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Performance Evaluation of Heartbeat-style Failure Detector over Routing Protocols for Mobile Ad Hoc Network
Zhao Hai-jun, Huang Xiao-hong, Zhao Fang, Ma Yan, Su Yu-jie
Ad hoc wireless networks are characterized with multi-hop connectivity and frequently changing network topology. Routing protocol plays a very important role to ensure each packet reaches its destination node in Ad hoc wireless network. Many different routing protocols have been proposed in literature, but no performance comparison of heartbeat-style failure detection service over them is available. In this paper, we do the comprehensive simulations to investigate the performance of heartbeat-style failure detector over proactive and reactive routing protocols with ns-2 simulator. The performance different are analyzed using varying the number of nodes, mobility speed, traffic load, transmission range. Results show that DSDV performed better in average delay and average failure detection time, AODV performed better in normalized routing overhead, delivery ratio, energy consumption ratio, false detection ratio. The observations can be used to motivate and improve future implementations of failure detection service in Ad hoc wireless networks.
A functional Approach to Dynamic Channel Assignment for Multi-Radio Wireless Mesh Networks
Tope Kareem, Ntisbane Ntlatlapa, Anthony H. Chan
This paper investigates the challenges involve in designing a dynamic channel assignment (DCA) scheme for wireless mesh networks, particularly for multi-radio systems. It motivates the need for fast switching and process coordination modules to be incorporated in DCA algorithm for multi-radio systems. The design strategy is based on a reinterpretation of an adaptive priority mechanism as an iterative algorithm that recursively allocate a set of channels to radios in a fair and efficient manner in order to minimise interference and maximise throughputs. The algorithm, called Adaptive Priority Multi-Radio Channel Assignment (APMCA) is tested for overall performance to assess the effectiveness by determining its overall computational complexity. The combined advantages of fast switching time and process coordination modules make the APMCA a useful candidate towards automating the channel assignment method in multi-radio wireless mesh network planning and design.
On the Performance of Expected Transmission Count (ETX) for Wireless Mesh Networks
Xian Ni, Kun-chan Lan, Robert Malaney
In the past few years Wireless Mesh Networks (WMNs) have developed as a promising technology to provide flexible and low-cost broadband network services. The Expected Transmission Count (ETX) metric has been put forward recently as an advanced routing metric to provide high QoS for static WMNs. Most previous research in this area suggests that ETX outperforms other routing metrics in throughput and efficiency. However, it has been determined that ETX is not immune to load sensitivity and route oscillations in a single radio environment. Route oscillations refer to the situation where packet transmission switches between two or more routes due to congestion. This has the effect of degrading performance of the network, as the routing protocol may select a non optimal path. In this paper we solve the route oscillation problem using a route stabilization technique which forces data transmission on a fixed route. We implement this solution in AODV routing by disabling both error messages and periodic updating messages. However, a critical factor for our approach is that ETX must determine a high quality initial route in AODV. This paper investigates whether the ETX metric improves initial route selection in AODV compared to the HOPS metric in two representative client-server applications: the Traffic Control Network (TCN) and the Video Stream (VS) network. We evaluate the ETX and HOPS metrics in a range of scenarios which possess different link qualities and different traffic loads. We find the ETX metric greatly improves initial route selection in AODV compared to the HOPS in the network in which only a single flow exists. For networks in which there are multiple simultaneous flows, ETX behaves similar to HOPS in initial route selection. Based on these results, we find route stabilization in the context of ETX is only useful in the single flow case. To address multiple flows, we propose a modified solution in which we repeatedly broadcast RREQ (Route Request) packets. Simulation results show that our modified solution allows ETX to be useful in the initial route selection in both single flow and multiple flow cases.
Admission Control for VoIP and Data Traffic in IEEE 802.11 WLANs
P. Chatzimisios, P. Raptis, V. Vitsas, D. Amanatiadis K. Paparrizos
This paper presents an novel analytical model for calculation of throughput of the IEEE 802.11 Distributed Coordination Function (DCF) under variable packet length assuming ideal channel conditions. The proposed model applies to basic access scheme. Moreover, we use this model to present a simple algorithm to compute the voice capacity of an IEEE 802.11b WLAN and propose a simple admission control algorithm in order to maintain voice quality in a WLAN. Comparison of analytical results produced utilizing our proposed scheme against other admission control algorithms found in the literature shows fairly good performance.
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MODENETs 2008