107-109Rain attenuation studies were made at 11.7 GHz utilizing INSAT-2C satellite signals over s... more 107-109Rain attenuation studies were made at 11.7 GHz utilizing INSAT-2C satellite signals over southern India during rain events. The observed cumulative distribution of rain attenuation is compared with prominent prediction models. These are the first results observed on an operational earth-satellite path in India
The effects of multipath in relation to the deteriorated performance of a microwave communication... more The effects of multipath in relation to the deteriorated performance of a microwave communication link situated between Guntakal and Adoni over the Indian southern region have been investigated. The received signal level under normal condition is usually found ...
Studies on microwave signal propagation provide an opportunity to investigate the variable nature... more Studies on microwave signal propagation provide an opportunity to investigate the variable nature of the atmosphere. The present study deals with the effect of sea breeze on the propagation characteristics observed over a line-of-sight (LOS) microwave link operating ...
This paper describes cost-effective technique for the implementing rural wireless communication n... more This paper describes cost-effective technique for the implementing rural wireless communication network by exploiting remote RF concept and using existing power line as a physical medium. System level simulation consisting of power line communication (PLC) transmitter and receiver has been carried out using Simulink 5.0 for noise evaluation. PLC transmitter and receiver system is proposed using forward error correcting codes (FEC) and orthogonal frequency division multiplexing (OFDM). It is shown that OFDM can be effectively utilised for base band signal modulation to achieve both reduced EMI and improved signal-to-noise ratio. MATLAB simulation results indicating the probable choice of carrier frequencies for PLC are presented. There is a great disparity between the rural and urban masses in respect of access to Information and Communication Technologies (ICTs) and thus leading to greater digital divide between them. Although numerous techniques have been proposed to minimize this ...
Worldwide Interoperability of Microwave Access (WiMAX), as an open standard IEEE 802.16, offers a... more Worldwide Interoperability of Microwave Access (WiMAX), as an open standard IEEE 802.16, offers a low cost wireless broadband access. WiMAX supports ubiquitous broadband wireless access enabling real-time and multimedia applications. To bridge the digital divide, WiMAX networks are being deployed worldwide and the countries with no previous infrastructure are providing broadband access to users. Numerous statistical path loss (PL) models (e.g. Okumura- Hata, COST-231 Hata Model, ECC-33 Model) are available to predict the propagation loss, but are limited to the lower frequency bands (up to 2 GHz). Above 2GHz, propagation models require further validation and tuning through field measurements in different terrains and environments. The main objective of the work embodied in the present book is to provide design inputs for future WiMAX and advanced communication systems operating in the 2GHz band over India. An attempt has been made by the author to realize the objective by interpreti...
IEEE Transactions on Antennas and Propagation, 2014
ABSTRACT The objective of this presentation is to illustrate the accuracy of the Schelkunoff form... more ABSTRACT The objective of this presentation is to illustrate the accuracy of the Schelkunoff formulation over the Sommerfeld solution for a vertical electric dipole radiating over an imperfect ground. In an earlier paper, the alternate form of the Sommerfeld Green's function developed by Schelkunoff was presented (Schelkunoff, 1943 and Dyab, 2013). Here we demonstrate the application of this new methodology for two classes of problems. First, the problem of predicting the propagation path loss in a wireless communication environment is illustrated. The second application problem described in this paper deals with the verification of experimental data related to propagation over an Aluminum sheet at THz frequencies. It is seen that the main contribution of the reflected field is due to a specular image point as expected for a metal and the presence of surface waves in the total reflected field is absent, even though the permittivity of the metal is negative at these frequencies. Both theoretical predictions and experimental data demonstrate that there is little contribution to the reflected field due to a surface wave. Also, a clear definition is made to characterize surface waves as there is confusion as to what a surface wave really is.
ABSTRACT Received signal level measurements are frequently used to check the performance and the ... more ABSTRACT Received signal level measurements are frequently used to check the performance and the Quality Of Service (QOS) inside the coverage area in cellular networks. These expensive time consuming measurements are carried out using actual drive tests to assess the coverage area of a base station for a given cell and thus evaluate the QOS. In a drive test measurement system, a receiving antenna is placed on top of a vehicle and the vehicle is then driven along radial and circular lines around the base station to measure the received power and thus assess the QOS. These drive test measurements are also used to tune the empirical models in the radio planning tools which have to be carried out for various types of environments. This model tuning is a lengthy procedure. In this paper, it is shown that an electromagnetic macro modeling of the environment can provide simulation results comparable to the data as one would obtain in an actual drive test measurement for a cellular environment. The input parameters for the electromagnetic macro model can be generated using only the physical parameters of the environment like the height of the transmitting and receiving antennas over the ground, their tilts towards the ground, and the electrical parameters of the ground. Such analysis can provide realistic plots for the received power versus separation distance between the receiving and the transmitting base station antennas. The novelty of the electromagnetic analysis technique proposed in this paper lies in its ability to match the macro model-based simulation results and the drive test measurements without any statistical or empirical curve fitting or an adhoc choice of a reference distance. In addition, a new concept called proper route is introduced to enhance the analysis of the measured data. A method of moments-based integral equation solver code has been used to simulate the effects of the macro parameters of the environment on the propagation path loss of the signals emanating from a base station antenna. The perfect match between the simulation results and the drive test data is illustrated by monitoring the signal levels from some cellular base stations in western India and Srilanka and then comparing the observed results with the simulated results. The goal here is to illustrate that these numerical simulation tools can accurately predict the propagation path loss in a cellular environment without tweaking some non-physical models based on statistical modeling or heuristic assumptions.
