Wireless Transmission Distance Research Articles

A passive wireless surface acoustic wave (SAW) sensor system for detecting warfare agents based on fluoroalcohol polysiloxane film

Long-term monitoring of environmental warfare agengts is a challenge for chemical gas sensors. To address this issue, we developed a 433 MHz passive wireless surface acoustic wave (WSAW) gas sensor for dimethyl methylphosphonate (DMMP) detection. This WSAW gas sensor includes a YZ lithium niobate (LiNbO3) substrate with metallic interdigital transducers (IDTs) etched on it, and an antenna was placed near the IDT. A DMMP-sensitive viscoelastic polymer fluoroalcoholpolysiloxane (SXFA) film was prepared on a LiNbO3 substrate, and mode modeling coupling was used to optimize the design parameters. The sensor can function properly in an environments between −30 °C and 100 °C with humidity less than 60% RH. When the wireless transmission distance was within the range of 0–90 cm, the sensor noise increased with distance, and the stability was less than 32°/h. While optimizing the film thickness of SXFA, a relationship was observed between sensor sensitivity and film thickness. When the film thickness of SXFA reached 450 nm, the optimal value was reached. At a distance of 20 cm between the transmitting and receiving antennas, DMMP was detected at different concentrations with the developed WSAW gas sensor. The lower detection limit of DMMP was 0.48 mg/m3, the sensitivity of the sensor was 4.63°/(mg/m3), and repeatable performance of the sensor was confirmed.

Long-range photonics-aided 17.6 Gbit/s D-band PS-64QAM transmission using gate recurrent unit algorithm with a complex QAM input.

D-band fiber-wireless technique that overcomes the bandwidth bottleneck of electrical devices has been popularized, but long-range D-band wireless transmission is still limited by the large absorption loss. So, the exploration of m-QAM formats is essential for the D-band long distance wireless transmission due to their different spectrum efficiency and SNR requirement. Moreover, nonlinearity in photonics-aided millimeter-wave (mm-wave) system is also a significant problem caused by fiber, photoelectrical devices and power amplifiers. So it is critical to employ a machine learning-based nonlinear compensation algorithm especially for long-distance D-band wireless delivery. A novel Gate Recurrent Unit (GRU) algorithm with a complex QAM input is proposed to further improve the receiver sensitivity of coherent D-band receiver, which effectively preserves the relative relationship between I/Q components of QAM signals and has memory capabilities with a better precision. We mainly discuss three learners with a complex QAM input, including complex-valued neural network (CVNN), single-lane Long Short-Term Memory (SL-LSTM) and single-lane Gate Recurrent Unit (SL-GRU). Thanks to these adaptive deep learning methods, we successfully realize 135 GHz 4Gbaud QPSK and PS-64QAM signal wireless transmission over 4.6 km, respectively. Considering the aspects of transmission capacity and recovery precision, CVNN equalizer is suitable for QPSK recovery, SL-GRU would be the best choice for PS-64QAM over D-band long range wireless transmission link up to km magnitude. The effective data rate can be achieved up to 17.6 Gbit/s. Therefore, we believe that the combination of high-order modulation and NN supervised algorithms with a complex input has an application prospect for the future 6 G mobile communication.

23.1-Gb/s 135-GHz Wireless Transmission Over 4.6-Km and Effect of Rain Attenuation

