Fuping Hu

Efficient Localized Localization Algorithm for Wireless Sensor Networks

The location of sensor nodes in wireless sensor networks plays an important role in most applications. In this paper, we address the localization problem by characterizing some sufficient conditions such that technical convenience for the collection of local information used for network localization can be enabled. The main contribution of this paper is as follows. Some latest research results on the graph rigidity theory are introduced and incorporated, and a feasible node localization scheme is presented. More specifically, a tree structure termed BN-tree is introduced to construct a localizable collaborative body. Especially, the localizable collaborative body can be constructed dynamically with the variety of the network topology. Simulation results, which show that the quality of localization is well bounded by the range of communication, are also provided to validate the proposed algorithm

Secure cooperative spectrum sensing for Cognitive Radio networks

A key enabling functionality in implementing Cognitive Radio is to reliably detect the licensed users. In recent literature, cooperation among spectrum sensing terminals is suggested to offer reliable sensing performance. We consider the problem that the presence of malfunctioning or malicious sensing terminals will severely degrade the performance of cooperative spectrum sensing. In this paper, we extend the Weighted Sequential Probability Ratio Test (WSPRT) by replacing the binary local report with N-bits local report to achieve a better detection performance. Additionally, three types of reputation rating evaluation schemes are introduced: neutral, punitive and heavy punitive. Simulation results show that the extended WSPRT technique improves detection performance. Moreover, the extended WSPRT with heavy punitive scheme is shown to be the most robust against the malfunctioning or malicious sensing terminals.

Energy Detection for Spectrum Sensing in Cognitive Radio Sensor Network over Fading Channels

With the exciting progress of wireless sensor networks (WSN), a major difficulty will be faced in that the limited frequency spectrum, even with the industrial, scientific and medical (ISM) bands, will be extremely crowded. Moreover purchasing spectrum rights with millions or billions of dollars is unreasonable under an emphasis on low-cost to WSN. Thus an alternate method based on the concept of Cognitive Radio is explored to capture spectrum for WSN. A cooperative energy detection technique is introduced. The probabilities of detection of proposed technique are evaluated over some classical fading channels. The quantization case is also considered for practicality. The simulation results show that the quantization case exhibits almost comparable performance with the optimum Neyman-Pearson detector, while it has much less overhead.

On connectivity for wireless sensor networks localization

Node localization in wireless sensor networks has been a topic of active research in recent years. Network connectivity has been shown to be effective with respect to increasing localization performance via redundant nodes. In this paper, we study the connectivity of wireless sensor networks from a network self-localization prospective. To the best of our knowledge, theoretic analyses of the network connectivity for node self-localization have not been previously studied in the networking literature. Assuming a spatial Poisson distribution of network nodes, we modeled the network as random graph and derived an analytical expression that allows the determination of the localizable probability of any an unknown node for given network density /spl rho/. The problems have also been investigated by simulation in various scenarios. Our results are of practical value for designing sensor network considering of node self-localization.

Cognitive Radio Based Multiple Access Algorithm for Differential Frequency Hopping Network

Cognitive radio (CR) is a revolutionary technology of wireless mobile communication. Smart users can use the CR technology to sense the surrounding environment, search for available spectrum resources and access spectrum dynamically. Differential frequency hopping (DFH) was believed to be an effective FH technique for increasing data rate of HF communication system. The cognitive radio technology is introduced in DFH. And a cognitive radio based multiple access algorithm (ITMA) is proposed. This algorithm is based on the interference temperature model, which is applied to the DHF network with the MAI-tolerant. The scenario simulations of the ITMA DFH network and the conventional DFH network are performed, respectively. The results show that the ITMA DFH network can obtain favorable network performance.

CogDFH- a Cognitive-Based differential frequency hopping network

Cognitive radio (CR) is a revolutionary wireless mobile communication technology. Smart users can use the CR technology to sense the surrounding environment, search for available spectrum resources and access spectrum dynamically. Differential frequency hopping (DFH) is known as an effective FH technique for increasing data rate of HF communication system. In this study, the cognitive radio technology was applied in DFH, and a CogDFH network was proposed. This network which is built upon the interference temperature model, IC-colorings and IC-indices of graphs, was applied to the DHF network with easy build, high robustness and low interference. The scenario simulations of both Cognitive-Based DFH Network and traditional DFH were performed. The results indicate that the network performance can be improved by CR.

DOA Estimation of Coherent Signal Using MUSIC Algorithm with Nonuniform Sampling

The channel outputs are sampled on nonuniform sampling sets, and an analysis of the decorrelation based on nonuniform sampling (NUS) is investigated. It is demonstrated that MUSIC algorithm with NUS of various array elements may be capable of selecting the signal of interesting including the coherent group. NUS in the time domain is equivalent to alter the relative distance between sensors and leads to the radiant sources impinging the different arrays between two snapshots just as a virtual array spatial smoothing preprocessing. Simulations are conducted to verify that MUSIC based on nonuniformity of sensor sampling is effective to estimate direction-of-arrival (DOA) of incident signals in the coherent environment. Simultaneously, its beneficial to greatly improve the estimation accuracy and angular resolution as a result of larger array aperture introduced but no angle-measure ambiguity and offer a better performance in lower SNR than weighted spatial smoothing (WSS) with MUSIC algorithm.

A method improving accuracy of self-localization in wireless sensor networks

Determining the location of nodes with error as low as possible in wireless sensor networks is an essential task for many applications. It can be shown that, in some case, evident location estimation errors would be brought even if the ranging error is low. This work involves a parameter called geometry favorable factor (GFF) to filter these ill case. We propose an improving method choosing the available beacon nodes (nodes with prior known locations) with the best GFF for sensor location estimation. Simulation results show that the improving method lead to a significant improvement in location estimation accuracy compared with normal method that without filtering, while some decrease in population of localizable nodes.

Wireless sensor networks solution for space environmental monitoring

Wireless Sensor Networks (WSNs) is a novel technology in acquiring and processing information and has been an active research area in recent years. Because of the energy constraints of sensor nodes, such systems necessitate an energy-aware design to ensure the longevity of monitoring mission. In this paper, we present a remote space environmental monitoring system using wireless sensor networks. Some key technologies are investigated and discussed in detail. Firstly, the architecture of WSN is provided as well as the component structure of sensor nodes. Then, the key technologies including energy aware routing and localization scheme involved in the system are investigated. By simulation software OMNeT++, we include a performance study demonstrating the advantages of our approach based on simulation study. Simulation results show that the quality of localization is well bounded by the range of communication and the topology control is effective.