Impulse Radio Research Articles

Smartly Time of Arrival Interpretation in the Wide Band Ranging System

In the field of sensor networks, impulse radio 60 GHz wide band signals which is even much more practical for ranging and localization systems due to high time and multipath resolution. Typically, the 60GHz accurate ranging estimation is very important. In order to improve the precision of the ranging, a new threshold selection algorithm using neural network (NN) is proposed which is based on a joint metric of the skewness, kurtosis and standard deviation after energy detector (ED). Simulation results are presented which show the proposed NN algorithm provides better precision and robustness in both high and low SNR environments than other ED-based algorithms in the IEEE 802.15.3c channel models.

Threshold Selection Algorithm Based on Skewness and Standard Deviation Using Back Propagation Artificial Neural Networks in the 60GHz Wireless Communication Systems

Accurate localization has gained significant interest in the field of sensor networks, impulse radio 60GHz signals which is low cost, low complexity are even much more practical for ranging, localization and tracking systems because of the high time and multipath resolution and so on. Typically, accurate Time of Arrival (TOA) estimation of the 60GHz signals is very important. In order to improve the precision of the TOA estimation, a new threshold selection algorithm using Back Propagation Artificial Neural Networks (BP-ANN) is proposed which is based on a joint metric of Skewness and Standard Deviation after Energy Detection. The best threshold based on the signal-to-noise ratio (SNR) is investigated and the effects of the integration period and channel model are examined. Simulation results are presented which show that for the IEEE802.15.3c channel models CM1.1 and CM2.1, the proposed BP-ANN algorithm provides better precision and robustness in both high and low SNR environments than other ED-based algorithms.

Spectrum sensing in cognitive UWB impulse radio communication system

This paper emphasizes on the issue of spectrum sensing or awareness in cognitive UWB impulse radio (CUWB). Three spectrum sensing schemes are proposed in this paper: The first scheme is based on frame-level block processing, while the second scheme aims at real time chip-level processing. Analytical results show that scheme 1 outperforms scheme 2 in terms of the probability of detection and false-alarm, nevertheless, high detection delay may render the applicability of scheme 1 in CUWB. Employing the low duty cycle characteristics of the UWB IR signal, we propose a chip-level based sequential processing and diversity detection scheme (scheme 3). Through extensive simulations, the results demonstrate that scheme 3 has the best receiver operating characteristic (ROC) curve that can attain the design goal of high probability of detection and low probability of false alarm. Both analytical and numerical results in terms of the “mean detection delay” and the “average false alarm run length” have also been presented in this paper. It is verified that by employing the diversity combining, scheme 3 outperforms scheme 1 in that it requires much less detection time for spectrum sensing.

A High-Fidelity All-Textile UWB Antenna With Low Back Radiation for Off-Body WBAN Applications

A novel all-textile UWB antenna with full-ground plane and high on-body fidelity is presented in this work. Due to the combined requirements of backward radiation reduction in WBANs and high-fidelity prerequisite for UWB pulse transmission/reception, a multilayered structure is implemented. The structure consists of two patches and a ground plane implemented on two layers of 2-mm-thick substrate. The full ground plane on the lower layer shields users against on-body radiation. Numerical and experimental evaluations both in free space and on human body prove the antenna operation within the FCC UWB bandwidth of 3.1–10.6 GHz. Its high-measured on-body system fidelity values of between 95% and 97% at a distance of 1 m show that the textile UWB antenna is suitable for body-worn UWB impulse radio communication.

A Novel Transceiver Architecture Based on Wavelet Packet Modulation for UWB-IR WSN Applications

In last few years, several recent developments concern a new proposed techniques of communication for WSN (Wireless Sensors Network) using a complex methods and technics. This network is considered a future platform for many applications like: medical, agriculture, industrial, monitoring and others. The challenge of this work consists in proposing a new design of transceiver for WSN based on IDWPT (Inverse Discrete Wavelet Packet Transform) in emitter and DWPT (Discrete Wavelet Packet Transform) in receiver for mono and multi users using AWGN Channel. We will propose in this paper, a new concept of impulse radio communication for multiband orthogonal communication for UWB (Ultra-wideband) applications. The main objective of this work is to present a new form of pulse communication adapted to low through-put short-range applications and is scalable according to the type of use but also the number of sensors.

