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 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 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.

scholarly journals Performance Evaluation of a 4 × 20-Gbps OFDM-Based FSO Link Incorporating Hybrid W-MDM Techniques

2021 ◽  
Vol 9 ◽  
Author(s):  
Mehtab Singh ◽  
Saleh Chebaane ◽  
Sana Ben Khalifa ◽  
Amit Grover ◽  
Sanjeev Dewra ◽  
...  
Keyword(s):  
Wavelength Division Multiplexing ◽  
Free Space ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Research Work ◽  
Weather Conditions ◽  
Free Space Optics ◽  
Limiting Factor ◽  
Future Health ◽  
Space Optics

Free space optics (FSO) has been recognized as a crucial technique to meet the high-bandwidth requirements in future wireless information transmission links. It provides a feasible solution to the last-mile bottleneck problem due to its merits that include high-speed data transportation and secure and low-latency networks. Due to these merits, FSO is a reliable technology for future health-care and biomedical services like the transmission of biomedical sensor signals. But the main limiting factor in the data transmission employing FSO links is adverse atmospheric weather conditions. This research work reports the designing and simulative evaluation of the performance of a high-speed orthogonal frequency division multiplexing–based free space optics link by incorporating wavelength division multiplexing of two independent frequency channels (193.1 THz and 193.2 THz) along with mode division multiplexing of distinct spatial laser Hermite–Gaussian modes (HG01 and HG03). Four independent 20-Gbps quadrature amplitude-modulated data signals are transported simultaneously under different atmospheric weather conditions using the proposed link. Also, the link performance has been investigated for an increasing beam divergence angle.

Empirical Evaluation of High-speed Cost-effective Ro-FSO System by Incorporating OCDMA-PDM Scheme under the Presence of Fog

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Sushank Chaudhary ◽  
Sunita Choudhary ◽  
Xuan Tang ◽  
Xian Wei
Keyword(s):  
Free Space ◽  
High Speed ◽  
Optical Network ◽  
Empirical Evaluation ◽  
Cost Effective ◽  
Free Space Optics ◽  
Space Optics ◽  
Optical Cable ◽  
Application Systems ◽  
Support Cost

AbstractRadio over free space optics (Ro-FSO) innovation saddles the vast limit of optical fiber and the portability from local to remote systems. To enhance the capacity of Ro-FSO systems without compromising the bandwidth, this work incorporates use of hybrid polarization division multiplexing (PDM) with optical code division multiplexing (OCDMA) schemes. Due to low deployment time and support cost, the vast majority of the current optical network application systems adopts free space optics (FSO) as the elective answer for suitably supplanting fiber optical cable. This study has incorporated PDM and OCDMA schemes to design a 50 Gbps Ro-FSO link. Ten channels, each with 5 Gbps of data, are transported via FSO link of 3500 m. In addition, the proposed PDM-OCDMA-Ro-FSO link is evaluated under various atmospheric commotions.

Design of high speed multistream free space optics link under clear weather conditions

2020 ◽  
Vol 3 (3/4) ◽  
pp. 195
Author(s):  
Shantanu Jagdale ◽  
Brijesh Iyer ◽  
Sanjay L. Nalbalwar ◽  
Shankar B. Deosarkar
Keyword(s):  
Free Space ◽  
High Speed ◽  
Weather Conditions ◽  
Free Space Optics ◽  
Space Optics ◽  
Clear Weather

A long-reach radio over free space optics (Ro-FSO) system using hybrid orthogonal frequency division multiplexing (OFDM)-multibeam concept with enhanced detection

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peramandai Govindasamy Kuppusamy ◽  
Kotteswaran Rajkumar ◽  
Rajagopal Maheswar ◽  
Soundarapandian Sheeba Rani ◽  
Iraj Sadegh Amiri
Keyword(s):  
Free Space ◽  
Orthogonal Frequency Division Multiplexing ◽  
Free Space Optics ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Detection Mechanism ◽  
Space Optics ◽  
Modulation Format ◽  
Single Sideband Modulation ◽  
Improved Performance

AbstractThis paper focuses on designing of a 10 Gbit/s-10GHz hybrid Orthogonal frequency division multiplexing (FDM) based Radio over Free Space Optics (Ro-FSO) transmission link using optical single sideband modulation format and its performance has been compared using a different number of transmission beams. The proposed link has been simulated and compared using 1-beam, 2-beam, and 4-beam in the system. We show that by using the 4-beam system in the OFDM-Ro-FSO link, a 3000 m range has been achieved reliably, which a notable improvement when compared to previous work is. Also, we show an improved performance of the system by using an enhanced detection mechanism using a Square root module (SRm) at the receiver side.

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