Performance Of Ultra-wideband Systems Research Articles

A Solution to the Non-Ideal Delay Line Problem in Transmitted Reference Pulse Cluster Schemes for UWB Communications

The conventional transmitted reference (TR) technique in ultra wide-band (UWB) communications has provided a springboard for a lot of studies, and a TR pulse cluster (TRPC) structure was proved to have robust performance. Most of TR and TRPC related studies hitherto are based on the assumption that the delay lines (DLs) in their schemes are ideal. However, the group delay ripple (GDR) of nonideal DLs triggered by practical imperfect factors at implementation causes an unexpected distortion in both TR and TRPC UWB systems, and there are few studies so far. In this article, we first analyze the impact of the GDR of nonideal DLs on the performance of TR and TRPC UWB systems. Then a new design solution for both TR and TRPC transceivers is proposed, where the GDR information of the nonideal DL at the receiver side is introduced into transmitter side. The performance of the new design solution is analyzed and simulation results prove the robustness and efficiency of this new design method in reducing the impaction caused by nonideal DLs. Moreover, the proposed design solution can also greatly relieve the high design requirement of DLs in both the transmitter and receiver side and therefore offer valuable insight for the practical transceiver design in both TR and TRPC related UWB systems.

Devices and Fibers for Ultrawideband Optical Communications

Wavelength-division multiplexing (WDM) has historically enabled the increase in the capacity of optical systems by progressively populating the existing optical bandwidth of erbium-doped fiber amplifiers (EDFAs) in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -band. Nowadays, the number of channels—needed in optical systems—is approaching the maximum capacity of standard <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -band EDFAs. As a result, the industry worked on novel approaches, such as the use of multicore fibers, the extension of the available spectrum of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -band EDFAs, and the development of transmission systems covering <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> - and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula> -bands and beyond. In the context of continuous traffic growth, ultrawideband (UWB) WDM transmission systems appear as a promising technology to leverage the bandwidth of already deployed optical fiber infrastructure and sustain the traffic demand for the years to come. Since the pioneering demonstrations of UWB transmission a few years ago, long strides have been taken toward UWB technologies. In this review article, we discuss how the most recent advances in the design and fabrication of enabling devices, such as lasers, amplifiers, optical switches, and modulators, have improved the performance of UWB systems, paving the way to turn research demonstrations into future products. In addition, we also report on the advances in UWB optical fibers, such as the recently introduced nested antiresonant nodeless fibers (NANFs), whose future implementations could potentially provide up to 300-nm-wide bandwidth at less than 0.2 dB/km loss.

Deep Learning Noncoherent UWB Receiver Design

Ultrawideband (UWB) is a promising technology for positioning and wireless communications in Internet-of-things (IoT) applications. However, UWB system's performance is limited by multiple interferences for low complexity noncoherent signal detection methods. Further, deep learning (DL)-based solutions have been envisioned for wireless communications in inaccurate system modeling scenarios. In this letter, we propose a deep learning noncoherent (DLN) UWB receiver to overcome the effect of various interferences such as multiuser interference (MUI), narrowband interference (NBI), and intersymbol-interference (ISI). The DLN is trained offline using the UWB channel statistics, and then, it is used online for data symbol detection. The proposed DLN efficiently learns a nonlinear relationship between input and output in an interference scenario and gives highly accurate data symbol detection, even for training data obtained in a very short period. Numerical results clearly show the proposed DLN UWB receiver's superiority, especially MUI, NBI, and ISI scenarios, over the conventional noncoherent detection method.

A High-Accuracy Indoor Localization System and Applications Based on Tightly Coupled UWB/INS/Floor Map Integration

High-accuracy localization systems for non-line-of-sight (NLOS) environments have been a popular focus of research on indoor positioning. In particular, the use of ultra-wideband (UWB) technology for ranging is emerging as an effective method of indoor localization due to its high accuracy. To improve the overall performance of UWB systems, combining UWB technology with an inertial navigation system (INS) is a commonly used indoor positioning approach. However, UWB measurements are affected by outliers under the NLOS propagation of radio signals. In addition, INS tend to suffer from error accumulation without constraints imposed by observations from other sensors. To address these problems, an adaptive robust extended Kalman filter algorithm based on tightly coupled UWB/INS/floor map integration is proposed, with which the noise in the UWB observations can be adaptively adjusted. The integrated system performs NLOS identification based on a map line segment matching algorithm; then, abnormal observations are abandoned, or their weights are reduced to prevent the error accumulation of the INS from being incorrectly constrained. Finally, an evaluation based on experimental data shows the significant enhancement achieved with the proposed algorithm based on the integration of UWB technology, an INS and a floor map, which can achieve a 2-D positioning accuracy that corresponds to a root mean square error of 0.27 m. Thus, substantial improvements can be achieved for long-term operation in NLOS environments using the proposed integration scheme.

