Multiband UWB Research Articles

Development of Two UWB Multiband MIMO Antennas with Enhanced Isolation and Cross-Correlation

An Ultra-Wide Band (UWB) MIMO antenna working at millimeter-wave is proposed in this research. It is composed of eight radiating elements with various shapes. It is designed with a rectangular structure and various carved slots. The carved slots are used to increase the antenna's bandwidth. The antenna's radiating elements are placed near one another, and thus, isolation is widespread. In order to improve the isolation of the MIMO antenna, parasitic elements and a defective ground structure are used. Antenna parameters such as Correlation Coefficient (CC), Envelope Correlation Coefficient (ECC), Diversity Gain (DG), and Total Active Reflection Coefficient (TARC) depend on the isolation. Parasitic elements with a rectangular form are positioned between the radiating patches. Rectangular-shaped ground structures with defects comprise the ground plane. An FR-4 substrate is used to fabricate the antenna. The analysis of the antenna shows that there is less than -14dB return loss, less than -40dB isolation, less than 0.0010 cross-correlation, less than 0.10 TARC, and higher than 500MHz bandwidth. The antenna uses a fractional bandwidth higher than 35% (UWB) for the 6GHz frequency and operates on a variety of bands. This antenna is suitable for many different wireless system applications.

A new insightful exploration into a low profile ultra-wide-band (UWB) microstrip antenna for DS-UWB applications

Designing a simple and planar antenna for high speed short distance ultra-wideband (UWB) communication has become a buzzword over the last few years. There are two very different categories of UWB technologies of vital relevance, i.e. (i) carrier-free direct sequence UWB (DS-UWB), and (ii) the Multi-Band orthogonal frequency division multiplexing UWB (OFDM UWB) technology. In, Multi-Band OFDM UWB technology, multi narrowband UWB antennas with frequency notches are required. However, in DS-UWB technology, the frequency spectrum of very short duration transmitted pulses occupies wide bandwidth, and hence to transmit it, the antenna should be fully matched over the entire bandwidth without the presence of any frequency notch. In this paper, a novel, small and completely planar air gap and defected ground slot integrated rectangular microstrip antenna with dual shorting posts have been thoroughly investigated to yield UWB, i.e. (109%) bandwidth without the presence of any frequency notch.

Wide to multiband elliptical monopole reconfigurable antenna for multimode systems applications

Wideband-multiband reconfigurable elliptical monopole antenna is investigated in this paper. By having conventional elliptical monopole antenna, wideband operating frequency is obtained. With the combination of dual pairs of slotted arms and a band-pass filter on the ground plane of the elliptical monopole, multiband is achieved. Dual-band operating frequencies at 1.6 GHz and 2.6 GHz while wideband operates from 3.35 GHz to 9 GHz. Therefore, wide range of wireless communication systems is obtained from the proposed antenna to support the multiband mode (i.e. GPS and LTE) and UWB systems. Frequency reconfigurable is achieved by controlling the switches integrated on the antenna structure. Simulated results of reflection coefficient, radiation patterns and gain performance are presented. The proposed antenna design is suitable candidate for different wireless communication applications.

Performance of multi-band OFDM UWB communication systems in presence of IEEE802.11n WLAN interference for different antenna scheme configurations

Multi-band orthogonal frequency division multiplexing ultra-wideband (MB OFDM UWB) communication system has been a leading proposal in the IEEE 802.15.3a standard and has been adopted in the ECMA standard for wireless personal area networks. In this paper, the performance of the MB-OFDM UWB communication system in the Saleh-Valenzuela multi-path UWB channel model using different antenna scheme configurations has been analytically evaluated. The analytical evaluation has been investigated for the three antenna scheme configurations which are the single input multiple output (SIMO), the multiple input single output (MISO), and the multiple input multiple output (MIMO). The issue of existence of high power inband interference signal such as the IEEE802.11n has been also analytically evaluated. A practical link budget analysis is considered. It was shown that the performance of the desired MB-OFDM UWB SIMO/MISO/MIMO communication system can severely deteriorated due to presence of such high power inband interference signal. The obtained analytical results are validated with the aid of extensive simulation results.

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.

Converged transport of 10 Gbit/s 4-PAM signal and 1 Gbit/s MB-UWB signal over single wavelength

A novel scheme for simultaneous transport of multi-level pulse-amplitude modulation (M-PAM) wired baseband signal and multi-band ultra-wideband (MB-UWB) wireless signal over single wavelength is proposed and demonstrated. Because MB-UWB signal has some unique advantages such as flexible center frequency and narrower bandwidth, the available spectrum range for transmiting wired baseband signal is expanded in hybrid services. In addition, M-PAM signal is employed to enhance the bitrate of wired baseband signal that is limited by the available spectrum range. In this letter, converged transmission of 1Gbit/s MB-UWB signal and 10Gbit/s 4-PAM signal over 20-km standard single mode fiber (SSMF) is demonstrated. The proposed approach will greatly promote the transmission ability of WDM-PON network incorporating UWBoF system for broadband wireless access.

