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M. Africa, Aaron Don. "Radio Wave Propagation: Simulation of Free Space Propagation Path Loss." International Journal of Emerging Trends in Engineering Research 8, no. 2 (February 15, 2020): 281–87. http://dx.doi.org/10.30534/ijeter/2020/07822020.
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Kharchenko, Volodymyr, Yuri Barabanov, and Andrii Grekhov. "MODELING OF ADS-B DATA TRANSMISSION VIA SATELLITE." Aviation 17, no. 3 (October 7, 2013): 119–27. http://dx.doi.org/10.3846/16487788.2013.840057.
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For modelling transmission of ADS-B messages via low-orbit satellite constellation Iridium, the original model of a communication channel “Aircraft-to-Satellite-to-Ground Station” was built using MATLAB Simulink. The model comprises “Aircraft Uplink Transmitter” (Bernoulli Random Binary Generator, Convolutional Encoder, BPSK Baseband Modulator, High Power Amplifier with a memoryless nonlinearity, Transmitter Dish Antenna Gain), “Uplink Path” (Free Space Path Loss, Phase/Frequency Offset), “Satellite Transponder” (Receiver Dish Antenna Gain, Satellite Receiver System Temperature, Complex Baseband Amplifier, Phase Noise, Transmitter Dish Antenna Gain), “Downlink Path” (Free Space Path Loss, Phase/Frequency Offset), “Ground Station Downlink Receiver” (Receiver Dish Antenna Gain, Ground Receiver System Temperature, Viterbi Decoder), “Error Rate Calculation” block and “Display”. The modelling was realized without and with convolutional coding (r = 3/4, K = 7) at different noise temperatures and free space losses. Dependencies of a Bit Error Rate on free space path losses, antenna's diameter, phase/frequency off-sets, satellite transponder linear gain, aircraft and satellite transponder high power amplifier back-off level, and phase noise were received and analysed.
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Israr, Imran, Mahmood Ashraf Khan, Shahzad A. Malik, Shahid A. Khan, and Mustafa Shakir. "Path Loss Modeling of WLAN and WiMAX Systems." International Journal of Electrical and Computer Engineering (IJECE) 5, no. 5 (October 1, 2015): 1083. http://dx.doi.org/10.11591/ijece.v5i5.pp1083-1091.
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<p>With the advancement in technology, there was need for efficient and high speed internet through which we could have access to multiple networks as per the user requirement. WLAN met this need to some extent but, due to its low range it was not recommended commercially. With the introduction of WiMAX there was an emerging need to select the best network amongst WiMAX or WLAN depending upon the user location. Pathloss with respect to these particular networks also needs to be compared. In this paper we compare the pathloss modelling for WiMAX and WLAN systems. Different Models have been compared with each other to know which model performs better by keeping same simulation environment. Path Loss models used for WLAN are Okumura, Hata, Cost-231 and Free Space Path Loss whereas models used for WiMAX are Free Space Path Loss, Okumura-Hata, Cost231-Hata and Stanford University Interim. In case of WiMAX three different scenarios Urban, Sub-Urban and Rural is considered where as in case of WLAN only outdoor environment is considered. With the Path Loss comparison, power received for these two technologies; WiMAX, and WLAN is also simulated. MATLAB is the tool used for simulations. Antenna Specifications for WiMAX and WLAN is kept same for all simulation environments.</p>
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Al-samman, Ahmed M., Tharek Abd Rahman, and Marwan Hadri Azmi. "Indoor Corridor Wideband Radio Propagation Measurements and Channel Models for 5G Millimeter Wave Wireless Communications at 19 GHz, 28 GHz, and 38 GHz Bands." Wireless Communications and Mobile Computing 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/6369517.
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This paper presents millimeter wave (mmWave) measurements in an indoor environment. The high demands for the future applications in the 5G system require more capacity. In the microwave band below 6 GHz, most of the available bands are occupied; hence, the microwave band above 6 GHz and mmWave band can be used for the 5G system to cover the bandwidth required for all 5G applications. In this paper, the propagation characteristics at three different bands above 6 GHz (19, 28, and 38 GHz) are investigated in an indoor corridor environment for line of sight (LOS) and non-LOS (NLOS) scenarios. Five different path loss models are studied for this environment, namely, close-in (CI) free space path loss, floating-intercept (FI), frequency attenuation (FA) path loss, alpha-beta-gamma (ABG), and close-in free space reference distance with frequency weighting (CIF) models. Important statistical properties, such as power delay profile (PDP), root mean square (RMS) delay spread, and azimuth angle spread, are obtained and compared for different bands. The results for the path loss model found that the path loss exponent (PLE) and line slope values for all models are less than the free space path loss exponent of 2. The RMS delay spread for all bands is low for the LOS scenario, and only the directed path is contributed in some spatial locations. For the NLOS scenario, the angle of arrival (AOA) is extensively investigated, and the results indicated that the channel propagation for 5G using high directional antenna should be used in the beamforming technique to receive the signal and collect all multipath components from different angles in a particular mobile location.
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Chen, Jie, Dong Ya Shen, Na Yao, and Ren Zhang. "3-D Research about Walfisch-Bertoni Model." Applied Mechanics and Materials 385-386 (August 2013): 1527–30. http://dx.doi.org/10.4028/www.scientific.net/amm.385-386.1527.
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Walfisch - Bertoni model is used to predict the average signal field intensity of the main street. The model considers the path loss of the free space, diffraction loss along the path, and the influence of the height of the building. There are six City parameters in Walfisch - Bertoni model influence communication quality. In this paper, the researches about path loss and its characteristics is under the case of considering two city parameters at the same time. Facts have proved that this case is more close to the actual that the wireless signal propagation environment. This paper mainly researched the path loss, probability density function (PDF) and cumulative distribution function (CDF) of the path loss.
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Balaguer, C., A. Barrientos, F. J. Rodriguez, R. Aracil, E. A. Puente, and U. Peter. "Reduction of free-space-loss for good and rapid 3D path planning of 6DOF robots." Journal of Intelligent & Robotic Systems 13, no. 3 (July 1995): 263–78. http://dx.doi.org/10.1007/bf01424010.
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Al-Saman, Ahmed, Marshed Mohamed, and Michael Cheffena. "Radio Propagation Measurements in the Indoor Stairwell Environment at 3.5 and 28 GHz for 5G Wireless Networks." International Journal of Antennas and Propagation 2020 (December 27, 2020): 1–10. http://dx.doi.org/10.1155/2020/6634050.
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To cover the high demand for wireless data services for different applications in the wireless networks, different frequency bands below 6 GHz and in millimeter-wave (mm-Wave) above 24 GHz are proposed for the fifth generation (5G) of communication. The communication network is supposed to handle, among others, indoor traffic in normal situations as well as during emergencies. The stairway is one of those areas which has less network traffic during normal conditions but increases significantly during emergencies. This paper presents the radio propagation in an indoor stairway environment based on wideband measurements in the line of sight (LOS) at two candidate frequencies for 5G wireless networks, namely, 3.5 GHz and 28 GHz. The path loss, root mean square (RMS) delay spread, K-factor results, and analysis are provided. The close-in free-space reference distance (CI), floating intercept (FI), and the close-in free-space reference distance with frequency weighting (CIF) path loss models are provided. The channel parameters such as the number of clusters, the ray and cluster arrival rates, and the ray and cluster decay factors are also obtained for both frequencies. The findings of the path loss show that the CI, FI, and CIF models fit the measured data well in both frequencies with the path loss exponent identical to the free-space path loss. Based on clustering results, it is found that the cluster decay rates are identical at both bands. The results from this and previous measurements indicate that at least one access point is required for every two sections of the stairway to support good coverage along the stairwell area in 5G wireless networks. Moreover, for 5G systems utilizing mm-Wave frequency bands, one access point for each stair section might be necessary for increased reliability of the 5G network in stairwell environments.
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Mohd Razali, Siti Harliza, Razali Ngah, Yoshihide Yamada, and Kamilia Kamardin. "Performance analysis of patch antenna for underwater wireless communication in seawater." Indonesian Journal of Electrical Engineering and Computer Science 22, no. 2 (May 1, 2021): 857. http://dx.doi.org/10.11591/ijeecs.v22.i2.pp857-865.
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<span lang="EN-US">Underwater wireless communication in seawater is becoming more interesting and challenging in recent years. The development of antenna for underwater wireless communication in seawater at 900 MHz UHF range frequency is implemented by using patch antenna. In this paper, the antennas were designed using FEKO, an electromagnetic simulation software, and a suitable size for rectangular patch antenna for seawater application was developed to study the relevance between λ0 with W and L in seawater. The difference between the patches in free space and seawater was the L size, which was slightly bigger, about 0.9 mm, than free space size. But the gain for patch antenna in seawater was found at -2.51 dBi, lower than patch antenna in free space, which was 5.76 dBi due to the path loss in seawater. This shows that attenuation happened, and a better antenna will be design. The one that has better gain, which is around above 2 dBi in seawater, in order to get better performance antenna in seawater environment.</span>
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Mohd Nordin, Muhammad Akramuddin, and Huda Adibah Mohd Ramli. "PERFORMANCE ANALYSIS OF 5G PATH LOSS MODELS FOR RURAL MACROCELL ENVIRONMENT." IIUM Engineering Journal 21, no. 1 (February 20, 2020): 85–99. http://dx.doi.org/10.31436/iiumej.v21i1.1247.