In this article, we have experimentally demonstrated a fiber-wireless-integration <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$</tex-math> </inline-formula> -band (110–170 GHz) transmission system. To extend the wireless transmission distance while maintaining the wireless bit rate as high as possible, we designed high-gain lens horn antenna modules consisting of a pair of dielectric plano-convex lenses and horn antennas for long-haul wireless links. In addition, we employ the Volterra nonlinear equalization (VNE) algorithm based on the multiple-input–multiple-output (MIMO) structure to precisely compensate for the in-phase/quadrature (I/Q) imbalance and nonlinear impairment of quadrature amplitude modulation (QAM) signals mainly caused by photoelectric (O-E) conversion and electric-photo (E-O) conversion. Meanwhile, one of the methods adopted in our experiment to decrease the influence of nonlinearity on high-order QAM signals is coupling the high-order modulation format with the probabilistic shaping (PS) technology. As a result of outdoor field experimental verification, the demonstration at 135 GHz carrier with a net rate of 23.1 Gb/s over 10 km optic-fiber and 4.6 km wireless transmission distance has been successfully carried out. It is, as we know, the first time that a record-breaking product of net bit rate and wireless transmission distance, i.e., 23.1 Gb/s <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 4.6 km <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$=$</tex-math> </inline-formula> 106.3 Gb/s <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot$</tex-math> </inline-formula> km, has been accomplished based on a fiber-wireless-integration system. Also, for the first time, we have measured the effect of rain attenuation for the 135 GHz millimeter-wave (mm-wave) wireless link and established more accurate rainfall models for the Shanghai region of China by comparing them with multiple rainfall models. This work can be used as a complement to the International Telecommunication Union-Radiocommunication sector (ITU-R) recommendations.

Underwater Wireless Video Communication Using Blue Light

Interest in wireless blue light communication is increasing because this technology shows promise for realizing high-speed, long-distance and full-duplex underwater communication. Here, we demonstrate an underwater wireless communication system, OceanLink, to establish full-duplex data transmission using blue light. Both the transmitter and receiver are housed together to independently transmit and receive data simultaneously. To obtain a longer transmission distance and better light field distribution, the transmitter is composed of an array of three light-emitting diode (LED) units with the dominant emission peak wavelength centered around 452 nm, each of which merges four LEDs in series. These LEDs are synchronously driven via a main processing unit to pulse blue light using a nonreturn-to-zero on-off keying modulation scheme. At the receiver, light passes through a neutral density (ND) filter and a focus lens to hit the transducer, which converts light signals into electrical signals. The waterproof OceanLink achieves a bidirectional communication rate of 4 Mbps with a wireless transmission distance of 12 m in a swimming pool, wherein the ND factor is 256 and the nephelometric turbidity unit is 1.7. Thus, real-time full-duplex underwater video communication is experimentally demonstrated.

High-Speed and Long-Distance Photonics-Aided Terahertz Wireless Communication

Terahertz (THz) photonics technique can break through the bandwidth limitation of electronic mixing method and be seamless integrated with optical access networks, which has bright prospects in future 6G broadband communication. However, due to the bottleneck of photoelectric conversion efficiency of uni-travelling photodiode (UTC-PD), the power of the generated THz-wave signal is usually only in the microwatt level, and the THz-wave wireless transmission distance is short. In this paper, we summarize the key techniques we use to extend the wireless range for photonics-aided THz-wave communication, which includes THz-wave amplifiers and antennas, heterodyne detection, probabilistic shaping (PS) technique as well as advanced digital signal processing (DSP). Meanwhile, we report our recent research including 104\200\400-m photonics-aided THz-wave wireless transmission records.

Beamforming Technologies for Ultra-Massive MIMO in Terahertz Communications

Terahertz (THz) communications with a frequency band 0.1-10 THz are envisioned as a promising solution to future high-speed wireless communication. Although with tens of gigahertz available bandwidth, THz signals suffer from severe free-spreading loss and molecular-absorption loss, which limit the wireless transmission distance. To compensate for the propagation loss, the ultra-massive multiple-input-multiple-output (UM-MIMO) can be applied to generate a high-gain directional beam by beamforming technologies. In this paper, a review of beamforming technologies for THz UM-MIMO systems is provided. Specifically, we first present the system model of THz UM-MIMO and identify its channel parameters and architecture types. Then, we illustrate the basic principles of beamforming via UM-MIMO and discuss the far-field and near-field assumptions in THz UM-MIMO. Moreover, an important beamforming strategy in THz band, i.e., beam training, is introduced wherein the beam training protocol and codebook design approaches are summarized. The intelligent-reflecting-surface (IRS)-assisted joint beamforming and multi-user beamforming in THz UM-MIMO systems are studied, respectively. The spatial-wideband effect and frequency-wideband effect in the THz beamforming are analyzed and the corresponding solutions are provided. Further, we present the corresponding fabrication techniques and illuminate the emerging applications benefiting from THz beamforming. Open challenges and future research directions on THz UM-MIMO systems are finally highlighted.