Performance Evaluation of an Improved Multiband Impulse Radio UWB Communication System Based on Sub-Band Selection

Performance Evaluation of an Improved Multiband Impulse Radio UWB Communication System Based on Sub-Band Selection

무선광대역 시스템을 위한 블록 부호화 상관기 기반의 효율적인 수신기 설계 기법

Noncoherent receivers are favored for block-code-modulated ultrawideband impulse radio (UWB-IR) systems because of their low implementation complexity compared with coherent rake receivers. However, existing noncoherent schemes, such as transmitted reference (TR) systems and averaged differential receivers (ADR), suffer from performance degradation and energy efficiency loss. Codeword matching and signal aggregation (CMSA) is a low complexity noncoherent receiver for UWB-IR. As the frame/symbol duration is shortened to boost data rate, interframe interference (IFI) or intersymbol interference (ISI) occurs and degrades the detection performance of CMSA. In this paper, block coded correlator which consists of the delay components and the reference signal is proposed to improve the performance of the receiver. Simulation results show that the proposed system leads to the better performance compared to the conventional CMSA receiver.

A statistical analysis of multipath interference for impulse radio UWB systems

In this paper, we develop a statistical characterization of the multipath interference in an Impulse Radio (IR)-UWB system, considering the standardized IEEE 802.15.4a channel model. In such systems, the chip length has to be carefully tuned as all the propagation paths located beyond this limit can cause interframe/intersymbol interferences (IFI/ISI). Our approach aims at computing the probability density function (PDF) of the power of all multipath components with delays larger than the chip time, so as to prevent such interferences. Exact analytical expressions are derived first for the probability that the chip length falls into a particular cluster of the multipath propagation model and for the statistics of the number of paths spread over several contiguous clusters. A power delay profile (PDP) approximation is then used to evaluate the total interference power as the problem appears to be mathematically intractable. Using the proposed closed-form expressions, and assuming minimal prior information on the channel state, a rapid update of the chip time value is enabled so as to control the signal to interference plus noise ratio.

Energy-Harvesting Active Networked Tags (EnHANTs)

This article focuses on a new type of wireless devices in the domain between RFIDs and sensor networks—Energy-Harvesting Active Networked Tags (EnHANTs). Future EnHANTs will be small, flexible, and self-powered devices that can be attached to objects that are traditionally not networked (e.g., books, furniture, toys, produce, and clothing). Therefore, they will provide the infrastructure for various tracking applications and can serve as one of the enablers for the Internet of Things. We present the design considerations for the EnHANT prototypes, developed over the past 4 years. The prototypes harvest indoor light energy using custom organic solar cells, communicate and form multihop networks using ultra-low-power Ultra-Wideband Impulse Radio (UWB-IR) transceivers, and dynamically adapt their communications and networking patterns to the energy harvesting and battery states. We describe a small-scale testbed that uniquely allows evaluating different algorithms with trace-based light energy inputs. Then, we experimentally evaluate the performance of different energy-harvesting adaptive policies with organic solar cells and UWB-IR transceivers. Finally, we discuss the lessons learned during the prototype and testbed design process.

Impulse radio UWB receiver analysis of non‐coherently detected orthogonal signal

In this Letter, performance analysis of an impulse radio (IR) ultra wideband (UWB) correlation based receiver utilising non-coherent detection of orthogonal signalling is provided. The receiver's performance is presented through analysis and simulations in the additive white Gaussian noise (AWGN) channel. Results which show that in non-coherent detection of binary orthogonal signalling there is a difference between the traditional narrowband and IR approaches are provided. In the narrowband communication, there is a well-known, approximately 1 dB, difference between coherent and non-coherent orthogonal signal detection in AWGN. It is demonstrated here that in the binary orthogonal signalling of IR receiver the difference between coherent and non-coherent detection is insignificant, only tenths of decibels. This can be significant piece of information while considering different receiver structures for wireless sensor networks.

