Showing papers in "Wireless Sensor Network in 2009"

An Energy-Efficient MAC Protocol for Wireless Sensor Networks

Abstract: This paper proposes S-MAC, a medium-access control (MAC) protocol designed for wireless sensor networks. Wireless sensor networks use battery-operated computing and sensing devices. A network of these devices will collaborate for a common application such as environmental monitoring. We expect sensor networks to be deployed in an ad hoc fashion, with individual nodes remaining largely inactive for long periods of time, but then becoming suddenly active when something is detected. These characteristics of sensor networks and applications motivate a MAC that is different from traditional wireless MACs such as IEEE 802.11 in almost every way: energy conservation and self-configuration are primary goals, while per-node fairness and latency are less important. S-MAC uses three novel techniques to reduce energy consumption and support self-configuration. To reduce energy consumption in listening to an idle channel, nodes periodically sleep. Neighboring nodes form virtual clusters to auto-synchronize on sleep schedules. Inspired by PAMAS, S-MAC also sets the radio to sleep during transmissions of other nodes. Unlike PAMAS, it only uses in-channel signaling. Finally, S-MAC applies message passing to reduce contention latency for sensor-network applications that require store-and-forward processing as data move through the network. We evaluate our implementation of S-MAC over a sample sensor node, the Mote, developed at University of California, Berkeley. The experiment results show that, on a source node, an 802.11-like MAC consumes 2–6 times more energy than S-MAC for traffic load with messages sent every 1–10s.

High Resolution MIMO-HFSWR Radar Using Sparse Frequency Waveforms

Abstract: In high frequency surface wave radar (HFSWR) applications, range and azimuth resolutions are usually lim-ited by the bandwidth of waveforms and the physical dimension of the radar aperture, respectively. In this paper, we propose a concept of multiple-input multiple-output (MIMO) HFSWR system with widely sepa-rated antennas transmitting and receiving sparse frequency waveforms. The proposed system can overcome the conventional limitation on resolutions and obtain high resolution capability through this new configura-tion. Ambiguity function (AF) is derived in detail to evaluate the basic resolution performance of this pro-posed system. The advantages of the system of fine resolution and low peak sidelobe level (PSL) are demon-strated by the AF analysis through numerical simulations. The impacts of Doppler effect and the geometry configuration are also studied.

Voronoi-Based Coverage Optimization for Directional Sensor Networks

Abstract: Sensing coverage is a fundamental problem in sensors networks. Different from traditional isotropic sensors with sensing disk, directional sensors may have a limited angle of sensing range due to special applications. In this paper, we study the coverage problem in directional sensor networks (DSNs) with the rotatable orientation for each sensor. We propose the optimal coverage in directional sensor networks (OCDSN) problem to cover maximal area while activating as few sensors as possible. Then we prove the OCDSN to be NP-complete and propose the Voronoi-based centralized approximation (VCA) algorithm and the Voronoi-based distributed approximation (VDA) algorithm of the solution to the OCDSN problem. Finally, extensive simulation is executed to demonstrate the performance of the proposed algorithms.

A Cognitive Radio Receiver Supporting Wide-Band Sensing

Abstract: The specification of IEEE 802.22 defines the world-wide first cognitive radio (CR) standard. Within a range of 40 MHz to 910 MHz CR systems are allowed to allocate spectrum besides the currently established radio services like radio and TV broadcasting. In order to fulfill the regulative guidelines of interference limita-tions, a capable spectral sensing and user detection has to be provided. Due to the wide frequency range specified in IEEE 802.22 and the high dynamic range of signals allocated in this band there are high de-mands on the CR receiver’s front-end. Especially the performance requirements on analog-to-digital con-verters increase significantly compared to current wireless systems. Based on measurements taken in this frequency range requirements to CR’s ADCs are figured out. Furthermore, the measurement results are ana-lyzed regarding expectable allocation scenarios and their impacts to spectral sensing. Derived from this re-sults and a comparison of general spectral sensing mechanisms an approach for a CR receiver supporting wide-band sensing is presented. Considering the apriori information resulting from scenario analysis and including adapted information processing in the terminal the ADC’s performance requirements can be re-duced.

