Transmitter-receiver Location Research Articles

Analysis of Propagation Characteristics according to the Change of Transmitter-Receiver Location in Indoor Environment

Analysis of Propagation Characteristics according to the Change of Transmitter-Receiver Location in Indoor Environment

RadioUNet: Fast Radio Map Estimation With Convolutional Neural Networks

In this paper we propose a highly efficient and very accurate deep learning method for estimating the propagation pathloss from a point x (transmitter location) to any point y on a planar domain. For applications such as user-cell site association and device-to-device link scheduling, an accurate knowledge of the pathloss function for all pairs of transmitter-receiver locations is very important. Commonly used statistical models approximate the pathloss as a decaying function of the distance between transmitter and receiver. However, in realistic propagation environments characterized by the presence of buildings, street canyons, and objects at different heights, such radial-symmetric functions yield very misleading results. In this paper we show that properly designed and trained deep neural networks are able to learn how to estimate the pathloss function, given an urban environment, in a very accurate and computationally efficient manner. Our proposed method, termed RadioUNet, learns from a physical simulation dataset, and generates pathloss estimations that are very close to the simulations, but are much faster to compute for real-time applications. Moreover, we propose methods for transferring what was learned from simulations to real-life. Numerical results show that our method significantly outperforms previously proposed methods.

Probability Distribution of the Coherence Bandwidth of a Reverberation Chamber

A theoretical probability distribution and associated statistics for the coherence bandwidth of an ideal mode-stirred reverberation chamber are derived. The stochastic model assumes and exploits the ergodicity of a dynamic wave chaotic cavity by expressing the coherence bandwidth in terms of the random effective excitation bandwidth and by replacing spatial averaging of transmitter-receiver locations with stir (ensemble) averaging. The theoretical model is validated through comparison with the empirical cumulative distribution function (cdf) extracted from measured S-parameter data from a real chamber, and through simulation using analytical calculations for a fictitious wall-stirred chamber. The results are particularly relevant to the improvement of transmission quality and uncertainty quantification of wireless multipath propagation.

Optimisation of channel capacity for multiple-input multiple-output smart antenna using a particle swarm optimiser

In this study, the channel capacity of indoor multiple-input multiple-output ultra-wide band (MIMO-UWB) transmission for a smart antenna is described. A particle swarm optimiser (PSO) is used to synthesise the radiation pattern of the directional circular arc array to maximise the capacity performance in an indoor MIMO-UWB communication system. The UWB impulse responses of the indoor channel for any transmitter-receiver location are computed by applying shooting and bouncing ray/image techniques, inverse fast Fourier transform and Hermitian processing. By using the calculated frequency response, the capacity performance of the synthesised antenna pattern on an MIMO-UWB system can be computed. Based on the topography of the circular antenna array and the capacity formula, the array pattern synthesis problem can be reformulated into an optimisation problem and solved by the PSO algorithm. PSO optimisation is applied to a high-order non-linear optimisation problem. The novelties of our approach are not only choosing capacity as the cost function instead of the sidelobe level of the antenna pattern, but also considering the antenna feed length effect of each array element. The cost function for the problem is non-smooth and discontinuous with respect to the antenna pattern. It is difficult to solve by gradient methods, since the derivative is hard to derive. The strong point of the PSO algorithm is that it can find out the solution even if the performance index cannot be formulated by simple equations. The simulation results show that the synthesised antenna array pattern is effective to focus maximum gain on the line-of-sight path which scales as the number of array elements.

MIMO-UWB smart antenna communication characteristics for different antenna arrays of transmitters

The channel capacity of indoor multiple-input multiple-output ultra-wide band (MIMO-UWB) transmission for smart antenna is presented. The genetic algorithm (GA) is used to synthesize the radiation pattern of the directional antenna array to maximize the capacity performance in indoor MIMO-UWB communication system. Three types of antenna arrays such as circular shape, L shape and Y shape arrays are used in the transmitter and their corresponding capacity on several paths in the indoor environment are calculated. The UWB impulse responses of the indoor channel for any transmitter-receiver location are computed by applying shooting and bouncing ray/image (SBR/image) techniques, inverse fast Fourier transform and Hermitian processing. By using the calculated frequency response, the capacity performance of the synthesized antenna pattern on MIMO-UWB system can be computed. Based on the topography of the antenna array and the capacity formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the GA algorithm. The GA algorithm optimization is applied to a high order nonlinear optimization problem. The novelties of our approach is not only choosing capacity as the cost function instead of sidelobe level of the antenna pattern, but also considering the antenna feed length effect of each array element. The cost function for the problem is nonsmooth and discontinuous with respect to the antenna pattern. It is difficult to solve by gradient methods, since the derivative is hard to derive. The GA algorithm is employed to optimize the excitation voltages and feed lengths for these antenna arrays to increase the capacity. The strong point of the GA is that it can find out the solution even if the performance index cannot be formulated by simple equations. Numerical results show that the synthesized antenna array pattern is effective to focus maximum gain to the LOS path for these antenna arrays. In other words, the receiver can increase the received signal energy to noise ratio. The synthesized array pattern also can mitigate severe multipath fading in complex propagation environment. As a result, the capacity can be increased substantially in indoor MIMO-UWB communication system. The investigated results can help communication engineers improve their planning and design of indoor wireless communication. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.

