Wireless Transmission Distance Research Articles

Cost-Effective Photonics-Based THz Wireless Transmission Using PAM-N Signals in the 0.3 THz Band

We investigate the feasibility of pulse amplitude modulation-N (PAM-N) signal transmission over a photonics-based cost-effective THz wireless link. A direct detection-based THz wireless link was established by using commercialized optical and electrical components designed for the WR 3.4 frequency band (220-330 GHz). At the THz signal transmitter, a uni-traveling carrier photodiode (UTC-PD) was used as a photomixer. The maximum output power of the UTC-PD was ~47 μW when it was supplied with +17 dBm of optical power. At the THz signal receiver, the Schottky barrier diode was used as a diode detector; an offline digital signal processor (DSP) with a decision feedback equalizer was also used to mitigate the inter-symbol interference penalty. In the back-to-back configuration (i.e., antenna of Tx and Rx are placed at a distance of ~1 cm), the driving condition of the optical modulator was optimized to obtain the best transmission performances of the PAM-N signal. A carrier frequency of 300 GHz is carefully selected considering the bit error rate (BER) dependency on the carrier frequency. After the optimization procedure, the BER performances were analyzed by varying the PAM order, baud rate, and wireless transmission distance. Finally, a 90 Gb/s PAM-8 signal is successfully transmitted over a wireless distance of 1.4 m, in which the measured BER is below the 20% soft-decision forward error correction threshold (2.0 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ).

Wireless Energy Transmission Link Optimization considering Microwave Energy Relay

With the widespread application of intelligent unmanned units and the development of wireless energy transmission technology, it has become an urgent requirement in the field of using wireless power transmission to extend the continuous working time of unmanned units. To improve the wireless transmission energy efficiency in practical application as much as possible based on the current development level of wireless transmission technology, this paper first enumerates and analyzes existing wireless energy supply methods and shows that microwave wireless energy transmission technology is most suitable in this study. Then, the necessity of power transmission relay in long-distance microwave wireless power transmission is discussed. Based on the idea of microwave energy relay transmission, the paper constructs a microwave wireless transmission link planning model which considers power relay and uses the evolutionary algorithm to solve the wireless transmission link planning model with two-layer optimization. Finally, the results show that, when the wireless transmission distance exceeds a certain threshold, adding relay nodes to the link can improve the energy transmission efficiency from the power supply node to the power receiving node.

Channel Coding Scheme for Relay Edge Computing Wireless Networks via Homomorphic Encryption and NOMA

Edge computing extends the service resources of cloud computing to the edge of the network, providing less latency and higher bandwidth utilization. The relay edge computing wireless network (RECWN) with intelligent edge device can effectively solve the problem of wireless signal transmission distance and attenuation. However, the relay node’s forwarding brings greater risks to the leakage of private information. In this article, we propose a homomorphic encryption and non-orthogonal multiple access (NOMA) based channel coding scheme to address the problem of stealing private information from users by incompletely trusted relay node or potential malicious nodes. Specifically, the homomorphic encryption algorithm is adopted to protect the privacy of users’ private information. Furthermore, the code domain NOMA and LDPC algorithm are introduced to compensate for the problem of drastic drop in communication performance caused by poor sub-channel conditions, thereby improving the efficiency of data transmission, and guaranteeing the users’ QoS requirements and fairness. The simulation results demonstrate that the proposed channel coding scheme has better performance than the existing approaches in terms of privacy preservation and data transmission efficiency.