ContSteg: Contourlet-Based Steganography Method

Abstract: A category of techniques for secret data communication called steganography hides data in multimedia me-diums. It involves embedding secret data into a cover-medium by means of small perceptible and statistical degradation. In this paper, a new adaptive steganography method based on contourlet transform is presented that provides large embedding capacity. We called the proposed method ContSteg. In contourlet decomposi-tion of an image, edges are represented by the coefficients with large magnitudes. In ContSteg, these coeffi-cients are considered for data embedding because human eyes are less sensitive in edgy and non-smooth re-gions of images. For embedding the secret data, contourlet subbands are divided into 4×4 blocks. Each bit of secret data is hidden by exchanging the value of two coefficients in a block of contourlet coefficients. Ac-cording to the experimental results, the proposed method is capable of providing a larger embedding capacity without causing noticeable distortions of stego-images in comparison with a similar wavelet-based steg-anography approach. The result of examining the proposed method with two of the most powerful steganaly-sis algorithms show that we could successfully embed data in cover-images with the average embedding ca-pacity of 0.05 bits per pixel.

An Energy-Efficient MAC Protocol for Ad Hoc Networks

Abstract: A mobile ad hoc network (MANET) is a collection of nodes equipped with wireless communications and a networking capability without central network control. Nodes in a MANET are free to move and organize themselves in an arbitrary fashion. Energy-efficient design is a significant challenge due to the characteristics of MANETs such as distributed control, constantly changing network topology, and mobile users with limited power supply. The IEEE 802.11 MAC protocol includes a power saving mechanism, but it has many limitations. A new energy-efficient MAC protocol (EE-MAC) is proposed in this paper. It is shown that EE-MAC performs better than IEEE 802.11 power saving mode and exceeds IEEE 802.11 with respect to balancing network throughput and energy savings.

Real-Time Automatic ECG Diagnosis Method Dedicated to Pervasive Cardiac Care

Abstract: Recent developments of the wireless sensor network will revolutionize the way of remote monitoring in dif-ferent domains such as smart home and smart care, particularly remote cardiac care. Thus, it is challenging to propose an energy efficient technique for automatic ECG diagnosis (AED) to be embedded into the wireless sensor. Due to the high resource requirements, classical AED methods are unsuitable for pervasive cardiac care (PCC) applications. This paper proposes an embedded real-time AED algorithm dedicated to PCC sys-tems. This AED algorithm consists of a QRS detector and a rhythm classifier. The QRS detector adopts the linear time-domain statistical and syntactic analysis method and the geometric feature extraction modeling technique. The rhythm classifier employs the self-learning expert system and the confidence interval method. Currently, this AED algorithm has been implemented and evaluated on the PCC system for 30 patients in the Gabriel Monpied hospital (CHRU of Clermont-Ferrand, France) and the MIT-BIH cardiac arrhythmias da-tabase. The overall results show that this energy efficient algorithm provides the same performance as the classical ones.

Research on ZigBee Wireless Sensors Network Based on ModBus Protocol

Abstract: The information transmission is transparent for the user in the ZigBee wireless sensors network, which are lack of interactivity and self-constrain. The information in the ZigBee wireless sensors network can not be viewed in a real time by a friendly interface. Modbus protocol is embedded into ZigBee stack, in this way, we can implement interaction well and the information can be viewed in a friendly interface. The paper presents the measures to embed the Modbus protocol into the ZigBee stack provided by Chipcon company, which contains address bound mechanism, information centralized storage, and flexible monitoring, by which we can monitor the real time information from the ZigBee wireless network and use some instructions to control the remote device in a friendly interface, which can be used well in the middle and small ZigBee monitoring wireless sensors network. We implement it in the plant physiological ecology monitoring system.

An Energy Balanced Reliable Routing Metric in WSNs

Abstract: In WSNs’ applications, not only the reliable end-to-end communications are must be ensured, but also the reduction of energy consumption and the entire network’s lifetim e should be optimized. All of the above have become to be an important way to evaluate the performance of routing protocols. In this paper, an optimization model for WSNs’ lifetime is firstly advanced. Secondly, the shortage of ETX based routing metric is solved with the help of the optimization model. Thirdly, an energy balanced routing metric is advanced which is called EBRM in this paper. The result of simulation in NS-2 shows that, the EBRM metric can not only prolong the network’s lifetime, but also can ensure the reliable end-to-end communication.