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5G networks are expected to use the Millimeter Wave (mmWave) frequency band and this frequency provides wider bandwidth allowing a better quality of service to be offered to the users. However, the mmWave frequencies may lead to a higher path loss due to several factors including blockages,rain and atmosphere. Therefore, to allow optimal positioning of the 5G base stations, the study of path loss model in this 5G mmWave frequencies is crucial. This paper investigates the 5G path loss models as well as their parameters that are most suitable for cross-polarized antennas under rural macrocell environment in Malaysia. Path loss models namely Close In Free Space Reference Distance Path Loss Model (CI) model, and Alpha Beta Gamma (ABG) or Floating Intercept (FI) Model along with their parameters achieved from the previous studies were evaluated by comparing the parameters and models that are closest to the sampled path loss when using antennas that have different patterns and polarizations in an open-source simulator. Results obtained indicate that FI model can be adapted to the majority of the environment where this model showed the lowest Root Mean Square Error (RMSE). The study of path loss models by using advanced simulator or field measurement, and studies on other rural areas from other states in Malaysia will be considered in future works.
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Subramanyam, A. V. G., D. Siva Reddy, V. K. Hariharan, V. V. Srinivasan, and Ajay Chakrabarty. "High Power Combline Filter for Deep Space Applications." International Journal of Microwave Science and Technology 2014 (September 14, 2014): 1–11. http://dx.doi.org/10.1155/2014/396494.
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An S-band, compact, high power filter, for use in the Mars Orbiter Mission (MOM) of Indian Space Research Organization (ISRO), has been designed and tested for multipaction. The telemetry, tracking, and commanding (TT&C) transponder of MOM is required to handle continuous RF power of 200 W in the telemetry path besides simultaneously maintaining an isolation of greater than 145 dBc to its sensitive telecommand path. This is accomplished with the help of a complex diplexer, requiring high power, high rejection transmit path filter, and a low power receive path filter. To reduce the complexity in the multipaction-free design and testing, the transmit path filter of the diplexer is split into a low rejection filter integral to the diplexer and an external high rejection filter. This paper highlights the design and space qualification phases of this high rejection filter. Multipaction test results with 6 dB margin are also presented. Major concerns of this filter design are isolation, insertion loss, and multipaction. Mission performance of the on-board filter is normal.
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Avella-Cely, Sandy Enrique, Juan Carlos Muñoz-Pérez, Herman Antonio Fernández-González, Lorenzo Rubio-Arjona, Juan Ribera Reig-Pascual, and Vicent Miguel Rodrigo-Peñarrocha. "Path Loss Characterization in an Indoor Laboratory Environment at 3.7 GHz in in Line-Of-Sight Condition." Revista Facultad de Ingeniería 29, no. 54 (October 31, 2020): e12015. http://dx.doi.org/10.19053/01211129.v29.n54.2020.12015.
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The objective of this work is to propose experimental path loss propagation models for communication channels in indoor environments. In this sense, an experimental path loss characterization has been achieved, according to the measurements campaign carried out in a typical scenario of a university campus. These narrowband measurements were collected in the laboratory environment at 3.7 GHz in line-of-sight (LOS) condition. Also, these measurements were carried out at night to simulate stationary channel conditions. Thus, the results obtained show the values of the parameters of the close-in (CI) free space reference distance and floating-intercept (FI) path loss models, in terms of the transmitter and receiver separation distance. It should be noted that these values of the path loss models have been extracted applying linear regression techniques to the measured data. Also, these values agree with the path loss exponent values presented by other researchers in similar scenarios. The path loss behavior can be described with the implementation of these models. However, more measurement campaigns are needed to improve the understanding of propagation channel features, as well as to obtain better precision in the results obtained. This, in order to optimize the deployment and performance of next fifth-generation (5G) networks that combine indoor environments to offer their services and applications.
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Kosz, Paweł. "An Empirical Propagation Model for Corridors in Office Buildings." International Journal of Electronics and Telecommunications 63, no. 1 (March 1, 2017): 5–10. http://dx.doi.org/10.1515/eletel-2017-0001.
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Abstract This paper presents an empirical propagation path loss model for corridors in office buildings. The proposed model estimates changeable character of radio signal attenuation, based on a special approach as a combination of the simple free-space model with the author’s model. The measurement stand and measurement scenario are described. The propagation path loss research have been made in corridor for different frequencies in range 30 MHz to 290 MHz. A significant number of measurement results were allowed an analysis of the radio wave propagation conditions in the environment. In general, the propagation path loss increases for each measurement frequencies with length of propagation route. Based on measurement data, the new empirical propagation path loss model was developed. For this purpose, the regression analysis was made. The novelty of this model is that it could be used for estimate propagation path loss in measured environment for different radio wave frequencies. At the end, in order to justification the practical usefulness of described method for estimate a radio wave attenuation, the statistical evaluation was made. Thus, the results of the statistical analysis (ME, SEE and R2 values) are satisfactory for each measured radio wave frequency.
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Ashigwuike, Evans Chinemezu, Ale Felix, and Farouq Eneuma Shaibu. "The Impact of Soil Texture on Path Loss Modelling of an FM Signal Using Diffraction Technique." European Journal of Engineering Research and Science 4, no. 4 (April 11, 2019): 56–63. http://dx.doi.org/10.24018/ejers.2019.4.4.1231.
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A novel solution to predict path loss of an FM signal using diffraction technique is proposed. Diffraction technique and soil texture impact are used to improve the Friis free-space model to predict the received signal strength and propagation path loss of an FM signal between a transmitter site and receiver site, while studying the impact of soil texture to the FM signal in the case of surface wave propagation. Measurement of signal strengths with an interval of 5KM along two different routes (1 and 2) were taken with a Digital Field Strength Meter (DW-400), in some selected open/rural environments of Kogi State. A solid-state transmitter (BE 20S), with broadcast frequency of 101.5MHz at antenna height of 120m was considered as the transmitting point source. Bluetooth signal strength meter software was used to visualize this impact of soil texture, where different types of soil were considered within the coverage area of the FM radio station, with the application of a Wireless Personal Area Network (WPAN) technology. Measurements taken along the two different routes were compared against predictions made by the modified model of Friis Free Space. The model showed quite large mean path loss prediction errors, and places with poor signal strength for Prime FM Radio Nigeria were revealed. The result shows that an FM signal induces current in the ground over which it passes and it is attenuated as a result of absorption of energy by the soil, depending on the soil type.
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Puri, Parul, Parul Garg, and Mona Aggarwal. "Analysis of spectrally efficient two-way relay assisted free space optical systems in atmospheric turbulence with path loss." International Journal of Communication Systems 29, no. 1 (May 6, 2014): 99–112. http://dx.doi.org/10.1002/dac.2801.
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Cama-Pinto, Alejandro, Gabriel Piñeres-Espitia, José Caicedo-Ortiz, Elkin Ramírez-Cerpa, Leonardo Betancur-Agudelo, and Francisco Gómez-Mula. "Received strength signal intensity performance analysis in wireless sensor network using Arduino platform and XBee wireless modules." International Journal of Distributed Sensor Networks 13, no. 7 (July 2017): 155014771772269. http://dx.doi.org/10.1177/1550147717722691.
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Today, through the monitoring of agronomic variables, the wireless sensor networks are playing an increasingly important role in precision agriculture. Among the emerging technologies used to develop prototypes related to wireless sensor network, we find the Arduino platform and XBee radio modules from the DIGI Company. In this article, based on field tests, we conducted a comparative analysis of received strength signal intensity levels, calculation of path loss with “log-normal shadowing” and free-space path loss models. In addition, we measure packet loss for different transmission, distances and environments with respect to an “Arduino Mega” board, and radio modules XBee PRO S1 and XBee Pro S2. The tests for the packet loss and received strength signal intensity level show the best performance for the XBee Pro S2 in the indoor, outdoor, and rural scenarios.
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Lakshmanan, Madan Kumar, and Homayoun Nikookar. "Mitigation of wideband interference on UWB-IR transmission using multi-carrier templates." International Journal of Microwave and Wireless Technologies 1, no. 1 (February 2009): 73–81. http://dx.doi.org/10.1017/s1759078709000129.
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Ultra wideband (UWB) wireless systems are highly susceptible to interference from other services. To reduce the effect of interference from co-existing sources such as the WLAN standard IEEE 802.11a on UWB Communication, the construction of a modified template waveform using multi-carrier sinusoids is proposed in Ohno and Ikegami (2003), Ohno et al. (2004), Ohno and Ikegami (2006), and Lakshmanan and Nikookar (2007). However, the work in Ohno and Ikegami (2003), Ohno et al. (2004), Ohno and Ikegami (2006), and Lakshmanan and Nikookar (2007) considers a free space propagation channel model with no treatment of the frequency dependence of the path loss. In this paper, we broaden the study by taking into consideration a frequency-dependent path loss environment. The novelty of the work is in the investigation of the effect of frequency dependency of the path loss on the performance of interference mitigation schemes.
