Ultra-wideband Communication Systems Research Articles

Optimal Selection of Fourier Coefficients for Compressed Sensing-Based UWB Channel Estimation

In this letter, we propose a compressed sensing-based approach for channel estimation in wireless ultra-wideband (UWB) communication systems. The channel is estimated from a minimum number of received signal Fourier coefficients, using a measurement matrix dependent on the transmitted waveform. The optimal subset of coefficient locations, which lowers the coherence of this matrix and maximizes the reconstruction performance, is derived. Furthermore, additional constraints are considered on the subset, to allow the corresponding coefficients to be recovered with a low-complexity sub-Nyquist sampling scheme, as well as to enhance the reconstruction stability to noise. The performance improvement of the UWB channel estimation is demonstrated and the proposed approach is validated using both simulated and measured signals from an experimental setup.

Low-density parity-check codes for noncoherent UWB communication systems

In order to guarantee reliable data transmission, powerful channel coding techniques are usually required in noncoherent ultra- wideband (UWB) communication systems. Accordingly, several forward error correction (FEC) codes, such as Reed-Solomon and convolutional codes have been used in noncoherent UWB systems to improve the bit error rate (BER) performance. In this paper, low-density parity-check (LDPC) codes are further studied as more powerful FEC candidates for noncoherent UWB systems. Two LDPC codes and the corresponding decoding procedures are presented for noncoherent UWB systems. Moreover, performance comparison between the LDPC codes and other FEC codes are provided for three major noncoherent UWB communication systems, namely, noncoherent pulse position modulation (NC-PPM), transmitted reference (TR) and transmitted reference pulse cluster (TRPC). Both theoretical analysis and simulation results show that the two investigated LDPC codes outperform other existing FEC codes with limited penalty in terms of complexity and therefore they are promising FEC candidates for noncoherent UWB systems with low- cost and low-power consumption.

Analytical BER Calculation of TAS/MRC-Based Two Hop UWB Communication System Over IEEE 802.15.4a Channel

ABSTRACTIn this paper, we calculate the bit error rate (BER) of the orthogonal binary signals in the two hop ultra-wideband (UWB) communication system with the transmit antenna selection scheme at the source and the relay terminals. In the two hop UWB system, relay is configured to perform the decode and forward cooperative strategy. In order to calculate the BER of the investigated UWB system, we consider the characteristic function- based approach to model the sum of path gains of the IEEE 802.15.4a channel. We assume that all the IEEE 802.15.4a channel links are independent and identically distributed and perfect channel state information is available at the transmitter. The results exhibit that the derived BER is a good match with the simulations and it has been significantly improved over the BER of the conventional UWB systems.

On the Error Performance of Coding and Equalization in Low-Complexity Ultra-Wideband Communication Systems

In this paper, the performance of various channel coding schemes is investigated in pulse-based ultra-wideband(UWB) communication systems for applications in short-range indoor environments. Pulse-based binary (BPSK) modulation and decision-feedback equalization (DFE) is considered. Concatenated adaptive equalization and coding is explored as an alternative to the more complex and often impractical joint coding and equalization. A block length of approximately 1000 bits is considered in this paper as it results in a static channel with minimal latency while still yielding relatively good error performance. The error performance of a previously proposed turbo product code (TPC), based on two identical Hamming (31,26) codes, is simulated and compared with that of otherchannel coding schemes of similar rate and code length. These include a regular LDPC (1057,813) code, a memory-6 rate-3/4 punctured convolutional code, a Reed-Solomon (127,89) code and a concatenated (off-the-shelf) code with a Reed-Solomon (255,239) outer code and a memory-6 rate-3/4 punctured convolutional inner code. The inclusion of the concatenated Reed-Solomon scheme serves as a reference, as this is an off-the-shelf classical and still popular solution. The simulation results show that, among the coding schemes considered, the LDPC code offers the best error performance.

