Long-distance Wireless Communication Research Articles

Three-Hop Underwater Wireless Communications: A Novel Relay Deployment Technique

Underwater long-distance wireless communication (ULWC) is a critical challenge in many applications, such as marine environmental monitoring, underwater remote control, and underwater navigation, to name a few. However, very little literature focuses on ULWC, especially where the communication distance ups to thousands of kilometers, which is urgently required in the underwater Internet of Things (UIoT) in the large-scale and deep sea. In this paper, to improve the underwater communication capacity at a level of thousands of kilometers, we propose a three-hop underwater wireless acoustic communication (3H-UWAC) structure based on the Sound Fixing and Ranging (SOFAR) channel. The proposed 3H-UWAC consists of transmitters, relay stations (RSs), and receivers. Different from the existing ULWC, 3H-ULWC can improve energy efficiency with a small vertical directivity angle (VDA). Due to the characteristics of UWAC, the straight-line communication link can be realized in the proposed three hops, and the communication distance can be increased to thousands of kilometers. Respecting the randomness of underwater devices, tools from stochastic geometry are used to model the spatial distributions of transmitters’, receivers’, and RSs’ locations. RSs are set on the SOFAR channel at a known depth. In the first hop, the transmitter sends information to the nearest first relay station (NFRS) on the SOFAR plane. In the second hop, the NFRS sends information to the nearest relay station, which is called the nearest second relay station (NSRS), to the receiver on the SOFAR plane. In the third hop, SNFS sends information to the receiver. All three communication hops can be achieved with a narrow beam width, where the energy efficiency is improved critically. With given densities of transmitters, RSs, and receivers, the coverage probabilities (CPs) of the three hops (transmitter to FRS, FRS to SRS, and SRS to receiver) are analyzed, and the final CP from a transmitter to a receiver through the 3H link is derived. Insights about the effects of VDAs at the transmitters, FNRS, and SNRS, as well as the depths of transmitters and receivers, are revealed. A rapid optimization method is proposed based on the analytical results. The accuracy of the analysis is verified by Monte-Carlo simulations.

Ultra-narrow linewidth dual-cavity opto-mechanical microwave oscillator based on radial guided acoustic modes of single-mode fiber

A dual-cavity opto-mechanical microwave oscillator (OM-MO) for microwave photonic (MWP) generation with ultra-narrow linewidth based on radial (R) guided acoustic modes of a single-mode fiber (SMF) is proposed and investigated experimentally. The dual-cavity OM-MO consists of a 5 km SMF main ring, which provides forward stimulated Brillouin scattering (FSBS) gain, and a 300 m SMF subring that achieves single-frequency output of the R07 guided acoustic mode based MWP (R07-MWP) with Vernier effect. At 300 mW 980 nm pump threshold power, the 319.79 MHz R07-MWP is generated by adjusting polarization controllers based on nonlinear polarization rotation effect, corresponding to the 7437th harmonic of the 43 kHz cavity round trip frequency. The 3 Hz ultra-narrow linewidth of R07-MWP is achieved by decreasing the intrinsic linewidth of the passive ring resonator. The acoustic-mode and longitudinal-mode suppression ratios reach 22 and 36 dB, respectively. Within 20 min of the stability experiment, the power and frequency stability fluctuation of the R07-MWP are ±1 dB and ±0.05 MHz, respectively. This ultra-narrow linewidth MWP generation technology has great potential in the communication field, especially in long-distance wireless communication transmission.

An IIoT-Based Approach to the Integrated Management of Machinery in the Construction Industry

In recent years, considerable advances in connecting industrial equipment to the Internet allowed a higher level of operational efficiency, productivity, and automation. Nevertheless, the construction industry still presents challenging requirements, like long-distance wireless communication, interconnection of out-of- coverage areas, constant mobility of machinery, and support for legacy and proprietary systems. All these requirements pose different challenges when compared with traditional smart factory Industry 4.0 solutions. This paper discusses some of the current key questions regarding fleet management in the construction industry, identifies requirements for heavy-duty machinery, and proposes an Industrial Internet of Things (IIoT)-based solution for the integrated monitoring of such machinery. Also, it proposes and presents an open, innovative solution for the integrated management of non-standardized civil construction vehicle technologies. The developed prototype uses the J1939 protous and protocol to collect machinery status and Long-Range Wide Area Network (LoRaWAN) to communicate the monitored data. The solution was assessed at the construction site of the new port of Sines in Portugal. A detailed description of the proposed system is provided, along with information on trials and evaluation results regarding its performance. Additionally, the paper provides insights into open issues and challenges in this field and how our solution can contribute to overcoming them.

