scholarly journals Chip-interleaved optical code division multiple access relying on a photon-counting iterative successive interference canceller for free-space optical channels

2013 ◽  
Vol 21 (13) ◽  
pp. 15926 ◽  
Author(s):  
Xiaolin Zhou ◽  
Xiaowei Zheng ◽  
Rong Zhang ◽  
Lajos Hanzo
Keyword(s):  
Free Space ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Photon Counting ◽  
Free Space Optical ◽  
Optical Channels ◽  
Code Division Multiple ◽  
Interference Canceller

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.

Enhancement of reliability and security in spatial diversity FSO-CDMA wiretap channel

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jianjia Zhang ◽  
Bing Wu ◽  
Fang Peng ◽  
Zihua Zheng ◽  
Jianhua Ji
Keyword(s):  
Free Space ◽  
Physical Layer Security ◽  
Multiple Access ◽  
Multiple Access Interference ◽  
Spatial Diversity ◽  
Physical Layer ◽  
Closed Form Expression ◽  
Free Space Optical ◽  
Wiretap Channel ◽  
Code Division Multiple

AbstractDue to atmospheric turbulence, the reliability and security of free space optical (FSO) communication will be affected seriously. In this paper, we propose a novel scheme of quasisynchronous spatial diversity free-space optical code division multiple access (FSO-CDMA) wiretap channel based on gamma-gamma distribution. Considering multiple access interference, shot noise, thermal noise and background noise, performances of bit error rate (BER) and physical-layer security are analyzed theoretically. The physical-layer security of quasisynchronous spatial diversity FSO-CDMA wiretap channel is evaluated by secrecy capacity and interception probability. Closed-form expression of interception probability is obtained. In order to compare the performances between conventional spatial diversity FSO-CDMA and the proposed scheme, Optisystem simulation is carried out. The results indicate that quasisynchronous spatial diversity FSO-CDMA scheme can improve the reliability and physical-layer security simultaneously.

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.

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