Wireless Sensor Network Management and Functionality: An Overview

Abstract: Sensor networks are dense wireless networks of small, low-cost sensors, which collect and disseminate en-vironmental data. Wireless sensor networks facilitate monitoring and controlling of physical environments from remote locations with better accuracy. They have applications in a variety of fields such as environ-mental monitoring; military purposes and gathering sensing information in inhospitable locations. Sensor nodes have various energy and computational constraints because of their inexpensive nature and adhoc method of deployment. Considerable research has been focused at overcoming these deficiencies through more energy efficient routing, localization algorithms and system design. Our survey presents the funda-mentals of wireless sensor network, thus providing the necessary background required for understanding the organization, functionality and limitations of those networks. The middleware solution is also investigated through a critical presentation and analysis of some of the most well established approaches.

An Energy-Efficient MAC Protocol for WSNs: Game-Theoretic Constraint Optimization with Multiple Objectives

Abstract: In WSNs, energy conservation is the primary goal, while throughput and delay are less important. This re-sults in a tradeoff between performance (e.g., throughput, delay, jitter, and packet-loss-rate) and energy con-sumption. In this paper, the problem of energy-efficient MAC protocols in WSNs is modeled as a game-theoretic constraint optimization with multiple objectives. After introducing incompletely cooperative game theory, based on the estimated game state (e.g., the number of competing nodes), each node independ-ently implements the optimal equilibrium strategy under the given constraints (e.g., the used energy and QoS requirements). Moreover, a simplified game-theoretic constraint optimization scheme (G-ConOpt) is pre-sented in this paper, which is easy to be implemented in current WSNs. Simulation results show that G-ConOpt can increase system performance while still maintaining reasonable energy consumption.

The Effect of Notch Filter on RFI Suppression

Abstract: Radio Frequency Interference (RFI) suppression is an important technique in the ultra-wideband synthetic aperture radar (UWB SAR). In this paper, we mainly analyze the performance of a notch filter for RFI sup-pression. The theoretical output from notch filter is presented based on RFI signal’s narrowband property. The research conclusion shows that the notch filter has significant effect on sidelobes of the system response, which might be considered to be false targets, however it has little effect on the resolution of the system re-sponse. The theoretical result is verified by simulation and experimental data processing both in one dimen-sion (range dimension) and in two dimensions (range and azimuth dimension).

An Adaptive Data Aggregation Algorithm in Wireless Sensor Network with Bursty Source

Abstract: The Wireless Sensor network is distributed event based systems that differ from conventional communica-tion network. Sensor network has severe energy constraints, redundant low data rate, and many-to-one flows. Aggregation is a technique to avoid redundant information to save energy and other resources. There are two types of aggregations. In one of the aggregation many sensor data are embedded into single packet, thus avoiding the unnecessary packet headers, this is called lossless aggregation. In the second case the sensor data goes under statistical process (average, maximum, minimum) and results are communicated to the base station, this is called lossy aggregation, because we cannot recover the original sensor data from the received aggregated packet. The number of sensor data to be aggregated in a single packet is known as degree of ag-gregation. The main contribution of this paper is to propose an algorithm which is adaptive to choose one of the aggregations based on scenarios and degree of aggregation based on traffic. We are also suggesting a suitable buffer management to offer best Quality of Service. Our initial experiment with NS-2 implementa-tion shows significant energy savings by reducing the number of packets optimally at any given moment of time.

Blending Sensor Scheduling Strategy with Particle Filter to Track a Smart Target

Abstract: We discuss blending sensor scheduling strategies with particle filtering (PF) methods to deal with the prob-lem of tracking a ‘smart’ target, that is, a target being able to be aware it is being tracked and act in a manner that makes the future track more difficult. We concern here how to accurately track the target with a care on concealing the observer to a possible extent. We propose a PF method, which is tailored to mix a sensor scheduling technique, called covariance control, within its framework. A Rao-blackwellised unscented Kal-man filter (UKF) is used to produce proposal distributions for the PF method, making it more robust and computationally efficient. We show that the proposed method can balance the tracking filter performance with the observer’s concealment.