Video Error-Resilience Encoding and Decoding Based on Wyner-Ziv Framework for Underwater Transmission

Limited by the characteristics of underwater acoustic channels, the video transmission applications targeting deep-sea detection and operation tasks are facing severe challenges such as network failure and high delay, resulting in loss of video details, color distortion, blurring, and even bit errors, which seriously affect decoding quality of the video transmission and reception. In order to solve the problems of deep-sea long-distance wireless communication, this paper proposes an improved Wyner-Ziv coding scheme (UnderWater-WZ) for video transmission through acoustic channels. The implementation process includes controlling error range by using MJPEG coding, combining motion compensation time interpolation with calibration information to generate high-quality side information. And intraframe quantization matrix is designed to weaken the change of video scene. The experimental results show that under the highest packet loss rate of 20%, this scheme can achieve 2.6~3.5 dB improvements in terms of video reconstruction compared to the previous methods, which is close to the error-free level.

Frame Boundary Detection and Deep Learning-Based Doppler Shift Estimation for FBMC/OQAM Communication System in Underwater Acoustic Channels

Underwater acoustic (UWA) communication is the only option for underwater long-distance wireless communication. However, its data rate is very low, in tens of kbps, and the time-varying nature of the UWA channel exhibits a Doppler effect. The data rate can be increased using a multicarrier technique, such as Filter Bank Multicarrier (FBMC). The FBMC-OQAM system does not require a cyclic prefix (CP) to eliminate intersymbol interference (ISI). Therefore, compared to other multicarrier techniques, the FBMC-OQAM system achieves the maximum spectral efficiency. Despite the well-designed filter, synchronisation errors cause performance degradation in the FBMC-OQAM system. In this paper, we propose frame boundary and Doppler frequency estimation methods for the FBMC-OQAM system under UWA channels. In this study, we propose a preamble-based frame boundary. The conjugate symmetry property is used in the frame boundary estimation. The performance of the proposed technique was studied under different UWA channels with different Doppler scale. The proposed time synchronisation technique yielded multiple peaks under UWA channels. A method for identifying the peak that represents the frame boundary is proposed. We compared the performance of proposed timing metric with existing three reference timing metrics. The proposed timing metric exhibited superior over two metrics and almost identical performance with the Liming’s metric with less computational complexity. In addition, we propose a convolutional neural network (CNN)-based Doppler scale estimation method. The proposed technique was shown to estimate a wide range of Doppler scale factors. The performance of the proposed technique was studied by considering different UWA channels at different SNRs. The proposed CNN architecture is analysed by changing the CNN parameters. Stacked autoencoders were adopted for Doppler scale estimation and the performance of the proposed CNN-based Doppler scale estimation method was compared with the stacked autoencoders based Doppler scale estimation method. Simulation results show that the proposed CNN-based Doppler Scale estimator exhibits good performance in UWA channels at different SNRs and Doppler scale factors.

Averaging Techniques for Balancing Learning and Tracking Abilities Over Fading Channels

With the wide use of networks in repetitive systems, channels between a plant and a controller may experience random fading, which is a common problem in long-distance wireless communication. However, the control problem over fading channels is far from resolved. In this article, we investigate learning control over fading channels to gradually improve tracking performance. We observe that the effect of fading on input transmission greatly compromises tracking ability in practical implementations. We examine three average techniques: moving average, general average with all historical information, and forgetting-based average. The results reveal a tradeoff between learning ability and tracking ability for learning control algorithms, where learning ability refers to the convergence rate of a proposed learning algorithm, and tracking ability refers to the final tracking precision of the output to the desired reference. The convergence results for the three schemes with these averaging techniques are strictly proved. The results demonstrate that the forgetting-based average operator-based scheme can connect the other two schemes by tuning the forgetting factor. We also provide extensions of several general scenarios to expand the application range. Illustrative simulations verify the theoretical results.

Assessing the Potential of LPWAN Communication Technologies for Near Real-Time Leak Detection in Water Distribution Systems.