Optimization of a Printed UWB Antenna: Application of the invasive weed optimization algorithm in antenna design

This article presents a general approach to design and optimize printed ultrawideband (UWB) antennas by using invasive weed optimization (IWO), a well-known global optimization algorithm. To achieve the required radiation parameters over a wide bandwidth, a frequency-related cost function with optimal weighting coefficients is suggested. Two prototypes of the optimized antenna have been manufactured and examined. The experimental outcomes show good agreement with the simulated ones that validate the proposed optimization approach. The optimized antenna has a compact size of 50 mm × 50 mm. The operational bandwidth of the antenna for S 11 <; -10 dB, from both measurement and simulation, is 150%, based on the center frequency of 6.4 GHz (1.6-11.2 GHz), which also covers the UWB (3.1-10.6 GHz) applications. The time-domain response of the antenna was also investigated by measurement of the group delay. Finally, the efficiency of the optimized antenna in terms of bandwidth, size, and gain are compared with a number of previously proposed designs. Comparison results show that the optimized antenna outperforms other designs cited. The experimental outcomes in frequency as well as the time domain show that the antenna is suitable for use in UWB or other communication systems.

Sparsity-based narrowband interference mitigation in ultra wide-band communication for 5G and beyond

In real operating environments, the performance of low power large bandwidth ultra wide-band (UWB) communication systems suffers due to narrowband interference (NBI) from high power narrowband interferers. Since noise is not spectrally white in the presence of NBI in UWB systems, conventional matched filter based receivers are not optimum in such scenarios. Although NBI mitigation methods have been proposed using NBI subspace and/or limiters for UWB systems, subspace-based approaches are usually not feasible due to no apriori knowledge of the NBI subspace in a real scenario, and the limiter-based approach is also non-optimum. In this paper, we propose a sparsity-based NBI mitigation method that exploits distinct characteristics of UWB signals and NBI, and does not require a limiter. Improved performance of the proposed receiver has been validated via time hopping binary phase shift keying (TH-BPSK) UWB signal transmission in both additive white Gaussian noise and multipath fading channels.

Koch fractal-based hexagonal patch antenna for circular polarization

The design and performance of an inset feed modified hexagonal patch antenna for possible applications in ultrawideband communication systems is reported. The inset feed hexagonal patch antenna is modified by introducing a fractal up to the second iteration. A right-angled isosceles triangular microstrip antenna is used in the Koch fractal structure on the edges. The proposed antenna is a combination of two standard fractal structures, i.e. Sierpinski and Koch. A rectangular defect in the ground has also been done. The antenna is simulated by applying CST Microwave Studio simulation software. The results are verified by fabricating the antenna and tested using a vector network analyzer. The developed design shows good matching with the feed network at frequencies of 3.1 GHz, 6.9 GHz, 7.3 GHz, 8.5 GHz, and 9.1 GHz. The simulated peak gain of the antenna at resonant frequencies is 4.08 dB, 4.79 dB, 3.85 dB, 3.46 dB, and 3.01 dB. The antenna is fabricated on FR-4 substrate having size 30 $\times $ 35 $\times $ 1.59 mm$^{3}$. It covers the S and X band range. It can be used for microwave applications as it is a part of the microwave spectrum, for wireless networking devices coming under IEEE standards. It can also be used for multimedia applications like mobile TV and satellite radio that use the S band as their frequency range and in home-based consumer electronics like microwave ovens, cordless phones, and wireless headphones. For higher ranges, i.e. in the X band, it can be used in radars, satellites, and military appliances.

Performance Evaluation of High Data Rate M-OAM UWB Physical Layer for Intelligent Transportation Systems

In this paper, a high data rate modulation scheme for impulse radio ultra-wideband (IR-UWB) communication system using orthogonal waveforms is presented. The proposed M-state Orthogonal Amplitude Modulation (M-OAM) is evaluated under additive White Gaussian noise and indoor multipath channels IEEE.802.15. The simulation results show that the proposed system performance, in term of bit error rate (BER), is of the same order as that of the traditional UWB modulation. In addition, the M-OAM modulations provide a high data rate for short range wireless applications. Nevertheless, the multipath effect reduces the quality of transmission. Thus, the performances of three receiver architectures, that employ different pulse combining schemes, are investigated. Namely, a conventional matched filter receiver, a RAKE receiver and a minimum mean square error equalizer are considered. This study shows that the proposed M-OAM communication system offers good performances in term of quality of services, channel capacity and BER.

