2-ray Model Research Articles

Time‐Varying Channel Estimation Based on Air‐Ground Channel Modelling and Modulated Learning Networks

To improve the time-varying channel estimation accuracy of orthogonal frequency division multiplexing air-ground datalink in complex environment, this paper proposes a time-varying air-ground channel estimation algorithm based on the modulated learning networks, termed as MB-ChanEst-TV. The algorithm integrates the modulated convolutional neural networks (MCNN) with the bidirectional long short term memory (Bi-LSTM), where the MCNN subnetworks accomplish channel interpolation in frequency domain and compress the network model while the Bi-LSTM subnetworks achieve channel prediction in time domain. Considering the unique characteristics of airframe shadowing for unmanned aircraft systems, we propose to combine the classical 2-ray channel model with the tapped delay line model and present a more realistic channel impulse response samples generation approach, whose code and dataset have been made publicly available. We demonstrate the effectiveness of our proposed approach on the generated dataset, where experimental results indicate that the MB-ChanEst-TV model outperforms existing state-of-the-art methods with a lower estimation error and better bit error ratio performance under different signal to noise ratio conditions. We also analyze the effect of roll angle of the aircraft and the duration percentage of the airframe shadow on the channel estimation.

Evaluation and Performance of Path Profile Characteristics in Communication System

This study presents the evaluation and performance of path profile characteristics in communication system, to determine the path profile characteristics such as margin fade (dB), receiver power (dBm), 2-ray propagation model (dB), free space propagation model (dB), LOSMAX (km) and critical distance (km). Data were obtained from Network ‘A’, using three different links within a geographical location in Edo State. Receiver power is mathematic model, the sensitivity of the receiver, which depends on the bandwidth (data rate) (dBm) of antennas were considered in this analysis. All the path profile characteristics were determined, it was observed, that increase in path length distance of microwave line of sight, will necessitate the increase in transmitter power in decibel. The Path length distance and margin fade of the three basic mobile propagation links were determined. It was observed that path length distance characteristic as such the length of distance, obstacle, reflection, diffraction from ground, water bodies and atmosphere resulted to the pattern of radio margin fade signal obtained in receiver antenna. The margin fade determined are 28.83 dB, 12.95 dB and 21.24 dB for the three different links considered from Network ‘A’ in Auchi, Nigeria.

MBOC(6,1,4/33) 신호의 다중경로 영향 완화를 위한 새로운 Strobe 펄스 설계

In this paper, we propose a novel strobe pulse to mitigate the multipath effect of MBOC (6,1,4/33) signal and analyze its performance. By additionally modulating a passband Direct Sequence/Spread Spectrum (DS/SS) signal with a Binary Offset Carrier (BOC) sub-carrier, the signal band can be moved to a desired band, thereby increasing frequency efficiency. In addition, the correlation characteristics of the correct code synchronization point are improved, so that the multipath effect can be reduced to compare with the existing Binary Phase Shift Keying (BPSK) modulated signal. However, the multipath effect is still one of the major performance limitations of the Global Navigation Satellite Systems (GNSSs). A conventional scheme to mitigate multipath effects of GNSS is the Strobe pulse technique. In this paper, we design a new strobe pulse that can effectively mitigate the multipath effects of MBOC (6,1,4/33) signals, and multipath mitigation in the 2-Ray model, a representative channel environment to assess the multipath mitigation performance by computer-based simulation. In order to compare the performance of the proposed new strobe pulse, the W2 pulse scheme with similar implementation complexity is considered. The W2 pulse technique is the one of the Strobe pulse technique for BOC signal. Based on the output of the discriminator in multipath free environment, the pull-in range of the W2 pulse technique is about 0.2 chips, whereas the proposed scheme is about 0.6 chips, which is about 3 times wider. And the false-lock point of the proposed scheme is less than about 20% to compare the W2 scheme. In the same environment, the multipath error envelope of the W2 and the proposed schemes is shown, and both techniques are affected only by the closed-in multipath signal. Among them, the proposed scheme has significantly lower multipath errors due to the closed-in multipath signal compared to the W2 technique, and the maximum value of the proposed scheme based on the running average of the multipath errors is about 32% compared to the W2 scheme.

