Impulse Radio Research Articles

Performance of Two-Way Code-Multiplexed UWB Relay Networks

Recently, two-way relay network has been taken attention. In this paper, the two-way relayprotocols of ultra-wideband (UWB) network based on code-multiplexed transmitted-reference (CMTR)impulse radio have been studied. Based on code-multiplexed scheme, a new two-way relayingstrategy for two-slots protocol is designed. The corresponding bit error rate (BER) performance isevaluated via simulations and compared with three-slots scheme which can get path diversity gainfrom direct link between terminals. Simulation results reveal that the performance of the two-slotsrelaying scheme is almost same with that of the three-slots scheme. Meanwhile the throughput ispromoted about 33% over three-slots scheme.

On the Nonlinear Teager-Kaiser Operator for Energy Detection Based Impulse Radio UWB Receivers

In this paper, by modeling a narrowband interference (NBI) as a wide-sense stationary (WSS), zero-mean Gaussian bandpass random process, a systematic theoretical framework is developed for the first time to characterize the operation and performance improvement of energy detection (ED) based impulse radio ultra-wideband (IR-UWB) receivers that employ a nonlinear Teager-Kaiser operator (TKO) and a highpass filter. Furthermore, through both theoretical analysis and simulations, we have identified (1) that the TKO technique can effectively mitigate not only the performance degradation caused by an NBI but also that caused by additive white Gaussian noise and (2) that a larger bandwidth of the UWB signal leads to better mitigation. Therefore, the TKO technique is considered as a very promising technique to improve the overall performance of ED-based IR-UWB receivers no matter an NBI is present or not.

Performance Comparison of UWB Chirp IR TR and UWB FM-DCSK TR Systems Implemented with Autocorrelation Receiver

Transmitted reference modulation scheme with autocorrelation receiver offers a robust and simple transceiver configuration for ultra-wideband communications. However this configuration provides only a poor noise performance. The contribution shows how the noise performance can be considerably improved by introducing pulse compression technique. The paper compares the noise performance of the well known FM-DCSK system, as a reference, to the proposed UWB chirp impulse radio featuring pulse compression. It can be concluded, that assuming a real case scenario the improvement in the noise performance is 7.8 dB at BER = 10

Improved Propagator Method-based Joint TOA and DOA Estimation in Impulse Radio Ultra WideBand

Improved Propagator Method-based Joint TOA and DOA Estimation in Impulse Radio Ultra WideBand

Techniques for Clutter Suppression in the Presence of Body Movements during the Detection of Respiratory Activity through UWB Radars

This paper focuses on the feasibility of tracking the chest wall movement of a human subject during respiration from the waveforms recorded using an impulse-radio (IR) ultra-wideband radar. The paper describes the signal processing to estimate sleep apnea detection and breathing rate. Some techniques to solve several problems in these types of measurements, such as the clutter suppression, body movement and body orientation detection are described. Clutter suppression is achieved using a moving averaging filter to dynamically estimate it. The artifacts caused by body movements are removed using a threshold method before analyzing the breathing signal. The motion is detected using the time delay that maximizes the received signal after a clutter removing algorithm is applied. The periods in which the standard deviations of the time delay exceed a threshold are considered macro-movements and they are neglected. The sleep apnea intervals are detected when the breathing signal is below a threshold. The breathing rate is determined from the robust spectrum estimation based on Lomb periodogram algorithm. On the other hand the breathing signal amplitude depends on the body orientation respect to the antennas, and this could be a problem. In this case, in order to maximize the signal-to-noise ratio, multiple sensors are proposed to ensure that the backscattered signal can be detected by at least one sensor, regardless of the direction the human subject is facing. The feasibility of the system is compared with signals recorded by a microphone.

Performance of Monobit Digital Receivers with Inter-Symbol Interference

Implementation complexity and power consumption are the two most crucial problems in impulse radio (IR) communications, which is seen as a promising contender for broadband wireless systems. To address such issues, monobit sampling with Nyquist rate was introduced, and the corresponding receiver without inter-symbol interference (ISI) was obtained. In this paper, we consider the case with ISI, especially when the data rate is high, e.g. 100 mega-bits per second (Mbps). For implementation simplicity, the interference from other symbols is approximated as Gaussian noise, and thus the monobit receiver for the ISI case is obtained. To boost receiving performance, high autocorrelation training sequence is employed. The performance loss of the proposed receiver is analyzed, based on the typical Saleh-Valenzuela (S-V) model of indoor channels. The simulation and analysis results show that the proposed monobit receiver has only about 1dB signal-to-noise ratio (SNR) loss compared with the one without ISI, when the data rate is up to 250Mbps.