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Yu, Junyi, Wei Chen, Kun Yang, Changzhen Li, Fang Li, and Yishui Shui. "Path Loss Channel Model for Inland River Radio Propagation at 1.4 GHz." International Journal of Antennas and Propagation 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/5853724.
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In this paper, a propagation path loss model for inland river is proposed by three improvements compared with the Round Earth Loss (REL) model for open-sea environment. Specifically, parameters optimization uses Okumura-Hata model in dB scale to replace the equation transformed from the free space loss in REL model; secondly, diffraction loss caused by the obstacles (e.g., large buildings, bridges, or some other facilities near the river bank) is also taken into account; mixed-path methodology as another improvement is used for Inland River (IR) model because the actual propagation environment between transmitter (TX) antenna and receiver (RX) antenna contains both land part and water part. The paper presents a set of 1.4 GHz measurements conducted along the Yangtze River in Wuhan. According to the comparison between path loss models and experimental results, IR model shows a good matching degree. After that, Root Mean Square Error (RMSE), Grey Relation Grade and Mean Absolute Percentage Error (GRG-MAPE), Pearson Correlation Coefficient, and Mean Absolute Percentage Error (PCC-MAPE) are employed to implement quantitative analysis. The results prove that IR model with consideration of mixed path and deterministic information is more accurate than other classic empirical propagation models for these scenarios.
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Cama-Pinto, Dora, Miguel Damas, Juan Antonio Holgado-Terriza, Francisco Gómez-Mula, and Alejandro Cama-Pinto. "Path Loss Determination Using Linear and Cubic Regression Inside a Classic Tomato Greenhouse." International Journal of Environmental Research and Public Health 16, no. 10 (May 17, 2019): 1744. http://dx.doi.org/10.3390/ijerph16101744.
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The production of tomatoes in greenhouses, in addition to its relevance in nutrition and health, is an activity of the agroindustry with high economic importance in Spain, the first exporter in Europe of this vegetable. The technological updating with precision agriculture, implemented in order to ensure adequate production, leads to a deployment planning of wireless sensors with limited coverage by the attenuation of radio waves in the presence of vegetation. The well-known propagation models FSPL (Free-Space Path Loss), two-ray, COST235, Weissberger, ITU-R (International Telecommunications Union—Radiocommunication Sector), FITU-R (Fitted ITU-R), offer values with an error percentage higher than 30% in the 2.4 GHz band in relation to those measured in field tests. As a substantial improvement, we have developed optimized propagation models, with an error estimate of less than 9% in the worst-case scenario for the later benefit of farmers, consumers and the economic chain in the production of tomatoes.
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Sreedevi, A. G., T. Rama Rao, and M. Susila. "Device-to-Device Radio Link Analysis at 2.4, 3.4, 5.2, 28 and 60 GHz in Indoor Communication Environments." Frequenz 73, no. 3-4 (February 25, 2019): 131–41. http://dx.doi.org/10.1515/freq-2018-0158.
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Abstract Device-to-device (D2D) communication has become one of the major areas of research ever since the industry was advancing to LTE and 5G. In this nascent stage of transformation, this research work characterizes the radio link behavior of D2D communication network in an indoor environment utilizing licensed and unlicensed band experiments and ray-tracing based simulations at frequencies of 2.4, 3.4, 5.2, 28 and 60 GHz. The path loss exponent (PLE) and standard deviation are estimated and compared with free space path loss (FSPL), log normal shadowing (LNS), International Telecommunication Union (ITU) model and also, compared with other research works. This work also studied the impact of indoor environments on D2D communications along with link budget, channel capacities and required performance improvements.
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Al-Samman, Ahmed Mohammed, Tharek Abd. Rahman, Tawfik Al-Hadhrami, Abdusalama Daho, MHD Nour Hindia, Marwan Hadri Azmi, Kaharudin Dimyati, and Mamoun Alazab. "Comparative Study of Indoor Propagation Model Below and Above 6 GHz for 5G Wireless Networks." Electronics 8, no. 1 (January 1, 2019): 44. http://dx.doi.org/10.3390/electronics8010044.
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It has been widely speculated that the performance of the next generation based wireless network should meet a transmission speed on the order of 1000 times more than the current cellular communication systems. The frequency bands above 6 GHz have received significant attention lately as a prospective band for next generation 5G systems. The propagation characteristics for 5G networks need to be fully understood for the 5G system design. This paper presents the channel propagation characteristics for a 5G system in line of sight (LOS) and non-LOS (NLOS) scenarios. The diffraction loss (DL) and frequency drop (FD) are investigated based on collected measurement data. Indoor measurement results obtained using a high-resolution channel sounder equipped with directional horn antennas at 3.5 GHz and 28 GHz as a comparative study of the two bands below and above 6 GHz. The parameters for path loss using different path loss models of single and multi-frequencies have been estimated. The excess delay, root mean square (RMS) delay spread and the power delay profile of received paths are analyzed. The results of the path loss models show that the path loss exponent (PLE) in this indoor environment is less than the free space path loss exponent for LOS scenario at both frequencies. Moreover, the PLE is not frequency dependent. The 3GPP path loss models for single and multi-frequency in LOS scenarios have good performance in terms of PLE that is as reliable as the physically-based models. Based on the proposed models, the diffraction loss at 28 GHz is approximately twice the diffraction loss at 3.5 GHz. The findings of the power delay profile and RMS delay spread indicate that these parameters are comparable for frequency bands below and above 6 GHz.
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Sabri, N., Mohammed S. S, Sarah Fouad, Syed A. A, Fahad Taha AL-Dhief, and Auda Raheemah. "Investigation of Empirical Wave Propagation Models in Precision Agriculture." MATEC Web of Conferences 150 (2018): 06020. http://dx.doi.org/10.1051/matecconf/201815006020.
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Wireless Sensor Networks have highly proved its contribution in precision agriculture. Communication channel modelling investigation is a highly demanded to achieve a successful communication system where a good wave propagation model is crucially needed. Precision agriculture degrades the traveling waves in various forms in addition to the effects of the large-scale path losses models. This paper reviews the most known theoretical large-scale path losses models such as free space (FSPL) and Plane earth (PE) models as well as the vegetation models represented by Weissberger, ITU-R, FITU-R and COS235 models. Indeed, this work illustrates the effects of many factors on the total path losses such as separation distance between transceivers, antenna heights and the depth of vegetation that presence in the path propagation. In conclusion, the total path loss is computed based on large-scale path losses and the vegetation losses in protected vegetation environment.
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Gao, Zhenran, Weijing Li, Yan Zhu, Yongchao Tian, Fangrong Pang, Weixing Cao, and Jun Ni. "Wireless Channel Propagation Characteristics and Modeling Research in Rice Field Sensor Networks." Sensors 18, no. 9 (September 15, 2018): 3116. http://dx.doi.org/10.3390/s18093116.
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Wireless channel propagation characteristics and models are important to ensure the communication quality of wireless sensor networks in agriculture. Wireless channel attenuation experiments were carried out at different node antenna heights (0.8 m, 1.2 m, 1.6 m, and 2.0 m) in the tillering, jointing, and grain filling stages of rice fields. We studied the path loss variation trends at different transmission distances and analyzed the differences between estimated values and measured values of path loss in a free space model and a two-ray model. Regression analysis of measured path loss values was used to establish a one-slope log-distance model and propose a modified two-slope log-distance model. The attenuation speed in wireless channel propagation in rice fields intensified with rice developmental stage and the transmission range had monotone increases with changes in antenna height. The relative error (RE) of estimation in the free space model and the two-ray model under four heights ranged from 6.48–15.49% and 2.09–13.51%, respectively, and these two models were inadequate for estimating wireless channel path loss in rice fields. The ranges of estimated RE for the one-slope and modified two-slope log-distance models during the three rice developmental stages were 2.40–2.25% and 1.89–1.31%, respectively. The one-slope and modified two-slope log-distance model had better applicability for modeling of wireless channels in rice fields. The estimated RE values for the modified two-slope log-distance model were all less than 2%, which improved the performance of the one-slope log-distance model. This validates that the modified two-slope log-distance model had better applicability in a rice field environment than the other models. These data provide a basis for modeling of sensor network channels and construction of wireless sensor networks in rice fields. Our results will aid in the design of effective rice field WSNs and increase the transmission quality in rice field sensor networks.
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Rubio, Lorenzo, Rafael P. Torres, Vicent M. Rodrigo Peñarrocha, Jesús R. Pérez, Herman Fernández, Jose-Maria Molina-Garcia-Pardo, and Juan Reig. "Contribution to the Channel Path Loss and Time-Dispersion Characterization in an Office Environment at 26 GHz." Electronics 8, no. 11 (November 1, 2019): 1261. http://dx.doi.org/10.3390/electronics8111261.
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In this paper, path loss and time-dispersion results of the propagation channel in a typical office environment are reported. The results were derived from a channel measurement campaign carried out at 26 GHz in line-of-sight (LOS) and obstructed-LOS (OLOS) conditions. The parameters of both the floating-intercept (FI) and close-in (CI) free space reference distance path loss models were derived using the minimum-mean-squared-error (MMSE). The time-dispersion characteristics of the propagation channel were analyzed through the root-mean-squared (rms) delay-spread and the coherence bandwidth. The results reported here provide better knowledge of the propagation channel features and can be also used to design and evaluate the performance of the next fifth-generation (5G) networks in indoor office environments at the potential 26 GHz frequency band.