Wireless surface acoustic wave humidity sensor with chitosan/porous cyclodextrin–TiO2 composites for monitoring air and human respiration

Wireless surface acoustic wave (SAW) technology can be used for real-time and contactless humidity measurements, as well as for monitoring human respiration and environmental humidity. In this study, we developed a wireless humidity sensor based on a 433 MHz SAW resonator covered with chitosan (CS)/heat-treated cyclodextrin(α-, β-, γ-CD)–TiO2 sensitive films. The mesoporous distribution and hydrophilicity of the CD–TiO2 composite, which affect the sensitivity of the CS/CD–TiO2/SAW sensor response to humidity, can be controlled through the CD type and TiO2 content of the composite. The frequency shift of the optimized CS/β-CD–TiO2/SAW sensor varied linearly with the relative humidity (RH) in the RH ranges of 0%76% and 76%90% with the corresponding sensitivities of − 2.96 and − 99.71 kHz%−1, respectively. The response and recovery times at 70% RH were 13.3 and 28.8 s, respectively, with an insignificant hysteresis of 0.61%. The excellent humidity response was due to the hydrophobicity of the inner cavity in the β-CD template molecule and the hydrogen bond adsorption between the surface of the CS/β-CD–TiO2 and H2O molecules. The response rates of the wireless SAW sensor system to normal air humidity and human exhaled/inhaled humidity were 3.13% and 30% RH s−1, respectively, and the wireless transmission distance was 30 m. The wireless CS/β-CD–TiO2/SAW humidity sensor has considerable application potential in forest fire early warning and firefighter tracking systems that require the remote monitoring of air humidity and human respiration.

Designing and analyzing multi-coil multi-layers for wireless power transmission in stent restenosis coronary artery

Wireless power transfer technology features shorter power transmission distances in biomedical applications. This is a result of the small size of the implanted coils, biocompatible material conductivity, and the large distances between the receiving and transmitting coils. There have been numerous attempts to improve the power transfer efficiency across longer distances. Multiple coils, including 2-, 3-, 4-, and multi-layered coils, were previously considered. This study proposes a novel approach to achieve higher power transmission efficiency by integrating a single coil on the receiving side and three asymmetric coils on the transmitter side. As such, it delivers power to the sensor implanted within the coronary artery that monitors the blood pressure while introducing a uniquely shaped stent. The efficiency of power transmitted to the stent in its dual implanted forms, helical and zigzag helical, was examined as well, with the wireless power transmission system thereby analyzed at the 27 MHz Industrial Scientific Medical band operating frequency. For the four-coil technique, the power transmission efficiency at a distance of 25 mm between the receiver and transmitter sides by using biological human tissue as a medium between the transmission coils and the receiver stent can reach 56.42%, whereas other approaches show lower efficiencies: the three-coil method’s efficiency is 32.88%, the double-layer parallel method’s efficiency is 27.75%, the two-coil method’s efficiency is 24.76%, the triple-layer parallel method’s efficiency is 17.31%, the double-layer series method’s efficiency is 0.501%, and the triple-layer series method’s transmission efficiency is 0.092%. In addition, the suggested approach is demonstrated to be more efficient than prior designs with regard to the size of the implanted coils, which represent stents.