Cordate-shaped UWB-MIMO antenna with notch band characteristic and high isolation

PurposeThis paper aims to design a most demanding low profile and compact ultra-wide band (UWB) antenna system for various wireless applications. The performance (in terms of data rate) of UWB system is improved by using multiple-input-multiple-output (MIMO) technology with it. Owing to the overlap of other existing licensed bands with that of UWB, electromagnetic signals can interfere. So, notched band UWB MIMO antenna system reported here which is highly compact, bandwidth efficient, superior data rate and high inter-element isolation comparatively to other reported designs.Design/methodology/approachA 49 × 49 × 1.6 mm3 quad-port UWB MIMO antenna with specific bandwidth elimination property is designed. The proposed planar MIMO configuration comprises unique four identical “Cordate-shaped” monopole radiators fed by 2.3-mm thick microstrip-lines. The radiators are located right-angled to each other to enhance inter-element isolation. Further, a different approach of slitted-substrate is applied to minimize the overall size and mutual coupling of the MIMO antenna, as a substitute of decoupling and matching structures. The defected ground structure is used to obtain −10 dB impedance bandwidth in entire UWB band, without compromising with the lower cut-off frequency response. Further, to eliminate the undesired resonant band (WLAN at 5.5 GHz) from UWB, a rounded split ring resonator is introduced in monopole patch.FindingsIn the entire operating band of 2.8 to 11 GHz, isolation among elements is more than 24 dB, envelope correlation coefficient less than 0.002, diversity gain greater than 9.99 dB and TARC less than −7 dB are obtained at all 4-ports.Research limitations/implicationsThe measured parameters of the fabricated prototype antenna on FR4 substrate are found in good agreement with the simulated results. The small variation in software results and hardware results are observed due to hardware design limitations.Practical implicationsThe proposed design may be used for any wireless application following in the range of UWB.Originality/valueIt can be shown from graphs of measured parameters of the fabricated prototype antenna. They found to be in good agreement with the simulated results.

Mean Bit Error Rate Analysis of High Rate IEEE 802.15.3.a UWB Channels

In this work, the performance of ultra-wide band systems (UWB) in high-speed wireless networks is studied. At the physical layer of wireless personal area networks, dual carrier modulation driving multiband orthogonal frequency division multiplexing is implemented for 480 Mbps data rates over 4 classes of UWB scattering channels (CM1, CM2, CM3, CM4) bundeled as per the IEEE 802.15.3a UWB standard. Generalized wireless fading models are presented and canonical expressions for mean bit error rates (MBER) are derived for different modulation and receiver diversity combining schemes. A generating model in terms of the characteristic function of the signal-to-noise ratio is introduced for MBER under general statistical fading conditions, which further develops our previous work. The power density spectral characteristic of the multi-user noise is tuned to a novel generalized innovation-matched filter (GIMF) which is at the core of the UWB receiver. Because of its robustness at also capturing the fading characteristics of the UWB channels, the GIMF detector yields better performance than the classical matched filter and a 10-finger RAKE receiver. The relatively flat CM1 channel is proven to have the best performance, while the highly frequency selective CM4 suffers from the worst performance. CM3 channel slightly outperforms CM4 channel between 0 and 5 dB and exhibits significant improvement over CM4 above 5 dB SNR. CM3 and CM4 channels are proven to have nearly identical performance below 0 dB margins. A comparative analysis was also conducted for the MBER of our model and that of the CF-based model at a 10-finger RAKE receiver developed by Wang et al. It was found that our model outperforms that of the CF-model for CM1 and CM2 channels for a wide dynamic range of SNR values. For CM3 and CM4 channels, our model's performance was superior for SNR values below 8 dB.

