Satellite Optical Communication System Research Articles

Mid-wave infrared optical receiver based on an InAsSb-nBn photodetector using the barrier doping engineering technique for low-power satellite optical wireless communication.

This paper proposes a new nBn photodetector (nBn-PD) based on InAsSb with a barrier doping engineering technique [core-shell doped barrier (CSD-B) nBn-PD] for utilization as a low-power receiver in satellite optical wireless communication (Sat-OWC) systems. In the proposed structure, the absorber layer is selected from an I n A s 1-x S b x (x=0.17) ternary compound semiconductor. The difference between this structure and other nBn structures is the placement of the top and bottom contacts in the form of a PN junction, which increases the efficiency of the proposed device through the creation of a built-in electric field. Also, a barrier layer is placed from the AlSb binary compound. The presence of the CSD-B layer with the high conduction band offset and very low valence band offset improves the performance of the proposed device compared to conventional PN and avalanche photodiode detectors. By applying -0.1V bias at 125K, the dark current is demonstrated at 4.31×10-5 A/c m 2 by assuming high-level traps and defect conditions. Examining the figure of merit parameters under back-side illumination with a 50% cutoff wavelength of 4.6µm shows that at 150K, the responsivity of the CSD-B nBn-PD device reaches about 1.8A/W under 0.05W/c m 2 light intensity. Regarding the great importance of using low-noise receivers in Sat-OWC systems, the results indicate that the noise, noise equivalent power, and noise equivalent irradiance are calculated as 9.98×10-15 A H z -1/2, 9.21×10-15 W H z 1/2, and 1.02×10-9 W/c m 2, respectively, at -0.5V bias voltage and 4µm laser illumination with the influence of shot-thermal noise. Also, D ∗ obtains 3.26×1011 c m H z 1/2/W without using the anti-reflection coating layer. In addition, since the bit error rate (BER) plays an essential role in the Sat-OWC systems, the effect of different modulations on the BER sensitivity of the proposed receiver is investigated. The results represent that the pulse position modulation and return zero on-off keying modulations create the lowest BER. Attenuation is also investigated as a factor that significantly affects BER sensitivity. The results clearly express that the proposed detector provides the knowledge to achieve a high-quality Sat-OWC system.

Ultra-High Capacity Optical Satellite Communication System Using PDM-256-QAM and Optical Angular Momentum Beams.

Twisted light beams such as optical angular momentum (OAM) with numerous possible orthogonal states have drawn the prodigious contemplation of researchers. OAM multiplexing is a futuristic multi-access technique that has not been scrutinized for optical satellite communication (OSC) systems thus far, and it opens up a new window for ultra-high-capacity systems. This paper presents the 4.8 Tbps (5 wavelengths × 3 OAM beams × 320 Gbps) ultra-high capacity OSC system by incorporating polarization division multiplexed (PDM) 256-Quadrature amplitude modulation (256-QAM) and OAM beams. To realize OAM multiplexing, Laguerre Gaussian (LG) transverse mode profiles such as LG00, LG140, and LG400 were used in the proposed study. The effects of the receiver's digital signal processing (DSP) module were also investigated, and performance improvement was observed using DSP for its potential to compensate for the effects of dispersion, phase errors, and nonlinear effects using the blind phase search (BPS), Viterbi phase estimation (VPE), and the constant modulus algorithm (CMA). The results revealed that the proposed OAM-OSC system successfully covered the 22,000 km OSC link distance and, out of three OAM beams, fundamental mode LG00 offered excellent performance. Further, a detailed comparison of the proposed system and reported state-of-the-art schemes was performed.

Research of Surface Scattering Characteristics of Metal Structures in Satellite Optical Communication System

Research of Surface Scattering Characteristics of Metal Structures in Satellite Optical Communication System

Probability density function of fiber-coupling efficiency and temporal power spectrum of irradiance fluctuations in the anisotropic non-Kolmogorov satellite-to-ground downlink

As many related experimental and theoretical results are identified, scholars have found that the anisotropy of turbulence cells is indispensable in the atmospheric turbulence. In this paper, based on a new anisotropic non-Kolmogorov turbulence spectrum for the satellite links that is applicable to both vertical and slant links, the probability density function of fiber-coupling efficiency and the temporal power spectrum of irradiance fluctuations for a plane wave propagating through the weak anisotropic non-Kolmogorov satellite-to-ground downlink are developed. The results show that when the zenith angle is greater than a certain angle, the probability density function of fiber-coupling efficiency shifts to the side with smaller coupling efficiency with the rising of anisotropic factor, and the temporal power spectrum of irradiance fluctuations and the absolute value of power exponent at high frequencies increase with the growing of anisotropic factor and power law, but while the zenith angle is less than the certain angle, the opposite trend will appear. It is anticipated that this work will benefit the understanding of laser beam transmission in anisotropic non-Kolmogorov satellite links and provide the theoretical basis for the design and parameter optimization of satellite optical communication systems based on fiber-coupling.

