Ultra-wideband Radio Frequency Research Articles

Simultaneous frequency up/down converting interface based on a single hardware incorporating two phase-correlated photonic mixers.

A novel photonic frequency up/down-converting interface (FCI) with the capability of up-converting an intermediate frequency (IF) signal to a radio frequency (RF) signal and simultaneously down-converting a RF signal to a low IF signal is proposed, and a new application scenario, where both up and down frequency conversion stages of a deramp-on-receive linearly frequency modulated (LFM) continuous wave (CW) radar system are replaced by the FCI, is demonstrated. The five-port photonic FCI can be seen as two ultra-wideband phase-correlated photonic RF mixers incorporated in a single hardware, and the working frequency range of the FCI is up to Ka-band. The FCI is tested by an LFM waveform with 1GHz bandwidth in a deramp-on-receive LFM CW imaging radar system. In the test, the LFM signal can be transmitted and received correctly, and deramp output signals are able to coherently combine among multiple pulses, which generates a clear image of two point-targets with a 3dB range resolution of 15cm.

Photonics-Assisted Ultrawideband RF Self-Interference Cancellation With Signal of Interest Recovery and Fiber Transmission

Self-interference and chromatic dispersion are two main limiting factors that influence the recovery of the signal of interest (SOI) in in-band full-duplex (IBFD) radio-over-fiber (RoF) links. An ultrawideband photonic-assisted approach to radio-frequency (RF) self-interference cancellation (SIC) with high-speed SOI recovery and fiber transmission capability is proposed. The key to achieve the above optimum performances in a compact system is the combined use of fiber dispersion induced RF time delay and optical carrier phase-shifted double sideband (CPS-DSB) modulation. A high precision and tunable time delay matching between the reference signal and the SI signal can be achieved by dispersion induced RF time delay. Meanwhile, the equal amplitude, phase reversal, and dispersion-induced SOI power fading compensation conditions are satisfied simultaneously by manipulating the optical carrier phase of the CPS-DSB signal. For 25 km fiber transmission, 30 dB cancellation depth over 2.7 GHz bandwidth, 160 Mbit/s 16-quadrature amplitude modulation (16-QAM) SOI recovery, and good immunity to fiber dispersion are experimentally demonstrated. In addition, the proposed scheme facilitates multipath SIC by implementing an array of tunable lasers (TLs) with a shared electro-optic modulator at the reference branch.

A tunable ultra‐wideband superheterodyne radio frequency receiver with high‐image‐rejection levels

This article presents the superheterodyne radio frequency (RF) receiver composed of two receiving channels, which can realize an ultra-wide receiving frequency band. The RF signal can be received and demodulated in a variable frequency band by controlling the voltage of RF switches, which makes the RF signal enter the appropriate frequency conversion channel and tuning the local oscillator frequency according to the RF signal frequency. Therefore, the receiver realizes the adjustable working frequency band and an ultra-wide receiving frequency band. The designed superheterodyne RF receiver is simulated, manufactured, and measured. Finally, the article achieves a tunable ultra-wideband superheterodyne RF receiver with an image-rejection architecture that can provide rejection of more than 29.0 dB. The receiving frequency band of the receiver is 2.5 GHz –12 GHz. When the proposed receiver link receives multiple types of quadrature signals with a symbol rate of 50 M Baud, the error vector magnitude is less than 1.90%.

The Correlation between the Development of IoT Robot Technology and the Effect of Economic Development

In order to explore the application of IoT technology in robots and the promotion of IoT robot technology to the economy, by comparing traditional technology and IoT intelligent robot technology, this article combines it with economic development to analyze the promotion of IoT robot to economic development. Based on the ultra-wideband ranging method, this paper designs an ultra-wideband radio frequency positioning system and applies it to the robot’s positioning process. Moreover, this article combines the application of robots in the current social and economic development to construct the system structure, and conducts functional analysis with manufacturing robots and monitoring robots as the main body. After constructing an intelligent robot based on the Internet of Things technology, by comparing the traditional technology and the intelligent robot technology of the Internet of Things, this article combines it with economic development to analyze the promotion of IoT robot to economic development. From the analysis results of this article, it can be seen that the advancement of IoT robot technology can effectively promote economic development.

