Ultra-wideband Wireless Sensor Networks Research Articles

Мультимедийные сенсорные сети на основе сверхширокополосных хаотических радиоимпульсов

The fast direction in information and communication systems of the wireless sensor network is discussed. Special attention was paid to ultra-wideband wireless sensor networks, which use chaotic radio pulses as information carriers for communication between sensor nodes. The creation of such systems became possible after many years of research on the creation and management of chaos in electronic systems. The requirements for transceivers for transmitting multimedia data in wireless sensor networks and the characteristics of existing systems are considered. The prospects of using ultra-wideband wireless systems based on direct chaotic data transmission in multimedia sensor networks are analyzed.

Avoidance of narrowband interference in UWB wireless sensor device using square low technology

Impulse radio ultra-wideband system has been adopted in wireless sensor networks research due to its high performance in conditions of active influence of various noises and interferences, the presence of reflections, etc. In this paper, this system represents a transmitter based on the controller STM32 and a receiver implemented using blocks of analog and digital processing based on FPGA. This paper focuses on a realisation of an additional device that can provide the avoidance of narrowband interference in ultra-wideband wireless sensor network system to improve a value of bit error rate. For this purpose, a real device with using square low technique has been developed. According to the results of experiments this approach enables to improve a dependence of the bit error rate on the signal-to-noise ratio.

A Novel Complex-Coefficient In-Band Interference Suppression Algorithm for Cognitive Ultra-Wide Band Wireless Sensors Networks.

With the rapid development of wireless communication systems and electronic techniques, the limited frequency spectrum resources are shared with various wireless devices, leading to a crowded and challenging coexistence circumstance. Cognitive radio (CR) and ultra-wide band (UWB), as sophisticated wireless techniques, have been considered as significant solutions to solve the harmonious coexistence issues. UWB wireless sensors can share the spectrum with primary user (PU) systems without harmful interference. The in-band interference of UWB systems should be considered because such interference can severely affect the transmissions of UWB wireless systems. In order to solve the in-band interference issues for UWB wireless sensor networks (WSN), a novel in-band narrow band interferences (NBIs) elimination scheme is proposed in this paper. The proposed narrow band interferences suppression scheme is based on a novel complex-coefficient adaptive notch filter unit with a single constrained zero-pole pair. Moreover, in order to reduce the computation complexity of the proposed scheme, an adaptive complex-coefficient iterative method based on two-order Taylor series is designed. To cope with multiple narrow band interferences, a linear cascaded high order adaptive filter and a cyclic cascaded high order matrix adaptive filter (CCHOMAF) interference suppression algorithm based on the basic adaptive notch filter unit are also presented. The theoretical analysis and numerical simulation results indicate that the proposed CCHOMAF algorithm can achieve better performance in terms of average bit error rate for UWB WSNs. The proposed in-band NBIs elimination scheme can significantly improve the reception performance of low-cost and low-power UWB wireless systems.

Experimental ultrawideband wireless sensor network for medical applications

Medical ultrawideband (UWB) wireless sensor networks (WSNs) in which chaotic radio pulses serve as data carriers are proposed. Several components of the UWB WSN are produced, fragments of networks with different topologies are constructed and experimental accumulation of medical data is performed for validation of the proposed approach and comparison of the physical properties and theoretical estimations.

Compressed Sensing of IR‐UWB Wireless Sensor Network Data Based on Two‐Dimensional Measurements

A novel Compressed sensing (CS) method based on two-dimensional measurements is proposed that can be effectively utilized in Impulse radio ultra-wideband wireless sensor networks (IR-UWB WSNs) to significantly reduce the energy consumption and sampling rate in sensor data transferring.We start by establishing the CS measurement model by taking both spatial and temporal correlations of Wireless sensor network (WSN) data into account. Since our model incorporates a new type of measurement matrix: the block quasi-Toeplitz structured matrix, we derive the Restricted isometry property (RIP) of the block quasi-Toeplitz structured matrix to ensure the performance of the two-dimensional recovery of WSNs data. We substantiate our mathematical analysis by numerical examples in the context of ideal spares vector and realWSN data, and results demonstrate that the approach achieves significantly saving of energy and sampling rate with small reconstruction error.