Performance Evaluation of WideMac Compared to ALOHA in term of Energy Consumption for IR-UWB based WSN

The introduction of the IR-UWB Technology in the field of WSN was promising for researchers especially for its low power consumption feature. To implement such a solution, we need a suitable MAC protocol to exploit the specific features of this technology. When introducing this Technology, ALOHA was the only candidate MAC protocol. Because of the high energy consumption of ALOHA, in this paper we present WideMac, a low power medium access control protocol designed specifically for Impulse Radio Ultra Wide Band transceivers. The IR-UWB channel offers ultra low power transmissions and unmatchable robustness to multiple access interference. WideMac takes advantage of these two key properties by using asynchronous periodic beacon transmissions from each network node. To test and evaluate the performance of WideMac protocol we used PhyLayerUWBIR class developed under MiXiM platform on OMNet++ as a physical layer. For the MAC layer we developed our own class WideMacLayer.

A 2.8-7.5 PJ/PULSE HIGHLY-FLEXIBLE IMPULSE-RADIO ULTRA-WIDEBAND PULSE-GENERATOR

A low-power on-off-keying impulse-radio (IR) ultra-wideband (UWB) pulse generator (PG) intended for wireless-powered IR-UWB radio applications is presented. The proposed PG has high flexibility, the center frequency, output power and pulse-width (PW) are controllable depending on channel conditions and data rates. Qualitative frequency-domain and transient analyses are presented. A new figure-of-merit (FoM) is proposed such that a more precise comparison between different PGs can be made. The PG is successfully implemented in a TSMC 90 nm CMOS process, measurements show the energy consumption and FoM to be 2.8-7.5 pJ/pulse and 1.6-2.6% respectively. The output swing and PW are 277-329 mVp-p and 509-1088 ps respectively. The core area is 0.092 mm 2 .

Experimental Evaluation of Implant UWB-IR Transmission With Living Animal for Body Area Networks

One of promising transmission technologies in wireless body area networks (BANs) is ultra-wideband (UWB) communication, which can provide high data rate for real-time transmission, and extremely low power consumption for increasing device longevity. However, UWB signals suffer from large attenuation in a wireless communication link, especially in implant BANs. Although several investigations on channel characterization have been far thus conducted for evaluating the UWB transmission performance, they have been limited to either computer simulations or experiments with biological-equivalent phantoms. Experimental evaluation with a living body has rarely been conducted, i.e., the performance in real implant BANs has been scarcely discussed. In this paper, therefore, we focus on a living animal experimental evaluation on the UWB transmission performance. To begin with, we develop an ultra-wideband impulse radio (UWB-IR) communication system with a multipulse pulse position modulation scheme, and then analyze the fundamental characteristics of the developed UWB-IR communication system by a liquid phantom experiment. Finally, we evaluate the performance of the developed UWB-IR communication system via the living animal experiment. From the experimental results, although we have observed that the path loss is more than 80 dB, the developed system can achieve a bit error rate of 10-2 within the communication distance of 120 mm with ensuring a high data rate of 1 Mb/s. This result first time gives a quantitative communication performance evaluation for the implant UWB transmission in a living body.

Polarity-Invariant Square Law Technology for Monobit Impulse Radio Ultra Wideband Receivers

In this paper, a novel nonlinear signal processing technology, which is denoted as the polarity-invariant square law (PISL) algorithm, is proposed to compensate nonlinear distortions caused by monobit digitization and to mitigate the performance degradation of impulse radio ultra wideband (IR-UWB) receivers employing monobit analog-to-digital converters (ADCs). An analytical framework based on characteristic functions has been developed to evaluate bit error rates of monobit transmitted-reference (TR) receivers and performance improvement offered by the PISL algorithm. Both theoretical analysis and simulations show that by employing the PISL algorithm, the monobit weighted TR (MWTR) receivers can achieve a bit-error-rate performance that is more than 10 dB over the direct-reference algorithm and is less than 1.5 dB away from the performance bound of the MWTR receivers in intravehicle UWB channels. Furthermore, the MWTR receiver employing the PISL algorithm is insensitive to a correlation interval; this feature not only reduces complexity of the receiver design but also ensures performance robustness over various multipath channels. Therefore, the PISL algorithm can be considered an enabling technology for the monobit IR-UWB receivers that demand high performance, lower power consumption, and low complexity.