The Use of Radio Frequency Identification Technologies for Preventing the Spread of Coronavirus

This article contains description of methods to prevent the spread of coronavirus using modern technologies. Businesses face significant challenges in complying with social distancing guidelines, and they do not have a real understanding of whether these guidelines are followed in their facilities. Many companies use Radio Frequency Identification (RFID) technology to ensure the safety of employees by tracking the proximity or location of each. Kinexon's SafeZone and Triax Proximity Trace are effective solutions to prevent the spread of coronavirus within the enterprise. SafeZone is a unique and powerful active RFID technology, the purpose of which is formation of a warning about the convergence and tracking of contacts in case of a positive test result for COVID-19. The solution consists of UWB labels, worn by employees, as well as cloud software to manage the collected data. Contact information allows companies to take steps to create a safe and healthy work environment. The SafeZone solution uses ultra-wideband (UWB) radio frequency tags. UWB uses the frequency bands 3.25 - 4.75 GHz and 6.25 - 6.75 GHz, which do not overlap with the bands of wireless networks (WLAN) and ISM. RTLS (Real-Time Locating Systems) - an automated system that provides identification, accumulation, processing and storage of information about the location and movement of people, objects, mobile machinery and vehicles to monitor technological and business processes, signaling, as well as for retrospective analysis of certain processes and situations. All RTLS systems consist of several main components: tags, readers and software for interpreting data. Use of active UWB tags in these systems allows to achieve high speeds at a distance of up to 10 m, the technology allows you to reach 110 Mbps. UWB module - a desktop device for setting up and accounting for UWB Tag devices. UWB hub - a device capable of performing thousands of scan scans per second at a distance of up to 30 cm. UWB Sensor - a device that detects pulses emitted by UWB tags and provides the exchange of operational information about resources. UWB reader is an access control device that uses the patented technology of short-pulse ultra-wideband (UWB) signals. UWB-tag - a device that can be attached to objects or clothing of personnel to track and track their location at any time in real time with incredible accuracy. Triax Proximity Trace technology provides active feedback, in the form of visual and audible signal, so people understand when they have violated the proper social distance. Due to Triax Proximity Trace it is possible to determine the degree of contact of employees with those who received a positive test, for example, according to the CDC classification. Components of the system: labels, gateways that are deployed in strategic places, cloud software and information panel for managing proximity event data. Triax Proximity Trace uses tags that operate at 900 MHz. Due to SafeZone and Triax Proximity Trace solutions the company can have a complete picture of potential patients and send for testing real contacts.

Novel MIMO-UWB-Based AG-UG-AG Routing With Microbit Sensors for WUSN

In this letter, empirical with analytical methodology to decode-and-forward packets over aboveground-to-underground-to-aboveground systems in the wireless underground sensor network environment is corroborated. Multiple-input-multiple-output ultrawideband (MIMO-UWB) radio frequency links were empirically characterized and exploited using microbit moisture-measuring white light-emitting diodes in different volumetric water content and orientation depths. Relay-routing and selection using the novel maximum available channel capacity technique was accomplished. The simulation performance demonstrates relay-routing and selection impacts on channel conditions, overall outage probability, transmission power, and energy consumption, without depreciated aggregate system throughput.

Research on channelized synthesis of ultra-wideband radio frequency signal based on dual optical frequency combs (Invited)

Research on channelized synthesis of ultra-wideband radio frequency signal based on dual optical frequency combs (Invited)

Circularly symmetric algorithm for UWB RF signal receiving channel based on noise cancellation

AbstractDue to the high redundancy of ultra-wideband (UWB) radio frequency (RF) signal receiving channel and the channel’s non-rotation invariance, the signal-to-noise ratio (SNR) of signal transmission is increased. In order to solve this problem, a circularly symmetric algorithm for the UWB RF signal receiving channel based on spectrum compression cannot effectively reduce the redundancy of UWB RF signal receiving channel; the channel does not have rotation invariance; and the effect of noise reduction is poor. A circularly symmetric algorithm for the UWB RF signal receiving channel based on noise cancellation is proposed, and a noise cancellation structure at the input stage of the receiving channel is constructed to ensure channel noise cancellation and reduce noise in the channel. On this basis, five power zones are used to reasonably select RF devices, receive and downconvert UWB RF signal receiving channel, and convert the received UWB RF signal channel into circular symmetric Gabor transform to reduce redundancy and ensure the strict rotation invariance of the channel. The experimental results show that the proposed algorithm guarantees the quality of the signal and the stable transmission of the signal information. The SNR is 3.8672, and the root mean square error is 0.4078. The third-order cross-modulation coefficient of the signal receiving channel controlled by the algorithm meets the requirements of the index and the mirror frequency rejection requirement of the index.