A highly sustainable multi-band orthogonal wavelet code division multiplexing UWB communication system for underground mine channel

The underground mine channel is highly hostile for communication. A sustainable communication system is required to be integrated as a multipurpose system capable of transferring all types of information such as data, voice and video on identical infrastructure. With its large bandwidth, the Ultra Wide Band (UWB) provides a promising solution to satisfy these requirements. The Multi-Band Orthogonal Frequency Division Multiplexing (MBOFDM) UWB system provides high resilience to Inter-Symbol Interference (ISI) caused by multipath fading channels. This study compares the performance of various existing multi-band UWB systems in the IEEE UWB channel and underground mine channel: MBOFDM, Multi-Band Orthogonal Frequency Code Division Multiplexing (MBOFCDM) and Multi-Band Orthogonal Wavelet Division Multiplexing (MBOWDM). Further, the application of 2D spreading to the MBOWDM UWB system is attempted, and as a result, the Multi-Band Orthogonal Wavelet Code Division Multiplexing (MBOWCDM) UWB system is proposed. The performance of the MBOWCDM system in the IEEE UWB channel and underground mine channel is investigated. The performance of the MBOWCDM UWB system is observed to be superior to those of other multi-band UWB systems. Moreover, the MBOWCDM UWB system supports a higher data rate with low complexity and lower overheads.

Modeling of UWB Channel With Population Density in Indoor LOS Environments

This letter deals with the effect of multiple human bodies on an ultrawideband (UWB) channel in indoor line-of-sight (LOS) environments. To assess this, we choose four environments and consider four scenarios that have a different number of people in each environment. A distance-dependent path-loss model, a frequency-dependent path-loss model, and time dispersion parameters are considered. We found that the distance-dependent path-loss exponent increases as population density increases, while the frequency-dependent path-loss exponent decreases. The time dispersion parameters decrease as population density increases. The results suggest that the effect of the presence of people on UWB channels should be considered when assessing the performance of UWB systems.

Performance Analysis of the Multiband Orthogonal Frequency Division Multiplexing Ultra-Wideband Systems for Multipath Fading and Multiuser Interference Channels

This paper presents the performance analysis of the multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) systems for multipath fading and multiuser interference channels. A closed form approximation of the BER performance of the MB-OFDM UWB system with multiple interferences is proposed. Based on the derived approximation, the effects on the BER performance for the choice of the codeword constraint lengths of the convolutional encoder, the length of the cyclic prefix, and the multiuser environments of two or more interferers are thoroughly discussed. Four UWB multipath fading channels are also investigated for the BER performance of the MB-OFDM UWB system. The simulated results provide us with useful information to appropriately choose the parameters of the MB-OFDM UWB system for the sake of achieving the BER performance that conforms to requirement of the FCC standards.

PERFORMANCE EVALUATION OF ADAPTIVE RECEIVERS FOR UWB COMMUNICATION

UWB (Ultra Wide Band) is a radio technology used at very low energy levels for short-range, high-bandwidth communications using a large portion of the radio spectrum. But MAI (Multiple Access Interference) degrades the performance of UWB systems. To suppress this, an α-stable model along with Fama/Roll-McCulloch parameter estimation technique is used. This model adapts to the noise and interference in the environment and hence it forms a robust technique for adaptive receiver designs. But this technique shows BER performance clearly only in high SNR region. Hence matched filter techniques are proposed here. From simulation results, it is verified that the proposed method provides better BER than the linear and myriad filter detectors.

A Survey on Various Receivers for UWB Communication

Ultra Wideband (UWB) is an inherent technology used in current wired and wireless communication systems. These systems share the radio frequency spectrum with narrowband signals and also provide high data rates, low cost, greater bandwidth, good time domain resolution and improved channel capacity. UWB technology has attracted a lot of inquisitiveness in researchers worldwide. There are several challenges in designing a UWB receiver such as channel estimation and interference mitigation. In multi-user environments, multiple access interference (MAI) degrades the performance of UWB systems. To prevail over these challenging issues, an adaptive and robust receiver needs to be designed to alleviate interference in all types of environments. In this paper, the different types of receiver structures like Rake, energy, correlation, suboptimal, near-optimal and adaptive nonlinear rake receivers are surveyed and their performances are analyzed. This survey helps to realize superior bit error rates (BER) and excellent signal-to-noise ratios (SNR). Keywords: Adaptive nonlinear rake receivers, Correlation receivers, Energy detectors, Rake receivers, Ultra wideband (UWB).

