scholarly journals Bipolar Optical Code Division Multiple Access Techniques Using a Dual Electro-Optical Modulator Implemented in Free-Space Optics Communications

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3583
Author(s):  
Shin-Pin Tseng ◽  
Eddy Wijanto ◽  
Po-Han Lai ◽  
Hsu-Chih Cheng
Keyword(s):  
Free Space ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Transmission Rate ◽  
Free Space Optics ◽  
Optical Modulator ◽  
Spectral Amplitude ◽  
Space Optics ◽  
Electro Optical Modulator ◽  
Code Division Multiple

This study developed a bipolar optical code division multiple access (Bi-OCDMA) technique based on spectral amplitude coding for the formation and transmission of optical-polarized and coded signals over wireless optical channels. Compared with conventional Bi-OCDMA schemes, the proposed free-space optics communication system that uses a dual electro-optical modulator design improves the transmission rate. In theory, multiple access interference can be removed by using correlation subtraction schemes. The experiment results revealed that the proposed system can be employed to accurately extract codewords from an M-sequence and subsequently reconstruct the desired original data. Moreover, the proposed architecture can be implemented easily in simple and cost-effective designs and may be beneficial for broadening the use of Bi-OCDMA schemes in wireless optical communications.

Performance comparison of code division multiple access and orthogonal frequency division multiplexing over turbulent effected free space optics link under the impact of advance coding formats

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Heena Arora ◽  
Vishal Sharma
Keyword(s):  
Free Space ◽  
Code Division Multiple Access ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
Data Rate ◽  
Free Space Optics ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Space Optics ◽  
Code Division Multiple

Abstract Free space optics (FSO) systems have gained considerable attention because of their numerous features and services. It has evolved into a promising technology for high data rate transmission in wireless communication systems. However, there are some atmospheric effects which inhibit its performance. In this paper, performance of code division multiple access–free space optics (CDMA–FSO) by combining multidiagonal (MD) codes and orthogonal frequency division multiplexing–free space optics (OFDM-FSO) systems over using advance line coding formats under the sway of turbulence conditions are investigated and compared. A comparative study has shown that CDMA–FSO offers better SNR with both CSRZ and AMI coding format under diverse conditions at data rate 15 and 20 Gbps.

scholarly journals Performance Analysis of Bipolar Optical Code Division Multiple Access with Dual Electro-Optical Modulator Scheme for Free-Space Optical Communication

2021 ◽  
Vol 20 (2) ◽  
pp. 67-82
Author(s):  
Eddy Wijanto
Keyword(s):  
Optical Communication ◽  
Fading Channel ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Optical Modulator ◽  
Free Space Optical ◽  
Electro Optical Modulator ◽  
M Sequence ◽  
Code Division Multiple ◽  
Hadamard Code

In this study, the performance of bipolar optical code division multiple access (OCDMA) with dual electro-optical modulator (EOM) scheme for multi-user scenario was tested and analyzed with OptiSystem version 10. The performance measurement was implemented for free-space optical (FSO) communication and includes the common noises in optical communication. Two different channels were used in the measurement, i.e., additive white Gaussian noise (AWGN) and fading channel. Two extreme weather conditions, strong rain and storm, were considered in the simulation. The performance between three spectral amplitude coding (SAC) codes, i.e., Modified M-Sequence code, Walsh-Hadamard code, and random diagonal (RD) code were measured and compared. The simulation results indicate that Modified M-Sequence code had the highest BER while RD code achieved the lowest BER in the short-range and Walsh-Hadamard code got the lowest BER for the medium-range of FSO, both for AWGN only and AWGN with fading channel. In strong turbulence condition, the performance of all codes become comparable after 500 m of FSO range. Modified M-Sequence suffered the lowest performance degradation while RD code endured the highest performance deterioration in all-weather condition. The results show that Modified M-Sequence can be applied for medium to long-range FSO.

Hybrid Analog/Digital Modulations Using Polarization Multiplexing OCDMA Scheme in Free Space Optics

2015 ◽  
Vol 764-765 ◽  
pp. 511-514
Author(s):  
Chih Ta Yen ◽  
Chia Yu Liu
Keyword(s):  
Free Space ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
High Speed ◽  
Base Station ◽  
Free Space Optics ◽  
Detection Scheme ◽  
Space Optics ◽  
Polarization Multiplexing ◽  
Code Division Multiple

With the development of the Internet, how to provide a high-speed and high-security comprehensive network has become urgent issue. In this project, we propose hybrid analog/digital transmissions format scheme which integrated optical code-division multiple-access (OCDMA) and polarization multiplexing technique in free space optics (FSO) transmission. Orthogonal frequency division multiplexing (OFDM) transmits as the analog format and (on-off keying) OOK transmits as digital format in the study, respectively. In the proposed hybrid OCDMA system, it has high-speed transmission, signal security and low cost...etc. we adopt quasi-orthogonal Walsh-Hadamard codes (WHC) that with fixed cross correlation value as the codeword for each base station. With the property, the multiple access interference (MAI) can be efficiently eliminated by using the balanced detection scheme at the receive end. The constellation and eye diagrams show that both OFDM signal as analog signal and OOK modulation as digital signal in the proposed hybrid OCDMA system perform good performance in FSO transmission.

Performance Analysis of Spectral Amplitude Coding Optical Code Division Multiple Access System using Modified Double Weight Codes with Adomian Decomposition Method

2018 ◽  
Vol 39 (4) ◽  
pp. 459-462 ◽  
Author(s):  
Monika Rani ◽  
Harbax Singh Bhatti ◽  
Vikramjeet Singh
Keyword(s):  
Code Division Multiple Access ◽  
Multiple Access ◽  
Decomposition Method ◽  
Adomian Decomposition Method ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Adomian Decomposition ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple ◽  
Multiple Access System

Abstract In this manuscript, we have analyzed a Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) System. The system performance is enhanced by reducing the effect of Multiple Access Interference (MAI) using uniform Fiber Bragg Gratings (FBGs) encoders and decoders at central office and subscriber’s end. The results are verified through a mathematical model and Modified Double Weight (MDW) codes for the proposed system using Adomian Decomposition Method (ADM). Further, we have demonstrated SAC-OCDMA system for transmission of 40 Gbps data rate up to a distance of 80 km by increasing the number of FBGs. The proposed system has been analyzed in terms of distance, bit error rate (BER) and Quality Factor.

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