5G new radio photonically-amplified Xhaul

Abstract This work reports the implementation and experimental performance analysis of innovative 5G new radio (NR) photonically-amplified mobile backhauls and fronthauls. We claim to utilize fiber-optic links not only for data transmission and transport but also for amplifying ultrawideband radiofrequency (RF) signals from all mobile communication generations, including the current 5G and future 6G networks. The photonics-assisted RF amplification (PAA) digital performance investigation has been evaluated from baseband, for the first time in literature, to extremely high frequency (EHF), demonstrating the feasibility of using the proposed solution for enhancing the power efficiency and/or extending the backhaul link reach. Furthermore, the PAA-based 5G NR fronthaul deployment enabled to increase the system throughput in 12.3 times, attaining 13.5 Gbit/s, and providing root mean square error vector magnitude (EVMRMS) in accordance to the 3GPP requirements for bandwidths up to 400 MHz.

An Ultra-Wideband Microwave Photonic Channelizer Based on Coherent Optical Frequency Combs and Image-Reject Down-Conversion

Radio frequency (RF) channelization receiver is one of the most effective methods for processing ultra-wideband RF signals. In this paper, an ultra-wideband microwave photonic channelizer based on coherent optical frequency combs (OFCs) and image-reject down-converter is proposed and demonstrated. The OFCs used in the system are generated by two dual parallel Mach–Zehnder modulators (DPMZM), and the free spectrum range (FSR) is flexibly adjustable. The image-reject down-converter can not only effectively achieve image separation but also suppress the seven-order distortion and DC offset using balanced detection. A K- and Ka-band RF signal covering the frequency band from 25 to 30 GHz is sliced into 5 sub-channels with 1-GHz bandwidth, two-tone signals with frequencies of 27.5 and 27.51GHz are used to measure the spurious free dynamic range (SFDR) which is 116.8 dB $\cdot $ Hz2/3, the image-rejection is over 66.4 dB, and the error vector magnitude (EVM) is 4.2%.

Soil type characterization for moisture estimation using machine learning and UWB-Time of Flight measurements

Soil moisture measurements are essential in fields such as Agriculture or Civil Engineering. The measurements of moisture via dielectric constant with electromagnetic techniques have become widespread over recent years. In this paper, we propose a new soil moisture estimation method using low cost and small size commercial Ultra-Wide Band (UWB) modules. These modules are capable of very precise measuring Times of Flights (ToF) of signals between two UWB-transceivers. We used this capability for more precise estimation of the soil dielectric constant. Besides Time of Flight, the used UWB-modules enabled measuring of channel impulse responses. We propose as the novelty using an impulse response signal shape for soil type characterization with machine learning, precisely, Support Vector Machine (SVM). So, the basic idea of the proposed method is, first, soil type characterization using machine learning and then, according to soil type, choosing an appropriate moisture-dielectric constant model for more accurate moisture measuring. The main advantages of the proposed method are smaller geometrical dimensions of the measuring equipment, i.e. UWB Radio-Frequency (RF) modules and probes (antennas), due to higher operating frequencies and, as proven with experiments, more accurate soil moisture estimation, especially for organic soils in comparison with equipment based on the conventional Time Domain Reflectometry (TDR) method.

Optical Comb Assisted OFDM RF Receiver

Orthogonal frequency-division multiplexing (OFDM) is a widely used signaling format in wireless communication and ultrawide band radio-frequency (RF) applications. An OFDM transceiver relies on a discrete Fourier transform (DFT) processor that matches both the resolution and the bandwidth of wireless link. A conventional wideband OFDM receiver necessarily relies on high-speed analog-to-digital converters (ADC) followed by a Fourier processing core. Both fundamental and practical ADC considerations that include bandwidth-resolution tradeoff impose strict limits on high precision digitization of the wideband OFDM signal. In addition to the quantization barrier, computational complexity of the high-speed DFT processor leads to high dissipation levels in conventional receivers. This report demonstrates an alternative OFDM receiver architecture that eliminates the need for high-speed ADC and digital DFT processor. The new design is based on hybrid, optoelectronic DFT processor, capable of generating DFT coefficients of wideband RF signal in real time. We demonstrate demodulation of a 4-quadratic amplitude modulation OFDM signal with 60 subcarriers positioned within 4–15.8 GHz band and separated by 200 MHz. The error vector magnitude is measured for all channels to characterize the performance of the comb-assisted OFDM RF receiver.