Wideband QAM-over-SMF/turbulent FSO downlinks in a PON architecture for ubiquitous connectivity

We propose and investigate for the first time a seamless millimeter-wave (mmW) radio-over-fiber (RoF) and radio-over-free-space optics (FSO)-based downlink for use in a passive optical network architecture using 4-, 16- and 64-quadrature amplitude modulation (QAM) for broadband wireless access (BWA) networks. The proposed system is implemented in both experiment and simulation to realize continuous and ubiquitous coverage in urban and rural areas. We outline, a proof-of-concept demonstration of 4-, 16- and 64-QAMs at data rates of 34, 67 and 100 Mb/s, respectively transmitted over a 15 km standard single-mode fiber (SMF), which is then optically up-converted to 25 GHz for transmission over a 10 km of SMF and a 2 m of FSO channel under a non-uniform turbulent condition. We show the measured error vector magnitude (EVM) values of 13, 9.2 and 7.3% for 4-, 16- and 64-QAM, respectively, which are below the corresponding standard EVM requirements and therefore confirm the practicality of the proposed hybrid system. Depending on the data rates, each modulation can be adaptively configured. We report a simulation of a 10 Gb/s 4- and 64-QAM hybrid RoF-FSO downlink under an extended non-uniform turbulence regime to verify the feasibility of the proposed scheme for use in practical applications. By implementing the decision-directed carrier phase recovery and linear electrical equalization, EVMs can be efficiently reduced below the required limits. We further evaluate the proposed system performance in terms of the bit error rates, constellation diagrams, received optical and mmW powers. Using state-of-the-art K-band power amplifiers and conical horn antennas, the maximum wireless transmission distance is estimated to be about 135 m for use in the last-mile BWA networks.

Design of Medical Cold Chain Information Acquisition System Based on Linear Prediction

There are many problems in existing medical cold chain information acquisition system, such as poor mobility of monitoring points, short wireless transmission distance, and frequent data errors. In order to deal with the above problems, a medical cold chain information acquisition system is designed based on 5G technology and LoRa self networking technology. At the same time, a self-adaptive secondary Kalman filter method is proposed to predict the collected information linearly. The system is divided into two parts, which are data acquisition module and coordinator. The collected information of the data acquisition module is reported to the coordinator through LoRa network. After the coordinator performs linear prediction processing on the information, the dada is uploaded to the cloud platform through 5G network, which can realize the monitoring of medical cold chain information at any time and anywhere. The system and the proposed method are simulated and tested. The test results show that the system can complete the data acquisition and processing accurately, the system error is small, and the occasional error can be eliminated in time. The proposed method has smaller prediction error than the traditional filtering method.

Design of Airport Wireless Bird Repellent Monitoring System

At present, the status detection of the bird driving equipment in the airport is completed by manual periodic inspection. This method can’t grasp the status of the bird repelling equipment in real time and cost human resources. In view of this situation, a remote monitoring system based on STM32 is proposed. The system uses the embedded STM32 as the control and data processing core to collect the signals of the temperature sensor, pressure sensor, power supply voltage and sound sensor of the bird-repelling equipment. It is uploaded to the host computer through ZigBee technology to analyze the working conditions of the bird-repelling equipment and the situation of the gas gun. Through the test of the design system, the results show that the detection accuracy of the system can meet the actual need, the correct rate of detecting sound signal is 100%. In the environment of two concrete buildings, the wireless transmission distance is within 800m, and the error rate is 0.

Numerical and Experimental Study on Design Optimization of Hybrid Metamaterial Slab for Wireless Power Transmission