While low-power wide-area network (LPWAN) technologies have been studied extensively for a broad spectrum of smart city applications, their potential for water distribution system monitoring in high temporal resolution has not been studied in detail. However, due to their low power demand, these technologies offer new possibilities for operating pressure-monitoring devices for near real-time leak detection in water distribution systems (WDS). By combining long-distance wireless communication with low power consumption, LPWAN technologies promise long periods of maintenance-free device operation without having to rely on an external power source. This is of particular importance for pressure-based leak detection where optimal sensor positions are often located in the periphery of WDS without a suitable power source. To assess the potential of these technologies for replacing widely-used wireless communication technologies for leak detection, GPRS is compared with the LPWAN standards Narrowband IoT, long-range wide area network (LoRaWAN) and Sigfox. Based on sampling and transmission rates commonly applied in leak detection, the ability of these three technologies to replace GPRS is analyzed based on a self-developed low-power pressure-monitoring device and a simplified, linear energy-consumption model. The results indicate that even though some of the analyzed LPWAN technologies may suffer from contractual and technical limitations, all of them offer viable alternatives, meeting the requirements of leak detection in WDS. In accordance with existing research on data transmission with these technologies, the findings of this work show that even while retaining a compact design, which entails a limited battery capacity, pressure-monitoring devices can exceed runtimes of 5 years, as required for installation at water meters in Austria. Thus, LPWAN technologies have the potential to advance the wide application of near real-time, pressure-based leak detection in WDS, while simultaneously reducing the cost of device operation significantly.

Drone-Enabled Internet-of-Things Relay for Environmental Monitoring in Remote Areas Without Public Networks

Advancements in the Internet of Things (IoT) have led to the revolutionary potential to achieve intelligent environmental monitoring. However, extreme conditions across hard-to-reach areas, where public ground networks do not provide sufficient coverage, have resulted in the difficult backhaul of monitoring data from remote areas of interest. Because of the urgent demand for low-cost data collection in such areas, this article proposes a novel drone-enabled IoT relay system to provide high-speed data collection to support remote environmental monitoring. The high-speed ability of 5-GHz communication technology was exploited to reduce the time required for data transmission between ground monitoring devices and drone. Meanwhile, the long-range (LoRa) technology, as a low-power and long-distance wireless communication technology, is adopted as a wake-up strategy for waking up the high-power 5-GHz module. Based on 5 GHz and LoRa technology, a drone-based onboard relay and ground intelligent terminal are designed. An application is used to demonstrate the feasibility of the designed system. Numerous real-world experiments validate the effectiveness of the designed drone-enabled IoT relay system and show its capability for high-speed data collection. The field experiments demonstrate that the system collects cached data with a stable 3.5-MB/s throughput at an altitude of 140 m. The breakthroughs in the drone-enabled IoT relay facilitate intelligent environmental monitoring in remote areas without public networks and provide a new perspective on data backhaul over areas of interest.

Field Study of Low-Energy Long-Distance Wireless Communication for IoT Application in Remote Areas

Long Range (LoRa) is a wireless radio frequency technology under the Low Power Wide Area Network (LPWAN). LoRa is able to communicate long range and low energy consumption. The communication range has become an essential element in the wireless radio frequency technology in the Internet of Things (IoT). The presence of LoRa is able IoT application performs in long communication distances with high noise sensitivity ability. People can operate, monitor, and do a variety of tasks from a remote distance. Therefore, this research aims to evaluate the performance of the LoRa connection between radio transceivers in remote locations. The different environment and structural elements affect the LoRa performance. This thesis will be supported by the experiment that LoRa communication in different environments and tests. This experiment tests in line of sight (LOS) and non-line of sight (NLOS). Two sets of LoRa parameters, including Spreading Factor (SF), Bandwidth, and coding rate, are tested in different environments. The experiment tests the LoRa performance in various aspects: received signal strength indicator (RSSI) and packet received ratio (PPR) at different coverage ranges. In addition, the LoRa performance is evaluated in university, residential areas and vegetation areas under similar temperature, weather, and time. The LoRa coverage distance in the vegetation area and university area is reached 900 meters in the LOS test. Still, the vegetation area's signal is more stable and able to receive weaker RSSI signals. The LoRa coverage distance in the NLOS test is shorter compared to the LOS test. NLOS test has only one-third of the LOS LoRa communication distance. It is due to the signal penetration on structural elements such as buildings and woods cause the signal power loss and only transmitting a shorter distance. The LoRa parameter with SF9, 31.25kHz bandwidth and 4/8 coding rate has a better coverage range and stable connection.