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Al-Saman, Ahmed, Marshed Mohamed, Michael Cheffena, and Arild Moldsvor. "Wideband Channel Characterization for 6G Networks in Industrial Environments." Sensors 21, no. 6 (March 12, 2021): 2015. http://dx.doi.org/10.3390/s21062015.
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Wireless data traffic has increased significantly due to the rapid growth of smart terminals and evolving real-time technologies. With the dramatic growth of data traffic, the existing cellular networks including Fifth-Generation (5G) networks cannot fully meet the increasingly rising data rate requirements. The Sixth-Generation (6G) mobile network is expected to achieve the high data rate requirements of new transmission technologies and spectrum. This paper presents the radio channel measurements to study the channel characteristics of 6G networks in the 107–109 GHz band in three different industrial environments. The path loss, K-factor, and time dispersion parameters are investigated. Two popular path loss models for indoor environments, the close-in free space reference distance (CI) and floating intercept (FI), are used to examine the path loss. The mean excess delay (MED) and root mean squared delay spread (RMSDS) are used to investigate the time dispersion of the channel. The path loss results show that the CI and FI models fit the measured data well in all industrial settings with a path loss exponent (PLE) of 1.6–2. The results of the K-factor show that the high value in industrial environments at the sub-6 GHz band still holds well in our measured environments at a high frequency band above 100 GHz. For the time dispersion parameters, it is found that most of the received signal energy falls in the early delay bins. This work represents a first step to establish the feasibility of using 6G networks operating above 100 GHz for industrial applications.
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B. Majed, Mohammed, Tharek A. Rahman, and Omar Abdul Aziz. "Propagation Path Loss Modeling and Outdoor Coverage Measurements Review in Millimeter Wave Bands for 5G Cellular Communications." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 4 (August 1, 2018): 2254. http://dx.doi.org/10.11591/ijece.v8i4.pp2254-2260.
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The global bandwidth inadequacy facing wireless carriers has motivated the exploration of the underutilized millimeter wave (mm-wave) frequency spectrum for future broadband cellular communication networks, and mmWave band is one of the promising candidates due to wide spectrum. This paper presents propagation path loss and outdoor coverage and link budget measurements for frequencies above 6 GHz (mm-wave bands) using directional horn antennas at the transmitter and omnidirectional antennas at the receiver. This work presents measurements showing the propagation time delay spread and path loss as a function of separation distance for different frequencies and antenna pointing angles for many types of real-world environments. The data presented here show that at 28 GHz, 38 GHz and 60 GHz, unobstructed Line of Site (LOS) channels obey free space propagation path loss while non-LOS (NLOS) channels have large multipath delay spreads and can utilize many different pointing angles to provide propagation links. At 60 GHz, there is more path loss and smaller delay spreads. Power delay profiles PDPs were measured at every individual pointing angle for each TX and RX location, and integrating each of the PDPs to obtain received power as a function of pointing angle. The result shows that the mean RMS delay spread varies between 7.2 ns and 74.4 ns for 60 GHz and 28 GHz respectively in NLOS scenario.
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Dayal, Navneet, Preeti Singh, and Pardeep Kaur. "Relay-assisted WDM-FSO System: A Better Solution for Communication under Rain and Haze Weather Conditions." Journal of Telecommunications and Information Technology 4 (December 20, 2017): 54–59. http://dx.doi.org/10.26636/jtit.2017.113917.
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Among various conventional wireless communication systems, Free Space Optics (FSO) may be distinguished as well, which provides a good level security, high data rates, an enormous bandwidth and negligible susceptibility to electromagnetic interference. The main problem arises with unfavorable weather conditions, which affect the system’s parameters and require an aversion to other paths. The weather conditions discussed are rain and haze. Elimination of their adverse effects is essential for establishing a better communication system. The routing path is a major issue, as its decreased parameters lead to the diversion of the transmitted signal or to its total loss. In this article, increased system path length and proficiency levels are demonstrated by using relays, which are assisted by Wavelength Division Multiplexing (WDM).
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Liccardo, Annalisa, Andrea Mariscotti, Attilio Marrese, Nicola Pasquino, and Rosario Schiano Lo Moriello. "Statistical characterization of the 2.45 GHz propagation channel aboard trains." ACTA IMEKO 4, no. 1 (February 5, 2015): 44. http://dx.doi.org/10.21014/acta_imeko.v4i1.162.
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<p class="Abstract"><span lang="EN-US">The propagation channel aboard trains is investigated with reference to the propagation path loss within cars, the delay spread and the coherence bandwidth. Results show that the path loss exponent is slightly smaller than in free space, possibly due to reflections by metal walls, and that it does not depend significantly on the position of transmitter and receiver. The delay spread and coherence bandwidth depend on both the polarization and distance between transmitter and receiver while the effect of interaction is not statistically significant. The best fit for both delay spread’s and coherence bandwidth’s experimental distribution is also investigated. Results show that it does not always match models suggested in the literature and that the fit changes with the values of the input parameters. Finally, the functional law between coherence bandwidth and delay spread is determined. Results typically match expectations although the specific measurement configuration effects the model parameters.</span></p>
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Li, Shuang-de, Yuan-jian Liu, Le-ke Lin, Zhong Sheng, Xiang-chen Sun, Zhi-peng Chen, and Xiao-jun Zhang. "Channel Measurements and Modeling at 6 GHz in the Tunnel Environments for 5G Wireless Systems." International Journal of Antennas and Propagation 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/1513038.
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Propagation measurements of wireless channels performed in the tunnel environments at 6 GHz are presented in this paper. Propagation characteristics are simulated and analyzed based on the method of shooting and bouncing ray tracing/image (SBR/IM). A good agreement is achieved between the measured results and simulated results, so the correctness of SBR/IM method has been validated. The measured results and simulated results are analyzed in terms of path loss models, received power, root mean square (RMS) delay spread, Ricean K-factor, and angle of arrival (AOA). The omnidirectional path loss models are characterized based on close-in (CI) free-space reference distance model and the alpha-beta-gamma (ABG) model. Path loss exponents (PLEs) are 1.50–1.74 in line-of-sight (LOS) scenarios and 2.18–2.20 in non-line-of-sight (NLOS) scenarios. Results show that CI model with the reference distance of 1 m provides more accuracy and stability in tunnel scenarios. The RMS delay spread values vary between 2.77 ns and 18.76 ns. Specially, the Poisson distribution best fits the measured data of RMS delay spreads for LOS scenarios and the Gaussian distribution best fits the measured data of RMS delay spreads for NLOS scenarios. Moreover, the normal distribution provides good fits to the Ricean K-factor. The analysis of the abovementioned results from channel measurements and simulations may be utilized for the design of wireless communications of future 5G radio systems at 6 GHz.
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Khanna, Himanshu, Mona Aggarwal, and Swaran Ahuja. "On the End-to-End Performance of a Mixed RF-FSO link with a Decode-and-Forward Relay." Journal of Optical Communications 40, no. 3 (July 26, 2019): 323–32. http://dx.doi.org/10.1515/joc-2017-0077.
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Abstract In this paper, we investigate the performance of a decode-and-forward relayed mixed radio frequency-free space optical (RF-FSO) dual-hop link. The transmitter to receiver link’s first-hop is a RF channel and the second-hop is a FSO channel. The RF link experiences long-term shadowing and short-term multi-path fading effects, while the FSO channel suffers atmospheric turbulence fading, path loss, and pointing error-induced misalignment fading. The performance of the system is analyzed considering the impact of these parameters. We model the RF link by generalized-K fading distribution and the atmospheric turbulence over the FSO link by the gamma–gamma fading. The expressions in closed form for the outage probability, symbol error rate for the system employing $q$-ary PSK modulation schemes, and the channel capacity of the system are derived. The obtained numerical results are also depicted by numerical plots.
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Khanna, Himanshu, Mona Aggarwal, and Swaran Ahuja. "Performance Analysis of an Inter-Relay Co-operation in FSO Communication System." Journal of Optical Communications 39, no. 2 (April 25, 2018): 199–208. http://dx.doi.org/10.1515/joc-2016-0115.
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AbstractIn this work, we analyze the outage and error performance of a one-way inter-relay assisted free space optical link. The assumption of the absence of direct link between the source and destination node is being made for the analysis, and the feasibility of such system configuration is studied. We consider the influence of path loss, atmospheric turbulence and pointing error impairments, and investigate the effect of these parameters on the system performance. The turbulence-induced fading is modeled by independent but not necessarily identically distributed gamma–gamma fading statistics. The closed-form expressions for outage probability and probability of error are derived and illustrated by numerical plots. It is concluded that the absence of line of sight path between source and destination nodes does not lead to significant performance degradation. Moreover, for the system model under consideration, interconnected relaying provides better error performance than the non-interconnected relaying and dual-hop serial relaying techniques.