Acoustic Local Positioning With Encoded Emission Beacons

Acoustic local positioning systems (ALPSs) are an interesting alternative for indoor positioning due to certain advantages over other approaches, including their relatively high accuracy, low cost, and room-level signal propagation. Centimeter-level or fine-grained indoor positioning can be an asset for robot navigation, guiding a person to, for instance, a particular piece in a museum or to a specific product in a shop, targeted advertising, or augmented reality. In airborne system applications, acoustic positioning can be based on using opportunistic signals or sounds produced by the person or object to be located (e.g., noise from appliances or the speech from a speaker) or from encoded emission beacons (or anchors) specifically designed for this purpose. This work presents a review of the different challenges that designers of systems based on encoded emission beacons must address in order to achieve suitable performance. At low-level processing, the waveform design (coding and modulation) and the processing of the received signal are key factors to address such drawbacks as multipath propagation, multiple-access interference, near–far effect, or Doppler shifting. With regards to high-level system design, the issues to be addressed are related to the distribution of beacons, ease of deployment, and calibration and positioning algorithms, including the possible fusion of information obtained from maps and onboard sensors. Apart from theoretical discussions, this work also includes the description of an ALPS that was implemented, installed in a large area and tested for mobile robot navigation. In addition to practical interest for real applications, airborne ALPSs can also be used as an excellent platform to test complex algorithms (taking advantage of the low sampling frequency required), which can be subsequently adapted for other positioning systems, such as underwater acoustic systems or ultrawideband radio-frequency (UWB RF) systems.

Design Considerations for Secure Wireless Sensor Communication Systems in Harsh Electromagnetic Environments of Nuclear Reactor Facilities

Wireless sensors can potentially play a significant role in safety, efficiency, and reliability of the instrumentation and control process in current and next generation nuclear power reactors. While conventional narrowband wireless sensors have shown a certain level of success in some nuclear power plants (NPPs), the radio frequency (RF) propagation challenges posed by the heavy metallic and cluttered environment of NPPs has prevented their widespread use in such operations. These challenges include RF wave propagation in harsh (reflective, absorptive, cluttered) environments, data security issues, and RF interference to and from other devices in the vicinity of a nuclear reactor core. In this paper, first we address how ultrawideband (UWB) RF technology can complement the narrowband (i.e., WiFi) solutions that have been used in some NPPs by providing an alternative solution in addressing the signal propagation issues in such electromagnetically harsh environments. Second, we discuss and present the UWB software simulation results on multipath harsh environments, and then address the data security issues. In the final sections of the paper, we present the experimental results of using UWB signaling in a representative harsh environment conducted at the Massachusetts Institute of Technology research reactor site. We plan to develop the UWB communications hardware based on the results of this paper and report on its performance in the field with emphasis on the security aspects of the system in a subsequent paper.

One to 40 GHz ultra‐wideband RF MEMS direct‐contact switch based on GaAs MMIC technique

This study presents a 1–40 GHz ultra-wideband radio frequency (RF) micro-electro-mechanical systems (MEMS) direct-contact switch based on a GaAs microwave monolithic integrated circuit (MMIC) process. The proposed switch utilises an inline cantilever membrane and a pull-in electrode to achieve ‘off’ and ‘on’ states. It has been manufactured by micro-machining, which is completely compatible with the GaAs MMIC process. An equivalent distributed parameter circuit model of the switch is established to analyse the microwave performances. The measured S-parameters show that the isolation (S21) in the ‘off’ state is better than 22.5 dB from 1 to 40 GHz. In the ‘on’ state, the input reflection coefficient (S11) is less than −20.9 dB and the forward transmission coefficient (S21) is better than −0.25 dB over the complete band. In addition, the measured pull-in voltage is ∼17.5 V. The measured maximum power handling capacity is 36.5 dBm. A lifetime of 2.4 × 107 switching cycles is also verified by this design. The whole structure is designed with the purpose of expanding its working bandwidth and achieving higher microwave performances over current state of art.