H-TOSSIM: Extending TOSSIM with Physical Nodes*

Abstract: As the development of Wireless Sensor Network (WSN), software testing for WSN-based applications be-comes more and more important. Simulation testing is an important approach to WSN-based software testing, and TOSSIM is the most widely used simulation testing tool targeted at TinyOS which is the most popular operating system nowadays. However, simulation testing tools such as TOSSIM can not reveal program er-rors about communication detail or timing, and lack accurate power consumption model and even can not support power consumption estimation. In this paper, a hybrid testbed H-TOSSIM is proposed, which ex-tends TOSSIM with physical nodes. H-TOSSIM uses three physical nodes, of which, one shares the simu-lated environment with all virtual nodes to test the WSN program, and the other two bridge the real world and the simulated environment. H-TOSSIM combines the advantages of both the simulation in physical node and the simulation testing tools in WSN software testing. Through experiments, we show that H-TOSSIM really reveals program errors which the pure simulation testing can not capture, and can support power con-sumption estimation for large WSN with high accuracy and low hardware cost.

Reconfigure ZigBee Network Based on System Design

Abstract: This article analyses key technology used by network layer based on ZigBee technology. Then a reconfigure network as well as its strategy of forming network and distributing node is given. The simulation proved that the stability of reconfigure network and the ability of transmitting pass through obstacle are better than tradi-tional network; it has an active significance for shorter delay because of the flexible of the improved forming network strategy.

Minimization of Collision in Energy Constrained Wireless Sensor Network

Abstract: Wireless Sensor Networks (WSNs) are one of the fastest growing and emerging technologies in the field of Wireless Networking today. The applications of WSNs are extensively spread over areas like Military, En-vironment, Health Care, Communication and many more. These networks are powered by batteries and hence energy optimization is a major concern. One of the factors that reduce the energy efficiency of the WSN is collision which occurs due to the high density of data packets in a typical communication channel. This paper aims at minimizing the effects of congestion leading to collision in the network by proposing an effective algorithm. This can be done by optimizing the size of the contention window by introducing pa-rameters like source count and α. If the contention window of a node is low, it results in collision. If the size of the contention window of a node is high then it results in a medium access delay. Thus minimizing colli-sion and medium access delay of data packets conserve energy.

A Novel DSA-Driven MAC Protocol for Cognitive Radio Networks

Abstract: With the deployment of more wireless applications, spectrum scarcity becomes an issue in many countries Recent reports show that the reason for this spectrum shortage is the underutilization of some spectrum re-sources Fortunately, the emergence of open spectrum and dynamic spectrum assess (DSA) technology in cognitive radio networks relieves this problem In this paper, we propose a novel DSA-driven cognitive MAC protocol to achieve highly efficient spectrum usage and QoS provisioning In the proposed protocol, secondary users are divided into several non-overlapping groups, and all leftover channels are allocated among groups taking the groups’ bandwidth requirements into consideration Moreover, the allocation of vacant channels can be adjusted dynamically when members join/leave groups or primary users return/leave the current network Simulations show that the proposed MAC protocol greatly improves the quality of ser-vice for secondary users and maximizes the utilization ratio of spectrum resources

Research on DOA Estimation of Multi-Component LFM Signals Based on the FRFT

Abstract: A novel algorithm for the direction of arrival (DOA) estimation based on the fractional Fourier transform (FRFT) is proposed. Firstly, using the properties of FRFT and mask processing, Multi-component LFM sig-nals are filtered and demodulated into a number of stationary single frequency signals. Then the one-dimensional (1-D) direction estimation of LFM signals can be achieved by combining with the tradi-tional spectrum search method in the fractional Fourier (FRF) domain. As for the multi-component LFM signals, there is no cross-term interference, the mean square error (MSE) and Cramer-Rao bound (CRB) are also analyzed which perfects the method theoretically, simulation results are provided to show the validity of our method. The proposed algorithm is also extended to the uniform circular array (UCA), which realizes the two-dimensional (2-D) estimation. Using the characteristics of time-frequency rotation and demodulation of FRFT, the observed LFM signals are demodulated into a series of single frequency ones; secondly, operate the beam-space mapping to the single frequency signals in FRF domain, which UCA in array space is changed into the virtual uniform circular array (ULA) in mode space; finally, the DOA estimation can be realized by the traditional spectral estimation method. Compared with other method, the complex time-frequency cluster and the parameter matching computation are avoided; meanwhile enhances the esti-mation precision by a certain extent. The proposed algorithm can also be used in the multi-path and Doppler frequency shift complex channel, which expands its application scope. In a word, a demodulated DOA esti-mation algorithm is proposed and is applied to 1-D and 2-D angle estimation by dint of ULA and UCA re-spectively. The detailed theoretical analysis and adequate simulations are given to support our proposed al-gorithm, which enriches the theory of the FRFT.