Transmit Antenna Selection in the Cooperative Communication Based UWB System

In this paper, We derived an expression of the average bit error rate (ABER) of the relay assisted two-hop ultra-wideband (UWB) communication system over IEEE 802.15.3a channel model incorporated with the transmit antenna selection at the source and relay nodes. In this two-hop system, each node equipped with the multiple antennas and relay is configured to perform decode and forward protocol. The analysis considers the numerically evaluated characteristic function of the sum of the path gains, which are specified in the IEEE 802.15.3a channel model. During the analysis, we assumed that all the channel links and channel paths are independent and identically distributed. Our result shows the derived ABER is well matched to the simulation. It also presents the comparison of the ABER between the investigated and the conventional UWB systems. This paper also presents the flowchart of the Monte-Carlo simulation of the investigated UWB system.

Design of reconfigurable active integrated pulse generator‐antenna with pulse‐shape modulation for ultra‐wideband applications

A novel design of ultra-wideband (UWB) reconfigurable pulse generator (PG) active-integrated antenna (AIA) is introduced and discussed in this study. The reconfigurable structure of the proposed PG AIA provides pulse-shape modulation which is desirable for most UWB communication systems. The presented design utilises only a single step-recovery diode and just a single positive-intrinsic-negative diode in order to generate sub-nanosecond switchable monocycle/doublet pulse shapes. Since in UWB communication systems the design of source pulses and transmitting/receiving antennas should be optimal for the performance of overall systems both frequency domain and time domain characteristics of the designed PG AIA are carefully investigated under realistic conditions. The pulse distortion is insignificant in the operating band and is verified by the measured PG AIA performance with low ringing level, high signal fidelity, and virtually steady group delay. The presented design is a good candidate for UWB transmission because of its simplicity, low cost, and good performance.

Improving the power efficiency of SOA-based UWB over fiber systems via pulse shape randomization

A simple pulse shape randomization scheme is considered in this paper for improving the performance of Ultra Wide band (UWB) communication systems using On Off Keying (OOK) or Pulse Position Modulation (PPM) formats. The advantage of the proposed scheme, which can be either employed for Impulse Radio (IR) or for carrier-based systems, is first theoretically studied based on closed-form derivations of power spectral densities. Then, we investigate an application to an IR-UWB over optical fiber system, by utilizing the 4-th and 5-th orders of Gaussian derivatives. Our approach proves to be effective for 1 Gbps-PPM and 2 Gbps-OOK transmissions, with an advantage in terms of power efficiency for short distances. We also examine the performance for a system employing an in-line Semiconductor Optical Amplifier (SOA) with the view to achieve a reach extension, while limiting the cost and system complexity.

Multi-objective optimization for UWB antenna array by APSO algorithm

In this paper, a uniform circular antenna array (UCAA) combining genetic algorithm (GA) or asynchronous particle swarm (APSO) for finding out global maximum of multi-objective function in indoor ultra-wideband (UWB) communication system is proposed. The algorithm is used to synthesize the radiation pattern of the directional UCAA to reduce the bit error rate (BER), to increase received energy and channel capacity in indoor UWB communication system. Using the impulse response of multipath channel, the BER of the synthesized antenna pattern on binary antipodal-pulse amplitude modulation system can be calculated. Based on topography of the antenna and the shooting and bouncing ray/image techniques, the synthesized problem can be reformulated into a multi-objective optimization problem which would be solved by the GA and APSO. Numerical results show that the fitness value and convergence speed by APSO is better than those by GA. The results also show that for multi-objective problem APSO compared to GA can reduce the BER substantially. Moreover, APSO can get better results for both line-of-sight and non line-of-sight cases.