A Study of LoRa Performance in Monitoring of Patient’s SPO2 and Heart Rate based IoT

In this research, a sensor that will be equipped with blood oxygen saturation function (SPO2) blood and Heart Rate is MH-ET Live max30102 Sensor with Library Max30105. The advantage of this sensor is compatible with ATmega 328P, which is the Arduino board, the first experiment using Arduino Uno. Therefore, MH-ET Sensor data is integrated with Wireless Sensor Network (WSN) devices, e.g, LoRa (Long Range) 915 MHz and calculate WSN path loss when sending sensor data in mountainous areas, the model used to represent signal analysis and measurements in this study is the Ground Reflection (2-ray) model. therefore, the conditions that can be explained are patients who will send their data over hilly areas and hospitals or medical treatments called receiving nodes or coordinator nodes in much lower areas, in the same situation adding routers is expected to be a comparison of whether the data sent faster or even no impact. Furthermore, in this study, it is expected to provide clear results on the function of the router as the sender of pulse sensor data. The point is patients who are in a higher area with the level of impossibility in bringing the patient due to the condition of the patient so that the SPO2 data transmission and heart rate of the patient are expected to be known quickly by the medical authorities through the sensor node device attached to the patient's body. The use of the Adaptive Data Rate (ADR) Algorithm is used to optimize data rate, time on air (ToA) or airtime and energy consumption in the network. Therefore, the End Device (ED) in the ADR algorithm must be static (non-mobile). In the process of measuring the ADR algorithm in the position of sending data (uplink) n-bits to n-gateway. Next, the application server used is ThingsSpeak or The Things Network (TTN).

Analytical Modelling of Terahertz Photomixing Antennas

Radiation from a Terahertz Photomixing Antenna (PMA) involves multi-physical phenomena. We introduce a simple analytical model that combines the multi-physical phenomena in the PMA using a conventional 2-ray model. We observe reasonably close agreement between the antenna output obtained from the proposed model and the available measured results. We extend our analytical framework to incorporate the presence of an additional signal source on one of the laser beams, intended towards producing modulation in the PMA output signal. We analytically investigate the active region current density and radiated fields of the PMA. We also present a brief discussion on the efficiency of the PMA and the different factors that impact the efficiency. The output power depends on some key parameters which can be utilized to make PMAs suitable for sensing as well as wireless communication applications.

Improved 2-Ray Model for Overwater Propagation Channels: Modeling the Instantaneous Variations in the Received Signal Strength

Based on analyzing two-day ship-to-shore propagation measurements performed simultaneously at two frequency bands (1.39 GHz and 4.5 GHz), we extract the small-scale fading (SSF) and show that the higher the frequency, the larger the amplitudes of the SSF. Consequently, we introduce a modification to the 2-ray model so that the behavior of the SSF at different frequency bands is captured. We model the effect of the randomness and the unknown dynamic details of the propagation environment as a zero-mean Gaussian random variable which is then superimposed on the length of the rays in the traditional 2-ray model. For the measured environment, it is found that a standard deviation in the sub-centimeter range is able to characterize these unknown details and almost replicate the behavior of the observed SSF at these two bands.

Unmanned Aerial Vehicle Propagation Datalink Tool Based on a Hybrid Multiscale Modeling

This article presents a hybrid computational method to address the datalink characteristics of an Unmanned Aerial Vehicle (UAV) relay. It uses the 3D far-field gain data from the antennas (UAV and ground station), separately computed or based on available measurements as inputs, and then applies the 2-Ray propagation model, taking into consideration the ground permittivity and the respective antenna heights. By doing so, different numerical approaches cover the two different physical scales. Since the installed antennas (i.e. antennas considered placed on the UAV fuselage) performances are considered, a higher reliability can be achieved with the covered procedure, at lower costs when compared to field measurements. Results for different example scenarios are presented and discussed.