The regional dust morphology and spectral refractive indices (RIs; governed by hematite, Fe2O3 co... more The regional dust morphology and spectral refractive indices (RIs; governed by hematite, Fe2O3 content at short wavelengths) are key elements for ascertaining direct radiative forcing of mineral dust aerosols. To provide morphological features of background mineral dust from a semi-arid zone in the vicinity of the Thar Desert, we carried out an expedition to the Jaipur city during late winter of 2012. Morphological analysis reveals the predominance of “Layered”, “Angular” and “Flattened ” particles while the frequency distribution of a total of 235 dust particles shows the aspect ratio, AR and circularity parameter, CIR (measures of particle’s non-sphericity) typically ~1.4 and ~0.8, respectively. Sensitivity analysis at 550 nm wavelength reveals the equivalent sphere model may underestimate Single Scattering Albedo, SSA for the dust with low (~1.1%) hematite by ~3.5%. Both underestimation (by ~5.6%) and overestimation (up to 9.1%) are probable in case of dust with high hematite con...
In this paper details of development and applications of a navigation system known as GPS-GSM Int... more In this paper details of development and applications of a navigation system known as GPS-GSM Integrator (G2I) are presented. G2I system consists of two modules namely In Vehicle Module (IVM) and Control Room Module (CRM). The IVM is micro controller based system equipped with Global Positioning System (GPS) receiver and Global System for Mobile communication (GSM) modem. The CRM consists of a Personal Computer (PC) and GSM mobile phone. Relevant software is developed for obtaining position information of vehicle. Drive tests are conducted with G2I system (in different modes) for cellular coverage area determination and for developing comprehensive digital reference Geographical Information System (GIS) maps in real time vehicle tracking. During these tests, the Received Signal Strength Indications (RSSI) of the cellular signal at various locations (latitude and longitude) in urban and rural regions are recorded and coverage area classification is done. The developed G2I system woul...
107-109Rain attenuation studies were made at 11.7 GHz utilizing INSAT-2C satellite signals over s... more 107-109Rain attenuation studies were made at 11.7 GHz utilizing INSAT-2C satellite signals over southern India during rain events. The observed cumulative distribution of rain attenuation is compared with prominent prediction models. These are the first results observed on an operational earth-satellite path in India
The effects of multipath in relation to the deteriorated performance of a microwave communication... more The effects of multipath in relation to the deteriorated performance of a microwave communication link situated between Guntakal and Adoni over the Indian southern region have been investigated. The received signal level under normal condition is usually found ...
Studies on microwave signal propagation provide an opportunity to investigate the variable nature... more Studies on microwave signal propagation provide an opportunity to investigate the variable nature of the atmosphere. The present study deals with the effect of sea breeze on the propagation characteristics observed over a line-of-sight (LOS) microwave link operating ...
This paper describes cost-effective technique for the implementing rural wireless communication n... more This paper describes cost-effective technique for the implementing rural wireless communication network by exploiting remote RF concept and using existing power line as a physical medium. System level simulation consisting of power line communication (PLC) transmitter and receiver has been carried out using Simulink 5.0 for noise evaluation. PLC transmitter and receiver system is proposed using forward error correcting codes (FEC) and orthogonal frequency division multiplexing (OFDM). It is shown that OFDM can be effectively utilised for base band signal modulation to achieve both reduced EMI and improved signal-to-noise ratio. MATLAB simulation results indicating the probable choice of carrier frequencies for PLC are presented. There is a great disparity between the rural and urban masses in respect of access to Information and Communication Technologies (ICTs) and thus leading to greater digital divide between them. Although numerous techniques have been proposed to minimize this ...
Worldwide Interoperability of Microwave Access (WiMAX), as an open standard IEEE 802.16, offers a... more Worldwide Interoperability of Microwave Access (WiMAX), as an open standard IEEE 802.16, offers a low cost wireless broadband access. WiMAX supports ubiquitous broadband wireless access enabling real-time and multimedia applications. To bridge the digital divide, WiMAX networks are being deployed worldwide and the countries with no previous infrastructure are providing broadband access to users. Numerous statistical path loss (PL) models (e.g. Okumura- Hata, COST-231 Hata Model, ECC-33 Model) are available to predict the propagation loss, but are limited to the lower frequency bands (up to 2 GHz). Above 2GHz, propagation models require further validation and tuning through field measurements in different terrains and environments. The main objective of the work embodied in the present book is to provide design inputs for future WiMAX and advanced communication systems operating in the 2GHz band over India. An attempt has been made by the author to realize the objective by interpreti...