Compact filtering monopole patch antenna with dual-band rejection.

In this paper, a compact ultra-wideband patch antenna with dual-band rejection is proposed. The proposed antenna filters 3.3–3.8 GHz WiMAX and 5.15–5.85 GHz WLAN by respectively rejecting these bands through a C-shaped slit and a λg/4 resonator. The λg/4 resonator is positioned as a pair, centered around the microstrip line, and a C-type slit is inserted into an elliptical patch. The impedance bandwidth of the proposed antenna is 2.9–9.3 GHz, which satisfies the bandwidth for ultra-wideband communication systems. Further, the proposed antenna provides dual-band rejection at two bands: 3.2–3.85 and 4.7–6.03 GHz. The radiation pattern of the antenna is omnidirectional, and antenna gain is maintained constantly while showing −8.4 and −1.5 dBi at the two rejected bands, respectively.

Circular Patch Antenna with Defected Ground for UWB Communication with WLAN Band Rejection

&lt;p&gt;The design and performance of coplanar waveguide fed modified circular patch antenna for possible application in ultra wideband communication systems with band rejection for upper wireless local area network band (5.15 GHz - 5.85 GHz) is reported. This antenna is designed on glass epoxy FR4 substrate having size 30 mm × 20 mm × 1.59 mm. The coplanar waveguide fed circular patch antenna is modified by introducing L shaped slits in ground plane and U shaped slot in patch and performance analysis of antenna is simulated by applying CST microwave studio simulation software. Different designed antennas were tested with available experimental facilities. The developed end product shows a nice matching with feed network at frequencies 2.62 GHz, 3.94 GHz and 8.50 GHz and provides 10.38 GHz (3.33 GHz - 13.71 GHz) impedance bandwidth with wireless local area network 5.5 GHz (4.74 GHz - 6.15 GHz) band rejection. The co and cross polar patterns in elevation and azimuth planes at two frequencies namely 2.62 GHz and 3.94 GHz are obtained which dictate that co-polar patterns are significantly better than cross polar patterns. The simulated peak gain of antenna is close to 3.86 dBi and gain variation with frequency shows a sharp gain decrease in the frequency range 4.74 GHz to 6.15 GHz.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Design and simulation of a compact ultra-wideband bandpass filter with a notched band using multiple-mode resonator technique

A novel, compact, and highly selective ultra-wideband (UWB) bandpass filter with a narrow notched band is presented. Apart from having a basic structure of a slotline multiple-mode resonator (MMR) and microstrip feed lines, this novel design introduces a cross-coupling between the input and output feed lines to enhance the filter selectivity. The design strictly follows the theory and verified by electromagnetic (EM) simulation and experiments. In addition, the narrow notched band is introduced by embedding a pair of split ring resonators (SRR) in order to reject any undesired existing radio signals that may interfere with the Federal Communications Commission (FCC)-defined UWB band. By changing the structural parameters of SRR, it can be easily tuned to any desired frequency. This filter can be integrated in UWB communication systems and efficiently improve the interference immunity from undesired signals such as wireless local area network (WLAN).

Two-Stage Channel Estimation With Estimated Windowing for MB-OFDM UWB System

We propose a two-stage channel estimation technique for high rate ultra-wideband communication system. In the preamble-stage, we perform initial channel estimation using least square approach followed by frequency-domain smoothing operation. Estimated channel at this stage is then windowed by a rectangular window of Hannan–Quinn criteria-optimized length. In the payload-stage, estimated channel from the previous stage is further refined by applying time- and frequency-redundancy in a decision-directed manner followed by smoothing and windowing. Link level simulation shows that the two-stage method with optimized windowing provides a good estimation performance close to that of the minimum-mean-square-estimation (MMSE) scheme with significant reduction in computational cost.

