Model of Increase of Spectral Efficiency of Use of Frequency Resource of Low-Orbit System with Architecture of the Distributed Satellite

Introduction: This article is based on the recent research work in the field of two subjects: signal data parameters in fiber optic communication links, and dispersive properties of optical signals caused by non-homogeneous material phenomena and multimode propagation of optical signals in such kinds of wired links.Purpose: Studying multimode dispersion by analyzing the propagation of guiding optical waves along a fiber optic cable with various refractive index profiles of the inner optical cable (core) relative to the outer cladding, as well as dispersion properties of a fiber optic cable due to inhomogeneous nature of the cladding along the cable, for two types of signal code sequences transmitted via the cable: return-to-zero and non-return-to-zero ones.Methods: Dispersion properties of multimode propagation inside a fiber optic cable are analyzed with an advanced 3D model of optical wave propagation in a given guiding structure. The effects of multimodal dispersion and material dispersion causing the optical signal delay spread along the cable were investigated analytically and numerically.Results: Time dispersion properties were obtained and graphically illustrated for two kinds of fiber optic structures with different refractive index profiles. The dispersion was caused by multimode (e.g. multi-ray) propagation and by the inhomogeneous nature of the material along the cable. Their effect on the capacity and spectral efficiency of a data signal stream passing through such a guiding optical structure is illustrated for arbitrary refractive indices of the inner (core) and outer (cladding) elements of the optical cable. A new methodology is introduced for finding and evaluating the effects of time dispersion of optical signals propagating in fiber optic structures of various kinds. An algorithm is proposed for estimating the spectral efficiency loss measured in bits per second per Hertz per each kilometer along the cable, for arbitrary presentation of the code signals in the data stream, non-return-to zero or return-to-zero ones. All practical tests are illustrated by MATLAB utility.

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INNOVATIVE METHOD OF SATELLITE COMMUNICATION

Visnyk Universytetu “Ukraina” ◽

10.36994/2707-4110-2019-1-22-17 ◽

2019 ◽

Author(s):

Teodor Narytnik ◽

Vladimir Saiko

Keyword(s):

Communication Systems ◽

High Speed ◽

Satellite Communication ◽

Radio Channel ◽

Satellite Communications ◽

Service Area ◽

Satellite Systems ◽

Orbit Satellite ◽

Geometric Size ◽

Distributed Satellite

The technical aspects of the main promising projects in the segments of medium and low-orbit satellite communication systems are considered, as well as the project of the domestic low-orbit information and telecommunications system using the terahertz range, which is based on the use of satellite platforms of the micro- and nanosatellite class and the distribution of functional blocks of complex satellite payloads more high-end on multiple functionally related satellites. The proposed system of low-orbit satellite communications represents the groupings of low-orbit spacecraft (LEO-system) with the architecture of a "distributed satellite", which include the groupings of the root (leading) satellites and satellite repeaters (slaves). Root satellites are interconnected in a ring network by high-speed links between the satellites. The geometric size of the “distributed satellite” is the area around the root satellite with a radius of about 1 km. The combination of beams, which are formed by the repeater satellites, make up the service area of the LEO system. The requirements for the integrated service area of the LEO system (geographical service area) determine the requirements for the number of distributed satellites in the system as a whole. In the proposed system to reduce mutual interference between the grouping of the root (leading) satellites and repeater satellites (slaves) and, accordingly, minimizing distortions of the information signal when implementing inter-satellite communication, this line (radio channel) was created in an unlicensed frequency (e.g., in the terahertz 140 GHz) range. In addition, it additionally allows you to minimize the size of the antennas of such a broadband channel and simplify the operation of these satellite systems.

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The Real-Time ObjectAgent Software Architecture for Distributed Satellite Systems

10.21236/ada451712 ◽

2001 ◽

Cited By ~ 7

Author(s):

Derek M. Surka ◽

Margarita C. Brito ◽

Christopher G. Harvey

Keyword(s):

Software Architecture ◽

Real Time ◽

The Real ◽

Satellite Systems ◽

Distributed Satellite

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Analysis of Optimum Precoding schemes in Millimeter Wave System

Recent Advances in Computer Science and Communications ◽

10.2174/2666255813666200102124758 ◽

2020 ◽

Vol 13 ◽

Author(s):

Divya Singh ◽

Aasheesh Shukla

Keyword(s):