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Dou, Jianwu, Nan Zhang, Li Tian, Xiaoyi Yang, Xi Yuan, Suping Mei, and Haiming Wang. "Propagation Channel Comparison between 23.5 and 45 GHz in Conference Scenario." Chinese Journal of Engineering 2016 (March 15, 2016): 1–9. http://dx.doi.org/10.1155/2016/7124267.
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The characteristics of propagation channel at 23.5 and 45 GHz in an indoor conference room are studied based on hybrid approach. A ray-based simulator which includes the reflection, penetration, diffraction, and diffuse scattering is adopted to generate the massive channel realizations. This platform is well calibrated in path and power delay profile (PDP) levels according to some specified measurements at different frequencies. Subsequently, according to the simulated channel samples, the statistical channel model for both the large and small scale characteristics is established based on the alpha-beta approach and extended Saleh-Valenzuela (S-V) structure, respectively. Results show that the slope of fitted path loss (PL) is less than free space due to the waveguide effect for both 23.5 and 45 GHz in indoor scenario and larger PL is experienced at higher frequency. Additionally, the cluster is more centralized with less spreads and decaying faster in delay domain at 45 GHz.
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Al azzawi, Fatima Faydhe. "LTE RF receiver modeling and each part testing with MATLAB simulink." Indonesian Journal of Electrical Engineering and Computer Science 14, no. 3 (June 1, 2019): 1251. http://dx.doi.org/10.11591/ijeecs.v14.i3.pp1251-1257.
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fourth generation cellular network based on Long Term Evaluation (LTE) air interface. LTE is specifically designed for packet data communications, where the emphasis of the technologies high spectral efficiency, high peak data rates, low latency, and frequency flexibility. In this paper a LTE physical layer design and implemented using MATLAB codes and Simulink, where MATLAB codes generate the 64 QAM transmitting signal and simulating LTE frames while Simulink model perform the physical layer which including the band limiting, free space path loss adding, channel, RF receiver, demodulation, 10-bit ADC, DC offset cancellation, saving data to preform EVM measurements, and viewing the spectrum signal after each block, finally QAM with multi –order tested under AWGN.
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Lopez-Iturri, Peio, Erik Aguirre, Mikel Celaya-Echarri, Leyre Azpilicueta, Alejandro Eguizábal, Francisco Falcone, and Ana Alejos. "Radio Channel Characterization in Dense Forest Environments for IoT-5G." Proceedings 4, no. 1 (November 14, 2018): 19. http://dx.doi.org/10.3390/ecsa-5-05731.
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The attenuation due to vegetation can limit drastically the performance of Wireless Sensor Networks (WSN) and the Internet of Things (IoT) communication systems. Even more for the envisaged high data rates expected for the upcoming 5G mobile wireless communications. In this context, radio planning tasks become necessary in order to assess the validity of future WSN and IoT systems operating in vegetation environments. For that purpose, path loss models for scenarios with vegetation play a key role since they provide RF power estimations that allow an optimized design and performance of the wireless network. Although different propagation models for vegetation obstacles can be found in the literature, a model combining path loss and multipath propagation is rarely considered. In this contribution, we present the characterization of the radio channel for IoT and 5G systems working at 2.4 GHz, focusing on the radio links blocked by oak and pine trees modelled from specimens found in a real recreation area located within a dense forest environment. This specific forest, composed of thick in-leaf trees, is called Orgi Forest and it is situated in Navarre, Spain. In order to fit and validate a radio channel model for this type of scenarios, both measurements and simulations by means of an in-house developed 3D Ray Launching algorithm have been performed, offers as outcomes the path loss and multipath information of the scenario under study. A geometrical and dielectric model of the trees were created and introduced in the simulation software. The path loss was then estimated as dependent of the radio link range for two species of trees at 2.4 GHz. We concluded that the scattering produced by the tree can be divided into two zones with different dominant propagation mechanisms: a free-space zone far from the tree and a diffraction zone around the edge of the tree. 2D planes of delay spread value are also presented which similarly reflects the proposed two-zone model.
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Zheng, Yi, and Yu Wen Wang. "Hardware in the Loop Simulation for Low-Altitude UAV Link in the Complex Terrain." Applied Mechanics and Materials 336-338 (July 2013): 1907–12. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.1907.
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In order to investigate the influence of complex terrain on the quality of the unmanned aerial vehicle (UAV) communication link and simulate it accurately, the HITL simulation platform of the UAV-ground link, which was based on EXata software and Hardware-in-the-loop (HITL) module, was built. In the virtual terrain scenarios, the Free-space loss model and the Irregular Terrain Model (ITM) were used to modeling and conduct the semi-physical simulation experiments, respectively. Then, a new method of the HITL simulation for the wireless communication link was put forward, which achieved the real-time video stream interaction with the virtual networks. The simulation results showed the real-time changes of path loss in the complex terrain and the specific affection on the UAV-ground link communication quality from numerical and video transmission effect. The method enhanced the accuracy and rationality of the UAV-ground link simulation.
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Al-Samman, Ahmed M., Marwan Hadri Azmi, Y. A. Al-Gumaei, Tawfik Al-Hadhrami, Tharek Abd. Rahman, Yousef Fazea, and Abdulmajid Al-Mqdashi. "Millimeter Wave Propagation Measurements and Characteristics for 5G System." Applied Sciences 10, no. 1 (January 2, 2020): 335. http://dx.doi.org/10.3390/app10010335.
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In future 5G systems, the millimeter wave (mmWave) band will be used to support a large capacity for current mobile broadband. Therefore, the radio access technology (RAT) should be made available for 5G devices to help in distinct situations, for example device-to-device communications (D2D) and multi-hops. This paper presents ultra-wideband channel measurements for millimeter wave bands at 19, 28, and 38 GHz. We used an ultra-wideband channel sounder (1 GHz bandwidth) in an indoor to outdoor (I2O) environment for non-line-of-sight (NLOS) scenarios. In an NLOS environment, there is no direct path (line of sight), and all of the contributed paths are received from different physical objects by refection propagation phenomena. Hence, in this work, a directional horn antenna (high gain) was used at the transmitter, while an omnidirectional antenna was used at the receiver to collect the radio signals from all directions. The path loss and temporal dispersion were examined based on the acquired measurement data—the 5G propagation characteristics. Two different path loss models were used, namely close-in (CI) free space reference distance and alpha-beta-gamma (ABG) models. The time dispersion parameters were provided based on a mean excess delay, a root mean square (RMS) delay spread, and a maximum excess delay. The path loss exponent for this NLOS specific environment was found to be low for all of the proposed frequencies, and the RMS delay spread values were less than 30 ns for all of the measured frequencies, and the average RMS delay spread values were 19.2, 19.3, and 20.3 ns for 19, 28, and 38 GHz frequencies, respectively. Moreover, the mean excess delay values were found also at 26.1, 25.8, and 27.3 ns for 19, 28, and 38 GHz frequencies, respectively. The propagation signal through the NLOS channel at 19, 28, and 38 GHz was strong with a low delay; it is concluded that these bands are reliable for 5G systems in short-range applications.
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Adnan, Farasatul, Valon Blakaj, Sendy Phang, Thomas M. Antonsen, Stephen C. Creagh, Gabriele Gradoni, and Gregor Tanner. "Wireless power distributions in multi-cavity systems at high frequencies." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, no. 2245 (January 2021): 20200228. http://dx.doi.org/10.1098/rspa.2020.0228.
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The next generations of wireless networks will work in frequency bands ranging from sub-6 GHz up to 100 GHz. Radio signal propagation differs here in several critical aspects from the behaviour in the microwave frequencies currently used. With wavelengths in the millimetre range (mmWave), both penetration loss and free-space path loss increase, while specular reflection will dominate over diffraction as an important propagation channel. Thus, current channel model protocols used for the generation of mobile networks and based on statistical parameter distributions obtained from measurements become insufficient due to the lack of deterministic information about the surroundings of the base station and the receiver-devices. These challenges call for new modelling tools for channel modelling which work in the short-wavelength/high-frequency limit and incorporate site-specific details—both indoors and outdoors. Typical high-frequency tools used in this context—besides purely statistical approaches—are based on ray-tracing techniques. Ray-tracing can become challenging when multiple reflections dominate. In this context, mesh-based energy flow methods have become popular in recent years. In this study, we compare the two approaches both in terms of accuracy and efficiency and benchmark them against traditional power balance methods.
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Sun, Y. Y., S. W. Cheung, and T. I. Yuk. "Planar Monopoles with Different Radiator Shapes for UWB Body-Centric Wireless Communications." Journal of Engineering 2013 (2013): 1–13. http://dx.doi.org/10.1155/2013/683428.
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This paper presents a study on the performances of a group of planar monopoles using radiators of different shapes, such as triangle, rectangle, square, annual ring, circle, horizontal ellipse, vertical ellipse, pentagon, and hexagon, for ultra-wideband (UWB) body-centric wireless communications. The planar monopoles have the radiators with microstrip-fed line printed on one side of the substrate and a ground plane on the other side. Simulation studies show that, among these monopoles, the horizontal elliptical, vertical elliptical, and hexagonal monopoles have better overall performances in terms of bandwidth, gain, efficiency, and radiation pattern in free space. A solid-body phantom mimicking human tissue is used for studies of these three monopoles for body-centric communications. Simulated and measured results of these monopoles on the phantom show that the horizontal elliptical monopole achieves the widest impedance bandwidths, highest average peak gain and efficiency, least path loss, best fidelity, and good radiation pattern, making it a good candidate for UWB body-centric wireless communications.
