Performance Analysis of an Inter-Relay Co-operation in FSO Communication System

2018 ◽  
Vol 39 (2) ◽  
pp. 199-208
Author(s):  
Himanshu Khanna ◽  
Mona Aggarwal ◽  
Swaran Ahuja

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.

2021 ◽  
Author(s):  
Muhammad Salman Bashir ◽  
Ming-Cheng Tsai ◽  
Mohamed-Slim Alouini

Free-space optical (FSO) communications is an important technology that will be used for supporting high data-rates in the backhaul of next generation of wireless communication networks. In this paper, we have compared the probability of error performance of two types of receivers used in FSO today: a receiver based on a single detector, and a receiver based on an array of detectors. The performance of these two receivers is compared for a number of fusion algorithms for an array of detectors such as equal gain combiner (EGC), selection combiner (SC), switched combiner (SWC) and the maximal ratio combiner (MRC). From this study, we conclude that even though the array of detectors adds more noise in the sufficient statistic by virtue of large number of detectors, using more computationally expensive fusion algorithms (such as SC and MRC) can help us achieve a superior probability of error performance as opposed to a single-detector receiver for practical channel conditions. <br>


2019 ◽  
Vol 40 (3) ◽  
pp. 323-332 ◽  
Author(s):  
Himanshu Khanna ◽  
Mona Aggarwal ◽  
Swaran Ahuja

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.


2021 ◽  
Author(s):  
Muhammad Salman Bashir ◽  
Ming-Cheng Tsai ◽  
Mohamed-Slim Alouini

Free-space optical (FSO) communications is an important technology that will be used for supporting high data-rates in the backhaul of next generation of wireless communication networks. In this paper, we have compared the probability of error performance of two types of receivers used in FSO today: a receiver based on a single detector, and a receiver based on an array of detectors. The performance of these two receivers is compared for a number of fusion algorithms for an array of detectors such as equal gain combiner (EGC), selection combiner (SC), switched combiner (SWC) and the maximal ratio combiner (MRC). From this study, we conclude that even though the array of detectors adds more noise in the sufficient statistic by virtue of large number of detectors, using more computationally expensive fusion algorithms (such as SC and MRC) can help us achieve a superior probability of error performance as opposed to a single-detector receiver for practical channel conditions. <br>


2021 ◽  
Author(s):  
Muhammad Salman Bashir ◽  
Ming-Cheng Tsai ◽  
Mohamed-Slim Alouini

Free-space optical (FSO) communications is an important technology that will be used for supporting high data-rates in the backhaul of next generation of wireless communication networks. In this paper, we have comparedthe probability of error performance of two types of receivers used in FSO today: a receiver based on a single detector, and a receiver based on an array of detectors. The performance of these two receivers is compared for a number of fusion algorithms for an array of detectors such as equal gain combiner (EGC), selection combiner(SC), switched combiner (SWC) and the maximal ratio combiner (MRC). From this study, we conclude that even though the array of detectors adds more noise in the sufficient statistic by virtue of large number of detectors,using more computationally expensive fusion algorithms (such as SC and MRC) can help us achieve a superior probability of error performance as opposed to a single-detector receiver for practical channel conditions.


Frequenz ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Himanshu Khanna

AbstractThe performance of a generalized mixed free-space-optical (FSO)/millimeter (mm)-wave radio-frequency (RF) two-hop link model is investigated in this work. The first-hop FSO channel considers the influence of path loss, atmospheric turbulence which is modeled by the gamma–gamma (GG)-distribution, and generalized misalignment errors which incorporate the effects of non-zero boresight errors, different jitter standard deviations along the horizontal and vertical directions, and correlation between the horizontal and vertical displacements. The second-hop RF link is modeled by an extended-generalized-K (EGK) distribution which is a versatile distribution and can characterize various fading conditions in mm-wave wireless channels where the transmission frequency is in excess of 60 GHz, and considers non-homogeneous propagation, interference effects due to multiuser transmission, multipath fading and shadowing effects observed in mm-wave RF wireless channels. The considered system employs fixed-gain amplify-and-forward (AF) relay-assisted transmission. The statistical characteristic for the end-to-end SNR, i.e., cumulative distribution function (cdf), is obtained for the considered system model in this work. Based on the obtained result for cdf, the outage and error performance is evaluated, and closed form expressions for the same are derived. The derived analytical results have been illustrated through numerical plots.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Rajat Kumar Giri

Abstract In this paper, a hybrid-subcarrier-intensity-modulation (hybrid-SIM) technique for the performance improvement of free-space-optical (FSO) communication system has been proposed. Subsequently, for further error performance improvement, avalanche photodiode (APD) based receiver is used in the proposed system. The system performance is analyzed at various atmospheric turbulence levels over weak and strong turbulence channels. The bit error rate (BER) is theoretically derived using Gauss–Hermite approximation and Meijer-G function and it is simulated in the MATLAB environment. The simulation result shows that the BER performance of hybrid-SIM is better than BPSK-SIM technique irrespective of the channel types and also the significant BER performance improvement is observed by APD receiver.


2008 ◽  
Vol 57 (4) ◽  
pp. 2014-2026 ◽  
Author(s):  
David W. Matolak ◽  
Indranil Sen ◽  
Wenhui Xiong

We describe results from a channel measurement and modeling campaign for the airport surface environment in the 5-GHz band. Using a 50-MHz bandwidth test signal, thousands of power delay profiles (PDPs) were obtained and processed to develop empirical tapped-delay line statistical channel models for large airports. A log-distance path loss model was also developed. The large airport surface channel is classified into three propagation regions, and models are presented for each of the regions for two values of bandwidth. Values of the median root-mean-square (RMS) delay spread range from 500 to 1000 ns for these airports, with the 90 th percentile RMS delay spreads being approximately 1.7 ms. Corresponding correlation bandwidths (i.e., correlation value 1/2) range from approximately 1.5 MHz in non-line-of-sight (NLOS) settings to 17.5 MHz in line-of-sight (LOS) settings. Two types of statistical nonstationarity were also observed: 1) multipath component persistence and 2) propagation region transitions. We provide the multipath component probability of occurrence models and describe Markov chains that are used for modeling both phenomena. Channel tap amplitude statistics are also provided, using the flexible Weibull probability density function (pdf). This pdf was found to best fit fading tap amplitude data, particularly for frequently observed severe fading, which is characterized by fade probabilities that are worse than the commonly used Rayleigh model. Fading parameters equivalent to Nakagami-m-model values ofmnear 0.7 were often observed (withm= 1 being Rayleigh and m &lt; 1 being worse than Rayleigh). We also provide channel tap amplitude correlation coefficients, which typically range from 0.1 to 0.4 but occasionally take values greater than 0.7.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Bithi Mitra ◽  
Md. Jahedul Islam

AbstractIn this paper, the performance of two-dimensional (2-D) wavelength-hopping/time-spreading (WH/TS) optical code division multiple access (OCDMA) system over free space optical (FSO) channel is analyzed in the presence of pointing error and different weather conditions. Prime code scheme is employed for both wavelength-hopping and time-spreading to address user code-matrix. The operating central wavelength of 1550 nm is considered to demonstrate the bit error rate (BER) performance of the proposed system as a function of various system parameters. The required optical power of the proposed system is determined to maintain a BER value of 10−9. The numerical evaluation interprets that the BER performance is highly dependent on transmission length, transmitted power, pointing error angle as well as the number of simultaneous user. It is also observed that the 2-D OCDMA system over free space needs minimum required optical power in case of rainy atmospheric condition, but it is maximum for foggy atmospheric condition.


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