A software reconfigurable optical multiband UWB system utilizing a bit-loading combined with adaptive LDPC code rate scheme

Abstract In this paper, an effective bit-loading combined with adaptive LDPC code rate algorithm is proposed and investigated in software reconfigurable multiband UWB over fiber system. To compensate the power fading and chromatic dispersion for the high frequency of multiband OFDM UWB signal transmission over standard single mode fiber (SSMF), a Mach-Zehnder modulator (MZM) with negative chirp parameter is utilized. In addition, the negative power penalty of −1 dB for 128 QAM multiband OFDM UWB signal are measured at the hard-decision forward error correction (HD-FEC) limitation of 3.8 × 10 −3 after 50 km SSMF transmission. The experimental results show that, compared to the fixed coding scheme with the code rate of 75%, the signal-to-noise (SNR) is improved by 2.79 dB for 128 QAM multiband OFDM UWB system after 100 km SSMF transmission using ALCR algorithm. Moreover, by employing bit-loading combined with ALCR algorithm, the bit error rate (BER) performance of system can be further promoted effectively. The simulation results present that, at the HD-FEC limitation, the value of Q factor is improved by 3.93 dB at the SNR of 19.5 dB over 100 km SSMF transmission, compared to the fixed modulation with uncoded scheme at the same spectrum efficiency (SE).

UWB pulse design using constraint convex sets method

SummaryIn this paper, we propose a constrained convex sets–based method for designing ultra‐wideband (UWB) pulse. The UWB pulses designed using earlier proposed methods either do not fit well in UWB spectral mask or require extra processing circuitry for pulses to fit in the UWB spectral mask. The proposed constraint sets–based method is flexible and optimum for the UWB mask. The pulse designed by the proposed method is Federal Communication Commission compliant and has an autocorrelation function similar to the Gaussian pulse. The bit error rate performance of time hopping binary phase shift keying using the proposed method and some of the existing methods such as Norman and Lee pulses and sixth derivative Gaussian pulse is analyzed in additive white Gaussian noise and Saleh‐Valenzuela channels. Pulse designed using the proposed method outperforms existing pulse design, and the same is verified through simulations. The proposed algorithm is flexible and can also be used to mitigate narrow band interference, multiband UWB pulse generation and any other Federal Communication Commission (or other regulatory body) compliant spectrum mask by modifying the parameter of the proposed constraint set(s).

Design & analysis of a microstrip line multi band UWB filter

In this article, a simple and compact multi band Ultra Wide Band Pass Filter is implemented and electrical analysis of this filter is presented. The proposed filter consists of five short circuited stubs of quarter wave length and three embedded U-shaped open circuited stubs, each of length λ/4, in the ground plane. The notches provide good rejection at 4.6GHz, 5.6GHz and 8.5GHz which removes the interference in UWB band for INSAT C-band, WLAN and X-band applications. The proposed structure is simulated on the commercially available CST MWS software and fabricated using GML1000 substrate with a dielectric constant of 3.2 and a height of 30mil. The frequency responses of this filter are obtained for the circuit model on SERENIDE, for structure simulated on CST MWS and the response measured on VNA. All three responses are showing close resemblance. This filter gives a better performance and is easily fabricated having dimension of about (0.99λg×0.279λg) where λg=0.030m.

Multiband Ultra-Wideband Signal Generation With Quadrupled Capacity by a Single Modulator

We propose and experimentally demonstrate a photonic generation scheme for multiband ultra-wideband (MB-UWB) signal by employing a dual-drive Mach–Zehnder modulator (DDMZM). In this scheme, four electrical binary pulse streams with different bit rates are combined to drive one radio frequency (RF) port of the DDMZM, while the other RF port is modulated by the sum of their 1-b delayed duplicates. By properly adjusting the bit rate and the amplitude of each pulse stream, as well as the bias voltage of the DDMZM, an MB-UWB signal with four sub-bands can be obtained and the transmission capacity can be quadrupled. The feasibility of the proposed scheme is verified by a system demonstration, where the signal modulated by amplitude-phase-shift-key format reaches a high bit rate of 2 Gb/s.