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Janssen, Thomas, Noori BniLam, Michiel Aernouts, Rafael Berkvens, and Maarten Weyn. "LoRa 2.4 GHz Communication Link and Range." Sensors 20, no. 16 (August 5, 2020): 4366. http://dx.doi.org/10.3390/s20164366.
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Recently, Semtech has released a Long Range (LoRa) chipset which operates at the globally available 2.4 GHz frequency band, on top of the existing sub-GHz, km-range offer, enabling hardware manufacturers to design region-independent chipsets. The SX1280 LoRa module promises an ultra-long communication range while withstanding heavy interference in this widely used band. In this paper, we first provide a mathematical description of the physical layer of LoRa in the 2.4 GHz band. Secondly, we investigate the maximum communication range of this technology in three different scenarios. Free space, indoor and urban path loss models are used to simulate the propagation of the 2.4 GHz LoRa modulated signal at different spreading factors and bandwidths. Additionally, we investigate the corresponding data rates. The results show a maximum range of 133 km in free space, 74 m in an indoor office-like environment and 443 m in an outdoor urban context. While a maximum data rate of 253.91 kbit/s can be achieved, the data rate at the longest possible range in every scenario equals 0.595 kbit/s. Due to the configurable bandwidth and lower data rates, LoRa outperforms other technologies in the 2.4 GHz band in terms of communication range. In addition, both communication and localization applications deployed in private LoRa networks can benefit from the increased bandwidth and localization accuracy of this system when compared to public sub-GHz networks.
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Qasem, Nidal. "Enhancing the Capacity of the Indoor 60 GHz Band Via Modified Indoor Environments Using Ring Frequency Selective Surface Wallpapers and Path Loss Models." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 5 (October 1, 2018): 3003. http://dx.doi.org/10.11591/ijece.v8i5.pp3003-3020.
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<span>The 60 GHz band has been selected for short-range communication systems to meet consumers’ needs for high data rates. However, this frequency is attenuated by obstacles. This study addresses the limitations of the 60 GHz band by modifying indoor environments with ring Frequency Selective Surfaces (FSSs) wallpaper, thereby increasing its utilization. The ring FSS wallpaper response at a 61.5 GHz frequency has been analyzed using both MATLAB and Computer Simulation Technology (CST) Microwave Studio (MWS) software. ‘Wireless InSite’ is also used to demonstrate enhanced wave propagation in a building modified with ring FSSs wallpaper. The demonstration is applied to Single Input Single Output (SISO) and Multiple Input Multiple Output (MIMO) systems to verify the effectiveness of FSSs on such systems’ capacity. The effectiveness of the suggested modification over delay spread has been studied for the MIMO scenario, as well as the effect of the human body on capacity. Simulation results presented here show that modifying a building using ring FSS wallpaper is an attractive scheme for significantly improving the indoor 60 GHz wireless communications band. This paper also presents and compares two large-scale indoor propagation Path Loss Models (PLMs), the Close-In (CI) free space reference distance model and the Floating Intercept (FI) model. Data obtained from ‘Wireless InSite’ over distances ranging from 4 to 14.31 m is analyzed. Results show that the CI model provides good estimation and exhibits stable behavior over frequencies and distances, with a solid physical basis and less computational complexity when compared to the FI model. </span>
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Sultana, Maliha, Agnila Barua, Jobaida Akhtar, and Mohammad Istiaque Reja. "Performance Investigation of OFDM-FSO System under Diverse Weather Conditions of Bangladesh." International Journal of Electrical and Computer Engineering (IJECE) 8, no. 5 (October 1, 2018): 3722. http://dx.doi.org/10.11591/ijece.v8i5.pp3722-3731.
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Free space optical (FSO) communication systems which are deployed for last mile access, being considered as a suitable alternative technology for optical fiber networks. It is one of the emerging technologies for broadband wireless connectivity which has also been receiving growing attention due to high data rate transmission capability with low installation cost and license free spectrum. However, the widespread use of FSO technology has been hampered by the randomly time varying characteristics of propagation path mainly due to atmospheric turbulence, sensitivity to diverse weather conditions and the nonlinear responsivity of laser diode. This paper presents the performance investigation of an OFDM-FSO system over atmospheric turbulence channels under diverse weather conditions of Bangladesh. The channel is modeled with gamma-gamma distribution using 16-QAM modulation format and 4×4 multiple transceiver FSO system. All possible challenges are imposed on the system performance such as atmospheric attenuation, turbulence, pointing error, geometric loss etc. The refractive index structure parameter and atmospheric attenuation coefficient for different weather conditions are calculated by using the data, collected from Bangladesh Meteorological Department. The acquired results can be fruitful for scheming, forecasting and assessing the OFDM-FSO system’s ability to transmit wireless services over turbulent FSO links under actual conditions of Bangladesh.
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Lambrechts, Johannes W., and Saurabh Sinha. "Estimation of signal attenuation in the 60 GHZ band with an analog BiCMOS passive filter." International Journal of Microwave and Wireless Technologies 7, no. 6 (July 17, 2014): 645–53. http://dx.doi.org/10.1017/s1759078714000956.
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Prediction of millimeter(mm)-wave radio signals can be beneficial in recreating and repeating atmospheric conditions in a controlled, laboratory environment. A path-loss model has been proposed that accounts for free-space losses, oxygen absorption, reflection and diffraction losses, and rain-rate attenuation at mm-wave frequencies. Two variable passive low-pass-integrated circuit filter structures for attenuation in the 57–64 GHz unlicensed frequency band have been proposed, designed, simulated, prototyped in a 130-nm SiGe bipolar complementary metal-oxide semiconductor process, and measured. The filters are based on the Butterworth and Chebyshev low-pass filter topologies and investigate the possibility of using the structures to perform amplitude attenuation of mm-wave frequencies over a short distance. Both filters are designed and matched for direct coupling with equivalent circuit models of dipole antennas operating in this frequency band. Full integration therefore allows prediction of atmospheric losses on an analog, real-time, basis without the requirement of down-converting (sampling) to analyze high-frequency signals through a digital architecture. On-wafer probe measurements were performed to limit parasitic interference from bonding wires and enclosed packaging.
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Periola, A. A., and E. Obayiuwana. "Intelligent learning diversity mechanism for unmanned aerial vehicles applications." Nigerian Journal of Technology 39, no. 2 (July 16, 2020): 514–27. http://dx.doi.org/10.4314/njt.v39i2.22.
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The increased use of drones and aerial vehicles in applications poses challenges of airspace safety for aviation organizations. It is important to ensure the safety of the airspace when a significant number of unmanned aerial vehicles are deployed by civilian users. A solution that meets this requirement is important to promote innovation in the commercialization of air space for civilian users deploying unmanned aerial vehicle. The discussion in this paper proposes a mechanism that uses artificial intelligence to address this challenge. The proposed mechanism utilizes a low altitude platform (LAP) and entities in terrestrial wireless networks. The low altitude platform (LAP) observes, develops insights and training data (with human aid). The training data is used to develop learning mechanisms which determine the suitable unmanned aerial vehicles flight parameters in different scenarios. The use of the LAP reduces the burden of communicating with terrestrial base stations. The unmanned aerial vehicles have a reduced altitude between the LAPs in comparison to terrestrial base stations. This reduces the free space path loss and rain-induced attenuation. The performance benefit of the proposed mechanism in comparison to existing solution is examined via MATLAB simulations. Evaluation shows that the proposed mechanism reduces the network access costs by up to 90% on average. The proposed mechanism also increases available flight power and improves airspace safety by 37.3% and up to 53.2% on average respectively.
Keywords: Autonomous unmanned aerial vehicles, Intelligence Paradigm; Aviation Safety, Capital Constrained Aviation Organizations.
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Pérez Santacruz, Javier, Simon Rommel, Ulf Johannsen, Antonio Jurado-Navas, and Idelfonso Tafur Monroy. "Candidate Waveforms for ARoF in Beyond 5G." Applied Sciences 10, no. 11 (June 4, 2020): 3891. http://dx.doi.org/10.3390/app10113891.
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5G mobile networks aim to support a large variety of services with different and demanding requirements. To achieve this, analog radio over fiber (ARoF) fronthaul along with millimeter-wave (mmWave) cells is a strong candidate to be part of the 5G architecture. Very high throughput can be achieved by using mmWave signals due to the large available bandwidths, which combines well with the advantages of employing ARoF technology. Nevertheless, combined mmWave and ARoF systems face a particular challenge as the impacts of both channels—such as high free-space path loss, phase noise, chromatic dispersion, and other degrading effects—affect the signal without the possibility for intermediate restoration. The selection of the signal waveforms plays an important role in reducing these defects. In addition, waveforms are one of the keys in the physical layer available towards satisfying the requirements for 5G and beyond. In this manuscript, several key requirements are presented to determine the merit of candidate waveform formats to fulfill the 5G requirements in the mmWave ARoF architecture. An overview of the different suitable waveforms for this architecture is provided, discussing their advantages and disadvantages. Moreover, a comprehensive comparison in terms of different requirements is also presented in this paper.
