scholarly journals Average Channel Capacity of Amplify-and-forward MIMO/FSO Systems Over Atmospheric Turbulence Channels

2018 ◽  
Vol 8 (6) ◽  
pp. 4334
Author(s):  
Duong Huu Ai
Keyword(s):  
Atmospheric Turbulence ◽  
Channel Capacity ◽  
Multiple Input Multiple Output ◽  
Mathematical Expression ◽  
Relay Channel ◽  
Free Space Optical ◽  
Amplify And Forward ◽  
Average Channel Capacity ◽  
Link Distance ◽  
Gamma Distributions

In amplify-and-forward (AF) relay channel, when the direct link between source and destination terminals is deeply faded, the signal from the source terminal to the destination terminal propagates through the relay terminals, each of which relays a signal received from the previous terminal to the next terminal in series. This paper, we theoretically analyze the performance of multiple-input multiple-output (MIMO) AF free-space optical (FSO) systems. The AF-MIMO/FSO average channel capacity (ACC), which is expressed in terms of average spectral efficiency (ASE) is derived taking into account the atmospheric turbulence effects on the MIMO/FSO channel. They are modeled by log-normal and the gamma-gamma distributions for the cases of weak-to-strong turbulence conditions. We extract closed form mathematical expression for the evaluation of the ACC and we quantitatively discuss the influence of turbulence strength, link distance, different number of relay stations and different MIMO configurations on it.

scholarly journals BER analysis of amplify-and-forward relaying FSO systems using APD receiver over strong atmospheric turbulence channels

2019 ◽  
Vol 9 (5) ◽  
pp. 3678
Author(s):  
Duong Huu Ai ◽  
Van Loi Nguyen
Keyword(s):  
Atmospheric Turbulence ◽  
Closed Form Expression ◽  
Free Space Optical ◽  
Amplify And Forward ◽  
Transmission Distance ◽  
Link Distance ◽  
Optimal Value ◽  
Atmospheric Loss ◽  
The Impact ◽  
Relay Stations

<span lang="EN-US">In this paper, we theoretically analyze the performance of amplify-and-forward (AF) serial relaying free-space optical (FSO) systems using avalanche photodiodes (APD) and subcarrier quadrature amplitude modulation (SC-QAM) over strong atmospheric turbulence channels modelled by gamma-gamma distribution. Closed-form expression for average bit error rate (BER) of system is theoretically derived talking into account APD shot noise, thermal noise as well as the impact of atmospheric loss and turbulence. The numerical results show that using AF relay stations can extend the transmission distance and help to improve performance of FSO system significantly when compared with the direct transmission. Moreover, the selection of APD gain value is indispensable to the system performance. The proposed system could be achieved the best performance by selecting an optimal APD gain value. In addition, the optimal value of APD gain also significantly depends on various conditions, such as link distance, the number of relay stations and APD receiver noise.</span>

scholarly journals Performance Improvement for Mixed RF–FSO Communication System by Adopting Hybrid Subcarrier Intensity Modulation

2019 ◽  
Vol 9 (18) ◽  
pp. 3724 ◽  
Author(s):  
Jiang ◽  
Zhao ◽  
Liu ◽  
Deng ◽  
Luo ◽  
...  
Keyword(s):  
Atmospheric Turbulence ◽  
Channel Capacity ◽  
Communication System ◽  
Rayleigh Distribution ◽  
Intensity Modulation ◽  
Phase Shift Keying ◽  
Free Space Optical ◽  
Pointing Error ◽  
Shift Keying ◽  
Binary Phase Shift Keying

The improvement for hybrid radio frequency–free space optical (RF–FSO) communication system in wireless optical communications has acquired growing interests in recent years, but rarely improvement is based on hybrid modulation. Therefore, we conduct a research on end-to-end mixed RF–FSO system with the hybrid pulse position modulation–binary phase shift keying–subcarrier intensity modulation (PPM–BPSK–SIM) scheme. The RF link obeys Rayleigh distribution and the FSO link experiences Gamma–Gamma distribution. The average bit error rate (BER) for various PPM–BPSK–SIM schemes has been derived with consideration of atmospheric turbulence influence and pointing error condition. The outage probability and the average channel capacity of the system are discussed as well. Simulation results indicate that the pointing error aggravates the influence of atmospheric turbulence on the channel capacity, and the RF–FSO systematic performance is improved obviously while adopting PPM–BPSK–SIM under strong turbulence and severe pointing error conditions, especially, when the system average symbol length is greater than eight.

Performance Analysis of a STBC FDM FSO Communication System with Direct Detection Receiver under Turbulent Condition

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Bobby Barua ◽  
S. P. Majumder
Keyword(s):  
Atmospheric Turbulence ◽  
Channel Capacity ◽  
Communication System ◽  
Direct Detection ◽  
Weather Conditions ◽  
Optical Receiver ◽  
Communication Link ◽  
Link Distance ◽  
Receive Diversity ◽  
Turbulent Condition

AbstractWeather conditions are severely degraded the performance of FSO communication link. Atmospheric turbulence is one of the important weather conditions that degrade the performance even under clear sky condition. In this paper, we provide a noble analytical approach to evaluate the performance of STBC coded FDM FSO communication system with direct detection optical receiver under turbulent condition. Analysis is carried out to find the channel capacity of RF subcarrier modulation taking into consideration the effect of strong atmospheric turbulence which is modeled as gamma-gamma distribution and the probability density function of the conditional CNR, conditioned on a given turbulence-induced fading is derived considering equal gain receive diversity combining technique with direct detection optical receiver followed by RF synchronous demodulation. Results are evaluated numerically in terms of average CNR, BER and channel capacity for several system parameters like turbulence variance, link distance, data rate, etc.