Wireless power transmission (WPT) technique has advanced rapidly in the past two decades. For wireless power transmission distances from 40 to 200 mm, the resonance coupling WPT (R-WPT) technique has surpassed its original inductive coupling counterpart in terms of transmission efficiency. Nevertheless, the power transfer efficiency of a R-WPT system is still lower than that of a wired power transfer system. To increase the power transfer efficiency of a R-WPT system, metamaterial (MM) slabs are inserted between the transmitter and receiver. Moreover, it has recently been validated that a hybrid MM (HMM) slab with different resonance frequency unit cells behaves better than a homogeneous MM slab with identical resonance frequency unit cells in a R-WPT application. However, in the existing HMM slab designs for WPT applications, a trial and error approach, is commonly used to decide the physical and circuit parameters of the HMM slab due to the overwhelmingly high computational cost of numerical simulations using three-dimensional (3-D) finite element method. To overcome the deficiencies of the existing designing methodology and to fully automate the design process, a design-of-experiment (DOE) assisted sequential refinement methodology is proposed by introducing an adaptive surrogate model with tabu search method, for design optimizations of HMM slabs in R-WPT applications. Compared with the existing refinement searching procedures, the salient feature of the proposed one is its bi-directional characteristics, which can refine the searches in the promising sub spaces by intensifying sampling points; and use coarse searches or even discarding the exploitations in the worst sub spaces using some adaptive upper and lower limits of the decision parameters. To validate the feasibility and show the advantages of the proposed methodology, detailed numerical and experimental studies on a case study of a four-coil WPT system working at 13.88 MHz are conducted, and the results have shown that the HMM slab optimized by using the proposed methodology does have better performance in WPT applications when compared to its homogenous counterparts.

P.139 Dopaminergic modulation of reinforcement learning in stimulant drug addiction

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).

Photonics-Aided Millimeter-Wave Technologies for Extreme Mobile Broadband Communications in 5G

To meet the enhanced-mobile-broadband (eMBB) challenges in 5G, we have systematically explored the potential of the photonics-aided millimeter-wave (mm-wave) communication in terms of the wireless transmission capacity and distance it can accommodate. Enabled by various kinds of advanced multiplexing and digital-signal-processing (DSP) techniques, we have successfully achieved the significant enhancement of the wireless mm-wave signal transmission capacity from 100 Gb/s to 400 Gb/s, even to 1 Tb/s. Since our large-capacity (>100-Gb/s) experimental demonstrations typically have a very short wireless transmission distance of several meters, we have further explored the techniques for the extension of the wireless mm-wave signal transmission distance, and successfully achieved a series of field-trial demonstrations on photonics-aided long-distance (>100-m) wireless mm-wave signal transmission. We have realized the record-breaking product of wireless transmission capacity and distance, i.e., 54 Gb/s × 2.5 km.

Terahertz for high‐speed communications

terahertz for high‐speed communications

Decoding CMOS Rolling-Shutter Pattern in Translational or Rotational Motions for VLC

We propose and demonstrate a CMOS rolling-shutter pattern decoding scheme based on two newly introduced schemes, named row grayscale redistribution and differential grayscale packet selection to improve the performance in decoding the CMOS rolling-shutter pattern in translational or rotational motions. Results show that even the CMOS image sensor is in translational or rotational motions, no significant signal degradation is observed at wireless transmission distance up to 150 cm. The maximum visible light communication data rate at different wireless transmission distances is also analyzed.

Multi-Color Laser Diode Heterodyned 28-GHz Millimeter-Wave Carrier Encoded With DMT for 5G Wireless Mobile Networks

By using a multi-color laser diode carrier with orthogonal polarization and single-carrier modulation, the long-reach single-mode fiber (SMF) passive optical network and millimeter-wave wireless access network (WAN) with carrying narrow-band and channelized discrete multitone (DMT) data format at >1 Gbit/s/channel are demonstrated for 5G wireless mobile applications. For fiber wireline transmission from central office to remote node, the multi-color laser diode is directly encoded by DMT with quadrature amplitude modulation (QAM) levels ranged from 64 to 1024, and the total raw data rate of the received DMT can maintain as high as 88 Gbit/s at a limit modulation bandwidth of 9.125 GHz. The allowable data band consisting of 0.07–6 GHz for 1024 QAM, 6–9 GHz for 512 QAM and 9–9.125 GHz for 256 QAM is achieved even after long-reach transmission in 75-km-long SMF spool. For wireless transmission from remote node to user end with 28-GHz millimeter-wave carrier after optical heterodyne, the wireless transmission distance can lengthen up to 10 meters with allowable data capacity optimized to 29.6 Gbit/s with a modulation bandwidth of 4.1 GHz in total. Consequently, the achievable bit-loaded data band is 256 QAM within 0.07–2.5 GHz and 64 QAM within 2.5–4.1 GHz for 5G mobile WAN transmission via horn antenna pair.