Experimental demonstration of uncompressed 4K video transmission over directly modulated distributed feedback laser‐based terahertz wireless link

AbstractWe demonstrate the transmission of uncompressed 4K videos over the photonics‐based terahertz (THz) wireless link using a directly modulated distributed feedback laser diode (DFB‐LD). For optical heterodyne mixing and data modulation, a DFB‐LD was employed and directly modulated with a 5.94‐Gb/s non‐return‐to‐zero signal, which is related to a 6G‐serial digital interface standard to support ultra‐high‐definition video resolution. We derived the optimal frequency of the THz carrier by varying the wavelength difference between DFB‐LD output and Tunable LD output in the THz signal transmitter to obtain the best transmission performances of the uncompressed 4K video signals. Furthermore, we exploited the negative laser‐to‐filter detuning for the adiabatic chirp management of the DFB‐LD by the intentional discrepancy between the center wavelength of the optical band‐pass filter and the output wavelength of the DFB‐LD. With the help of the abovementioned methods, we successfully transmitted uncompressed 4K video signals over the 2.3‐m wireless transmission distance without black frames induced by time synchronization error.

3×3 MIMO 60-GHz OFDM-RoF System With Long-Distance Wireless Transmission Enabled by MIMO Volterra Filtering

A 3×3 60-GHz multiple-input multiple-output (MIMO) radio-over-fiber system with an MIMO Volterra filter was demonstrated. The main objective of the proposed scheme is to compensate for the nonlinear distortion caused by radio frequency (RF) power amplifiers (PAs) before the signals reaches the transmitter antennas—particularly when the PAs operate with a high input power to achieve a high output RF power for long-distance wireless transmission. When the required wireless transmission distance is only 7 m, the 3×3 MIMO system with careful control of the PA input power can achieve a data rate of 126 Gbps. However, the data rate decreases rapidly over a longer wireless distance because of the larger loss. By eliminating nonlinear distortion and interchannel interference simultaneously, MIMO Volterra filtering can significantly increase the achievable data rate of a long-distance system. When the required data rate is 90 Gbps (or 100 Gbps), the maximum wireless transmission distance is 118 m (or 70 m) with the aid of MIMO Volterra filtering, but it is only 74 m (or 40 m) without MIMO Volterra filtering.

The self-powered agricultural sensing system with 1.7 km wireless multichannel signal transmission using a pulsed triboelectric nanogenerator of corn husk composite film

Food security is related to national security and people's life. Using modern information technology to monitor the growth process of crops for fine management is an effective strategy to improve agricultural output. Here, a self-powered multichannel wireless agricultural sensing system based on pulsed triboelectric nanogenerator of corn husk composite film (CH-Pulsed-TENG) is developed. Corn husk has the advantages of wear-resisting, moisture-proof, pollution-free, and biodegradable, and CH-Pulsed-TENG has an output voltage and transferred charge of 3.2 kV and 300 nC, respectively. By integrating CH-Pulsed-TENG, passive power management circuit (PMC), voltage regulator circuit (VRC), sensors, signal transmitter and receiver, a self-powered multichannel wireless agricultural sensing system is developed. The energy storage efficiency of the passive PMC can reach 54.5%. Four different signals of temperature, humidity, light intensity, and soil moisture of the farmland can be simultaneously collected and transmitted, reaching a maximum wireless transmission distance of 1.7 km. Also, the self-powered sensing system is demonstrated to be driven by wind energy. The self-powered agricultural sensing system can not only continuously detect the environmental information of farmland, but also recycle the abandoned crops, having potential application in developing intelligent green agriculture.