System Level Design of Low Rate, Low Power 3.1-5GHz IEEE 802.15.4a UWB Transceiver for Medical Monitoring Applications

Low power consumption is one of the main targets in designing a radio for a Wireless medical devices for healthcare monitoring applications. The IEEE 802.15.4a standard has proprieties that make it a viable solution for this type of applications and environments. IEEE 802.15.4a standard adopts Impulse Radio Ultra Large Band (IR-UWB) to afford low data rates, low power and low complexity communication systems with enhanced communication range and robustness. This paper discusses the architecture parameters selection for low power, monolithic wireless sensor like frequency allocation, data rate, mean PRF, pulse shape and radio architecture. Then, link radio budget parameters required for the transceiver implementation have been established. 

Research on Multiband Impulse Radio UWB System based on PSWF in Multipath Fading Channel

This paper presents an architecture of Multiband Impulse Radio UWB (MB-IR-UWB) system based on Prolate Spheroidal Wave Function (PSWF) by binary time hopping pulse position modulation (TH-PPM) over multipath fading channel. In order to combat multipath fading, Rake receiver using maximal ratio combining (MRC) is applied to this system, which can successfully capture the unique multipath-rich property and multipath-clustering phenomenon of UWB channels. Through simulation, a comparison of system performance between different types of Rake receiver is analyzed. What’s more, considered multipath delay spread, a data rate estimation of the communicating system is given. Finally we get the conclusion that increasing data rate is best-achieved by increasing the number of subband instead of decreasing the symbol repetition period.

The Fractal Characteristics of Signals in IR-UWB Communication System

In this paper the fractal characteristics of the received multipath signals of impulse radio ultra-wideband communication system are analyzed and proved using over-value function. The scale-invaria...

Cooperative Impulse Radio Ultra-Wideband Communication Using Coherent and Non-Coherent Detectors: A Review

Ultra-wideband (UWB) is a booming technology in the field of wireless communication. This paper presents a brief idea related to the various coherent and non-coherent IR-UWB detectors. Due to the limitation in transmit power spectral density of UWB system, the major challenges faced by UWB system includes, achieving Quality of Service, system performance and coverage area. So, the combination of UWB system with cooperative communication will not only improve the system performance, but also help in expanding coverage area of signals. A brief review of the work done by various researchers in the field of cooperative impulse radio (IR) UWB communication is also presented in this paper. The working principle and performance analysis of the various coherent and non-coherent IR-UWB detectors using cooperative relay strategies are also discussed at large in this paper. The various fixed cooperative relay strategies used for cooperative UWB communication is Amplify and Forward, Decode and Forward and Detect and Forward. From the simulation results it can be inferred that, even though IR-UWB DTR receiver gives a much better BER performance than IR-UWB ED receiver using both cooperative and non-cooperative strategies, yet ED receiver is preferred because of its less complexity and low power consumption. Future prospects in the field of cooperative IR-UWB communication have also been discussed in this paper.

Analysis of energy detection receiver for TOA estimation in IR UWB ranging and a novel TOA estimation approach

Ultra wideband (UWB) localization has attracted a lot of attention, as it offers the capability of penetration and high precision positioning with low cost. Time-based UWB ranging can take full advantage of the characteristics of impulse radio (IR) signal. The energy detection (ED) receiver instead of the matched filter is used a lot in the area for its low complexity. In the ED receiver, many factors, such as the integration interval, signal waveform, the upper or lower limit of integration, noise floor and pulse width, affect the ranging performance. These factors have not been studied thoroughly on energy collection in ED-based receivers, while energy collection is very important for IR UWB ranging and localization. Many studies focus on how to estimate the time of arrival (TOA) based on the output of the ED receiver. In the study, we will examine the effects of these factors on energy collection and TOA estimation. Some qualitative conclusions are given. We propose an approach to solve some problems caused by these factors and further improve the ranging accuracy. The approach can break through the performance limitation of TOA estimation with the ED receiver to some extent with some low-cost delayers instead of the high sampling rate analog to digital converters. Simulation results prove that the approach works effectively compared with traditional methods under different channels.

