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This paper investigates an underlay cognitive radio (CR) that extracts energy from radio-frequency signals of one primary user. We assume that both the wireless energy harvesting and the secondary transmission processes of the CR suffer Rayleigh block fading. Considering the intrinsic harvesting- transmitting tradeoff, we optimize the harvesting time and transmit power of the CR to minimize the outage...
We study real-time multicast scheduling in multi- hop wireless sensor networks. Given multiple heterogeneous periodic multicast tasks, for each task, the data produced by the distinguished source node for a certain control application with sufficiently long time horizon need to be delivered to all target nodes periodically, the objective is to design an interference-aware routing and scheduling protocol...
Spectrum sensing is a critical component for cognitive radio networks. Most of the spectrum sensing algorithms and performance analysis, however, assume that the secondary users are stationary. In this paper, we investigate the performance analysis of spectrum sensing by mobile secondary users. Two performance metrics, false alarm probability and miss detection probability, are thoroughly investigated...
For wireless networks, coverage with different restrictions that can capture the practical requirements have received great research interests. We will study several restricted coverage problems. The first problem is about K-coverage, i.e., how to deploy wireless nodes such that each target is covered by at least K wireless nodes. We study the problem restricted to linear-A"-coverage where there...
We study real time periodic query scheduling for data collection in multihop Wireless Sensor Networks (WSNs). Given a set of heterogenous data collection queries in WSNs, each query requires the data from the source sensor nodes to be collected to the control center within a certain end-to-end delay. We first propose almost-tight necessary conditions for a set of different queries to be schedulable...
We study delay-efficient data aggregation scheduling in wireless sensor networks subject to signal to interference-plus-noise ratio (SINR) constraints. We construct a routing tree and propose two scheduling algorithms that can generate collision-free link schedules for data aggregation. We prove that the delay of each algorithm is $(O(R+\Delta ))$ time slots, where $(R)$ and $(\Delta)$ are respectively...
In many practical applications of wireless sensor networks, it is crucial to accomplish the localization of sensors within a given time bound. We find that the traditional definition of relative localization is inappropriate for evaluating its actual overhead. To address this problem, we define a novel problem called essential localization, and present the first rigorous study on the essential localizability...
Position information is important for spatial information grids. In accurate position of datum may lead to mistake decisions or even disastrous actions. In this paper, we study the problem of localization for spatial information grid in underwater environments. There are many challenges facing the localization in underwater environments, because the unavailability of radio frequency. Besides, there...
This paper introduces a high-performance vehicle detection algorithm for a parking management system based on wireless sensor technology. The parking lot is represented as a wireless sensor network cluster modeled as an m ?? n grid in a rectangle of size I ?? h. A wireless sensor node is deployed in each grid and one gateway is set for the cluster. The status of each parking space is detected by a...
Time synchronization is a key component in numerous wireless sensor network applications. Most of the current software based time synchronization approaches suffer from communication overhead and lack of scalability. In this paper, we propose a hardware based approach based on voltage controlled crystal oscillator and phase locked loop techniques to achieve and maintain sub microsecond level time...
In this paper, we investigate the impact of antenna orientation on the performance of wireless sensor networks. In the experiments conducted using Crossbow MicaZ motes we realized that the antenna orientation has a significant impact on the received signal strength (RSSI). It thus becomes important to incorporate the effects on RSSI due to variations in antenna orientations while performing simulations...
Achieving efficient bandwidth utilization in multi-channel sensor networks is a challenging research problem. In this paper, we present a cognitive load balance algorithm for single-hop multi-channel sensor networks. Based on the load distribution of all base stations, our algorithm dynamically alternates the communication channels. As a result, the extra load from over-loaded channels is directed...
In a wireless sensor network, an adversary may crack legal nodes or deploy malicious nodes to launch various attacks. These nodes are collectively called compromised nodes. In this paper, we define a data transmission quality (DTQ) function to differentiate the legitimate nodes and compromised nodes. The DTQ function is defined in a way that it will keep close to constant or change smoothly for legitimate...
Wireless sensor networks are often divided into clusters to gain high-performance and prolong network lifetime. In this paper we analyze the network capacity of two different architectures, named flat sensor network and clustered sensor network. For each network, we first define the network model and then analyze the network capacity and the factors that affect the capacity. Numerical results suggest...
While wireless sensor networks are proving to be a versatile tool, many of the applications in which they are implemented have sensitive data. In other words, security is crucial in many of these applications. Once a sensor node has been compromised, the security of the network degrades quickly if there are not measures taken to deal with this event. There have been many approaches researched to tackle...
Source and destination location privacy is a challenging and important problem in sensor networks. Nevertheless, privacy preserving communication in sensor networks is still a virgin land. In this paper, we propose to protect location privacy via a flooding backbone, which is modeled by a minimum connected dominating set (MCDS) in unit-disk graphs. We design an efficient and localized algorithm to...
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