Turbulence spectrum model and fiber-coupling efficiency in the anisotropic non-Kolmogorov satellite-to-ground downlink

Increasing experimental and theoretical results have confirmed that the anisotropy of turbulence cells cannot be ignored in the atmospheric turbulence. The satellite-to-ground downlink is the important part of satellite optical communication network, so the anisotropic non-Kolmogorov turbulence spectrum model for the satellite links needs to be established urgently. However, the previously derived turbulence spectrum model for the satellite links is only applicable to vertical links. In this paper, considering the ellipsoid hypothesis of turbulence cell, we derive a new anisotropic non-Kolmogorov turbulence spectrum for the satellite links that is applicable to both vertical and slant links. Then based on this spectrum, the fiber-coupling efficiency for a Gaussian-beam propagating through the weak-to-strong anisotropic non-Kolmogorov satellite-to-ground downlink is developed. The results show that when the zenith angle is greater than a certain angle, the coupling efficiency decreases with the rising of anisotropic factor, but while the zenith angle is less than the certain angle, the opposite trend will appear. It is anticipated that this work will benefit the understanding of laser beam transmission in the anisotropic non-Kolmogorov satellite links and provide the theoretical basis for the design and parameter optimization of satellite optical communication systems based on fiber-coupling.

Satellite platform vibration influence on acquisition system for intersatellite optical communications

Accurate pointing, acquisition and tracking systems are an important part of maintaining stable intersatellite optical communications links. Satellite platform vibration causes system instability and reduces the system precision during the building and maintaining satellite optical communication system. This manuscript studies the satellite platform vibration influence on acquisition system for intersatellite optical communications. Considering the scan parameters and platform vibration, an approximately analytical expression of scan lost possibility (SLP) is derived through newly models for acquisition analysis. Taken scanning restricted condition and SLP into account, vibration influence on the acquisition time of single-scan and multi-scan is also presented. And the theoretical result calculated by the proposed analytical expression is approximately to the result by Monte Carlo simulation.

Performance Analysis of Polar Codes and LDPC Codes in Optical Satellite Communication Systems

Performance Analysis of Polar Codes and LDPC Codes in Optical Satellite Communication Systems

Acquisition performance analysis for intersatellite optical communications with vibration influence**Project supported by the Program of Excellent Team in Harbin Institute of Technology, China.

A stable and accurate pointing, acquisition system is an important part of initially building intersatellite optical communication links. Satellite platform vibration can cause the system instability and reduce the system precision in building and maintenance of a satellite optical communication system. In this paper, vibration influence is consciously discussed by acquisition time for intersatellite optical communications. Analytical expression of acquisition possibility is derived, taking the scan parameters and platform vibration into account, and vibration influence on the multi-scan acquisition time is also presented. The theoretical result calculated by the proposed analytical expression is approximate to the result by the Monte Carlo simulation.

Performance analysis of interleaved LDPC for optical satellite communications

Optical wireless communications using a laser is a strong candidate for the next generation satellite communications due to its large bandwidth. However, the channel environment of satellite communications is very tough, suffering from fading by atmospheric turbulence. Therefore, an efficient channel coding such as low-density parity check (LDPC) coding is required to satisfy stable transmission. In this paper, fading noise from atmospheric turbulence is reproduced to simulate the satellite channel. Then, this time-varying signal is used to evaluate the performance of the LDPC codes in different channel environments. At the same time, in order to improve the system performance further, an interleaving method in combination with LDPC codes is proposed to overcome the problem of burst error, which frequently occurs in the optical satellite communication systems (OSC). Simulation results show that the block-interleaving scheme can achieve a 5 dB gain compared to the pure LDPC scheme. The processing time is considered to determine the proper size of interleaving blocks suitable for optical satellite communications.

Design And Analysis Of Ultra High Capacity DWDM System With And Without Square Root Module For Different Modulation Formats

In this paper, an ultra high capacity Inter satellite Optical Wireless Communication system (IsOWC) is simulated with and without square root module for different advanced modulation formats. The system is proposed by using 64 channels dense wavelength division multiplexing. For various input powers, the inter satellite link has been designed for external modulation of carrier suppressed return-to-zero(CSRZ), duo binary return-to-zero(DRZ), and modified duo binary return-to-zero(MDRZ) at different bit rate. The system is simulated without square root module at 10, 20 and 40Gbps and only at 40Gbps with square root module. The performance parameters Q-factor, eye diagram, received power are obtained for different bit rates to decide which modulation format is best. Results at 10 and 20Gbps shows that the CSRZ modulation performs better than the other two modulations but at 40Gbps MDRZ modulation performs the best. The results of previous system are only compared at 40Gbps with the new system which includes square root module and comparison shows that MDRZ still have the best performance but the performance of DRZ is very much enhanced as compared to without square root at 40Gbps.