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Biswas, Rajorshi, and Jie Wu. "Minimizing The Number of Channel Switches of Mobile Users in Cognitive Radio Ad-Hoc Networks." Journal of Sensor and Actuator Networks 9, no. 2 (May 5, 2020): 23. http://dx.doi.org/10.3390/jsan9020023.
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Cognitive radio (CR) technology is envisioned to use wireless spectrum opportunistically when the primary user (PU) is not using it. In cognitive radio ad-hoc networks (CRAHNs), the mobile users form a distributed multi-hop network using the unused spectrum. The qualities of the channels are different in different locations. When a user moves from one place to another, it needs to switch the channel to maintain the quality-of-service (QoS) required by different applications. The QoS of a channel depends on the amount of usage. A user can select the channels that meet the QoS requirement during its movement. In this paper, we study the mobility patterns of users, predict their next locations and probabilities to move there based on its history. We extract the mobility patterns from each user’s location history and match the recent trajectory with the patterns to find future locations. We construct a spectrum database using Wi-Fi access point location data and the free space path loss formula. We propose a machine learning-based mechanism to predict spectrum status of some missing locations in the spectrum database. We formulate a problem to select the current channel in order to minimize the total number of channel switches during a certain number of next moves of a user. We conduct an extensive simulation combining real and synthetic datasets to support our model.
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Schäfer, Sassan, Simon Müller, Daniel Schmiech, and Andreas R. Diewald. "Radar system with dedicated planar traveling wave antennas for elderly people monitoring." Advances in Radio Science 18 (December 10, 2020): 97–110. http://dx.doi.org/10.5194/ars-18-97-2020.
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Abstract. Radar systems for contactless vital sign monitoring are well known and an actual object of research. These radar-based sensors could be used for monitoring of elderly people in their homes but also for detecting the activity of prisoners and to control electrical devices (light, audio, etc.) in smart living environments. Mostly these sensors are foreseen to be mounted on the ceiling in the middle of a room. In retirement homes the rooms are mostly rectangular and of standardized size. Furniture like beds and seating are found at the borders or the corners of the room. As the propagation path from the center of the room ceiling to the borders and corners of a room is 1.4 and 1.7 time longer the power reflected by people located there is 6 or even 10 dB lower than if located in the center of the room. Furthermore classical antennas in microstrip technology are strengthening radiation in broadside direction. Radar systems with only one single planar antenna must be mounted horizontally aligned when measuring in all directions. Thus an antenna pattern which is increasing radiation in the room corners and borders for compensation of free space loss is needed. In this contribution a specification of classical room sizes in retirement homes are given. A method for shaping the antenna gain in the E-plane by an one-dimensional series-fed traveling wave patch array and in the H-plane by an antenna feeding network for improvement of people detection in the room borders and corners is presented for a 24 GHz digital beamforming (DBF) radar system. The feeding network is a parallel-fed power divider for microstrip patch antennas at 24 GHz. Both approaches are explained in theory. The design parameters and the layout of the antennas are given. The simulation of the antenna arrays are executed with CST MWS. Simulations and measurements of the proposed antennas are compared to each other. Both antennas are used for the transmit and the receive channel either. The sensor topology of the radar system is explained. Furthermore the measurement results of the protoype are presented and discussed.
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Sundqvist, J. O., and J. Puls. "Atmospheric NLTE models for the spectroscopic analysis of blue stars with winds." Astronomy & Astrophysics 619 (November 2018): A59. http://dx.doi.org/10.1051/0004-6361/201832993.
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Context. Clumping in the radiation-driven winds of hot, massive stars severly affects the derivation of synthetic observables across the electromagnetic spectrum. Aims. We implement a formalism for treating wind clumping – focusing in particular on the light-leakage effects associated with a medium that is porous in physical and velocity space – into the global (photosphere + wind) NLTE model atmosphere and spectrum synthesis code FASTWIND. Methods. The basic method presented here assumes a stochastic, two-component wind consisting of a mixture of optically thick and thin clumps embedded in a rarefied inter-clump medium. We have accounted fully for the reductions in opacity associated with porosity in physical and velocity-space (the latter due to Doppler shifts in an accelerating medium), as well as for the well-known effect that opacities depending on ⟨ρ2⟩ are higher in clumpy winds than in smooth ones of equal mass-loss rate. By formulating our method in terms of suitable mean and effective opacities for the clumpy wind, we are able to compute atmospheric models with the same speed (∼15 min on a modern laptop or desktop) as in previous generations of FASTWIND. Results. After verifying important analytic limits (smooth, optically thin, completely optically thick), we present some first, generic results of the new models. These include: i) Confirming earlier results that velocity-space porosity is critical for analysis of UV wind resonance lines in O-stars; ii) for the optical Hα line, we show that optically thick clumping effects are small for O-stars, but potentially very important for late B and A-supergiants; iii) in agreement with previous work, we show that spatial porosity is a marginal effect for absorption of high-energy X-rays in O-stars, as long as the mean-free path between clumps are kept at realistic values ≲R*; iv) whereas radio absorption in O-stars shows strong spatial porosity effects in near photospheric layers, it is negligible at their typical radio-photosphere radii ∼100R*; v) regarding the wind ionization balance, a general trend is that increased rates of recombination in simulations with optically thin clumps lead to overall lower degrees of ionization than in corresponding smooth models, but that this effect now is counteracted by the increased levels of light-leakage associated with porosity in physical and velocity space (i.e., by an increase of ionization rates). We conclude by discussing future work and some planned applications for this new generation of FASTWIND models.
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Clarke, G. K. C., G. M. Cross, and C. S. Benson. "Airborne UHF Radar Measurements of Caldera Geometry and Volcanic History, Mount Wrangell, Alaska, U.S.A." Annals of Glaciology 9 (1987): 236–37. http://dx.doi.org/10.1017/s0260305500000707.
Full textAbstract:
The ice-filled caldera of Mount Wrangell, Alaska, provides an unusual opportunity to examine the interaction between a glacier and an active volcano. The caldera acts as a giant calorimeter, preserving a rough balance between snow precipitation at the glacier surface and bottom melting. In April 1982 we sounded the glacier using an airborne 840 MHz pulsed radar (Narod B B, Clarke G K C 1983 UHF radar system for airborne surveys of ice thickness. Canadian Journal of Earth Sciences 20(7): 1073–1086). The data were recorded on magnetic tape, then computer processed and plotted as depth, rather than time, sections. In addition to mapping ice thickness, we detected extensive internal layers presumed to have been deposited during past eruptions of Mount Wrangell. The challenge of interpreting these internal reflectors inspired us to develop a unified interpretation model that incorporates both glaciological measurements and phenomenological equations for firn and ice. The interpretation model yields the variation with surface-normal depth z of temperature T, heat flux q, ice pressure p, density ρ, surface-normal component of flow velocity w, down-slope component of flow velocity u, depositional age ta, two-way wave travel time τ2, and two-way propagation loss P2. The following system of linear differential equations is integrated using the Runge-Kutta method: 1 2 3 4 5 6 7 8 9 together with physical property relations such as the following 10 11 12 13 14 The boundary conditions on the integration variables are T(0) = Ts,T(h) = TM, p(0) = 0, ρ(0) =ρs, w(0) = ws, u(h) = uB, t a(0) = 0, τ2(0) = 0, and P2(0) = 0, where Ts is surface temperature, TM is bottom temperature, ρs is surface density, ws is surface-normal velocity measured at the glacier surface, and uB is sliding velocity. The remaining variables are thermal conductivity K, specific heat capacity c, flow-law constant B0, creep activation energy Q, universal gas constant R, shape factor F, surface slope α, flow-law exponent n, gravity acceleration g, empirical constants m1, m2, and p* from Benson’s firn-densification law (Benson C S 1962 Stratigraphie studies in the snow and firn of the Greenland ice sheet. SIPRE Research Report 70), ice density ρI, surface value of two-dimensional flow divergence Δ0 = (∂u/∂x + ∂v/∂y)s, relative dielectric permittivity ∈, free-space electromagnetic wave velocity v0, propagation loss rate D,T0 = 273.16 °K, thermal conductivity of ice K.I, loss-law constant D0, and activation energy for propagation loss E. The units of temperature and density in the above equations are respectively K and kg m−3. Preliminary modelling has yielded an age-depth relationship for internal reflecting layers that roughly matches the known eruption record for Mount Wrangell and extends the volcanic history by more than 200 years. High signal absorption rates restrict interpretation of the caldera geometry. Reflections from the bed are not consistently detectable beyond a depth of approximately 350 m, suggesting a loss rate of 7–8 dB per 100 m of path length. The anomalous losses are attributed to abnormally high concentrations of ionic impurities and scattering sources.
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Clarke, G. K. C., G. M. Cross, and C. S. Benson. "Airborne UHF Radar Measurements of Caldera Geometry and Volcanic History, Mount Wrangell, Alaska, U.S.A." Annals of Glaciology 9 (1987): 236–37. http://dx.doi.org/10.3189/s0260305500000707.