Analog Radio-Over-Fiber Supported Increased RAU Spacing for 60 GHz Distributed MIMO Employing Spatial Diversity and Multiplexing

The improvements in coverage through spatial diversity and increased data rates through spatial multiplexing using a distributed multiple-input multiple-output (MIMO) system are important targets for future wireless communications. Here, the appropriate separation of remote antenna units (RAUs) at several user locations in a millimeter-wave system is demonstrated. An analog radio-over-fiber (RoF) fronthaul is used to achieve flexible spacing of distributed RAUs and transports two Gb/s data streams over 2.2 km of fiber and up to 8 m of 60 GHz wireless transmission distance. A performance comparison is performed between single-input single-output and MIMO operation using different antenna spacing and transmission distance. Results show that the wider RAU spacing enabled by the RoF distribution provides improved results at longer distances, for both spatial diversity and for spatial multiplexing. Verification of a method for measuring each channel coefficient individually and using subsequent MIMO processing on these coefficients enables an extension to the results showing the feasibility of 30 m indoor transmission.

Event-Triggered Fault Estimation for Stochastic Systems over Multi-Hop Relay Networks with Randomly Occurring Sensor Nonlinearities and Packet Dropouts.

Wireless sensors have many new applications where remote estimation is essential. Considering that a remote estimator is located far away from the process and the wireless transmission distance of sensor nodes is limited, sensor nodes always forward data packets to the remote estimator through a series of relays over a multi-hop link. In this paper, we consider a network with sensor nodes and relay nodes where the relay nodes can forward the estimated values to the remote estimator. An event-triggered remote estimator of state and fault with the corresponding data-forwarding scheme is investigated for stochastic systems subject to both randomly occurring nonlinearity and randomly occurring packet dropouts governed by Bernoulli-distributed sequences to achieve a trade-off between estimation accuracy and energy consumption. Recursive Riccati-like matrix equations are established to calculate the estimator gain to minimize an upper bound of the estimator error covariance. Subsequently, a sufficient condition and data-forwarding scheme are presented under which the error covariance is mean-square bounded in the multi-hop links with random packet dropouts. Furthermore, implementation issues of the theoretical results are discussed where a new data-forwarding communication protocol is designed. Finally, the effectiveness of the proposed algorithms and communication protocol are extensively evaluated using an experimental platform that was established for performance evaluation with a sensor and two relay nodes.

The remote farmland environment monitoring system based on ZigBee sensor network

In order to change the traditional management of agricultural production, ZigBee technology is used in short distance wireless transmission to design intelligent farmland environment remote monitoring system, which integrates communication, computer and all aspects of network technology. The real-time, accurate data collection of farmland soil pH value, the temperature and humidity surroundings of the plants, illumination intensity and crop chlorophyll content, all will provide reliable data for intelligent agricultural production, thereby, the level of intelligence of agricultural management is increased. Based on precision guidance, irrigation will become intelligent which can avoid the waste of water resources and low utilisation rate caused by free operation. At the same time, it will promote modernisation of agricultural production process.

Accurate Closed-Form Expressions for the Bit Rate-Wireless Transmission Distance Relationship in IR-UWBoF Systems

Efficient utilization of the extremely limited available power of impulse radio ultrawideband (IR-UWB) waveforms can significantly extend their wireless reach in the wireless transmission chain of IR-UWB over fiber (IR-UWBoF) systems. In this letter, the two most common types of photonically generated IR-UWB waveforms are considered and accurate closed-form analytical expressions for the bit rate—distance relationship in the wireless transmission chain of IR-UWBoF systems are developed. These analytical expressions are verified by simulations and optimized such that the wireless transmission distance of IR-UWB waveforms is maximized under the Federal Communications Commission spectral constraints.