Policy Based Self-Adaptive Scheme in Pervasive Computing

Abstract: Nowadays, application systems in pervasive computing have to be self-adaptive, which means adapting themselves to dynamic environments. Our aim is to enable systematic development of self-adaptive compo-nent-based applications. The paper first introduces a novel policy based framework for self-adaptive scheme in pervasive computing. Then the proposed policy ontology and policy language are well expressive and eas-ily extensible to support the design of policy which is based on the Separation of Concerns principle. Fur-thermore, the context-driven event channel decouples the communication between the suppliers and con-sumers for asynchronous communication. The proposed framework can provide both a domain-independent and a flexible self-adaptation solution.

Micro Controller Based Ac Power Controller

Abstract: This paper discusses the design and implementation of single phase PWM inverter using 8051 microcontrol-ler. The main features of 8051 based PWM inverter are simpler design, low cost, maximum range of voltage control and compact in size. The designed PWM inverter is tested on various AC loads like AC motor and intensity control of incandescent lamp in a closed loop environment.

Research on Blind Source Separation for Machine Vibrations

Abstract: Blind source separation is a signal processing method based on independent component analysis, its aim is to separate the source signals from a set of observations (output of sensors) by assuming the source signals independently. This paper reviews the general concept of BSS firstly; especially the theory for convolutive mixtures, the model of convolutive mixture and two deconvolution structures, then adopts a BSS algorithm for convolutive mixtures based on residual cross-talking error threshold control criteria, the simulation testing points out good performance for simulated mixtures.

Novel Tag Anti-Collision Algorithm with Adaptive Grouping

Abstract: For RFID tags, a Novel Tag Anti-collision Algorithm with Grouping (TAAG) is proposed. It divides tags into groups and adopts a deterministic method to identify tags within group. TAAG estimates the total number of tags in systems from group identifying result and then adjusts the grouping method accordingly. The performance of the proposed TAAG algorithm is compared with the conventional tag anti-collision algorithms by simulation experiments. According to both the analysis and simulation result, the proposed algorithm shows better performance in terms of throughput, total slots used to identify and total cycles.

Bandwidth Efficient Three-User Cooperative Diversity Scheme Based on Relaying Superposition Symbols

Abstract: Recently, Cooperative diversity in wireless communication systems has gained much attention. A simple two-user cooperative diversity scheme called decode-and-forward cooperation scheme has been presented by Laneman (2004). Each user has one partner to decode its information and retransmit it by employing repeti-tion coding. This scheme can offer diversity order of two. But the bandwidth efficiency is low. In this paper, we propose a bandwidth efficient three-user cooperative diversity scheme based on relaying superposition symbols. Each user has two partners and each partner relays superposition symbols of the other two users instead of repetition. Thus, the bandwidth efficiency is improved compared to the baseline decode- and-forward cooperative diversity scheme presented by Laneman. Moreover, the proposed scheme can also offer diversity order of two. Then, in order to improve the system performance, a new constellation labeling for the superposition 8PSK modulation is designed. It is a simple way to exploit the symbol mapping diver-sity and a gain of about 2 dB can be obtained. Furthermore, the performance improvement comes at no addi-tional power or bandwidth expense.

Antenna and Base-Station Diversity for WSN Livestock Monitoring

Abstract: Antenna and base-station diversity have been applied to a wireless sensor network for the monitoring of live-stock. A field trial has been described and the advantage to be gained in a practical environment has been assessed.