Broadband Spin-Decoupled Metasurface for Dual-Circularly Polarized Reflector Antenna Design

In this article, we theoretically and experimentally demonstrate a single-layered spin-decoupled metasurface and its application to a dual-circularly polarized reflector antenna. A developed method is first analyzed to guide the design of broadband spin-decoupled metasurface. Then, a quasi-I-shaped meta-atom, which exhibits a phase coverage of $2\pi $ and high cross-polarization conversion efficiency within 12–21 GHz, is accordingly designed to actualize spin-decoupled phase change by simultaneously tuning the structural parameters and self-rotation of the element. To illustrate the independent phase control of orthogonal spins, a dual-circularly polarized multiplexing reflector antenna is designed with offset configuration. The experimentally measured results of the assembled reflector antenna are in good agreement with the simulated ones, showing a peak gain of 29.5 and 29.6 dBic, peak aperture efficiency (AE) of 53% and 54%, 3 dB gain bandwidth (BW) of 13.2–20.2 GHz (41.9%) and 13.4–20.2 GHz (40.5%), and 3 dB axial ratio (AR) BW of 11.8–21 GHz (56.1%) and 11.5–22 GHz (62.7%) for left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) radiations, respectively. The design strategy and the well-performed multiplexing reflector antenna may have promising perspective in many practical applications, for example, satellite communication system and long-distance wireless communication system.

Cognitive Radio_Based Backup Protection Scheme for Smart Grid Applications

In this paper, a backup protection scheme is presented. The proposed scheme uses the concept of a cognitive radio-based wireless sensor network to implement a protection scheme without the need for conventional electric wires and/or optical fiber between current and voltage transducers, control panels, and circuit breakers. The proposed scheme uses unlicensed spectrum channels by applying spectrum sensing and frequency allocation algorithms that are used in cognitive radio based systems. The importance of the proposed scheme comes from its cost effectiveness compared to the Ethernet communication both wired and wireless if the data transfer and message exchange is done using cognitive radio_based communication for relatively long distances. The proposed scheme utilizes cognitive radio-based communication network to convey analog and digital signals within a substation. In this way, it saves the cost of the copper wires and/or optical fiber that would be used to transmit digital and analog signals. Further, it does not require the expensive spectrum licenses that would have been purchased if Ethernet long-distance wireless communications are utilized. To assess the benefits/challenges related to the application of cognitive radio_based communication, a detailed and realistic modeling of both power systems and cognitive radio_based communication systems is performed simultaneously. The proposed scheme is simulated using MATLAB/Simulink and performance of the proposed scheme was investigated under different communication scenarios.

Design of Embedded Medical Automatic Transfusion Supervision System

This paper puts forward a new type of automatic transfusion supervision system to solve the common problem that manual monitoring and manual replacement of medicine bottles take up more time and energy of family or nurses in the hospital, and devises the real-time monitoring and management function of the whole process of venous transfusion. The upper computer uses vb as the control interface, and the lower computer uses STM32 as the core controller, and the ZigBee self-networking technology is adopted to realize the long-distance wireless communication function. The controlled object is the stepping motor and transducer by using ZigBee Ad-Hoc Network technology to realize the function of remote wireless communication. Among them, in order to stabilize the process of replacing the bottle, the encoder is used to detect, and the PID control algorithm is designed. The experiment shows that this design can effectively reduce the flow of the infusion process, improve the working efficiency, so as to promote the digital development of the medical level in domestic.