The Study on Reducing Mixed Image Noise of Beacon Spot in Satellite Optical Communication

In satellite optical communication system, the spot centroid locating of a beacon plays an important role in establishment and maintenance of laser links. In this paper, we analyze the type and source of noises in a laser spot, and the principles of some denoising methods are summarized. To improve spot locating accuracy, four different methods are used to process the mixed noise. The simulation results show that denoising effect of Butterworth low-pass filtering is relatively good. This work provides guidance for spot locating in satellite optical communication system.

卫星光通信系统振动源的模拟设计

卫星光通信系统振动源的模拟设计

Design of a Standardized Inter Satellite Optical Wireless Communication (IsOWC) System with Minimum Input Power

This paper proposes a novel method for low power communication between two Low Earth Orbiting satellites. The IsOWC system is designed for minimum input power of 27.02 dBm and -7.6 dBm, at 2.5Gbps. A standardized system for a distance of 5000km and wavelength 1550nm is designed and its performance is analysed by varying the modulation schemes and filters. A Square root (SQRT) transfer function module (SRm) is used to compensate the square-law characteristic of the photodiode. By using SRm in the system 67% increment in system efficiency is observed. The optimized performance is obtained by using NRZ scheme and Bessel filter. Highest Q factor of 6.70dB and 6.72dB are obtained for simulation with NRZ scheme and Bessel filter respectively, with minimum BER 10-12.

Investigation of Costas Loop Synchronization Effect on BER Performance of Space Uplink Optical Communication System With BPSK Scheme

The Costas loop is the key technique of synchronous demodulation in the next generation of satellite optical communication systems. To better understand the Costas loop, the relationship between phase deviation of the Costas loop and bit error rate (BER) performance of a binary-phase-shift keying (BPSK) space uplink optical communication system is achieved. Furthermore, the BER performance versus frequency deviation, zenith angle, data rate, and divergence angle are analyzed. Simulation results indicate that BER performances are not sensitive for parameters when the phase deviation of the Costas loop is designed with restriction of $\pi/16$ . These results are helpful for enhancing BER performance and the design of space optical communication systems.

Reliability of laser diodes for laser satellite communication in space radiation environment

The reliability of laser diodes is important for use in satellite optical communication systems, which is significantly influenced by space radiation effects. Degradation of laser diodes is induced by incident particles whose arrivals obey Poisson distribution, and the impact of each particle obeys normal distribution. Therefore, degradation process is regarded as a composite process, and its distribution is subsequently deduced. Reliability characteristics are evaluated based on simulated degradation data, and the error of evaluation is analyzed.

Comparative Analysis of Inter Satellite Optical Wireless Channel for NRZ and RZ Modulation Formats for Different Levels of Input Power

Abstract Integration of DWDM in Optical wireless communication has undoubtedly revolutionized the satellite communication systems for use in the coming future. Thus OWC systems have become popular due to their outstanding performance uniqueness. This paper looks into the performance of Inter Satellite Optical Wireless Communication system link using DWDM multiplexing technique for long distance transmission. The Inter satellite link has been modeled at a data rate of 10 Gbps for communication range of 5000 kilometers. Furthermore, it demonstrates a comparative analysis of RZ (Return to zero) and NRZ (Non-return to zero) modulation formats by varying the levels of input power.

Comparative Investigation Of Different Receiver Filter In The Satellite Optical Wireless Communication Systems

Comparative Investigation Of Different Receiver Filter In The Satellite Optical Wireless Communication Systems

Markov process based reliability model for laser diodes in space radiation environment

The reliability of laser diodes is a prerequisite for use in satellite optical communication systems, which is significant influenced by both displacement damage effect and annealing effect. A reliability model was proposed to evaluate the reliability and lifetime for laser diodes in space radiation environment. Degradation process is separated into discrete states, and reliability model is subsequently established based on Markov process. The Markov process consists of a Poisson process and an exponential process, representing the displacement damage effect and annealing effect, respectively. Reliability characteristics of a given laser diode are simulated over 100,000h, and applicability of this reliability model is demonstrated by analyzing the variety trend of probability density of performance states.

Experimental research of gamma-ray radiation of the key components in optical satellite communication system

To verify the potential space radiation-induced degradation of optical satellite communication system, the γ ray radiation experiments of its key components have been developed. No obvious performance degradations of the DFB laser and photo detector module were found at the total dose less than 150krad. The EDFA seems to be the most radiation sensitive, and it comes to its malfunction through the radiation of 16.2krad. It is believed that the high energy particles’ radiation effect should be first considered when it refers to the optical terminals’ applications in the space.

Performance analysis of a multiple-input-single-output optical satellite communication system with correlated pointing errors

In this study, the performance of multiple-input-single-output optical communication schemes is analysed in the context of inter-satellite communication. The analysis covers two types of diversity schemes: selection combining (SC) and equal gain combining. Outage probabilities with correlated errors are derived. The main results are expressed in terms of the first-order Marcum Q-function. It is shown that the merit of combining is obvious when the correlation coefficient is less than 0.5 and equal gain combining (EGC) has an advantage over SC in power utilisation.