Characteristics analysis on a superconductor resonance coil WPT system according to cooling vessel materials in different distances

The interest in wireless power transfer (WPT) that can send power without using wires has been increasing recently. Especially, there is a great interest in the wireless power devices for portable IT devices. The WPT devices that have been developed so far use the magnetic induction method, and they are not active due to their distance problem. A magnetic resonance WPT method was developed and has been actively researched to resolve this problem. A superconductor coil was applied in this study to increase the efficiency of the magnetic resonance WPT. FRP, bakelite, polystyrene, aluminum, and iron were applied as the cooling vessel material to analyze the WPT distance. The distance between the transmitter and receiver coils started from 800mm and was increased by 200mm. The reflection coefficient was measured at each distance. As a result, FRP, bakelite, plastic PVC, polystyrene of the reflection coefficient was similar. From among these FRP being used for the cooling vessel made the transmission characteristics higher than any other materials when the distance between the transmitter and receiver coils was 2,000mm. On the other hand, the reflection coefficient dropped when iron was used. It is estimated based on the experimental results that the wireless power transmission characteristics and distance of sending power can be improved in the superconductor coil if the cooling vessel is made with FRP.

The remote farmland environment monitoring system based on ZigBee sensor network

In order to change the traditional management of agricultural production, ZigBee technology is used in short distance wireless transmission to design intelligent farmland environment remote monitoring system, which integrates communication, computer and all aspects of network technology. The real-time, accurate data collection of farmland soil pH value, the temperature and humidity surroundings of the plants, illumination intensity and crop chlorophyll content, all will provide reliable data for intelligent agricultural production, thereby, the level of intelligence of agricultural management is increased. Based on precision guidance, irrigation will become intelligent which can avoid the waste of water resources and low utilisation rate caused by free operation. At the same time, it will promote modernisation of agricultural production process.

Uplink Spectral Efficiency Analysis of In-Building Distributed Antenna Systems

Providing high data rate wireless transmissions has been difficult in indoor environments, particularly in multi-floor buildings. One way to achieve high data rate wireless transmissions is to reduce the radio transmission distance between the transmitter and the receiver by using distributed antenna systems (DASs) and employing frequency reuse. However, due to the reuse of the limited available spectrum, co-channel interference can severely degrade system capacity. In this paper, the uplink spectral efficiency of an in-building DAS with frequency reuse is studied, where remote antenna units (RAUs) deployed on each floor throughout the building are connected to a central unit (CU) where received signals are processed. The impact of co-channel interference on system performance is investigated by using a propagation channel model derived from multi-floor, in-building measurement results. The proposed scheme exploits the penetration loss of the signal through the floors, resulting in frequency reuse in spatially separated floors, which increases system spectral efficiency and also reduces co-channel interference. A comparative analysis with conventional co-located antenna deployment at the floor center is provided. Location based RAU selection and deployment options are investigated. System performance is evaluated in terms of location-specific spectral efficiency for a range of potential mobile terminal (MT) locations and various in-building propagation characteristics.

Photonic vector signal generation at W-band employing an optical frequency octupling scheme enabled by a single MZM

We propose photonic vector signal generation at millimeter-wave (mm-wave) bands enabled by a single Mach–Zehnder modulator (MZM) and phase-precoding technique, which can realize photonic frequency multiplication of the precoded microwave vector signal used for the drive of the single MZM. We also experimentally demonstrate the generation of quadrature-phase-shift-keying (QPSK) modulated vector signal at W-band adopting photonic frequency octupling (×8) based on our proposed scheme. The MZM is driven by a 12-GHz QPSK modulated precoded vector signal. Up to 4-Gbaud QPSK-modulated electrical vector signal at 96GHz is generated and then delivered over 3-m wireless transmission distance.