Development of a distributed hybrid seismic–electrical data acquisition system based on the Narrowband Internet of Things (NB-IoT) technology

Abstract. The ambiguity of geophysical inversions, which is based on a single geophysical method, is a long-standing problem in geophysical exploration. Therefore, multi-method geophysical prospecting has become a popular topic. In multi-method geophysical prospecting, the joint inversion of seismic and electric data has been extensively researched for decades. However, the methods used for hybrid seismic–electric data acquisition that form the base for multi-method geophysical prospecting techniques have not yet been explored in detail. In this work, we developed a distributed, high-precision, hybrid seismic–electrical data acquisition system using advanced Narrowband Internet of Things (NB-IoT) technology. The system was equipped with a hybrid data acquisition board, a high-performance embedded motherboard based on field-programmable gate array, an advanced RISC machine, and host software. The data acquisition board used an ADS1278 24 bit analog-to-digital converter and FPGA-based digital filtering techniques to perform high-precision data acquisition. The equivalent input noise of the data acquisition board was only 0.5 µV with a sampling rate of 1000 samples per second and front-end gain of 40 dB. The multiple data acquisition stations of our system were synchronized using oven-controlled crystal oscillators and global positioning system technologies. Consequently, the clock frequency error of the system was less than 10−9 Hz at 1 Hz after calibration, and the synchronization accuracy of the data acquisition stations was ±200 ns. The use of sophisticated NB-IoT technologies allowed the long-distance wireless communication between the control center and the data acquisition stations. In validation experiments, it was found that our system was operationally stable and reliable, produced highly accurate data, and it was functionally flexible and convenient. Furthermore, using this system, it is also possible to monitor the real-time quality of data acquisition processes. We believe that the results obtained in this study will drive the advancement of prospective integrated seismic–electrical technologies and promote the use of IoT technologies in geophysical instrumentation.

Development of Wireless Sensor Node and Controller Complying with Communication Interface Standard for Smart Farming

The sensor node is a basic unit of a greenhouse control system that collects environment data and sends them to an environment controller. It is important for the sensor node and the controller to share a common communication protocol to enable effective communication. The objective of this research was to develop a wireless sensor node complying with a communication interface standard between a sensor node and a controller and to evaluate variation in data transmission rate with distance. The TTAK.KO-06.0288-Part1/R1 standard was selected as a communication interface standard; it was analyzed and implemented with a C++ library. A sensor node and a controller were designed to communicate with the library wirelessly using Bluetooth. The system was tested in a greenhouse to evaluate the variation in data transmission rate with changes in the distance between the components. A C++ library, libgnode, was developed and successfully implemented for transmitting data from the sensor node to the controller, complying with the TTA standards. The data transmission rate was 100% up to a distance of 25 m between the sensor node and the controller. The libgnode library can be utilized to improve the interoperability between components of a greenhouse control system. However, further research into the use of long-distance wireless communication methods (e.g., Zigbee or LoRa) is warranted in order to extend the communication coverage area in the greenhouse.

DeepMorse: A Deep Convolutional Learning Method for Blind Morse Signal Detection in Wideband Wireless Spectrum

With the recent advances in wireless technologies, high frequency radio has become the primary medium for long-distance communication. Among various types of modulation in signal transmission, morse code stands out due to its simplicity and efficiency in information transmission while costing small bandwidth. In practice, however, it is extremely laborious to locate morse signals in wideband communication. It's a needle in a haystack, if morse code is sent in random carrier waves at random period. To avoid this, automatic morse signal detection has become a challenging task in wireless morse communications, and new solutions could be derived from the latest machine learning techniques. In this paper, we propose a deep learning framework, namely DeepMorse, to blindly detect morse signals in wideband spectrum data. In particular, we first develop a multi-signal sensing module to retrieve signal candidates from wideband spectrum without prior knowledge. Then, we construct a CNN-based module to extract informative features from the located candidates, in order to distinguish the morse signal from other types of modulation. To evaluate the proposed DeepMorse model, we set up a testbed utilizing commercialized long-distance wireless communication devices. The experimental results demonstrate that DeepMorse is able to effectively detect morse signals and outperform the state-of-the-art methods on four real-world datasets.

Path-optimization method for UAV-aided relay broadcast communication system

Unmanned aerial vehicle (UAV) relay technology is an important means of long-distance wireless communication. In this paper, we address a broadcast communication system using a fixed-wing UAV as a relay platform between a base station (BS) and a cluster of mobile-task UAVs. To improve the system performance, especially to ensure the quality of service (QoS) of high-priority task UAVs, the path-optimization method for the relay UAV is investigated.We first present the system and signal model of the UAV-aided relay broadcast communication system and derive the approximate expression of the ergodic capacity of the single link. Then, considering the different demands of the task UAVs, we propose a relay UAV path-optimization method based on the criterion of maximizing the weighted sum-ergodic capacity of each link. After that, the mathematical expressions of accurate outage probability and closed-form ergodic capacity of the relay links are derived to quantify the system performance. Finally, we give the optimal path of the relay UAV in two simulation scenarios and provide the effects of the task UAVs’ priority and maximal heading angle of relay UAV on optimal path of relay UAV and communication performance of links using the proposed method. The computer simulation results demonstrate the validity of the proposed method and the performance analysis expressions. Our work can provide a useful reference for UAV relay broadcast communication system design.