A Low-Energy Ultra-Wideband Internet-of-Things Radio System for Multi-Standard Smart-Home Energy Management

This work presents an Internet of Things (IoT) system for home energy management based on a custom-designed Impulse Radio Ultra-Wideband (IR-UWB) transceiver that targets a generic and multi-standard control system. This control system enables the interoperability of heterogeneous devices: it integrates various sensor nodes based on ZigBee, EnOcean and UWB in the same middleware by utilizing an ad-hoc layer as an interface between the hardware and software. The paper presents as a first the design of the IR-UWB transceiver for a portable sensor node integrated with the middleware layer, and also describes the receiver connected to the control system. The custom-designed low-power transmitter on the sensor node is fabricated with 130 nm CMOS technology. It generates a signal with a 1.1 ns pulse width while consuming 39 μW at 1 Mbps. The UWB sensor node with a temperature measurement capability consumes 5.31 mW, which is lower than the power level of state-of-the-art solutions for smart-home applications. The UWB hardware and software layers necessary to interface with the control system are verified in over-the-air measurements in an actual office environment. With the implementation of the presented sensor node and its integration in the energy management system, we demonstrate achievement of the broad flexibility demanded for IoT.

A low-power and high-data rate passive RFID transceiver using 28-nm CMOS technology

This paper presents a low power, high data rate transceiver for passive RFID tags. Asymmetric communication link between the reader and the tag was employed to overcome the passive systems׳ power constraints while providing higher data rates. For the uplink, a low power, digital Impulse Radio Ultra-wideband (IR-UWB) transmitter was employed to send large amounts of data from the several tags to the reader while maintaining the low power requirements. The uplink can achieve data rates as high as 100Mbps using BPSK modulation. On the other hand, the ISM band was used for the downlink. The downlink features slower data rate of 100Kbps and utilizes a new modulation scheme that is more suitable for passive systems. The proposed transceiver was designed and simulated in 28-nm CMOS technology.

Low complexity M‐PPM impulse‐radio ultra wideband over fiber system for wireless sensor networks applications

Ultra wideband over fiber (UWBoF) systems have been proposed to extend wireless range and to interconnect stand‐alone UWB networks. These systems have focused on high‐data‐rate applications. However, UWB will be a key enabler for low‐data‐rate wireless sensor network (WSN) deployments. In this letter, a low‐cost and low‐complexity M‐ary pulse position modulation (PPM) impulse radio (IR)‐UWBoF system designed for WSNs applications is proposed. A spectral line‐suppressive convolutional code is used to achieve spectral line suppression in the power spectral density (PSD). Experimental results show that the system does not distort or add spectral lines to the IR‐UWB signal PSD transmitted over 30 km of a single‐mode fiber, thus demonstrating its feasibility to interconnect WSN deployments. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Matlab- Based Interference Mitigation in WPAN IR-UWB

Impulse Radio - Ultra Wideband (IR-UWB) is a wireless technology system that offers a high data rate within a short range. Therefore, IR-UWB system is regarded as an excellent physical layer solution to the multi-piconet Wireless Personal Area Network (WPAN) applications. In spite of all the advantages of IR-UWB, there are several fundamental and practical challenges that need to be carefully addressed. The big and most important one among these challenges is the interference. Two types of Rake receivers are designed and simulated to highly mitigate the MUI these are (PRake receiver) and (SRake receiver).

Space temporal interference cancellation using TDL array antenna and waveform based OMF for IR-UWB systems

Abstract This paper provides a space temporal interference cancellation method for ultra wide-band (UWB) communication systems based on combination of tapped delay line array antenna and orthogonal matched filter. In order to reduce the interference from the other system using overlapping frequency band, space domain signal processing such as an array antenna has been proposed. However, principal array antenna cannot be applied to impulse radio (IR) UWB because IR-UWB does not have carrier signal. In this paper, we propose a novel tapped delay line array antenna combined with orthogonal matched filter detector. From the numerical evaluation, we show that the proposed system can make null direction to face to the interference signal direction. Additionally, we show that the proposed system can reduce interference signal even if the interference signal has equivalent pulse shape and equivalent incoming direction.