다중 사용자 환경에서 무선광대역 시스템의 시간도약 순열을 이용한 반복 부호의 복호화 기법

광대역통신 시스템에서 사용되는 시간도약 기법은 다중경로 페이딩을 완화시키고, 여러 사용자의 다중 접속기회를 제공하기 위하여 사용된다. 짧은 시간 동안의 펄스를 전송하는 광대역신호의 경우 다중경로 페이딩을 극복하고, 신뢰성 있는 통신을 위하여, 하나의 비트 시간 동안에 동일한 펄스를 반복되게 전송한다. 제안하는 복호화 기법은 다중 사용자 환경에서 두 개 이상의 펄스가 다중경로 페이딩에 의해서 프레임간 혹은 심볼간 간섭을 일으키는 프레임 내에서 시간도약 부호에 따라 결정되는 펄스간의 간격을 이용하여 반복 전송된 신호의 복호화 성능을 개선시키는 기법이다. 모의실험을 통하여, 단일 사용자 환경에서 BER=<TEX>$10^{-3}$</TEX>에서 0.5dB 정도의 이득을 얻는 것으로 나타났다. 다중사용자 환경에서도 시간도약 부호의 특성을 이용한 방식의 복호화 성능이 기존 방식에 비하여 우수한 성능을 보이는 것을 확인할 수 있다. Hopping sequences of Time Hopped Ultra Wideband Impulse Radio (TH-UWB-IR) system are to mitigate multipath fading and to provide the multiple access chances for multi users. For the reliable communications, the same pulses are repeatedly transmitted for a bit duration based on hopping sequences. The proposed decoding scheme utilizes the intervals of inter-codes in a frame where the short interval between two pulses leads to the large interference by the multipath fading. For a single user case, the proposed method obtains 0.5dB gain over the conventional method at BER=<TEX>$10^{-3}$</TEX>. Decoding performance of repeated pulses can be increased using the property of the hopping sequences of multi users.

Energy-adaptive Pulse Amplitude Modulation for IR-UWB Communications Under Renewable Energy

Impulse Radio Ultra-wideband (IR-UWB) technique has long been recognized for its unique carrierless operation as compared with other communication techniques. The simple and low-cost structure offers great advantages for self-powered embedded wireless systems, in which energy efficiency is a challenging issue due to the fact that most renewable energy sources only offer limited and unstable power supply. In this paper, we present an energy-adaptive Pulse Amplitude Modulation technique for self-powered IR-UWB based communication systems to improve data rate and or time coverage. The basic idea is derived from the fact that domain-specific information in such applications are often available; thus, by jointly exploiting the wireless channel conditions and the non-deterministic characteristics of renewable energy sources, the proposed technique dynamically adjusts the modulation level to enhance the sustainable operation under the unreliable energy supply. Simulation results demonstrate that the proposed technique achieves a much higher data rate and better time coverage than conventional UWB systems. The proposed technique is also insensitive to many practical issues such as the battery aging effect.

Optimal receiver antenna location in indoor environment using dynamic differential evolution and genetic algorithm

Abstract Using the impulse responses of these multipath channels, the bit error rate (BER) performance for binary pulse amplitude modulation impulse radio ultra-wideband communication system is calculated. The optimization location of receiving antenna is investigated by dynamic differential evolution (DDE) and genetic algorithm (GA) to minimize the outage probability. Numerical results show that the performance for reducing BER and outage probability by DDE algorithm is better than that by GA.

A UHF/UWB hybrid silicon RFID tag with on–chip antennas

In this contribution, we describe and analyse a miniature wireless radio frequency identification (RFID) chip with on-chip antennas (OCA) and ultra wideband (UWB) signalling by real-world measurements. With the on-chip antenna approach, no external antennas are required, and the size of the overall tag is identical to the size of the chip alone (3.5 mm×1 mm). The chip is powered through inductive coupling and controlled by an RFID signal at 866 MHz in the downlink, while the uplink transmits a quaternary pulse-position-modulated (4-PPM) UWB signal at 5.64 GHz with pulses having a duration in the order of nanoseconds. In this contribution, the hybrid or asymmetric communication scheme between prototype chip and reader, the embedded OCA, and the measurement setup are described. The prototype achieves 4-PPM bit rate of 126 Mbit/s based on a pulse-train transmission with a duration of 10 μs. The small size, high data rate, and fine time resolution of the UWB impulse radio offer new features and sensing capabilities for future RFID-like applications.

An Investigation of Total Ionizing Dose Damage on a Pulse Generator Intended for Space-Based Impulse Radio UWB Transceivers

We investigate, for the first time, the effects of total ionizing dose (TID) on a CMOS pulse generator implemented in a SiGe BiCMOS platform, and which is intended for use in space-based impulse radio ultra-wideband transceivers. The pulse generator was fabricated in Jazz Semiconductor's SBC18-H3 SiGe BiCMOS process technology, which combines 250 GHz SiGe HBTs and 180 nm CMOS. Total dose effects were examined using a 10-keV X-ray source. The effects of the TID on the performance of the pulse generator were investigated and a compensation scheme for mitigating these radiation effects is proposed.