Subarea Tree Routing (STR) in Multi-hop Wireless Ad hoc Networks

Abstract: Subarea Tree Routing (STR), a new routing protocol for multi-hop wireless ad hoc networks, is proposed. The novelty of the STR protocol is to divide the whole network into many subareas constructed as a result of establishing subarea trees. Its main idea is to identify root nodes by manual configuration or auto-discovery process firstly, then the root nodes originate the process of establishing subarea trees, and finally each node either joins in a subarea tree or become an interconnect node. STR belongs to hierarchical routing protocol and does not attempt to consistently maintain routing information in every node. Furthermore, through the use of tree’s intrinsic routing function, the STR protocol exhibits hybrid behavior of proactive and on-demand routing protocols. We prove the correctness of STR, and our simulation results show that the pro-posed scheme achieves lower route discovery delays, lower route discovery load and better performance of normalized routing load in large, mobile, ad hoc networks as compared with AODV.

Performance Improvement of the DSRC System Using a Novel S and Π-Decision Demapper

Abstract: Based on the constellation diagram of the different modulations, a novel S and Π-decision rule is designed for the analog demapper of the orthogonal frequency-division multiplexing (OFDM) systems. The dedicated short-range communications (DSRC) system is chosen as an OFDM platform to compare the performance among the proposed S and Π-decision decoder, hard-decision and soft-decision decoders. Simulation results demonstrate that both the complexity and performance of S and Π-decision demapper used for M-ary quad-rature amplitude modulation (QAM) OFDM system can be greatly improved. The number of decisions be-tween the received symbol and constellation points can be simplified to look up table times for M-ary QAM OFDM system.

Parameter optimization for amplify-and-forward relaying systems with pilot symbol assisted modulation scheme

Abstract: Cooperative diversity is a promising technology for future wireless networks. In this paper, we consider a cooperative communication system operating in an amplify-and-forward (AF) mode with a pilot symbol assisted modulation (PSAM) scheme. It is assumed that a linear minimum mean square estimator (LMMSE) is used for the channel estimation at the receiver. A simple and easy-to-evaluate asymptotical upper bound (AUB) of the symbol-error-rate (SER) is derived for uncoded AF cooperative communication systems with quadrature amplitude modulation (QAM) constellations. Based on the AUB, we propose a criterion for the parameter optimization in the PSAM scheme. We discuss how the pilot spacing and the length of the Wiener filter should be chosen under the constraint of a tradeoff between pilot overhead, estimation accuracy, and receiver complexity. We also formulate an power allocation problem for the considered system. It is shown that the power allocation problem can optimally be solved by means of a gradient search method. Numerical simulations are presented to verify the correctness of the theoretical results and to demonstrate the benefits of the parameter optimization.

EasiSim: A Scalable Simulator for Wireless Sensor Networks

Abstract: Traditional simulators have deficiencies of scalability, thus they are not so efficient in running simulations with large-scale networks. In this paper, we present a new simulator, namely EasiSim, specifically for evaluating sensor net-works on a large scale. EasiSim is featured by organizing its core components, including nodes, topology and scenario, in a hierarchically structured approach. The hierarchically structured organization enables nodes to process all the concurrent events in one batch, hence reducing the running time by an order of magnitude. Moreover, we propose a visualization scheme based on a Client/Server model which separates the graphical user interface (GUI) from the simulation engine, and therefore the scalability of the simulator will not be decreased by complex GUI. Extensive simulations show that EasiSim outperforms ns-2 in terms of real running time and memory usage.

Recurrent Polynomial Neural Networks for Enhancing Performance of GPS in Electric Systems

Abstract: Global Positioning System (GPS) is a worldwide satellite system that provides navigation, positioning, and timing for both military and civilian applications. GPS based time reference provides inexpensive but highly-accurate timing and synchronization capability and meets requirements in power system fault location, monitoring, and control. In the present era of restructuring and modernization of electric power utilities, the applications of GIS/GPS technology in power industry are growing and covering several technical and man-agement activities. Because of GPS receiver’s error sources are time variant, it is necessary to remove the GPS measurement noise. This paper presents novel recurrent neural networks called the Recurrent Pi-Sigma Neural Network (RPSNN) and Recurrent Sigma-Pi Neural Network (RSPNN). The proposed NNs have been used as predictor in GPS receivers timing errors. The NNs were trained using the dynamic Back Propagation (BP) algorithm. The actual data collection was used to test the performance of the proposed NNs. The ex-perimental results obtained from a Coarse Acquisition (C/A)-code single-frequency GPS receiver strongly support the potential of the method using RPSNN to give high accurate timing. The GPS timing RMS error reduces from 200 to less than 40 nanoseconds.