Radio Wave Propagation Characteristics Research Articles

Prediction of Indoor Millimeter Wave Propagation Characteristics Based on BP Neural Network

Due to the complexity of the millimetre-wave indoor propagation environment, using the conventional methods to analyze propagation characteristics of radio wave leads to great error, and the computational complexity is high. In view of the above problems, the prediction method for propagation characteristics of the indoor millimetre wave based on BP neural network is proposed; using its function approximation to describe the millimetre wave propagation parameter, finding out the mathematical relationship between its corresponding external factors and the signal attenuation, the mathematical logic relationship is constructed through establishing the prediction model. Simulation results show that using this method can quickly and intuitively obtain the relationship between the propagation distance and field intensity or path loss, respectively, with advantages of taking short time and high computational efficiency.

Study on the Propagation Characteristics of Radio Wave for Indoor Non-Line-of-Sight

The propagation characteristics of radio wave have been an important topic in wireless communications. Based on the ray tracing method, the propagation of radio wave for indoor NLOS environment is simulated and analyzed. In this paper, the received power is obtained by simulation, and we will analyze the impact of various factors on the received power. Later, the study can be used to simplify indoor radio wave propagation model and provide a theoretical basis, which is in favor of indoor wireless communication network planning and optimization and can lay the foundation of the development of future technology.

Design of Four-Arm Equiangular Spiral Antenna in Mine Communication

According to the propagation characteristics of radio wave in mine tunnels, in order to realize the communication and detection in underground tunnels, a four-arm equiangular spiral antenna is presented in the paper, which based on the principle and structure of traditional two-arm spiral antenna, and reduces the antenna size. CST software is used to construct and simulate the antenna model. The antenna is tested by the PNA3621 vector network meter. Simulation and measurement results show that the antenna has good performance in 652MHz-3.012GHz frequency range, antenna input voltage standing-wave ratio VSWR and return loss RL are ideal, and antenna pattern is better, which agrees well with the simulated results.

2.4 GHz Radio Wave Propagation Characteristics in Coal Mine Workface Tunnels

2.4 GHz Radio Wave Propagation Characteristics in Coal Mine Workface Tunnels

2.4 GHz Radio Wave Propagation Characteristics in Coal Mine Workface Tunnels

We proposed a novel ray-tracing based radio waves propagation (RTRWP) Law suitable for under-tunnel complex coal mine workface. The energy consumption model evaluation in complex coal mine workface is derived. Theoretical analysis about calculating the multiple reflections of the radio waves in coal mine workface is also provided. Computer simulations and field tests in workface tunnels show that this proposed RTRWP law can work effectively to describe the actual radio wave propagation environments in complex coal mine workface.

Simulation Research of the Underground Coal Mine Wireless Signal Transmission Characteristics

According to the special communication environment of the underground coal mine and the characteristic of high frequency electromagnetic wave approximation light propagation, this research adopts ray tracing method to simulate and analyze the characteristics of radio wave propagation in the underground roadway. The study not only is the theoretical basis for the development of wireless communication system in the underground, but also will provide an effective guarantee for safe production and modernization superintendence of coal mine.

Bit Error Probability of Spatial Modulation over Measured Indoor Channels

The Spatial Modulation (SM) transmission scheme boosts the spectral efficiency and achieves the multiplexing gain by activating a single transmit antenna in each time slot. Radio wave propagation characteristics determined by the environment is a decisive factor for the SM system. In this paper, we investigate the performance of the SM scheme over real-world 4×4 Multi-Input Multi-Output (MIMO) channels measured in typical indoor scenarios. Firstly, a MIMO channel sounder is established. Based on the sounder, 15150 complex 4×4 MIMO channel matrices are measured inside a typical teaching building under both Line of Sight (LOS) and None Line of Sight (NLOS) scenarios. Secondly, by comparing the SM system over the measured channel and commonly-used channel models, we prove that both the Independently and Identically Distribute (i.i.d.) Rayleigh and the Spatial Correlation (SC) channel model are oversimplified, and that only practical experiences can yield definitive answers to the achievable real-world system performance. Thirdly, the Average Bit Error Probability (ABEP) performance of the SM system is studied based on the measured data under a variety of system configurations. The study of different receive antenna array settings (4×4, 4×2 and 4×1 MIMO setups) approves the significance of combining scheme at the receiver. SM systems employing different signal constellations (Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK) and 16 Quadrature Amplitude Modulation (16QAM)) are also investigated and some interesting results are revealed. Lastly, performance assessment of SM against State-Of-The-Art (SOTA) MIMO schemes (Space-Time Block Code (STBC) and Vertical Bell Labs Layered Space-Time (V-BLAST) code) is conducted. Results show that for a 4×4 MIMO, the low-complexity SM scheme outperforms both STBC and V-BLAST.