Full textAbstract:
The ice-filled caldera of Mount Wrangell, Alaska, provides an unusual opportunity to examine the interaction between a glacier and an active volcano. The caldera acts as a giant calorimeter, preserving a rough balance between snow precipitation at the glacier surface and bottom melting. In April 1982 we sounded the glacier using an airborne 840 MHz pulsed radar (Narod B B, Clarke G K C 1983 UHF radar system for airborne surveys of ice thickness. Canadian Journal of Earth Sciences 20(7): 1073–1086). The data were recorded on magnetic tape, then computer processed and plotted as depth, rather than time, sections.In addition to mapping ice thickness, we detected extensive internal layers presumed to have been deposited during past eruptions of Mount Wrangell. The challenge of interpreting these internal reflectors inspired us to develop a unified interpretation model that incorporates both glaciological measurements and phenomenological equations for firn and ice. The interpretation model yields the variation with surface-normal depth z of temperature T, heat flux q, ice pressure p, density ρ, surface-normal component of flow velocity w, down-slope component of flow velocity u, depositional age ta, two-way wave travel time τ2, and two-way propagation loss P2. The following system of linear differential equations is integrated using the Runge-Kutta method:123456789 together with physical property relations such as the following 1011121314The boundary conditions on the integration variables are T(0) = Ts,T(h) = TM, p(0) = 0, ρ(0) =ρs, w(0) = ws, u(h) = uB, t a(0) = 0, τ2(0) = 0, and P2(0) = 0, where Ts is surface temperature, TM is bottom temperature, ρs is surface density, ws is surface-normal velocity measured at the glacier surface, and uB is sliding velocity. The remaining variables are thermal conductivity K, specific heat capacity c, flow-law constant B0, creep activation energy Q, universal gas constant R, shape factor F, surface slope α, flow-law exponent n, gravity acceleration g, empirical constants m1, m2, and p* from Benson’s firn-densification law (Benson C S 1962 Stratigraphie studies in the snow and firn of the Greenland ice sheet. SIPRE Research Report 70), ice density ρI, surface value of two-dimensional flow divergence Δ0 = (∂u/∂x + ∂v/∂y)s, relative dielectric permittivity ∈, free-space electromagnetic wave velocity v0, propagation loss rate D,T0 = 273.16 °K, thermal conductivity of ice K.I, loss-law constant D0, and activation energy for propagation loss E. The units of temperature and density in the above equations are respectively K and kg m−3.Preliminary modelling has yielded an age-depth relationship for internal reflecting layers that roughly matches the known eruption record for Mount Wrangell and extends the volcanic history by more than 200 years. High signal absorption rates restrict interpretation of the caldera geometry. Reflections from the bed are not consistently detectable beyond a depth of approximately 350 m, suggesting a loss rate of 7–8 dB per 100 m of path length. The anomalous losses are attributed to abnormally high concentrations of ionic impurities and scattering sources.
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Popoola, Jide Julius, Akinlolu Adediran Ponnle, Yekeen Olajide Olasoji, and Samson Adenle Oyetunji. "INVESTIGATION ON NEED FOR SPECIFIC PROPAGATION MODEL FOR SPECIFIC ENVIRONMENT BASED ON DIFFERENT TERRAIN CHARACTERISTICS." IIUM Engineering Journal 19, no. 2 (December 1, 2018): 90–104. http://dx.doi.org/10.31436/iiumej.v19i2.886.
Full textAbstract:
ABSTRACT: Owing to their speed of excution as well as their limited reliance on detailed knowledge of the terrain characteristics of the service environments, empirical propagation models have enjoyed general acceptability in the wireless communication research community. However, recent industrial observations show that no single propagation model can best fit all the radio service environments, which led to the hypothesis of specific models for specific environments. In order to scientifically verify this hypothesis, the study presented in this paper investigated the performance of the free space propagation loss (FSPL) model in two different radio environments characterised with different types of obstructions. The investigation was conducted through field strength distribution measurement of two broadcasting radio stations transmitting at 96.5 MHz and 102.3 MHz. The field strength measurement data obtained were analysed. The result of the analysis shows gross disparity between the measured path losses and calculated path losses using FSPL model. The disparity thus necessitates the modification of the FSPL model in order to develop each propagation model for each of the two radio stations employed and their environment. The developed models were then evaluated to ascertain their performances relative to the FSPL model. The performance evaluation results show that the predictions of the developed propagation models vary for each of the two environments. Furthermore, the comparative performance evaluation result of the developed models with similar studies in the literature shows that the developed models perform favourably. The overall result from the developed models confirms the hypothesis that each location requires a specific propagation model for proper radio wave design and quality of signal transmission and reception.
ABSTRAK: Kelebihan yang ada pada kelajuan perlaksanaannya dan juga kurang pergantungannya pada butiran terperinci ciri-ciri khusus bentuk rupa bumi di persekitaran servisnya, model penyebaran empirik telah diterima umum dalam komuniti kajian komunikasi tanpa wayar. Walau bagaimanapun, pemerhatian industri terkini menunjukkan tidak ada sebarang model penyebaran yang sesuai bagi semua keadaan servis radio, ini menghala kepada hipotesis keperluan model tertentu pada keadaan servis tertentu. Bagi menentusahkan secara saintifik hipotesis ini, kajian yang dibentangkan dalam kertas ini mengkaji tentang prestasi model kehilangan penyebaran pada ruang bebas (FSPL) dalam dua persekitaran radio berlainan melalui beberapa jenis halangan berbeza. Kajian telah dijalankan ke atas dua stesen radio penyiaran pada frekuensi 96.5 MHz dan 102.3 MHz melalui ukuran sebaran ruang keupayaan. Data ukuran ruang keupayaan telah diperoleh dan dianalisa. Keputusan analisis menunjukkan keputusan tidak seragam yang melampau antara ukuran kehilangan laluan dan pada kiraan model FSPL. Ketidaksamaan ini memungkinkan keperluan mengubah model FSPL bagi membangunkan model penyebaran pada setiap dua radio stesen yang digunakan dan persekitarannya. Model yang dibangunkan ini kemudiannya dinilai bagi mengesahkan prestasinya dengan model FSPL. Keputusan penilaian menunjukkan perbezaan pada jangkaan model penyebaran bagi setiap dua keadaan. Tambahan, keputusan perbandingan model yang dibangunkan dalam karya ini adalah serupa seperti kajian lain yang berkaitan. Secara keseluruhannya model yang dibangunkan ini mengesahkan hipotesis bahawa setiap lokasi memerlukan model penyebaran bagi rekaan gelombang radio yang sesuai dan juga kualiti signal penyebaran dan penerimaan.
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Domec, Jean-Christophe, Sari Palmroth, and Ram Oren. "Effects of Pinus taeda leaf anatomy on vascular and extravascular leaf hydraulic conductance as influenced by N-fertilization and elevated CO2 ." Journal of Plant Hydraulics 3 (March 26, 2016): e007. http://dx.doi.org/10.20870/jph.2016.e007.
Full textAbstract:
Silvicultural practices (e.g., nitrogen addition through fertilization) and environmental changes (e.g., elevated [CO2]) may alter needle structure, impacting mass and energy exchange between the biosphere and atmosphere through alteration of stomatal function. Hydraulic resistances in leaves, controlling the mass and energy exchanges, occur both in the xylem and in the flow paths across the mesophyll to evaporation sites, and therefore largely depends on the structure of the leaf. We used the Free-Air Carbon dioxide Enrichment (FACE) experiment, providing a unique setting for assessing the interaction effects of [CO2] and nitrogen (N) supply to examine how leaf morphological and anatomical characteristics control leaf hydraulic conductance (Kleaf) of loblolly pine (Pinus taeda L.) trees subjected to ambient or elevated (+200 ppmv) CO2 concentrations (CO2a and CO2e, respectively) and to soil nitrogen amendment (N). Our study revealed that CO2e decreased the number of tracheids per needle, and increased the distance from the xylem vascular bundle to the stomata cavities, perturbing the leaf hydraulic system. Both treatments induced a decrease in Kleaf, and CO2e also decreased leaf extravascular conductance (Kextravascular), the conductance to water flow from the xylem to the leaf-internal air space. Decline in Kleaf under CO2e was driven by the decline in Kextravascular, potentially due to longer path for water movement through the mesophyll, explaining the decline in stomatal conductance (gs) observed under CO2e. This suggests that the distance from vascular conduits to stomata sub-cavity was a major constraint of leaf water transport. Across treatments our results showed that needle vein conductivity was slightly more limited by the lumen than by the bordered-pits, the latter accounting for 30-45% of vein resistance. CO2e-induced reduction in Kleaf was also consistent with an increased resistance to xylem collapse due to thicker cell wall. In addition, stomatal closure corresponded to the water potential inducing a reduction in 50% of leaf vascular conductance (Kvascular) via xylem wall rupture. The water potential that was estimated to induce complete xylem wall collapse was related to the water potential at turgor loss. Our study provided a framework for understanding the interaction between CO2e and N availability in affecting leaf anatomy, and the mechanisms for the response of Kleaf to the treatments. These mechanisms can be incorporated into predictive models of gs, critical for estimating forest productivity in water limited environments in current and future climates and a landscape composed of sites of a range in soil N fertility.