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Wireless mesh networks: Opportunities and challenges
- Proceedings of World Wireless Congress
, 2005
"... Abstract — Wireless mesh networks have the potential to deliver Internet broadband access, wireless local area net-work coverage and network connectivity for stationary or mobile hosts at low costs both for network operators and customers. The core technology involves a network of wireless routers r ..."
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Abstract — Wireless mesh networks have the potential to deliver Internet broadband access, wireless local area net-work coverage and network connectivity for stationary or mobile hosts at low costs both for network operators and customers. The core technology involves a network of wireless routers relaying each others ’ packets in a multihop fashion. Many variations on targeted applications and implementation choices offer different opportunities to emerging companies in this emerging area. In this article, we will present an introduction to wireless mesh networks and present both the benefits enabled by this technology and the main hurdles that have to be overcome. I.
An Incentive-based Fairness Mechanism for Multi-hop Wireless Backhaul Networks with Selfish Nodes,” in
- IEEE Transactions on Wireless Communications
, 2008
"... Abstract — In this paper, we study the fairness problem in multi-hop wireless backhaul networks in the presence of selfish Transit Access Points (TAPs). We design an incentive-based mechanism which encourages TAPs to forward data for other TAPs, and thus eliminates the location-dependent unfairness ..."
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Abstract — In this paper, we study the fairness problem in multi-hop wireless backhaul networks in the presence of selfish Transit Access Points (TAPs). We design an incentive-based mechanism which encourages TAPs to forward data for other TAPs, and thus eliminates the location-dependent unfairness problem in the backhaul network. We prove the correctness and truthfulness of the proposed mechanism, and evaluate its performance via ns-2 simulations. The results show that the proposed mechanism achieves fairness even when there are idle TAPs in the network. Index Terms — Fairness, game theory, selfish node, wireless backhaul networks. I.
2012 32nd International Conference on Distributed Computing Systems Workshops Techniques for Enhancing TCP Performance in Wireless Networks
"... Abstract — Transmission Control Protocol (TCP) carries the maximum Internet traffic, so performance of TCP largely affects the performance of Internet. However, end-to-end throughput in TCP degrades notably when operated in wireless networks, since random packet losses and packet reordering are cons ..."
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Abstract — Transmission Control Protocol (TCP) carries the maximum Internet traffic, so performance of TCP largely affects the performance of Internet. However, end-to-end throughput in TCP degrades notably when operated in wireless networks, since random packet losses and packet reordering are considered as congestion. In wireless networks, due to high bit error rate and changing level of congestion, retransmission timeouts for packets lost in transmission is unavoidable. TCP misinterprets this loss to congestion and invokes congestion control by triggering fast retransmission and fast recovery, leading to under-utilization of the network resources. This paper presents various performance improvement mechanisms by which TCP does not consider every packet loss as congestion. These mechanisms help TCP to distinguish between congestion and packet loss and increase throughput performance.
Authors Declaration for Electronic
"... I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. public. I understand that my thesis may be made electronically available to the ii Multi-hop wireless networks based on 802.11 are being ..."
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I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. public. I understand that my thesis may be made electronically available to the ii Multi-hop wireless networks based on 802.11 are being used more widely as an alternative technology for last-mile broadband Internet access. Their benefits include ease of deployment and lower cost. Such networks are not without problems. Current research on such networks aims at a number of challenges, including overcoming capacity limitation and poor fairness. The focus of our research is for achieving fairness in multi-channel multi-hop wireless networks. First, we review the literature for different methods for representing link-contention areas, and the existing single-channel fairness computational model. Second, we generalize the fairness constraints applied to each link-contention area, defined in the existing single-channel fairness reference model, to multi-channel models. Third, by adopting the concepts of link-usage matrix and medium-usage matrix to represent network topology and flow status, and using Collision Domain theory and Clique Graph theory to represent link-contention area, we develop a computational model to com-pute optimal MAC-layer bandwidth allocated to each flow in a multi-channel multi-hop WMN. We simulate various network configurations to evaluate the performance of the fairness algorithm based on the above computational iii model in different scenarios. We have found that in the multi-channel envi-ronment, our extension to the Collision Domain model generally provides a more accurate estimation of network capacity. Based on this model, we have extended the source-rate-limiting mechanism, which limits the flow rate to its fair share computed by the computational model. Experimental results that validate these findings are presented in this thesis. iv
Privileging Long-life Packets in Multihop Wireless Networks
"... Abstract — The typical application of wireless mesh networks is Internet access. This application introduces a gateway, which becomes the preferred destination in the network. In such topology, the throughput share is unfair because the number of medium accesses increases with the distance to the ga ..."
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Abstract — The typical application of wireless mesh networks is Internet access. This application introduces a gateway, which becomes the preferred destination in the network. In such topology, the throughput share is unfair because the number of medium accesses increases with the distance to the gateway. In this work, we propose the Route-Length-based Fairness (RLF) mechanism to assign a higher priority on medium access for packets that traverse a high number of hops, named long-life packets. When comparing the proposed mechanism to IEEE 802.11g, the simulation results show a considerable improvement in fairness for applications running over UDP and TCP.