다양한 채널 환경에서 IEEE 802.15.4/ZigBee 시스템의 성능 분석

최근 무선 센서 네트워크(WNS: Wireless Sensor Network)가 큰 관심을 받고 있으며, IEEE 802.15.4 표준 규격을 기반으로 상위 계층 규격을 표준화하여 산업 분야에 적용하기 위한 ZigBee의 필요성이 대두되고 있다. 현재 IEEE 802.15.4/ZigBee 통신채널에 대한 많은 연구가 이루어지고 있으며, 다양한 채널 환경에 대한 성능 분석 또한 관심의 대상이다. 본 논문에서는 다양한 채널 환경에서의 IEEE 802.15.4 전파전파 특성분석을 통한 채널 모델을 제안한다. 또한 IEEE 802.15.4/ZigBee 표준의 2.4㎓ 대역 물리계층에서 각 채널 환경에 대한 성능을 비교 분석한다.

A New Approach Towards Large Scale Soil Moisture Mapping by Radio Waves

A new approach for obtaining integrated estimates of soil moisture content over larger regions of typically 10–50 km is described. It is based on a known correlation between propagation characteristics of low frequency radio surface waves and surface soil moisture, and provides valuable new benefits especially for meteorological prognostic models and for soil water estimation in agriculture. The paper consists of (1) a description of the theory of radio wave propagation with an extension of the classical theory of Norton (Proceedings of the Institute of Radio Engineers, Vol. 24, 1936), specifically the exploitation of the phase information, (2) demonstration of a method which guarantees the selection of reliable results from a large measurement data set, (3) a presentation of a new low cost measurement device to detect the amplitude and phase changes, and (4) results from initial measurements providing evidence that theoretical calculations are consistent with the measured change of electromagnetic signal properties due to soil moisture change.

Propagation Path Loss Prediction Model of Multi-Sensor Network in Forest

During the process of carrying on the master plan and design of multi-sensor network in forest, We must consider the coverage of the signal, how to find the best position, through predicting it from launching and checking to accepting the loss value of the electromagnetic wave checked, Can carry on planning and design. Based on the radio wave propagation loss model in free space and the characteristics of radio wave propagation in forest, this paper proposes the generalized predicting model of radio wave propagation loss, To validate the model, a radio propagation measurement campaign was carried out, The modeling results by measuring the parameters of some trees are good agreement with that of the literature

Characteristics of Cavity Slot Antenna for Body-Area Networks

Antennas and the propagation characteristics for body-area networks have become an active area of research. In this paper, a cavity slot antenna is proposed for onbody communications at 2.45 GHz. First, the antenna characteristics (input impedance, radiation pattern, and efficiency) are calculated by the finite-difference time-domain method. The results show that the proposed antenna has a relatively high efficiency of more than 50% even in the vicinity of the human body. Next, the onbody radio wave-propagation characteristics are investigated through numerical simulation and experimental measurements of the electric-field distributions around a phantom with a simplified shape of a human arm. Both sets of results are then compared and discussed. Finally, good agreement between the measured and the calculated results is confirmed.

An Experiment Study of the Propagation of Radio Waves in a Scaled Model of Long-Wall Coal Mining Tunnels

A long-wall coal mining tunnel is the most important working area in a coal mine. It has long been realized that radio communications can improve both productivity and safety in this dangerous area. Hence, many attempts to use radio communications in such an environment have been made. Unfortunately, no radio system has satisfactorily provided communication services there, which, we believe, is partially due to poor understanding of the propagation characteristics of radio waves in the long-wall mining tunnel. To have deeper physical insight into the propagation problem, a scaled model of the long-wall mining tunnel was built, and the propagation characteristics of UHF radio waves were measured. The experiment and the measured results are presented and discussed.

Study of Ionospheric Irregularities in the Vicinity of SED Region During a Super Geomagnetic Storm

基于IGS提供的TEC数据, 研究了2003年10月大磁暴期间的暴时密度增强(Storm Enhanced Density, SED)现象; 利用GPS观测数据, 计算出ROTI (Standard deviations of ROT)指数, 分析了SED边界附近电离层小尺度不均匀体结构的时间和空间演变. 研究表明, 在磁暴主相期间SED边界附近不均匀体随着磁暴的发展逐渐增多; 在主相的中后期不均匀体的分布密集度达到最大; 在恢复相期间, 不均匀体分布很少; 随着磁暴的发展, 不均匀体开始主要集中在40~45ºN范围内, 随后向高纬漂移, 主要集中在45~55ºN范围内.

Radio Wave Propagation Characteristics in FMCW Radar

FMCW Radar (Frequency Modulated Continuous Wave Radar) is used for various purposes, such as atmospheric Remote Sensing, inter-vehicle ranging, etc. FMCW radar systems are usually very compact, relatively cheap in purchase as well as in daily use, and consume little power. In this paper, FMCW radar determines a target range by measuring the beat frequency between a transmitted signal and the received signal from the target, and Combines between PO and radar single. The approach based on frequency domain physical optics for the scattering estimation and the linear system modeling for the estimation of time domain response, and FMCW Radar signal processing.