A method of obstacle identification in ultra wideband wireless sensor networks

Obstacle identification is a difficult task, which is more challenged in foliage environment. In this paper, a method of target detection is proposed, which attempts to extract information from the data being transmitted around the wireless sensor network (WSN) to identify targets that might be within the local, foliage obscured scene. The selected bispectra algorithm is applied to extract the feature vector, as well as radial–basis function (RBF) neural network is used to realise the obstacle classification. According to the experiment results, this method is able to identify the existence and the different distances of the obstacles measured in outdoor foliage scene with a good recognition rate.

Fast 3D Node Localization in Multipath for UWB Wireless Sensor Networks Using Modified Propagator Method

A fast three-dimensional (3D) node localization algorithm in multipath for ultra-wideband (UWB) wireless sensor networks is developed. The algorithm employs a modified propagator method (MPM) for time delay estimation and then uses a marriage algorithm of 3D Chan and Taylor for range-based multilateral localization and node position computation. In the proposed algorithm, the traditional propagator method (PM) for direction-of-arrival (DOA) estimation is extended to frequency-domain time-of-arrival (TOA) estimation in multipath, which can effectively measure the distance between an unknown sensor node and an anchor node. MPM algorithm requires neither spectral searching nor covariance matrix estimation and its eigenvalue decomposition, which reduces the computational complexity. The marriage location algorithm enhances the robustness and accuracy of node localization. The simulations validate the effectiveness of the proposed algorithm in locating multiple unknown nodes of UWB wireless sensor networks in 3D space.

ADLU: a novel anomaly detection and location-attribution algorithm for UWB wireless sensor networks

Wireless sensor networks (WSNs) are gaining more and more interest in the research community due to their unique characteristics. Besides energy consumption considerations, security has emerged as an equally important aspect in their network design. This is because WSNs are vulnerable to various types of attacks and to node compromises, and as such, they require security mechanisms to defend against them. An intrusion detection system (IDS) is one such solution to the problem. While several signature-based and anomaly-based detection algorithms have been proposed to date for WSNs, none of them is specifically designed for the ultra-wideband (UWB) radio technology. UWB is a key solution for wireless connectivity among inexpensive devices characterized by ultra-low power consumption and high precision ranging. Based on these principles, in this paper, we propose a novel anomaly-based detection and location-attribution algorithm for cluster-based UWB WSNs. The proposed algorithm, abbreviated as ADLU, has dedicated procedures for secure cluster formation, periodic re-clustering, and efficient cluster member monitoring. The performance of ADLU in identifying and localizing intrusions using a rule-based anomaly detection scheme is studied via simulations.

Analysis and Mitigation of the Narrowband Interference Impact on IR‐UWB Communication Systems

The impact of narrowband interference signals on impulse radio ultrawideband (UWB) communication systems has been investigated. A closed form expression for the bit error rate performance of UWB communication system in a Log‐normal flat fading channel under such impact is evaluated. The actual UWB channel model is known as a multipath fading channel; however flat fading channel model can be considered with some of the UWB wireless applications such as UWB wireless sensor networks which are characterized by size and energy constraints. Thus, a simple and low‐cost one‐finger Rake receiver can be used with such wireless systems. It was proven that UWB systems unavoidably suffer from the interference caused by the coexisting systems due to the restraint on their transmission power levels. To this end, we propose an interference canceller scheme which is capable of suppressing the impact of such interference and enhancing the performance of UWB communication systems. The interference canceller scheme performance is also investigated in various scenarios of operation such as the presence of multiple narrowband interference signals, symbol timing error, and a comparison with a notch filter‐based case.

Distributed Detection in UWB Wireless Sensor Networks

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In this paper, we study distributed detection in ultrawideband (UWB) wireless sensor networks (WSNs) over frequency selective channels. Several schemes with different requirements on channel state information (CSI) are proposed, analyzed, and compared. We study the error exponent and asymptotic optimality for these schemes under different energy, and time–bandwidth product requirements. Our study shows that to achieve a nonzero error exponent, the no-feedback scheme requires large energy and time–bandwidth product but has advantages of no synchronization requirement and no feedback overhead. On the other hand, schemes requiring feedback are suitable for energy and bandwidth limited settings but require quasi-synchronization. </para>

TOA Estimation Based on Match-Filtering Detection for UWB Wireless Sensor Networks