Ray Tracing-Based Maritime Channel Analysis for Millimeter Radiowaves

In this work, we present and analyze the simulation results of millimeter-wave propagation channel performed over the sea surface for ship to ship scenario. We present a channel characterization study where channel parameters such as path loss, received power, root mean square delay spread, and power delay profile are inspected by taking the ray tracing advantages of the “Wireless InSite” software. 35 GHz and 94 GHz are the bands of interest, as they have minimum water and oxygen attenuation and their performances in practice would be the best among the other frequency bands. In our study, we investigate the effect of ray spacing, Earth’s curvature, and the sea surface roughness on marine channel characteristics. Our results demonstrate that 2-ray analytical model should be only used for some short ranges over the sea surface propagating at high frequencies. Besides, free-space path loss model cannot predict the behavior of channel over the sea surface in high frequencies even for the short ranges. Therefore, a new path loss model is proposed to compensate the defects of existing path loss models by the means of changing the reflection coefficient and modifying the original 2-ray path loss model. This proposed model is able to better follow the simulated or measured propagation loss with less error, when it is compared with Free Space and 2-ray path loss models. Hence, this new model can be used for the path loss calculations at the mentioned frequencies especially for large distances between transmitter and receiver.

Performance Evaluation of LoS MIMO Microwave Radio Systems Over Frequency Selective Multipath Fading Channels

Although spectrally efficient microwave LoS-MIMO (Line of Sight-Multiple Input Multiple Output) systems seem to be practically attractive mainly at higher frequency bands (above 15 GHz), also at lower frequency bands, where frequency selective multipath fading is the dominant impairment for the outage time, they could play a significant role. Under this perspective, the paper analyzes performance of LoS-MIMO systems affected by frequency selective fading, taking into account the necessary equalization for satisfying the outage objectives. For the purpose of the analysis, we adopted a frequency selective $$2 \times 2$$ LoS-MIMO channel model extrapolated from the 2-ray model historically used in SISO (Single Input Single Output) systems and, exploiting the full statistical behaviour of the propagation channel model, we described a methodology for the evaluation of frequency selective LoS-MIMO outage performance. Then the proposed methodology is used to investigate the effectiveness of equalization in the intersymbol and mutual interference reduction of two equalizer structures, linear MMSE and MMSE Partial Response, using as a practical reference the target outage probability predicted on the same link for a SISO system. Finally, it is discussed the opportunity of using the Condition Number of the LoS-MIMO channel matrix transfer function as an exhaustive indicator of the channel quality.

장거리 공중-지상 영상정보용 데이터링크의 수신 안테나 최적 고각 제어 방법

영상정보용 데이터링크는 장거리의 공중-지상 환경에서 영상과 신호정보를 전송하도록 설계된 통신 시스템이다. 본 논문은 장거리 공중-지상 채널환경의 신호 분석에 적합한 곡면지구 2-Ray 모델을 사용하여 영상정보용 데이터 링크의 통신거리에 따른 수신전력 변화 폭을 분석하고 지면 반사파에 의한 수신전력의 변화폭을 경감할 수 있는 수신 안테나의 최적 고각 제어방법을 제안한다. 제안된 방법은 추가적인 하드웨어 성능 향상 없이도 기존의 고각 제어 방법에 비하여 추가적인 링크마진을 확보할 수 있다. Common data link systems are designed to transmit the imaginary and signal intelligence data at long distance air-ground line of sight(LOS) link. In this paper, we analyze the received power variation according to the communication distance of the common data link using curved earth 2-Ray model suitable for received signal power analysis of long distance air-ground wireless channel. We propose optimal elevation angle control method of the receiving antenna to reduce a power variation caused by ground-reflected wave. Proposed method can get additional link margin compared to the conventional method without any additional hardware performance enhancement.

Analysis of field intensity distribution in inhomogeneous propagation environment based on two-ray model

This paper is concerned with an analysis of field intensity distribution caused by sensor nodes located on inhomogeneous terrestrial surfaces. First, we introduce 1-ray and 2-ray models with two mo...