Mini UWB-Bluetooth Antenna Design with Band-Notched Characteristics

Objective: In this paper a novel small size antenna for Ultra Wide Band (UWB) and Bluetooth application is proposed which there by minimize the potential interference between the UWB system and WLAN system. Band notch are designed to reject 5.15-5.5825 GHz frequency band f Wireless Local Area Network (WLAN) application based on IEEE 802.11 standard. Methods/Statistical Analysis: This is achieved by choosing a small monopole antenna with U shaped radiator and a rectangular ground plane. A pair of L shaped slot is etched on the ground to obtain the WLAN band notched characteristics. Findings: The antenna consisting of fork shaped radiating element is fed to a 50 ohm micro strip line. Dimension of the central arm govern the Bluetooth band while the U shaped monopole antenna govern the Ultra Wide Band UWB. Furthermore by placing two L shaped slot on the ground plane. Adjusting the total length of the L shaped slots on the ground plane the desired band notched frequency can be controlled to minimize the potential interference in the system. The characteristics of the designed structure are achieved using finite element method based electromagnetic simulator, HFSS and the fabrication is done using FR4 substrate. Applications/Improvements: The dimensions are varied to get the desired radiation promising return loss data with good matching, high gain, good efficiency and reject bands. The experimental result shows that the proposed antenna is a good candidate for application in UWB communication systems.

Industrial WSN Based on IR-UWB and a Low-Latency MAC Protocol

AbstractWireless sensor networks for industrial communication require high reliability and low latency. As current wireless sensor networks do not entirely meet these requirements, novel system approaches need to be developed. Since ultra wideband communication systems seem to be a promising approach, this paper evaluates the performance of the IEEE 802.15.4 impulse-radio ultra-wideband physical layer and the IEEE 802.15.4 Low Latency Deterministic Network (LLDN) MAC for industrial applications. Novel approaches and system adaptions are proposed to meet the application requirements. In this regard, a synchronization approach based on circular average magnitude difference functions (CAMDF) and on a clean template (CT) is presented for the correlation receiver. An adapted MAC protocol titled aggregated low latency (ALL) MAC is proposed to significantly reduce the resulting latency. Based on the system proposals, a hardware prototype has been developed, which proves the feasibility of the system and visualizes the real-time performance of the MAC protocol.

DS-UWB pulse design in IEEE802.15.3a multipath fading channel for cognitive radio applications

This paper presents a novel spectrum shaping technique in direct sequence ultra-wideband (DS-UWB) communication systems. This proposed pulse introduces spectral nulls to limit the interference impact of high power coexisting narrowband signals and to elevate the applications of cognitive radio. The idea depends on the addition and subtraction of several UWB Gaussian derivative pulses in order to design a new pulse that has spectral null at the operating frequency of the narrowband interference (NBI) signal. The use of the Gaussian derivative ensures that the UWB spectrum mask established by the Federal Communications Commission (FCC) is met. The NBI signals are modelled as either the wireless local area network (WLAN) IEEE802.11n which operates in the 5 GHz frequency band or multi tone signals. The power spectral density of the proposed transmitted UWB pulse is derived analytically. The bit error rate performance of the proposed pulse is derived in the multi-path IEEE802.15.3a UWB fading channel models and validated with simulations. Results show that the impact of either the IEEE802.11n interference signal or the multi tone interference signals can be effectively suppressed by transmitting and matched filtering the new pulse with a single or multiple spectral nulls at the interference operating frequencies.

Применение вейвлетов и функций Эрмита для моделирования СШП импульсов под требования маски ГКРЧ

This work is concerned on research of potentialities of Hermiteans and wavelets using for design of pulse with spectral density, which satisfies to spectral mask approved by State Committee of Radio Frequencies for indoor ultra-wideband device emission level. We defined a problem of pulse form optimization and researched two classes of functions. First, is based on Hermit polynomials, while the second is based on B-wavelet frequency spline. We researched pulse form dependence on parameters, function order, and performed pulse simulation. The mask utilization coefficient was used as criterion for comparison of simulated and known pulse forms proposed in other publications listed in reference. We propose to apply these pulse forms for ultra-wideband communication systems due to simple generation and high value of mask utilization coefficient.