The TOA (time of arrival) estimation algorithms based on match-filtering detection for UWB (ultra wideband) wireless sensor networks are extensively studied in this paper. Based on the analysis of the drawbacks of the algorithms in the literature, a three-step algorithm is proposed: first, determine the search region for DP (direct path) detection; then, a rough detection of DP is made by threshold comparison; and last, the precise location of DP, i.e., the center of the arriving pulse, is obtained by a refined search process. The threshold factor used to calculate the threshold in the second step is set dynamically by using a model in terms of the kurtosis of the match-filtering output. The model is well independent of the channel model, and its effectiveness is proved through the comparison of the resulted performance with that of using fixed threshold factor. By comparing the performance of this algorithm with that of other algorithms, it can be observed that the proposed three-step algorithm has achieved a good trade-off between computational efficiency and estimation accuracy, thus more appropriate for current applications. In addition, the reliability of TOA estimation result is discussed through statistical analysis. Two levels of reliability are defined with regard to the corresponding kurtosis of the TOA estimation, and the probability density function for TOA estimation errors of each level is modeled. Properly incorporating the reliability information into the positioning algorithm will definitely improve the final location estimation accuracy.

Analytical performance evaluation of ultra-wideband multiple access schemes for different wireless sensor network application environments

One of the most promising uses for ultra-wideband (UWB) is wireless sensor networks (WSNs). Since WSNs offer a wide variety of services for different application areas, the UWB propagation channel characteristics of each application environment show fundamental differences from each other in many aspects. A reliable and energy-efficient multiple access scheme is thus required to coordinate the transmissions of sensor nodes in these various application channel environments. We develop an analytical framework for evaluating the performance of UWB time-hopping (TH), direct sequence (DS) and orthogonal frequency division multiplexing (OFDM) multiple access schemes with multi-node interference in the following UWB propagation channel environments that have a high importance for WSN applications: residential, office, suburban outdoor, industrial and agricultural. The objective is to determine the most appropriate multiple access scheme to be applied for a particular WSN application channel environment. Performance is evaluated in terms of the average information throughput efficiency, a relevant progress-related measure for multihop WSNs. The mathematical expression of this metric is derived in detail, and is used in numerical evaluations for assessing the performance of the three schemes operating under UWB propagation channel models of the various environments that are characterised by distinct channel parameters and specific valid distance ranges. TH-UWB is shown to be the most suitable multiple access scheme to be adopted for UWB WSNs. It outperforms both the DS-UWB and OFDM-UWB schemes for all application environments and is the most robust and energy efficient. OFDM-UWB is the poorest performing whereas DS-UWB provides similar performance to TH-UWB below a specific threshold number of interfering nodes.

A MAC protocol for low-rate UWB wireless sensor networks using directional antennas

Ultra-wideband (UWB) is a key solution for wireless connectivity, characterized by ultralow power consumption and a good degree of robustness to interference and multipath fading. Evidence of its significance, is its recent use in the IEEE 802.15.4a standard. UWB technology with joint consideration of directional antennas can benefit when compared to classical omni-directional antennas from the energy conservation viewpoint, which is of fundamental concern when it comes to wireless sensor networks (WSNs). However, exploiting directionality requires new approach in the design of a medium access control (MAC) protocol to be applied. In this work, idle nodes continuously rotate their receiving beams over 360^o until a predefined preamble trailer is detected. The resulting scheme is a directional ultra-wideband MAC protocol, named DU-MAC, which deals effectively with the problem of deafness and the problem of determination of neighbors' location. Simulation-based studies will demonstrate the effectiveness of the proposed protocol in many critical parameters, such as throughput and network lifetime.

Bounds on lifetime of cluster-based ultra-wide band wireless sensor network

The asymptotic lower and upper bounds on the lifetime of cluster-based Time-Hopping Impulse Radio Ultra-Wide Band (TH-IR UWB) wireless sensor networks with n static sensor nodes randomly located on a square of area S are considered. We derive the lower and upper bounds on the lifetime of cluster-based TH-IR UWB sensor networks. The results indicate that the lifetime of cluster-based network is Θ((n/S log n)α), which is at least (n1/2/(log n)α-1/2) times longer than that of non-cluster-based TH-IR UWB network; thus clustering can significantly improve the network lifetime. The bounds also reveal that the network lifetime increases with node density n/S, thus the large-scale dense cluster-based TH IR UWB wireless sensor network is more practical.