Robust Ultra-Wideband Direction Finding in Dense Cluttered Environments

Ultra-wideband impulse radio (UWB-IR) exhibits good immunity to the multipath in dense cluttered environments because of its high temporal resolution. However, UWB-IR source direction finding is more challenging due to the frequency-selective distortion. Furthermore, the multipath interferences in both far-field and near-field regions affect the direct path resolution. This paper presents a robust solution for direction finding using UWB-IR in the presence of far-field and near-field multipath components overlapping with the direct path signal. An alternating projection (AP) method is proposed to separate the multiple interfering plane waves for better angle-of-arrival (AOA) estimation accuracy based on the signal subspace of UWB discrete Fourier transform (DFT). Detection of the number of plane waves is suggested before AOA estimation for fast computational convergence. Compared to the MUSIC algorithm based on IEEE 802.15.4a channel simulation, the AP has average root mean square error (RMSE) of less than 2.3° while the MUSIC has poorer RMSE of 22.6° in angular resolution when the signal-to-noise ratio (SNR) ranges from 41 dB to 15 dB. The AP is also found to perform well in the presence of strong multipath overlapping with the direct path with AOA average RMSE error of less than 3.4°.

An In-Body Impulse Radio Transceiver With Implant Antenna Miniaturization at 30 MHz

For real-time image/video transmission in implant body area networks, we have developed an in-body transceiver at around 30 MHz. The transceiver employs impulse radio (IR) technology with multi-pulse position modulation (MPPM) scheme. The transmit antenna was realized in a dimension of 1 × 2 cm by forming the radiation elements on a flexible magnetic sheet. Experimental results in a biological-equivalent liquid phantom have demonstrated a bit error rate smaller than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> in a depth of 26 cm with a data rate at least 1.25 Mbps.

Energy-Based Collaborative Spectrum Sensing for Cognitive UWB Impulse Radio

This paper focuses on the issue of collaborative spectrum sensing in cognitive ultra wideband (CUWB) impulse radio. We employ energy-based signal detection method and apply the Neyman-Pearson (NP) decision rule to determine the optimum threshold. Two cooperative spectrum sensing schemes are developed in this paper. The decision fusion scheme is based on hard decision, in which each cooperating cognitive user (CU) sends its own local decision to the fusion center (FC). The FC then makes a final decision according to the majority voting rule. Alternatively, the data fusion scheme is based on soft decision, in which each local CU sends its observed value directly to the FC. The FC combines these values, compares to a threshold and then makes the final decision. The performances of both schemes are studied by using analytical tools and computer simulations. The receiver operating characteristics (ROC), which reveal the probability of detection versus false-alarm curve, are employed to evaluate the system performance under different scenarios. Simulation results demonstrate that the data fusion scheme outperforms the decision fusion scheme and verify that the collaborative spectrum sensing has practical importance in CUWB networks.

Soft-Input Soft-Output Non-Coherent Detection for Differential Space-Time Block Code Systems

A soft-input soft-output non-coherent detection algorithm is proposed for multi-antenna systems, where differential space-time block code is employed. The proposed algorithm aims to calculate a posteriori probabilities of the information bits by means of forward and backward message passing of the BCJR approach. The proposed algorithm can exploit the soft information effectively with the aid of the bidirectional message passing mechanism. In addition, the proposed algorithm can be exploited in conjunction with channel decoding to obtain an effective iterative detection and decoding approach. In view of low implementation complexity, the application of the proposed scheme is instantiated with the ultra-wideband impulse radio (UWB-IR) systems. Simulations show that the proposed approaches improve detection performance for UWB-IR systems.

Design of Interference-Resilient Medium Access for High Throughput WLANs

The proliferation of wireless communications systems poses new challenges in terms of coexistence between heterogeneous devices operating within the same frequency bands. In fact, in case of high-density concentration of wireless devices, like indoor environments, the network performance is typically limited by the mutual interference among the devices themselves, such as for wireless local area networks (WLANs). In this paper, we analyze a protocol strategy for managing multiple access in wireless networks. A network of sensors colocated with the WLAN terminals forms a control layer for managing the medium access and scheduling resources in order to limit collisions and optimize the WLAN data traffic; this control layer is based on a low-power wideband technology characterized by interference robustness, like CDMA (code division multiple access) or UWB (ultra-wideband) for sensors. In this work, we perform an analytical and simulative performance study of the saturated throughput, showing numerical results for the UWB-IR (Impulse Radio) sensors case and highlighting the advantage that can be provided particularly in very high capacity systems, which constitute the necessary evolution of current WLAN versions.