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A disruption-tolerant network (DTN) attempts to route packets between nodes that are temporarily connected. Difficulty in such networks is that nodes have no information about the network status and contact opportunities. The situation is different in public bus networks because the movement of buses exhibits some regularity so that routing in a deterministic way is possible. Many algorithms use a...
The application of directional antennas in wireless ad hoc networks brings numerous benefits, such as increased spatial reuse and mitigated interferences. Most MAC protocols with directional antennas are based on the RTS/CTS mechanism which works well in wireless ad hoc networks using omnidirectional antennas. However, RTS/CTS frames cannot mitigate the interference completely. Besides, they also...
In performance studies of vehicular ad hoc networks (VANETs), the underlying mobility model plays an important role. Since conventional mobile ad hoc network (MANET) routing protocols do not work efficiently in vehicular environments due to the rapid topology changes, the Delay-Tolerant Network (DTN) model is often applied. In this paper, we construct a new mobility model, the Shanghai Urban Vehicular...
This paper overviews the opportunities and challenges of distributed computing over optical network. The terabits optical network integrated computing environment (TONICE) project and the integrated resources management system (IRMS) are presented.
The number of available channels in a specific wireless network is bounded. Therefore, co-channel interference is inevitable in most wireless networks. The co-channel interference problem in wireless mesh networks is more serious than that in single-hop wireless networks. It is preferable for mesh nodes to dynamically adjust channels to elevate the interference level of networks. In this paper, we...
Sensor networks may generate a large amount of data during the monitoring process. It is crucial to conserve energy when processing these data. The detected sensory data vary in long monitoring period. The problem is how to design query processing with minimal energy and obtain correct result. In this paper, we propose a history-based approach to optimizing top-k query processing in sensor network...
Interference is a key factor that impacts the performance of wireless networks, especially when each node is equipped with multiple interfaces. Based on the classification criterion presented in this paper, we classify current interface assignment strategies into three types: static, dynamic and hybrid. We mainly address the problems of characterizing and evaluating interference effects of static...
It is crucial to design algorithms for energy-efficient query processing for a sensor network since sensor nodes are battery-powered, and thus their lifetimes are limited. We propose a history-based approach to optimizing query processing. We apply the approach to the top-k query problem and design new algorithms. Energy consumption can be reduced by pruning unnecessary sub-queries or guiding the...
In this paper, we address the following problem: given a set of wireless nodes on the plane, what is the number of channels needed to ensure a schedulable conflict-free communication? While the exact number of channels needed is very difficult to compute, we focus on an upper bound for this number, in terms of the node density D. In particular, we derive several upper bounds in terms of D based on...
In this work, we study the topology enhancement problem of wireless sensor networks. Our research focuses on reducing the path-based vulnerability. The objective is to get as much information as possible for any target moving out of the surveillance area. We study intelligent targets that have the knowledge of existing sensor distribution. Under such assumption, we find the vulnerable paths that rational...
Due to using the simplified interference model, IEEE 802.11 MAC protocol introduces the hidden and exposed terminal problems which significantly decrease the performance of ad hoc wireless networks. In this paper, we propose a novel Interference Graph based MAC protocol (IG-MAC) to improve the throughput of ad hoc wireless networks. The key point is to model the interference information by means of...
Although directional antennas have been used in mobile communications systems for quite a long time, realistic applications of directional or smart antennas in wireless ad hoc network have emerged just in recent years. Directional antennas provide numerous benefits, such as higher gains, increased transmission range and low interferences. Wireless medium access schemes play a crucial role in ensuring...
Although directional antennas have been used in mobile communications systems for quite a long time, realistic applications of directional or smart antennas in wireless ad hoc network have emerged just in recent years. Directional antennas provide numerous benefits, such as higher gains, increased transmission range and low interferences. Wireless medium access schemes play a crucial role in ensuring...
Multicast is important for realtime delivery of popular streaming media. Proxy-based multicast is an approach to implementing the multicast function by proxy servers at application levels. Many routing algorithms have been proposed to build an overlay network when proxy locations have been determined. On the other hand, the problem of where to place proxies has not been extensively studied yet. A...
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