Time reversibility of a Lamb wave for damage detection in a metallic plate

In this paper, an experimental study has been carried out to develop a baseline-freedamage detection technique using the time reversibility of a Lamb wave. The experimentshave been carried out on a metallic plate. Time reversibility is the process in which aresponse signal recorded at a receiver location is reversed in time and transmitted backthrough the receiver to the original transmitter location. In the absence of any defect ordamage in the path between the transmitter–receiver locations, theoretically thesignal received back at the original transmitter location (reconstructed signal)is identical to the original input signal. The initial part of the present work isaimed at understanding the time reversibility of a Lamb wave in an undamagedmetallic plate. This involves a thorough study of different parameters such asfrequency, pulse frequency band width, transducer size and the effects of tuning theseparameters on the quality of a reconstructed input signal. This paper also suggests amethod to mitigate the effects of the frequency dependent attenuation of Lambwave modes (amplitude dispersion) and thus achieve better reconstruction foran undamaged plate. Finally, the time reversal process (TRP) is used to detectdamage in an aluminium plate without using any information from the undamagedstructure. A block mass, a notch and an area of surface erosion are considered asrepresentative of different types of damage. The results obtained show that theeffect of damage on TRP is significant, contrary to the results reported earlier.

BIT ERROR RATE REDUCTION FOR MULTIUSERS BY SMART UWB ANTENNA ARRAY

In this paper, a new ultra wideband circular antenna array (UCAA) combining genetic algorithm (GA) to minimize the bit error rate (BER) is proposed. The ultra wideband (UWB) impulse responses of the indoor channel for any transmitter-receiver location are computed by SBR/Image techniques, inverse fast Fourier transform and Hermitian processing. By using the impulse response of multipath channel, the BER performance of the binary pulse amplitude modulation (B-PAM) impulse radio (IR) UWB system with circular antenna array can be calculated. Based on the topography of the antenna and the BER formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the genetic algorithm. The novelties of our approach is not only choosing BER as the object function instead of sidelobe level of the antenna pattern, but also considering the antenna feed length efiect of each array element. The strong point of the genetic algorithm is that, it can flnd out the solution even if the performance index cannot be formulated by simple equations. Simulation results show that the synthesized antenna array pattern is efiective to focus maximum gain to the multiusers.

A NOVEL SMART UWB ANTENNA ARRAY DESIGN BY PSO

In this paper, a new ultra wideband circular antenna array (UCAA) combining particle swarm optimizer (PSO) to minimize the bit error rate (BER) is proposed. The ultra wideband (UWB) impulse responses of the indoor channel for any transmitter-receiver location are computed by applying shooting and bouncing ray/image (SBR/Image) techniques, inverse fast Fourier transform and Hermitian processing. By using the impulse response of multipath channel, the BER performance of the binary pulse amplitude modulation (B- PAM) impulse radio (IR) UWB system can be calculated. Based on the topography of the circular antenna array, and the BER formula, the array pattern synthesis problem can be reformulated into an optimization problem and solved by the PSO. The novelties of our approach is not only choosing BER as the object function instead of sidelobe level of the antenna pattern, but also consider the antenna feed length efiect of each array element. The strong point of the PSO is that it can flnd out the solution even if the performance index cannot be formulated by simple equations. Simulation results show that the synthesized antenna array pattern is efiective to focus maximum gain to the LOS path which scales as the number of array elements. In other words, the receiver can increase the received signal energy to noise ratio. The synthesized array pattern also can mitigate severe multipath fading in complex propagation environment. As a result, the BER can be reduced substantially in indoor UWB communication system.

