisms split the airtime into service intervals with contention-free period for quality of service guaranteed real-time sessions, and contention access period for other traffic sessions. The distributed resource reservation ensures that the resources are allocated to real-time sessions without the support of a centralised controller -this makes it suitable for ad-hoc networking applications. The proposed analytical framework models the quality of service (i.e. delay and throughput) performance of real-time sessions with dedicated resources in a distributed environment, and also estimates the overall capacity of the network. Moreover, the derived models can be used to investigate the impact of changes to individual system parameters, such as service interval or size of transmission opportunity. The simulation results show that the proposed analytical framework precisely models the quality of service performance of real-time sessions and predicts the optimum resource allocation for improved network capacity

Protocolo Cross-Layer Proactivo Basado en Técnicas de Inteligencia Artificial para Handover sin Fisuras en Ambientes Móviles WLAN

En este documento se presenta una nueva propuesta de protocolo predictivo basado en técnicas de inteligencia artificial para pronosticar la siguiente red a conectarse, este marco de referencia está basado en un protocolo de handover Cross-Layer y un pronosticador de siguiente red basado en cinco clasificadores: regresión logística, Bayes ingenuo, máquina de soporte vectorial, arboles de decisión y k vecinos más cercanos, obteniendo hasta un 92 % de exactitud en el pronóstico de red. Basado en este marco de referencia se obtiene un traspaso sin fisuras en ambientes móviles WLAN

Increasing the efficiency of the handover in real network environment

Cílem této práce je prostudovat metody handoveru používaných ve WiMAX a WLAN sítích, dále navrhnout možnosti simulace metod handoveru pro WLAN v simulačním prostředí Opnet Modeler. Tato práce se především zaměřuje na získání informací o okolních AP a následném výběru nového AP s využitím těchto informaci. Práce podrobně popisuje jednotlivé postupy řešení, které jsou použity pro implementaci nových skenovacích metod.The aim of this work is to study methods of handover used in WiMAX and WLAN networks, next suggest the posibility of simulation methods for WLAN handover in the simulation environment OPNET Modeler. This work is focused primarily on obtaining the information about neighboring AP and subsequent selection of a new AP using such information. The work describes in detail each processes solutions that are used to implement newscanning methods

MeshScan: a Fast and Efficient Handoff Scheme for IEEE 802.11 Wireless Mesh Networks

As a next generation network solution, Wireless Mesh Networks (WMN) provides fast Internet access to a large area, which is from university campus to city scale. In order to provide an uninterrupted Internet experience to a mobile client, a process called handoff is required to maintain the network connection from one Mesh Node (MN) to another MN. Ideally, handoff should be completely transparent to mobile users. A critical application like VoIP will require a handoff capability that transfers a call from one mesh node (MN) to another in less than 50 msec. However the current IEEE 802.11 standards do not address the handoff well. Studies have revealed that standard handoff on IEEE 802.11 WLANs incurs a latency of the order of hundreds of milliseconds to several seconds. Moreover, the discovery step in the handoff process accounts for more than 99% of this latency. The study addresses the latency in the discovery step by introducing an efficient and powerful client-side scan technique called MeshScan which replaces the discovery step with a unicast scan that transmits Authentication Request frames to potential MNs. A prototype of MeshScan has been developed based on the MadWifi WLAN driver on Linux operating systems. The feasibility of MeshScan to support fast handoff in WMNs has been demonstrated through extensive computer simulations and experiments under same given conditions. The results from the simulations and experiments show that the latency associated with handoff can be reduced from seconds to a few milliseconds by using the MeshScan technique. Furthermore, it is shown that MeshScan can continue to function effectively even under heavy traffic loads

A Neighbor Caching Mechanism for Handoff in IEEE 802.11 Wireless Networks

Seamless handover in IEEE 802.11 for Quality of Service (QoS) demanding applications is one of the critical issues because of handover latency. In this paper, we proposed the Neighbor Graph Cache (NGC) mechanism to reduce scanning latency while a mobile station tries to make a link-layer handover. The handoff latency can be greatly reduced through NGC algorithm. We use OPNET modeler as the simulation tool. The simulation results show that the handover delay by NGC is 2.614 ms. It is less than 50 ms and able to meet the criteria of VoIP application

Fast and seamless mobility management in IPV6-based next-generation wireless networks

Introduction -- Access router tunnelling protocol (ARTP) -- Proposed integrated architecture for next generation wireless networks -- Proposed seamless handoff schemes in next generation wireless networks -- Proposed fast mac layer handoff scheme for MIPV6/WLANs