Performance Analysis of a Multiple Subcarrier Modulated FSO Communication System using Direct Detection Optical Receiver under the Effect of Weak Atmospheric Turbulence

2020 ◽  
Vol 41 (4) ◽  
pp. 453-461
Author(s):  
Bobby Barua ◽  
S. P. Majumder
Keyword(s):  
Atmospheric Turbulence ◽  
Direct Detection ◽  
Optical Receiver ◽  
Closed Form Expression ◽  
Free Space Optical ◽  
Power Penalty ◽  
Link Distance ◽  
Distance Data ◽  
Channel Analysis ◽  
Log Normal

AbstractIn this paper, an analytical approach is presented to evaluate the bit error rate (BER) of a free space optical (FSO) link with radio frequency (RF) multiple subcarrier modulation, taking into account the effect of weak atmospheric turbulence considering a direct detection optical receiver followed by RF synchronous demodulator for each sub-channel. Analysis is carried out to find a closed-form expression for conditional BER at the output of the RF demodulators conditioned on a given value of atmospheric turbulence-induced fading and intermodulation distortion (IMD). The average BER for each sub-channel is then found by averaging the conditional BER over the probability density function of the atmospheric turbulence modeled as log-normal distribution. Degradations of BER due to atmospheric turbulence are evaluated for several values of system parameters like number of RF subcarrier, turbulence variance, link distance, data rate and power penalty suffered by the system due to atmospheric turbulence and IMD. For a given system bandwidth, it is found that the maximum power penalty occurs when the subcarrier number is around four and the performance gradually improves with increase in the number of subcarrier. For example, at a system bandwidth of 20 GHz with subcarrier number 4, the power penalty at a BER of 10–9 is found to be 30 dB for a link distance of 3.6 km, whereas the power penalty reduces to 13 dB when the number of subcarrier is increased to 32.

scholarly journals BER and Channel Capacity Performance of an FSO Communication System over Atmospheric Turbulence with Different Types of Noise

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3454
Author(s):  
Zixuan Xu ◽  
Guanjun Xu ◽  
Zhengqi Zheng
Keyword(s):  
Atmospheric Turbulence ◽  
Channel Capacity ◽  
Communication System ◽  
Thermal Noise ◽  
Quantum Noise ◽  
Atmospheric Environment ◽  
Free Space Optical ◽  
Channel Parameters ◽  
Different Types ◽  
Capacity Performance

The propagation performance of a free-space optical (FSO) communication system in an atmospheric environment is restricted and degraded due to the influence of atmospheric turbulence. In this paper, both the lognormal and Gamma–Gamma channel models are employed to characterize this turbulence under weak-to-strong conditions. In addition, the average bit error rate and average channel capacity of an FSO communication system under the influence of background noise, thermal noise and quantum noise (resulting from the environment, the device, manual operation, etc.) are considered. Moreover, the comparison of system performance under different turbulence conditions and various noises are conducted. Simulation results reveal that thermal noise has a dominant effect on the FSO system. In addition, both the channel parameters and the system parameters have a significant influence on the performance of an FSO communication system.

RoFSO System Based on BCH and RS Coded BPSK OFDM for 5G Applications in Smart Cities

2021 ◽  
Author(s):  
Abhishek Kumar ◽  
Prabu Krishnan
Keyword(s):  
Atmospheric Turbulence ◽  
Orthogonal Frequency Division Multiplexing ◽  
Smart Cities ◽  
Multiple Input Multiple Output ◽  
Weather Conditions ◽  
Error Correcting Codes ◽  
Free Space Optical ◽  
Pointing Error ◽  
Shift Keying ◽  
Input Multiple Output

Abstract In recent years, the radio over free space optical (RoFSO) communication system has become a popular research topic in the field of 5G communication. Atmospheric turbulence typically degrades the performance of RoFSO system. Multiple input multiple output, aperture averaging, error correcting codes, and robust modulation are common mitigation techniques used to reduce the effects of atmospheric turbulence. In this paper, a Reed Solomon (RS) and Bose-Chaudhuri-Hocquenghem (BCH) coded binary shift keying (BPSK) orthogonal frequency division multiplexing (OFDM) based RoFSO system is proposed for 5G applications in smart cities. The average bit error rate (ABER) of the proposed system is investigated for various turbulence, weather, and pointing error cases. The ABER results for uncoded, BCH, and RS coded cases are compared. The results show that the BCH coded system outperforms the RS coded and uncoded systems in all turbulence regimes, weather conditions, and pointing error scenarios.

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