A Pulse-Biasing Small-Signal Measurement Technique Enabling 40\u2009MHz Operation of Vertical Organic Transistors

Organic/polymer transistors can enable the fabrication of large-area flexible circuits. However, these devices are inherently temperature sensitive due to the strong temperature dependence of charge carrier mobility, suffer from low thermal conductivity of plastic substrates, and are slow due to the low mobility and long channel length (L). Here we report a new, advanced characterization circuit that within around ten microseconds simultaneously applies an accurate large-signal pulse bias and a small-signal sinusoidal excitation to the transistor and measures many high-frequency parameters. This significantly reduces the self-heating and therefore provides data at a known junction temperature more accurate for fitting model parameters to the results, enables small-signal characterization over >10 times wider bias I–V range, with ~105 times less bias-stress effects. Fully thermally-evaporated vertical permeable-base transistors with physical L = 200 nm fabricated using C60 fullerene semiconductor are characterized. Intrinsic gain up to 35 dB, and record transit frequency (unity current-gain cutoff frequency, fT) of 40 MHz at 8.6 V are achieved. Interestingly, no saturation in fT − I and transconductance (gm − I) is observed at high currents. This paves the way for the integration of high-frequency functionalities into organic circuits, such as long-distance wireless communication and switching power converters.

The WSN Monitoring System for Large Outdoor Advertising Boards Based on ZigBee and MEMS Sensor

With the increase of large outdoor advertising boards, the issues of public safety raised by the collapse of outdoor advertising boards have attracted great public concern. In this paper, a wireless sensor network (WSN) monitoring system is designed for the structural health monitoring of large outdoor advertising boards. By using the WSN technology, this system can judge the security of the outdoor advertising boards and give early warnings when the boards are being in danger. The monitoring system consists of two subsystems, one is the WSN structure system based on ZigBee wireless sensor nodes with a six-axis MEMS motion sensor integrated to capture the movement information, and the other is the monitoring center system controlled by ARM microcontroller for data processing and long-distance wireless communications with remote server through a GPRS module. The simulation model of outdoor advertising board is also built to analyze the deformed shape of the advertising board structure under wind load, and the early warning judgment standard is proposed. The performance of the monitoring system is evaluated through several experiments under the condition of laboratory in different aspects of the comparison experiments. The experimental results indicate that the WSN monitoring system can real timely and accurately monitor the state of the outdoor advertising boards.

Energy Efficiency Improvement of Coded OFDM Systems Based on PAPR Reduction

For long-distance wireless communications, a power amplifier (PA) is one of the most power-hungry devices at a transmitter. In many recent wireless standards that pursue higher spectral efficiency, signaling techniques with a high peak-to-average power ratio (PAPR) such as orthogonal frequency-division multiplexing (OFDM) have been adopted, but they typically end up with poor PA efficiency. A variety of PAPR reduction approaches have been thus proposed in literature to improve the power efficiency from the physical-layer perspective. In this paper, we investigate how much improvement in terms of the power efficiency can be achieved by such PAPR reduction techniques for OFDM signaling, and we evaluate the achievable coded frame error rate (FER) from a viewpoint of system-level design. It reveals that, in addition to the improvement of the PA efficiency, carefully designed PAPR reduction techniques in fact have a potential of reducing the required signal-to-noise power ratio at a receiver for achieving a given target FER and reducing the duty cycle of a transmitter circuit for a given target information rate. This in turn helps in reducing the total energy consumed at the transmitter of mobile terminals and thus leads to greener communication systems.

Temperature and Humidity Measuring System Based on ZigBee and GPRS

It is important for modern agricultural production to measure temperature and humidity in a real time way. This paper combined the short-distance wireless communication technology ZigBee with the long-distance wireless communication technology GPRS to design a solar-powered temperature and humidity measuring system. The system is easy to install and can run in low cost, so it is especially suitable for small and medium agricultural producers.