Precise Indoor Positioning Using UWB: A Review of Methods, Algorithms and Implementations

The demand and growth of indoor positioning has increased rapidly in the past few years for a diverse range of applications. Various innovative techniques and technologies have been introduced but precise and reliable indoor positioning still remains a challenging task due to dependence on a large number of factors and limitations of the technologies. Positioning technologies based on radio frequency (RF) have many advantages over the technologies utilizing ultrasonic, optical and infrared devices. Both narrowband and wideband RF systems have been implemented for short range indoor positioning/real-time locating systems. Ultra wideband (UWB) technology has emerged as a viable candidate for precise indoor positioning due its unique characteristics. This article presents a comparison of UWB and narrowband RF technologies in terms of modulation, throughput, transmission time, energy efficiency, multipath resolving capability and interference. Secondly, methods for measurement of the positioning parameters are discussed based on a generalized measurement model and, in addition, widely used position estimation algorithms are surveyed. Finally, the article provides practical UWB positioning systems and state-of-the-art implementations. We believe that the review presented in this article provides a structured overview and comparison of the positioning methods, algorithms and implementations in the field of precise UWB indoor positioning, and will be helpful for practitioners as well as for researchers to keep abreast of the recent developments in the field.

Combined US and UWB-RF imaging of concrete structures for identification and location of embedded materials

We describe how two different techniques: ultrasonic and ultrawide-band radio frequency inspections, can be used and combined to detect embedded structures in concrete. Joint analysis shall overcome limitations of the individual technologies, while providing further information on specimens. In this case, ultrasonic inspection achieves good spatial resolution, while radio-frequency analysis provides information on composition – i.e., material. The proposed techniques were tested on a concrete probe, with embedded reinforcement bars. Images resulting from multisensory fusion provided relevant information regarding the presence, location and material of the bars; and are well suited for in-site inspection, under real ambient conditions.

RF Safety Analysis of a Novel Ultra-wideband Fetal Monitoring System

The LifeWave Ultra-Wideband RF sensor (LWUWBS) is a monitoring solution for a variety of physiologic assessment applications, including maternal fetal monitoring in both the antepartum and intrapartum periods. The system uses extremely low power radio frequency (RF) ultra-wide band (UWB) signals to provide continuous fetal heart rate and contractions monitoring during labor and delivery. Even with the incorporation of three very conservative assumptions, (1) concentration of the RF energy in 1 cm, (2) minimal (2.5 cm) maternal tissue attenuation of fetal exposure, and (3) absence of normal thermoregulatory compensation, the maternal whole body spatial-averaged specific absorption rate (WBSAR) would be 34,000 times below the FCC public exposure limit of 0.08 W kg and, at 8 wk or more gestation, the peak spatial-averaged specific absorption rate (PSSAR) in the fetus would be more than 160 times below the localized exposure limit of 1.6 mW g. Even when using very conservative assumptions, an analysis of the LWUWBS's impact on tissue heating is a factor of 7 lower than what is allowed for fetal ultrasound and at least a factor of 650 compared to fetal MRI. The actual transmitted power levels of the LWUWBS are well below all Federal safety standards, and the potential for tissue heating is substantially lower than associated with current ultrasonic fetal monitors and MRI.

POSITIONING IN BLUETOOTH AND UWB NETWORKS

This article brings a comprehensive tutorial on radio-frequency (RF) positioning in Bluetooth and Ultra-Wideband (UWB) Wireless Personal Area Networks (WPANs), carrying out an extensive literature review, providing the reader an overview of Bluetooth and UWB RF positioning state-of-the-art. It also delves into some key issues, such as multi-lateration based solutions using received signal strength and time-of-arrival, multi-slope linear regression, RF fingerprinting and the use of clustering techniques to improve its localization accuracy, the interrelation between Bluetooth versions improvements and new positioning capabilities, as well as localization prospects in future UWB networks.

Frequency-Hopping Pulse Position Modulation Ultrawideband Receiver

Pulse position modulation (PPM) has been used in the radio-frequency (RF) domain to achieve both low-dissipation requirements and provide precision ranging. In ultrawideband (UWB) architectures, it underpins an asynchronous receiver, multiple access environments, and interference-resistant transmission. When combined with frequency hopping (FH), it allows for an additional level of immunity to jamming and low probability of intercept. Realization of a FH-PPM transceiver poses a practical challenge, particularly in the UWB RF range. With UWB pulses reaching the multi-gigahertz range, FH adds to the effective bandwidth at which the receiver must be operated, exceeding the performance of a modern quantizer and digital demodulation backplane. This study describes a new photonics-assisted FH-PPM receiver architecture that rests on mutually coherent frequency combs. The performance of the new receiver was characterized by receiving and decoding an 80–Mb/s rate FH-PPM UWB signal.