Power Consumption ◽

Millimeter Wave ◽

Spectral Efficiency ◽

Phase Shifter ◽

Phase Shifters ◽

Achievable Rate ◽

Wave System ◽

Digital To Analog Converter ◽

Hybrid Precoding ◽

Analog Converter

Background : Millimeter wave technology is the emerging technology in wireless communication due to increased demand for data traffic and its numerous advantages however it suffers from severe attenuation. To mitigate this attenuation, phased antenna arrays are used for unidirectional power distribution. An initial access is needed to make a connection between the base station and users in millimeter wave system. The high complexity and cost can be mitigated by the use of hybrid precoding schemes. Hybrid precoding techniques are developed to reduce the complexity, power consumption and cost by using phase shifters in place of converters. The use of phase shifters also increases the spectral efficiency. Objective: Analysis of Optimum Precoding schemes in Millimeter Wave System. Method: In this paper, the suitability of existing hybrid precoding solutions are explored on the basis of the different algorithms and the architecture to increase the average achievable rate. Previous work done in hybrid precoding is also compared on the basis of the resolution of the phase shifter and digital to analog converter. Results: A comparison of the previous work is done on the basis of different parameters like the resolution of phase shifters, digital to analog converter, amount of power consumption and spectral efficiency. Table 2 shows the average achievable rate of different algorithms at SNR= 0 dB and 5 dB. Table 3 also compares the performance achieved by the hybrid precoder in the fully connected structure with two existing approaches, dynamic subarray structure with and without switch and sub connected or partially connected structure. Table 4 gives the comparative analysis of hybrid precoding with the different resolutions of the phase shifter and DAC. Conclusion: In this paper, some available literature is reviewed and summarized about hybrid precoding in millimeter wave communication. Current solutions of hybrid precoding are also reviewed and compared in terms of their efficiency, power consumption, and effectiveness. The limitations of the existing hybrid precoding algorithms are the selection of group and resolution of phase shifters. The mm wave massive MIMO is only feasible due to hybrid precoding.

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Tributary Mapping Multiplexing an Efficient Technique for High Speed Fiber Optic Communication

Pakistan Journal of Engineering Technology & Science ◽

10.22555/pjets.v6i2.1963 ◽

2018 ◽

Vol 6 (2) ◽

Author(s):

Usman Illahi ◽

Javed Iqbal ◽

Muhammad Ismail Sulaiman ◽

Muhammad Alam ◽

Mazliham Mohd Su'ud

Keyword(s):

Spectral Efficiency ◽

High Speed ◽

Fiber Optic ◽

Single Channel ◽

Efficient Technique ◽

High Dispersion ◽

Optical Filtering ◽

Fiber Optic Communication ◽

Optic Communication ◽

Dispersion Tolerance

<p>A novel technique of multiplexing called Tributary Mapping Multiplexing (TMM) is<br />applied to a single channel wavelength division multiplexing system and performance is monitored on the basis of simulation results. To elaborate the performance of TMM in this paper, a 4-User TMM system over single wavelength channel is demonstrated. TMM showed significant tolerance against narrow optical filtering as compared to that of conventional TDM at the rate of 40 Gbit/s. The above calculations are made by optical filter bandwidth and dispersion tolerance that was allowed at minimum. The spectral efficiency achieved by this TMM was 1 b/s/Hz and it was executed by using transmitters and receivers of 10 Gbit/s without polarized multiplexing. The high spectral efficiency, high dispersion tolerance and tolerance against strong optical filtering makes TMM an efficient technique for High<br />Speed Fiber Optic Communication.</p>

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Analysis of the spectral efficiency of filter-assisted wavelength conversion for polarity-preserving operation

33rd European Conference and Exhibition on Optical Communication - ECOC 2007 ◽

10.1049/ic:20070169 ◽

2007 ◽

Author(s):

A.M. Melo ◽

K. Petermann

Keyword(s):

Spectral Efficiency ◽

Wavelength Conversion

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Towards Higher Spectral Efficiency: Spatial Path Index Modulation Improves Millimeter-Wave Hybrid Beamforming

IEEE Journal of Selected Topics in Signal Processing ◽

10.1109/jstsp.2019.2919232 ◽

2019 ◽

Vol 13 (6) ◽

pp. 1348-1359 ◽

Cited By ~ 2

Author(s):

Jintao Wang ◽

Longzhuang He ◽

Jian Song

Keyword(s):

Millimeter Wave ◽

Spectral Efficiency ◽

Path Index ◽

Hybrid Beamforming ◽

Index Modulation

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Low-complexity beam-domain channel estimation and power allocation in hybrid architecture massive MIMO systems

EURASIP Journal on Wireless Communications and Networking ◽

10.1186/s13638-019-1546-6 ◽

2019 ◽

Vol 2019 (1) ◽

Author(s):

Xiao Chen ◽

Zaichen Zhang ◽

Liang Wu ◽

Jian Dang

Keyword(s):

Channel Estimation ◽

Power Allocation ◽

Spectral Efficiency ◽

Communication Systems ◽

Mimo Systems ◽

Beam Steering ◽

Estimation Method ◽

Low Complexity ◽

Estimation Accuracy ◽

Hybrid Architecture

Abstract In this journal, we investigate the beam-domain channel estimation and power allocation in hybrid architecture massive multiple-input and multiple-output (MIMO) communication systems. First, we propose a low-complexity channel estimation method, which utilizes the beam steering vectors achieved from the direction-of-arrival (DOA) estimation and beam gains estimated by low-overhead pilots. Based on the estimated beam information, a purely analog precoding strategy is also designed. Then, the optimal power allocation among multiple beams is derived to maximize spectral efficiency. Finally, simulation results show that the proposed schemes can achieve high channel estimation accuracy and spectral efficiency.

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