IEEE Transactions on Antennas and Propagation, 2014
ABSTRACT The objective of this presentation is to illustrate the accuracy of the Schelkunoff form... more ABSTRACT The objective of this presentation is to illustrate the accuracy of the Schelkunoff formulation over the Sommerfeld solution for a vertical electric dipole radiating over an imperfect ground. In an earlier paper, the alternate form of the Sommerfeld Green's function developed by Schelkunoff was presented (Schelkunoff, 1943 and Dyab, 2013). Here we demonstrate the application of this new methodology for two classes of problems. First, the problem of predicting the propagation path loss in a wireless communication environment is illustrated. The second application problem described in this paper deals with the verification of experimental data related to propagation over an Aluminum sheet at THz frequencies. It is seen that the main contribution of the reflected field is due to a specular image point as expected for a metal and the presence of surface waves in the total reflected field is absent, even though the permittivity of the metal is negative at these frequencies. Both theoretical predictions and experimental data demonstrate that there is little contribution to the reflected field due to a surface wave. Also, a clear definition is made to characterize surface waves as there is confusion as to what a surface wave really is.
ABSTRACT Received signal level measurements are frequently used to check the performance and the ... more ABSTRACT Received signal level measurements are frequently used to check the performance and the Quality Of Service (QOS) inside the coverage area in cellular networks. These expensive time consuming measurements are carried out using actual drive tests to assess the coverage area of a base station for a given cell and thus evaluate the QOS. In a drive test measurement system, a receiving antenna is placed on top of a vehicle and the vehicle is then driven along radial and circular lines around the base station to measure the received power and thus assess the QOS. These drive test measurements are also used to tune the empirical models in the radio planning tools which have to be carried out for various types of environments. This model tuning is a lengthy procedure. In this paper, it is shown that an electromagnetic macro modeling of the environment can provide simulation results comparable to the data as one would obtain in an actual drive test measurement for a cellular environment. The input parameters for the electromagnetic macro model can be generated using only the physical parameters of the environment like the height of the transmitting and receiving antennas over the ground, their tilts towards the ground, and the electrical parameters of the ground. Such analysis can provide realistic plots for the received power versus separation distance between the receiving and the transmitting base station antennas. The novelty of the electromagnetic analysis technique proposed in this paper lies in its ability to match the macro model-based simulation results and the drive test measurements without any statistical or empirical curve fitting or an adhoc choice of a reference distance. In addition, a new concept called proper route is introduced to enhance the analysis of the measured data. A method of moments-based integral equation solver code has been used to simulate the effects of the macro parameters of the environment on the propagation path loss of the signals emanating from a base station antenna. The perfect match between the simulation results and the drive test data is illustrated by monitoring the signal levels from some cellular base stations in western India and Srilanka and then comparing the observed results with the simulated results. The goal here is to illustrate that these numerical simulation tools can accurately predict the propagation path loss in a cellular environment without tweaking some non-physical models based on statistical modeling or heuristic assumptions.
The regional dust morphology and spectral refractive indices (RIs; governed by hematite, Fe2O3 co... more The regional dust morphology and spectral refractive indices (RIs; governed by hematite, Fe2O3 content at short wavelengths) are key elements for ascertaining direct radiative forcing of mineral dust aerosols. To provide morphological features of background mineral dust from a semi-arid zone in the vicinity of the Thar Desert, we carried out an expedition to the Jaipur city during late winter of 2012. Morphological analysis reveals the predominance of “Layered”, “Angular” and “Flattened ” particles while the frequency distribution of a total of 235 dust particles shows the aspect ratio, AR and circularity parameter, CIR (measures of particle’s non-sphericity) typically ~1.4 and ~0.8, respectively. Sensitivity analysis at 550 nm wavelength reveals the equivalent sphere model may underestimate Single Scattering Albedo, SSA for the dust with low (~1.1%) hematite by ~3.5%. Both underestimation (by ~5.6%) and overestimation (up to 9.1%) are probable in case of dust with high hematite con...
In this paper details of development and applications of a navigation system known as GPS-GSM Int... more In this paper details of development and applications of a navigation system known as GPS-GSM Integrator (G2I) are presented. G2I system consists of two modules namely In Vehicle Module (IVM) and Control Room Module (CRM). The IVM is micro controller based system equipped with Global Positioning System (GPS) receiver and Global System for Mobile communication (GSM) modem. The CRM consists of a Personal Computer (PC) and GSM mobile phone. Relevant software is developed for obtaining position information of vehicle. Drive tests are conducted with G2I system (in different modes) for cellular coverage area determination and for developing comprehensive digital reference Geographical Information System (GIS) maps in real time vehicle tracking. During these tests, the Received Signal Strength Indications (RSSI) of the cellular signal at various locations (latitude and longitude) in urban and rural regions are recorded and coverage area classification is done. The developed G2I system woul...
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