Evaluation of System Performance of Ultra-Wide Band Jointing in MC Signaling in Correlated Environments

The evaluation of System Performance of UWB (ultra-wide band) jointing in MC (multi-carrier) signaling in correlated environments is presented in the report. The correlated Nakagami-m statistical distribution for the multipath fading model is assumed in this scenario. In fact to establish the model for analyzing in this article is using MC-CDMA (multi-carrier code-division multiple-access) system characterization combined with a UWB scheme. The average BER (bit error rate) is calculated and compared to a special case of previously published results. Studied results from this paper can be implied to approve the system performance for a UWB system combined with a MC-CDMA wireless communication system. It is worth noting that the Nakagami-m distributed fading parameter significantly dominates UWB system performance when it cooperates with MC signaling under a fading environment. Finally, it is worthy of noting that when the SNR (signal-to-noise ratio) at system’s receiver reaches a preset high threshold value, the parameter of power decay ratio effect could be not included.

A PSO-Based UWB Pulse Waveform Design Method

The pulse waveform design method for ultra wideband (UWB) communication based on particle swarm optimization (PSO) technique is discussed, and the performance of UWB system with designed pulse is analyzed. According to analysis, the design of pulse is transformed into a process of finding the minimal solution of a function about weighting coefficient. The weighting coefficients are made certain based on PSO algorithm. The properties such as bit error rate (BER) performance in both single link and multi-user, link budget of the UWB system employing the designed pulse are simulated. Compared with Scholtz’s monocycle and random combined pulse, the results showed that the pulse designed based on the PSO algorithm has better BER performance and communication performance.

Error Performance of Spatial-temporal Combining-based Spatial Multiplexing UWB Systems Using Transmit Antenna Selection

This paper applies transmit antenna selection algorithms to spatial-temporal combining-based spatial multiplexing (SM) ultra-wideband (UWB) systems. The employed criterion is based on the largest minimum output signal-to-noise ratio of the multiplexed streams. It is shown via simulations that the bit error rate (BER) performance of the SM UWB systems based on the two-dimensional Rake receiver is significantly improved by antenna diversity through transmit antenna selection on a log-normal multipath fading channel. When the transmit antenna diversity through antenna selection is exploited in the SM UWB systems, the BER performance of the spatial-temporal combining-based zero-forcing (ZF) receiver is also compared with that of the ZF detector followed by the Rake receiver.

Double Binary Turbo Coded Data Transmission of STBC UWB Systems for U-Healthcare Applications

In this paper, we analyze and simulate performance of space time block coded (STBC) binary pulse amplitude modulation-direct sequence (BPAM-DS) ultra-wideband (UWB) systems with double binary turbo code in indoor environments for various ubiquitous healthcare (u-healthcare) applications. Indoor wireless channel is modeled as a modified Saleh and Valenzuela (SV) model proposed as a UWB indoor channel model by the IEEE 802.15.SG3a in July 2003. In the STBC encoding process, an Alamouti algorithm for real-valued signals is employed because UWB signals have the type of real signal constellation. It is assumed that the transmitter has knowledge about channel state information. From simulation results, it is shown that the STBC scheme does not have an influence on improving bit error probability performance of the BPAM-DS UWB systems. It is also confirmed that the results of this paper can be applicable for u-healthcare applications.

Advanced System Level Simulation Platform for Three-Dimensional UWB Through-Wall Imaging SAR Using Time-Domain Approach

A previously developed simulation platform for localization purposes has been extended and customized to accurately analyze and simulate ultra wideband (UWB) through-wall imaging (TWI) synthetic aperture radar (SAR) systems as well. The newly added features/modules include electromagnetic simulator to account for wall presence and target scattering, a wideband backprojection imaging algorithm, and different transceiver architectures and antenna array configurations. The developed platform is capable of time gating to suppress early wall reflections and simulates various discrete components and functions of the UWB SAR system using both linear and nonlinear analysis. The simulator has been experimentally validated for both dielectric and metallic targets. The developed simulator can also be used to study various effects related to operation frequency, pulse width, pulse shape, wall dispersion, and carrier leakage. It predicts UWB system performance such as detection range, image resolution, and receiver dynamic range. The system's components can be re-optimized for high performance 3-D imaging based on our developed models. The simulation platform is also suitable for designing the optimal signal waveform that could improve the recovered image quality for TWI applications.