Soft, stretchable, wireless intelligent three‐lead electrocardiograph monitors with feedback functions for warning of potential heart attack

AbstractCardiovascular diseases (CVDs) are fatal chronic diseases, where electrocardiography (ECG) monitoring could be a prominent solution for early diagnosis. In spite of available commercialized, multilead ECG devices, bulky formats, discontinuous monitoring, and no safety alarm system significantly limit their practical applications. Herein, we present a soft, and stretchable, three‐lead ECG device allowing continuous monitoring and wireless transmission of ECG signals. A newly developed organohydrogel patch with a strong adhesive ability (~9.9 kPa) and higher conductivity (~6.5 kΩ) is applied for high‐quality ECG signals collection. With a long operation duration (6.5 h) and wireless transmission distance (20.9 m), it could fulfill most of the daily applications. Machine learning algorithms and the graphical user interface are used for real‐time ECG monitoring and cardiac abnormalities diagnosis. The vibratory flexible actuator, which is triggered by cardiac abnormalities that need immediate medical treatment, is also integrated as a warning system for the user. As a newly reported stretchable multi‐lead ECG device for long‐term ECG signal monitoring, there is a high potential for improving users' life quality with the high‐risk population of CVDs.

Research progress of wearable plantar pressure monitoring system

In order to rapidly promote the application of wearable plantar pressure monitoring system, the physiological structure of human foot, the source of plantar pressure and exercise step frequency are introduced. Based on the current research status of wearable plantar pressure monitoring systems, the fabrication materials and response principles of the fabric sensor-based integrated pressure monitoring socks are explored, the principle of selecting the features of the wearable plantar pressure monitoring system and its application in the field of the pressure monitoring system is explained. The principle of selecting the features of wearable plantar pressure monitoring system and its application in fall detection, foot disease diagnosis, and plantar pressure database are explained. Finally, we discussed the problems in the industrialization of wearable plantar pressure monitoring system at this stage. The problems of poor material performance and short wireless transmission distance in the industrialization of wearable plantar pressure monitoring systems are discussed, and a better integrated system based on biomechanics, textile materials and electronic communication is proposed. A better application prospect based on the cross-fusion integration of biomechanics, textile materials and electronic communication is proposed.

Delivery of 40 Gbit/s W-band signal over 4600 m wireless distance employing advanced digital signal processing

We experimentally built a photonics-aided long-distance large-capacity millimeter-wave wireless transmission system and demonstrated a delivery of 40 Gbit/s W-band 16-ary quadrature amplitude modulation (QAM) signal over 4600 m wireless distance at 88.5 GHz. Advanced offline digital signal processing algorithms are proposed and employed for signal recovery, which makes the bit-error ratio under 2.4×10-2. To the best of our knowledge, this is the first field-trial demonstration of >4 km W-band 16QAM signal transmission, and the result achieves a record-breaking product of wireless transmission capacity and distance, i.e., 184 (Gbit/s)·km, for high-speed and long-distance W-band wireless communication.

Research and application of key technologies for dam safety monitoring based on LoRa

Aiming at the problems of high power consumption, weak scalability and short wireless transmission distance of dam safety monitoring system, the key technology of dam safety monitoring based on Lora is proposed. An intelligent monitoring terminal is designed based on ARM LPC1788 and Lora wireless communication module. The low-power relay mode with Lora and 4G transmission function is adopted, and the active loop calling process and threshold trigger early warning process are designed. The platform software automatically receives data to realize the intelligent collection, analysis and early warning of dam multi factor safety data. The engineering application effect is good.

Cost-effective photonics-based THz wireless delivery system using a directly modulated DFB-LD

We present a cost-effective photonics-based THz wireless delivery system using a directly modulated distributed feedback laser diode (DFB-LD). A DFB-LD with non-return to zero (NRZ) modulation up to 25 Gbps and a uni-traveling-carrier photodiode (UTC-PD) with a horn antenna is employed to transmit a THz wave into free space in the photonics-based THz signal transmitter. A Schottky barrier diode (SBD) with a horn antenna is used to directly detect the THz wave from free space at the THz signal receiver. To achieve the best bit error rate performance, we varied the optimal THz carrier frequency in a photonics-based THz wireless delivery system. After THz carrier frequency optimization, bit error rates were measured by varying THz link operating conditions, such as the data rate, photocurrent of UTC-PD, and wireless transmission distance. We successfully transmitted a 25 Gb/s NRZ signal over 1.6 and 2.2 m wireless transmission distances before and after managing the adiabatic chirp characteristic of directly modulated DFB-LD using the laser-to-filter detuning effect, respectively, while satisfying the 7% hard decision-forward error correction (HD-FEC) threshold (3.4×10−3).

