Statistical characteristics and performance evaluation of FSO links with misalignment fading influenced by correlated sways

Khanna, Himanshu; Aggarwal, Mona; Ahuja, Swaran

doi:10.1016/j.aeue.2017.12.032

Cited by 9 publications

(6 citation statements)

References 22 publications

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“…The main idea of such transformation from Meijer-G to linear summation is taken from[51], Eq. (10)-(14). In this paper, no truncated value of n has revealed to show the convergence of the infinite series, because use of a truncated value of n does not lead to an exact result, and "=" sign should be changed to "~".…”

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confidence: 95%

“…The K distribution is a suitable model for strong turbulence conditions [12].The presence of wind, weak earthquake, and building vibration cause misalignment of the FSO transmitter and receiver [13]. This effect is called pointing error and severely degrades the performance of the FSO system [14].The FSO and RF links are complementary of each other; there is almost no condition that could disrupt both of them at the same time. Therefore, combining FSO and RF links is a good idea to achieve advantages such as high reliability, accessibility, and data rate.…”

mentioning

confidence: 99%

“…The presence of wind, weak earthquake, and building vibration cause misalignment of the FSO transmitter and receiver [13]. This effect is called pointing error and severely degrades the performance of the FSO system [14].…”

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Performance evaluation of a novel relay‐assisted hybrid FSO/RF communication system with receive diversity

Amirabadi

Vakili

2019

IET Optoelectronics

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One of the main problems in mobile communication systems is the degradation of Radio Frequency (RF) connection when mobile user is far from base station. One way to solve this problem is to increase the transmitter power, but the mobile transmitter is not able to supply much power. Another way is to use a relay; among relay schemes, amplify and forward is better for long range communications. Amplify and forward relay is not affordable in terms of power consumption and performance, because it consumes a lot of power inefficiently and enhances the noise. Therefore, in other cases, except in the case of long range links, other relay protocols, such as decode and forward, as well as demodulate and forward, are preferable. In this paper, a novel multi-hop hybrid Free Space Optical (FSO) / RF link is presented; it is made up of two main parts. The first part establishes the connection between the mobile user and source base station, and the second part establishes the connection between the source and the destination base stations. In the first part, a mobile user wants to connect to the source base station via a long range link; therefore, a fixed gain amplify and forward relay with multiple receive antennas is used for communication establishment. In the second part, the source and the destination base stations are connected via a multi-hop hybrid parallel FSO / RF link with demodulate and forward relaying. Considering the FSO link in Gamma-Gamma atmospheric turbulence with the effect of pointing error in moderate to strong regime and the Negative Exponential atmospheric turbulence in saturate regime, and the RF link in Rayleigh fading, new closed form exact and asymptotic expressions are derived for the Outage Probability and Bit Error Rate of the proposed structure. Derived expressions are verified with MATLAB simulations. The results show that the performance of the proposed structure does not change with changing channel conditions; therefore, this structure is reliable and does not require more processing or power consumption in order to maintain system performance in poor channel conditions. Hence, the proposed structure is particularly suitable for mobile communications with limitations in power, processing and latency. The innovations and contributions of this paper, which are first introduced in the multi-hop hybrid FSO / RF hybrid structure, include the novelty of the proposed structure, the presentation of new exact and asymptotic mathematical solutions, the use of receive diversity, Bit Error Rate analysis, using amplify and forward as well as decode and forward protocols, taking into account a wide range of atmospheric turbulences with the effect of pointing error, using opportunistic selection and selection combining schemes.The atmospheric turbulence causes the random oscillation of the received signal intensity [5]. Many statistical models have been presented to investigate the effects of atmospheric turbulence including Log-Normal [6], Gamma-Gamma [7], K [8], M [9], and Negative Exponential [10]. Am...