Novel Directional Radiation Pattern by Genetic Algorithms in Indoor Wireless Local Loop

The genetic algorithm is used to synthesize the radiation pattern of the directional circular arc array to minimize the bit error rate (BER) performance in indoor wireless communication system. The impulse responses of the indoor channel for any transmitter-receiver location are computed by shooting and bouncing ray/image techniques. By using the impulse response of multipath channel, the performance of the synthesized antenna pattern on BPSK (binary phase shift keying) system with phase and timing recovery circuits can be calculated. Based on the topography of the antenna and the BER formula, the synthesis problem can be reformulated into an optimization problem and solved by the genetic algorithm. The novelty of our approach is choosing BER as the object function instead of sidelobe level of the antenna pattern, i.e., BER performance is defined as a object function to optimize the excitation coefficient of array by the genetic algorithm. The strong point of the genetic algorithm is that it can find out the solution even if the performance index cannot be formulated by simple equations. Besides, the genetic algorithm will converge to global extreme instead of local extreme and achieves a good antenna pattern. Numerical results show that the synthesized antenna pattern is effective to combat the multipath fading and can increase the transmission rate of indoor millimeter wave system.

Ultra-wide Band Channel Calculation by SBR/Image Techniques for Indoor Communication

In this paper, we use ray tracing techniques and inverse Fourier transform to compute the impulse responses for ultra-wide band (UWB) indoor communication. First, the frequency responses of different indoor environments for any transmitter-receiver location are computed by shooting and bouncing ray/image (SBR/Image) techniques in UWB frequency ranges. The frequency dependence utilized in the structure on the indoor channel is accounted for in the channel calculation. Then, the impulse responses of channel is obtained by applying inverse Fourier transform to transform the frequency domain data into time domain. A realistic complex environment is simulated by our proposed method. By using the obtained impulse responses of these multi-path channels, the impact of metallic furniture to indoor multi-path environment is investigated. Numerical results have shown that the multi-path effect with metallic cabinets is more severe than that without metallic cabinets. Moreover, it is also found that when the receiver is located near metallic furniture, the multi-path effect caused by the metallic furniture is severe.

Wideband communication characteristics of subway stations with and without trains

The bit error rate (BER) performance for high-speed personal communication service in subway station with and without trains is investigated. The impulse responses of subway stations for any transmitter–receiver location are computed by shooting and bouncing ray/image techniques. By using the impulse responses of these multipath channels, the BER performance of binary phase shift keying (BPSK) with orthogonal frequency division multiplexing (OFDM) system are calculated. Numerical results have shown that the multipath effect by the trains in the subway stations is an important factor for BER performance. In addition, the effect of space diversity techniques and polarization diversity techniques as well as sectored antenna on mitigating the multipath fading is also investigated. Finally, it is worth noting that in these cases the present work provides not only comparative information but also quantitative information on the performance reduction. Copyright © 2004 John Wiley & Sons, Ltd.

Dual diversity combining and decision feedback equalizer in indoor millimetre‐wave channel

AbstractWideband communication characteristics of wireless indoor millimetre‐wave channel for arched and rectangular buildings are investigated. The impulse responses of arched and rectangular buildings for any transmitter–receiver location are computed by shooting and bouncing ray/image (SBR/Image) techniques. By using the impulse responses of these multipath channels, the impact of shapes of building is presented and the bit error rate performance of binary phase shift keying (BPSK) system with phase and timing recovery circuits are also calculated. Moreover, dual space antenna diversity technique and decision feedback equalizer (DFE) with four forward and three feedback taps are used to combat the multipath fading. Numerical results show that the mean root mean square (rms) delay spread for the arched building is smaller than that for the rectangular building. In addition, it is also found that the transmission rate can be up to 20 Mbps for indoor millimetre‐wave channel of these two buildings by using dual space diversity and DFE. Copyright © 2002 John Wiley & Sons, Ltd.

Impact of shapes of buildings and metallic furniture on indoor multipath environment and bit-error rate performance of millimeter-wave channel

Wideband communication characteristics of millimeter-wave channels for rectangular and arched buildings with and without metallic furniture are investigated. The impulse responses of rectangular and arched buildings for any transmitter–receiver location are computed by shooting and bouncing ray/image techniques. By using the impulse responses of these multipath channels, the impact of the shapes of building and metallic furniture on an indoor multipath environment is investigated. In addition, the outage probabilities for a BPSK (binary phase-shift keying) system with phase and timing recovery circuits are calculated. Numerical results show that the mean rms delay spread for arched buildings is smaller than that for rectangular buildings. Moreover, it is also found that when the receiver is located near metallic furniture, the multipath effect caused by the metallic furniture is severe. In addition, numerical results also show that the outage probability for an arched building is lower than that for a rectangular building. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 137–142, 1998.