The Application of WiFi 6 Technology in Underground Mine

Aiming at the problems of large power consumption of 5G communication technology equipment and short wireless transmission distance of wireless signal, the author designs the wireless network coverage scheme of WiFi 6 in coal mine to achieve the fully coverage of 5G communication. This paper makes an exposition of WiFi 6 technology from the aspects of technical principle, networking mode, antenna design and power consumption calculation. The WiFi 6 signal coverage scheme solves the problem of wireless network signal coverage in long-distance roadway underground coal mine by realizing the full coverage of wireless network. The data of laboratory experiments and coal mine roadway simulation show that with the characteristics of wide network communication coverage area, fast communication speed and low power consumption, WiFi 6 network scheme can fully meet the requirements of full wireless coverage in coal mine.

Pilot-Tone Assisted 16-QAM Photonic Wireless Bridge Operating At 250 GHz

A photonic wireless bridge operating at a carrier frequency of 250 GHz is proposed and demonstrated. To mitigate the phase noise of the free-running lasers present in such a link, the tone-assisted carrier recovery is used. Compared to the blind phase noise compensation (PNC) algorithm, this technique exhibited penalties of 0.15 dB and 0.46 dB when used with aggregated Lorentzian linewidths of 28 kHz and 359 kHz, respectively, and 20 GBd 16-quadrature amplitude modulation (QAM) signals. The wireless bridge is also demonstrated in a wavelength division multiplexing (WDM) scenario, where 5 optical channels are generated and sent to the Tx remote antenna unit (RAU). In this configuration, the full band from 224 GHz to 294 GHz is used. Finally, a 50 Gbit/s transmission is achieved with the proposed wireless bridge in single channel configuration. The wireless transmission distance is limited to 10 cm due to the low power emitted by the uni-travelling carrier photodiode used in the experiments. However, link budget calculations based on state-of-the-art THz technology show that distances >1000 m can be achieved with this approach.

Energy Efficient and High Dissemination Rate Method Considering Extended Transmission Distances on a Wireless Sensor Network

From the electric power consumed by sensor nodes comprising a wireless sensor network, a very large proportion is used to transmit and receive information wirelessly. Because most sensor nodes are battery-powered, long-term operation requires unnecessary wireless transmission to be minimized. There is currently insufficient research on cases involving increased wireless transmission distance and the accompanying increased power consumption. This paper proposes a new, effective method for information dissemination in situations with increased wireless transmission distances. The proposed method is able to minimize power consumption by not performing transmission if the message is considered already disseminated. Additionally, with increased wireless transmission distance, the number of instances of cancelled message transmission increases, further reducing the transmission and reception loads. Simulations demonstrated that the proposed method is effective at keeping power consumption increases to a minimum while greatly improving information dissemination rates, even in cases with increased transmission distances. Unlike the existing methods, the proposed method can improve dissemination rates without increasing power consumption in sensor networks, making it highly innovative and effective.

Design of High‐Power High‐Efficiency Wireless Charging Coils for EVs with MnZn Ferrite Bricks

In wireless power transmission systems, the inductance, equivalent resistance, and quality factors of the coils are the main factors that influence the system’s transmission efficiency. When designing high‐power wireless charging coils for electric vehicles (EVs), ferrite bricks that increase magnetic flux can be selected to increase the self‐inductance of the coils, improving the wireless transmission distance and transmission efficiency. In this paper, the effects of the ferrite bricks, the size of the coils, the charging distance, and many other factors in real applications have been extensively studied. After theoretical analysis and simulation, the wireless transmission system has been fabricated and measured. The measured and simulated results are in good agreement. High‐power high‐efficiency wireless power transmission has been achieved for EVs compared with many other previous literatures.