A Fair Medium Access Protocol using Adaptive Flowrate Control through Cooperative Negotiation among Contending flows in Ad hoc Wireless Network with Directional Antenna
"... Abstract. Medium Access Control protocols proposed in the context of ad hoc networks primarily aim to control the medium access among contending nodes using some contention resolution schemes. However, these protocols do not necessarily guarantee a fair allocation of wireless medium among contending ..."
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Abstract. Medium Access Control protocols proposed in the context of ad hoc networks primarily aim to control the medium access among contending nodes using some contention resolution schemes. However, these protocols do not necessarily guarantee a fair allocation of wireless medium among contending flows. Our objective in this paper is to adaptively adjust the flow-rates of contending flows, so that each gets fair access to the medium. This adaptive adjustment will also ensure high packet delivery ratio and optimal utilization of wireless medium. We use a deterministic approach to adaptively improve the performance of the suffered flows in the network through mutual negotiation between contending flows. In this paper we have also suggested the use of directional antenna to further reduce the contention between the flows in the wireless medium. The proposed scheme is evaluated on QualNet network simulator to demonstrate that our scheme guarantees fairness to all contending flows. 1
A Novel Queue Management Mechanism for IEEE 802.11s based Mesh Networks
, 2005
"... Abstract – Wireless Mesh networks exploit multi-hop wireless communications between Access Points to replace wired infrastructure. However, in multi-hop networks, effective bandwidth decreases with increasing number of hops, mainly due to increased spatial contention. Longer hop length flows suffer ..."
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Abstract – Wireless Mesh networks exploit multi-hop wireless communications between Access Points to replace wired infrastructure. However, in multi-hop networks, effective bandwidth decreases with increasing number of hops, mainly due to increased spatial contention. Longer hop length flows suffer from extremely low throughputs which is highly undesirable in the envisioned scenarios for mesh networks. In this paper, we show that Queue/Buffer management, at intermediate relay mesh nodes, plays an important role in limiting the performance of longer hop length flows. We propose a novel queue management algorithm for IEEE 802.11s based mesh networks that improves the performance of multihop flows by fairly sharing the available buffer at each mesh point among all the active source nodes whose flows are being forwarded. Extensive simulations reveal that our proposed scheme substantially improves the performance of multihop flows. We also identify some important design issues that should be considered for the practical deployment of such mesh networks. Nagesh S. Nandiraju et al. 2 of 13 1.
Probabilistic-Based Energy Aware Routing for Network Lifetime and Source Level Fairness in Wireless Sensor Networks
"... Wireless sensor networks usually sample the state of physical phenomena in space. Sensor nodes, which usually have limited energy, collect data locally and forward them to a sink node. Thus there are two operating domains pertinent to the performance of such networks: (1) in time, the network longev ..."
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Wireless sensor networks usually sample the state of physical phenomena in space. Sensor nodes, which usually have limited energy, collect data locally and forward them to a sink node. Thus there are two operating domains pertinent to the performance of such networks: (1) in time, the network longevity or lifetime, and (2) in space, the network coverage or source level fairness, which is the effectiveness of the collected spatial state being reported at the sink. In this paper we propose a simple, localized, probabilistic-based protocol that addresses performance issues in both domains. Our protocol addresses the time domain by exploring multiple paths for data delivery so that energy consumption can be uniformly distributed throughout the network and all available energy be utilized, and addresses the spatial domain by dropping packets selectively in congested nodes, so that data flows from all sources will have their share of bandwidth to reach the sink. 1.
Achieving Throughput Fairness in Wireless Mesh Networks Based on IEEE 802.11 Abstract—In IEEE 802.11 based Wireless Mesh Networks
"... (WMNs), unfair bandwidth sharing may arise since the CSMA/CA protocol is designed to provide per station fairness only in one hop. As the hop count from a mobile client to the gateway node increases, throughput of the node decreases drastically. In this paper, we propose a fair bandwidth allocation ..."
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(WMNs), unfair bandwidth sharing may arise since the CSMA/CA protocol is designed to provide per station fairness only in one hop. As the hop count from a mobile client to the gateway node increases, throughput of the node decreases drastically. In this paper, we propose a fair bandwidth allocation scheme for multi-radio multi-channel WMNs. This scheme provides fair bandwidth sharing among the nodes in a WMN regardless of their hop distance from the gateway node. To achieve the fairness, we first estimate the number of active nodes attached to each router, and calculate effective weights of routers based on the estimation. Then, we differentiate the contention window of them using their weights. For that, we derive a multi-hop packet collision model. The proposed scheme is fully distributed, and does not require any global information. Through an extensive simulation study, we show that our scheme ensures per node fairness without loss of the total aggregate throughput. I.