A study of VLF wave propagation characteristics in the earth-ionosphere waveguide

Abstract In the light of newly found applications for very low frequency (VLF) (3–30 kHz) measurements in the prediction of earthquakes and the detection of lightning discharges and gamma ray bursts, there has been a revival of interest in the study of VLF propagation in the earth-ionosphere waveguide. The propagation characteristics of VLF radiowaves in the earth-ionosphere waveguide critically depend upon the lower ionospheric ionization, which determines the conductivity profile of the upper boundary of the waveguide. In this context, it is potentially worthwhile to revisit the waveguide mode analysis to compute propagation parameters of long-distance VLF transmissions while taking into account different approximations to the ionospheric conductivity. We have carried out a waveguide mode analysis of 16-kHz VLF waves traveling great distances, assuming three different models for conductivity. The computational results show that at heights of less than 70 km, the change in the phase of the VLF waves due to changes in phase velocity is smaller when the ionosphere is sharply bound and assumed to have finite conductivity rather than infinite conductivity. The effect of a non-sharp or diffuse boundary at the top of the earth-ionosphere waveguide is found to cause a lowering of the height of reflection.

3-D Angular Spectrum Measurements at 5 GHz in a Residential Two-Story House

This paper presents an investigation of radio-wave propagation characteristics in the 5 GHz band in a residential two-story house. We investigated the 3-D angular spectra of incident waves when a transmitter and a receiver were situated on the first and second floors, respectively. First of all, correlation in the measured home environment containing furniture such as beds, a sofa and tables was determined to confirm a quasi-static environment. Then, 3-D angular spectra measurements were performed by using an eight-element Yagi-Uda antenna as a receiving antenna. Furthermore, the 4-by-4 MIMO channel capacity at each elevation angle was estimated by using elevation angular spectra and the propagation characteristics between the first and second floors were evaluated. The results indicated that the channel capacity in the elevation direction was strongly influenced by the direction of the transmitting antenna.

Some experimental and modeling results of widely varying urban environments on train mobile radio communication

AbstractA comparative study of urban mobile radio wave propagation characteristics in the UHF band has been carried out based on the field strength measurements conducted inside a moving train in two widely varying urban environments. Various prediction techniques are employed to compare the observed path losses with those of predicted ones in both the environments. The major fall out of the present study is the modification of Xia's model, which gave better agreement with the observed results. The deviations of the prediction techniques and their suitability have been discussed. Copyright © 2006 John Wiley & Sons, Ltd.

IEEE802.15.4 ESPARSKey (Encryption Scheme Parasite Array Radiator Secret Key)

When the transmission and reception locations of radio waves are different, the correlation of the radio wave propagation characteristics decays quickly. On the other hand, reciprocity of the radio wave propagation holds between two stations that can communicate with each other. Therefore, by making use of the information on the variation of the propagation path, it is possible to generate and share a secret key that cannot be eavesdropped by a third party at a different receiving location. Hence, a secret key generation and agreement system that does not require key management and key distribution can be realized. Also, the ESPAR (Electronically Steerable Parasitic Array Radiator) antenna, under development as a commercial antenna with a variable radiation pattern, can control its directive characteristics by the use of varactor diodes to change the capacitance. Therefore, it is possible to intentionally change the radio propagation characteristics significantly. This paper reports successful test development of a wireless secret key agreement system making use of the fluctuation of the radio propagation characteristics by means of an ESPAR antenna. Further, in a verification experiment using the test system, the key generation success probability was more than 99.998% when a 128-bit secret key was modified every 3 seconds. It is also confirmed by the correlation characteristics with an eavesdropping station that more than 7.19×104 years would be required for the eavesdropping station to decipher the secret key. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 89(12): 31–44, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20305

A Random Graph Model of Mobile Wireless Networks

Abstract We propose a time-invariable, integrated model of wireless networks working in hostile environment with obstructions and other factors causing interference. We present a new probabilistic model well suit for analysis of distributed algorithms requiring synchronous communication. The model is based on a random graph with a specific edge probability distribution, which is related to the radio wave propagation characteristics.

Experimental Characterization of Radio Wave Propagation in Hospitals

This paper reports the characterization of radio wave propagation in hospitals. In contrast to other buildings with usual walls, some rooms within hospitals are constructed with special walls that include metallic layers. The structure of the walls depends on the purpose of each hospital room. To consider all the different wall types, measurements were performed in all relevant areas of four hospitals. Rooms, such as operating rooms, X-ray and magnetic resonance tomography (MRT) rooms were taken into account. The measurements were performed at eight discrete frequencies ranging from 42.6 MHz up to 5.2 GHz. In order to investigate accurately the wave propagation properties, several antennas and measurement systems were used. Results show that radio wave propagation characteristics vary from room-to-room. It turned out that it is important to consider the room as a whole when determining the attenuation between adjacent rooms, because a small part of the wall is not enough. In addition to usual wave propagation phenomena such as reflection and transmission, slots and openings give rise to coupling effects through walls containing metallic layers in their structure. The measurement data is useful for hospital designers and hospital engineers.