Adaptive modulation and intra-symbol frequency-domain averaging scheme for multiband OFDM UWB over fiber system

To overcome the unbalanced error bit distribution among subcarriers caused by inter-subcarriers mixing interference (ISMI) and frequency selective fading (FSF), an adaptive modulation scheme based on 64/16/4QAM modulation is proposed and experimentally investigated in the intensity-modulation direct-detection (IM/DD) multiband orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) over fiber system. After 50km standard single mode fiber (SSMF) transmission, at the bit error ratio (BER) of 1×10−3, the experimental results show that the power penalty of the IM/DD MB-OFDM UWBoF system with 64/16/4QAM adaptive modulation scheme is about 3.6dB, compared to that with the 64QAM modulation scheme. Moreover, the receiver sensitivity has been improved about 0.52dB when the intra-symbol frequency-domain averaging (ISFA) algorithm is employed in the IM/DD MB-OFDM UWBoF system based on the 64/16/4QAM adaptive modulation scheme. Meanwhile, after 50km SSMF transmission, there is a negligible power penalty in the adaptively modulated IM/DD MB-OFDM UWBoF system, compared to the optical back-to-back case.

Integrated reconfigurable multiple‐input–multiple‐output antenna system with an ultra‐wideband sensing antenna for cognitive radio platforms

A compact, novel multi-mode, multi-band frequency reconfigurable multiple-input-multiple-output (MIMO) antenna system, integrated with ultra-wideband (UWB) sensing antenna, is presented. The developed model can be used as a complete antenna platform for cognitive radio applications. The antenna system is developed on a single substrate area of dimensions 65 × 120 mm 2 . The proposed sensing antenna is used to cover a wide range of frequency bands from 710 to 3600 MHz. The frequency reconfigurable dual-element MIMO antenna is integrated with P-type, intrinsic, N-type (PIN) diodes for frequency agility. Different modes of selection are used for the MIMO antenna system reconfigurability to support different wireless system standards. The proposed MIMO antenna configuration is used to cover various frequency bands from 755 to 3450 MHz. The complete system comprising the multi-band reconfigurable MIMO antennas and UWB sensing antenna for cognitive radio applications is proposed with a compact form factor.

Range impairments of multi-band OFDM UWB communication systems in the presence of OFDM-based WLAN interference

In this paper, a closed form expression for the bit error rate performance of the multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra wideband (UWB) communication system in the presence of interference is analytically analysed. The considered channel is the Saleh-Valenzuela multipath fading channel model. The interference is modelled as the OFDM-based IEEE802.11n wireless local area networks (WLANs). The dependence of the bit error rate performance of the MB-OFDM UWB communication system on the transmission range along with the impact of interference is also analytically investigated. Numerical results are validated with the aid of simulations. It is shown that the range performance of the MB-OFDM UWB communication system is severely deteriorated due to the presence of such interference.

A Cognitive Radio Reconfigurable MIMO and Sensing Antenna System

A planar, compact, single-substrate, multiband, frequency-reconfigurable multiple-input–multiple-output (MIMO) antenna system is presented. The proposed antenna elements are integrated with an ultrawideband (UWB) sensing antenna to develop a complete antenna platform for cognitive radio (CR) applications. The dual-element MIMO antenna is integrated with p-i-n and varactor diodes for frequency reconfigurability. Two modes of selection are used for the MIMO antenna system reconfigurability along with varactor tuning to sweep the frequency over a wide band especially below 1 GHz. The proposed sensing antenna is used to cover a wide range of frequency bands from $720\sim3440~\hbox{MHz}$ . The complete system comprising the multiband reconfigurable MIMO antennas and UWB sensing antenna for CR applications is proposed with a compact form factor. The antenna system is developed on a single substrate area of dimensions $65\times120\times1.56~\hbox{mm}^3$ .

Single and Multiband UWB Circular Patch Antenna for Wireless Communication Applications

This paper presents the design of an ultra-wide band (UWB) circular patch antenna with microstrip line feed and optimization of various antenna parameters. The antenna with dimension of (33 x 30 x 1.5) mm3 is fabricated on FR-4 epoxy substrate having permittivity constant er=4.3, loss tangent tanδ=0.002. The designed antenna has the capability of operating in the bands (2.7-4) GHz, (6.8-12.5) GHz and (14.6-18) GHz. The antenna performance was modified by inserting a slot in the ground plane to achieve impedance bandwidth (S11<-10dB) in (2.7-20) GHz. The modified antenna was fabricated and tested using the vector network analyzer. The simulated and measured results are presented and compared. The feed line used has characteristic impedance of 50Ω.

