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We present a performance study of a wireless mesh network based on off-the-shelf 802.11 technology. Unlike earlier work, we explore the practical constraints of the use of a “vanilla”, unmodified 802.11 MAC layer. We also consider the use of multiple radios, in the 5GHz band, to reduce interference. We establish the origin of degradation and limits in performance of practical deployments and study...
Emulation test beds are increasingly used to study the Internet. In this paper we briefly review various characteristics of a test bed based on the Emulab software that are necessary to conduct scientifically rigorous experiments: experiment fidelity and repeatability as well as measurement accuracy and interference. Our results indicate that the current trend of using emulation test beds is justified...
In this paper we have considered the channel assignment problem in multi-channel multi-radio wireless mesh networks. The problem is to assign channels to links in the network with the original topology preservation, and aim at minimizing the overall network interference which is proved to be NP-hard. We have first illustrated that the conversion from the channel assignment problem to the max k-cut...
The process of testing software that is to be deployed across an adhoc mobile networking environment is inherently challenging. The mobile domain introduces variable conditions mainly due to the wireless communications and the changing topology of the underlying network. Testing software is therefore difficult because of the sheer number of variables that must be considered in order to realistically...
In the last few years, long-distance WiFi networks have been used to provide Internet connectivity in rural areas. The strong requirement to support real-time applications in these settings leads us to consider TDMA link scheduling. In this paper, we consider the FRACTEL architecture for long-distance mesh networks. We propose a novel angular interference model, which is not only practical, but also...
The design/planning of WMNs is a key phase before any deployment. Few proposals can be found in the open literature that deals with the design problem; however, they do not take into account all the parameters that have an impact on the outcome of the design and they assume the existence of a physical topology where the location and the characteristics of nodes (e.g., number of channels, number of...
In this paper, we consider the problem of topology control by joint power control and routing to maximize the network throughput in wireless mesh networks. First, we present two mathematical formulations of the joint power control and routing problem according to two different definitions of network throughput: the total throughput and the minimal per-node throughput. To reduce the computation cost,...
In this paper, we address the problem of computing the transport capacity of Wireless Mesh Networks dedicated to Internet access. Routing and transmission scheduling have a major impact on the capacity provided to the clients. A cross-layer optimization of these problems allows the routing to take into account contentions due to radio interferences. We develop exact linear programs and provide an...
The assured forwarding (AF) service in a differentiated services network offers different levels of forwarding assurance for IP packets. Several studies have proposed to manipulate the contention window size to provide service differentiation in wireless networks. However, since network congestion in multi-hop wireless networks causes packet losses at the link layer, the contention window size based...
Opportunistic routing (OR) schemes, such as ExOR, have been shown to provide significant throughput gains over traditional best-path routing schemes for wireless networks. Though the performance of OR schemes depend on the bit-rate, they currently use a fixed rate for transmitting packets. While several schemes have been proposed for selecting bit-rate for unicast transmission to a single receiver,...
Wireless mesh network (WMN) has become a popular access network architecture. But because of its multi-hop nature, co-channel interference and contention, the attainable capacity of a wireless node in a WMN is significantly less than the radio capacity. We propose a overlay architecture for a WMN, where a wireless-ring (WRing) is deployed over the regular mesh for carrying wireless mesh traffic only...
In this paper, we introduce and evaluate ScaleMesh, a scalable miniaturized dual-radio wireless mesh testbed based on IEEE 802.11b/g technology- ScaleMesh can emulate large-scale mesh networks within a miniaturized experimentation area by adaptively shrinking the transmission range of mesh nodes by means of variable signal attenuators. To this end, we derive a theoretical formula for approximating...
In this paper, we propose an adaptive pacing scheme at the link layer for IEEE 802.11 based multihop wireless networks. Our objective is to improve the performance of higher layer protocols without any modifications to them. Our adaptive pacing scheme estimates the four-hop transmission delay in the network path without incurring any additional overheads, and accordingly paces the packets to reduce...
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