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Performance evaluation of a novel relay‐assisted hybrid FSO/RF communication system with receive diversity

Amirabadi

Vakili

2019

IET Optoelectronics

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“…Unlike optical wireless communication (1)(2)(3) where light is used to transmit data, wireless communication uses radio waves to transmit data. The concept of cell-free network in wireless communication, which is the core technology of sixth-generation (6G), is coined from small-cells (SC), distributed MIMO, and massive MIMO (4,5) .…”

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confidence: 99%

Downlink Learning-aided Precoding for Cell-Free networks Specially D esigned for beyond 5G Communication System

Deshpande,

Aggarwal,

Sabherwal

et al. 2024

IJST

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Objectives: With increase in number of access points in Cell-Free Massive Multiple Input Multiple Output (CFMM) system, spatial complexity of calculating precoding vector increases with traditional precoding schemes. So, to reduce computational complexity, network cost, and run time, a new deep learning -aided precoder is specially designed for CFMM system. The performance of downlink (DL) Cell-Free Massive Multiple Input Multiple Output (CFMM) system operating under Rayleigh fading channel model is analyze using new deep learning-based precoding scheme. Methods: We introduce new deep learning-aided precoder and an improved version of basic scalable pilot assignment algorithm which enhances system performance. We derive closed- form expression for average DL spectral efficiency (SE) for the proposed scheme, which is then compared with Minimum Mean Square Error Successive Interference Cancellation (MMSESIC), Regularized Zero Forcing (RZF), Least Square (LS) and Maximum Ratio (MR) combining techniques. We analyze the proposed scheme with perfect channel state information (CSI), instantaneous CSI, coherent transmission, non-coherent transmission, different pilot configuration. Findings: The spectral efficiency obtained with CFMM-MMSESIC and the proposed scheme is 3 bits/s/Hz, and 2.5bits/s/Hz respectively, which clearly indicates the difference of 20 % only. So, the proposed scheme gives near optimal results, and we can use simple linear combining techniques instead of complex non-linear combining techniques. Also, the proposed scheme with coherent data transmission gives performance curve, which is very close to MMSESIC scheme as desired. The performance of the proposed system is improved by reducing run time and computational complexity as compared to conventional linear precoding schemes. Novelty: The proposed precoder improves performance by reducing run time and computational complexity. Advanced pilot assignment algorithm enhances performance by reducing pilot contamination. Keywords: Cell-Free Massive Multiple Input Multiple Output, Pilot Contamination, Precoding, Minimum Mean Square Error Successive Interference Cancellation, Maximum Ratio, Regularized Zero Forcing (RZF), Least Square (LS)

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“…is the modified Bessel function of the second kind of order α − β, and α and β are the PDF parameters that describes the turbulence induced by waves, and in the case of zero-inner scale[26], they are given by α = exp 0+ 0.18χ 2 + 0.56σ 12/5 7/6 − + 0.9χ 2 + 0.62σ 12/5 5/6 −…”

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confidence: 99%

Secrecy Analysis for Multi-Relaying RF-FSO Systems With a Multi-Aperture Destination

Zhang

Pan

et al. 2020

IEEE Photonics J.

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In this paper, we investigate the physical layer security for an asymmetric dual-hop radio frequency-free space optical (RF-FSO) communication system, in which a source transmits information to a multi-aperture destination (D) through a best relay under the wiretapping of a multi-aperture eavesdropper (E). The best relay is selected by a partial relay selection scheme in terms of maximum instantaneous channel gain for the RF link. Moreover, equal gain combining scheme is also used to process the multiple copies of receiving signal at D and E. Assuming all the RF channels are subject to independent and identical distributed (i.i.d.) Nakagami-m fading and all the FSO channels are modeled by i.i.d. Gamma-Gamma process, the secrecy performance in terms of secrecy outage probability and the probability of strictly positive secrecy capacity are studied, and the accuracy of the analytical results is verified by Monte-Carlo simulations.

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Statistical characteristics and performance evaluation of FSO links with misalignment fading influenced by correlated sways

Cited by 9 publications

References 22 publications

Performance evaluation of a novel relay‐assisted hybrid FSO/RF communication system with receive diversity

Performance evaluation of a novel relay‐assisted hybrid FSO/RF communication system with receive diversity

Downlink Learning-aided Precoding for Cell-Free networks Specially D esigned for beyond 5G Communication System

Secrecy Analysis for Multi-Relaying RF-FSO Systems With a Multi-Aperture Destination

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