Performance Enhancement of Multi Band-OFDM Based Ultra Wide Band Systems for WPAN

Ultra wideband (UWB) technology is the foundation for future pervasive, wireless personal area networks (WPANs). The ability of UWB to utilize a large spectrum and thereby provide higher data rates, neither with the expense of multiple antennas nor the power requirements of narrow band transmissions, makes it ideal for low cost, high speed wireless communication. A detailed study of UWB properties in WPAN's, provides a solution to certain key challenges. The high data rate demand of multimedia WPAN's is achieved by utilizing the spectral resources efficiently. This requires UWB devices to be able to use the multiband-UWB (MB-UWB) technology with low complexity in low power systems. Accordingly, this paper proposes the use of UWB in the pulsed-OFDM system as an enhancement to incorporating LDPC coding and APSK modulation schemes that performs comparably to the existing system with low-complexity and power consumption. This thesis proposes the pulsed-OFDM modulation technique as an enhancement to the MB-OFDM system for UWB communications and also to reduce its power consumption and complexity. QPSK, QAM and DCM are the current modulation schemes used for MB-OFDM in the ECMA-368 standard which offers up to 480 Mbs instantaneous bit rate. Furthermore this paper proposes APSK modulation scheme that fits within the configuration of the current standard and increases the system throughput by achieving 960 Mbs. Practical UWB devices are limited to simple coding techniques to minimize both power consumption and device cost. LDPC codes have advantages with respect to the system complexity and hence they are utilized in designing the system.

Modeling, Design and Simulation of Low Complexity IR-UWB Transceiver for Medical Monitoring Applications

This paper presents the system architecture, modeling, design constraints and simulations for an integrated impulse radio ultra-wideband IEEE 802.15.4a transceiver intended for a wearable medical devices for monitoring vital signal parameters. The system design constraints are quantified and dealt off against implementation options with a strong focus on reducing complexity and power consumption. The radio supports low data rates of 110 kbps and ranging capabilities over short distances. The pulse generator which is the most important block in a multiband UWB transmitter is based on the modified triangular pulse shape and it is implemented as a set of four of pulse generators in parallel, allowing the data to be clocked at 125MHz. Simulations show an output pulses with a duration of 4.76ns, which corresponds to 423 MHz bandwidth. The simulated Transmitter has peak output amplitude of 1V, transmitted power of -13.77dBm, a noise figure of 8.3dB, a cascade gain of 18.52dB. The output spectrum centered at 3.4944, 3.9936 and 4.4928 GHz, respectively fully complies with the FCC spectral mask and the rectangular channel mask with more than 30dB of side lobes suppression without the need of additional filter. Receivers performances like noise figure, gain, IIP3, P-1dB are simulated and optimized to meet receiver specifications. The receiver simulations show 104.8dB conversion gain, -18 dBm IIP3,-27.3 dBm P-1dB, 15 dB return loss (S11), 5.34 dB NF and -86.18 sensitivity.

A microwave chaos generator with a flat envelope of the power spectrum in the range of 3–8 GHz

A promising type of ultrawideband (UWB) signals for communications and radar techniques operating in an unlicensed frequency range of 3.1–10.6 GHz, which has been actively developed in recent years, is offered by chaotic oscillations. We have designed and studied a chaotic oscillator with a uniform distribution of spectral power density in the range of 3–8 GHz. The possibility of using these oscillators in multiband UWB communication systems and noise generators for radio-engineering measurements is discussed.

Multiband-UWB Signals Generation Based on Incoherent Microwave Photonic Filters

A structure for multiband-UWB waveforms generation is proposed using an N tap microwave photonic filter with positive and negative taps. The system is based on phase inversion in electro-optical modulators and the sliced broadband source optical signal by means of a structure of AWGs, which permits us to obtain a high number of taps. System performance is experimentally shown by the generation of a uniform waveform. Capabilities as reconfigurability and frequency tuning have been also experimentally demonstrated. The flexibility of the system allows us to obtain multiband UWB waveforms, which fulfill the FCC spectral requirements.

UWB signal receiver with sub-Nyquist rate sampling based on compressed sensing

Purpose – The purpose of this paper is to present a compressed sensing (CS)-based sampling system for ultra-wide-band (UWB) signal. By exploiting the sparsity of signal, this new sampling system can sub-Nyquist sample a multiband UWB signal, whose unknown frequency support occupies only a small portion of a wide spectrum. Design/methodology/approach – A random Rademacher sequence is used to sense the signal in the frequency domain, and a matrix constructed by Hadamard basis is used to compress the signal. The probability of reconstruction is proved mathematically, and the reconstruction matrix is developed in the frequency domain. Findings – Simulation results indicate that, with an ultra-low sampling rate, the proposed system can capture and reconstruct sparse multiband UWB signals with high probability. For sparse multiband UWB signals, the proposed system has potential to break through the Shannon theorem. Originality/value – Different from the traditional sub-Nyquist techniques, the proposed sampling system not only breaks through the limitation of Shannon theorem but also avoids the barrier of input bandwidth of analog-to-digital converters (ADCs).