A Joint Chip Equalization Adaptive Rake Receiver for DS-CDMA UWB Systems over ISI Channels

There is serious inter-symbol interference (ISI) when ultra-wideband (UWB) wireless communication systems work at high data speed since there is much larger channel delay spread. The serious ISI becomes a major factor that affects the performance of UWB systems. In this paper, suppression ISI is developed for direct sequence spread-code division multiple access (DS-CDMA) UWB systems with a high data speed, and a joint chip equalization adaptive Rake (JCE-Rake) receiver is proposed. The proposed JCE-Rake receiver spreads the number of traditional Rake receiver taps to collect multi-path component and equalize the inter-chip interference simultaneously. Then the soft output of JCE-Rake receiver is despreaded with the user's spreading code. Finally the decision is made to recover the transmitted symbol. The simulation results verify that ISI is suppressed effectively and the system performance is improved evidently.

Deterioration of UWB positioning during construction

Abstract Effective planning and control for complex construction projects requires reliable material tracking, effective supply chain visibility, and accurate progress estimation. These applications highlight the importance of real time location and progress tracking technologies such as Radio Frequency Identification Devices (RFID), Global Positioning Systems (GPS), and Ultra Wide Band (UWB) Systems. This paper presents a performance analysis of a UWB positioning system as a material and activity tracking tool for indoor construction projects, with emphasis on field implementation and site validation. This research was designed in three phases and examined the performance deterioration of an UWB system in complete occlusion situations using timber and steel as blocking materials, analyzed the location dependency of UWB system error and investigated the potential for location based error modelling, and investigated the UWB system performance over the construction period of a progressively more heavily congested piping project. The statistical analysis of this research has produced confidence intervals for UWB system error in the various tested configurations to be used in future research. Also, the performance deterioration of the UWB system in an active construction environment has been quantified. Finally, recommendations are provided for effective system implementation in indoor construction projects.

Error Probability Analysis of Time-Hopping Biorthogonal Pulse Position Modulation UWB Systems with a RAKE Receiver over Indoor Multi-Path Fading Channels

This paper presents the error probability analysis of Time-Hopping Biorthogonal Pulse Position Modulation (TH-BPPM) ultra-wideband (UWB) systems with a RAKE receiver over indoor multi-path fading channels. UWB signals suffer from severe multi-path interference when employed in an indoor fading environment. A RAKE receiver can be used to improve the performance of UWB systems. TH-BPPM has attracted much attention in recent years due to its many advantages, such as low probability of error and low complexity. In this paper, the IEEE 802.15.3a indoor channel model is employed to analyze the performance of TH-BPPM UWB systems with different RAKE receivers. The bit error rate (BER) of ARake, PRake, and SRake TH-BPPM UWB systems is derived. The results indicate that ARake has the best performance, SRake is better than PRake when the number of fingers is same.

Performance analysis and optimisation of a cooperative frequency-modulated differential chaos shift keying ultra-wideband system under indoor environments

A cooperative frequency-modulated differential chaos shift keying (FM-DCSK) ultra-wideband (UWB) systems, named cooperative FM-DCSK UWB system, is investigated under indoor environments of IEEE 802.15.4a in this article. The performance of the cooperative FM-DCSK UWB system is evaluated in such channel models (CMs), that is, CM1–CM4, by means of the moment generating function. Monte Carlo simulation results show that the bit-error-rate performance of the proposed system is much better than the conventional multi-access FM-DCSK UWB system, which is showed to be highly consistent with the theoretical results. The integration interval of the proposed cooperative UWB system is optimised to further improve the system performance through the binary search algorithm. Meanwhile, aiming to provide a good compromise between the system performance and implementation complexity, the number of received antenna at the destination (single-input multiple-output architecture) is also investigated and discussed. For the aforementioned advantages, the proposed system can be seen as a viable alternative to other multi-access FM-DCSK UWB schemes for the low-rate and low-power wireless personal area network and wireless sensor network applications.