Performance Analysis of Duobinary and AMI Techniques Using LG Modes in Hybrid MDM-WDM-FSO Transmission System

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Zhenlei Zhou ◽  
Erkai Li ◽  
Haiguang Zhang

AbstractThis work is focused on transmission of duobinary and alternate mark inversion (AMI) modulation, adopting mode division multiplexing (MDM) of Laguerre Gaussian (LG) modes has been capitalized in wavelength division multiplexing (WDM) system, resulting in a 1.6 Gbps eight-channel free space optical communications (FSO) system. The simulation results show that duobinary offers better bit error rate (BER) performance compared to AMI for proposed hybrid MDM-WDM-FSO system.

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Zhenlei Zhou ◽  
Haiguang Zhang ◽  
Chun Lin ◽  
Abhishek Sharma

AbstractIn this paper, the bit error rate (BER) performance of Duobinary (DB) is compared with carrier-suppressed return-to-zero (CSRZ) based polarization interleaving (PI) schemes for high-speed transmission system. The system is integrated with wavelength-division multiplexing (WDM) scheme and PI scheme for free space optical communications (FSO). The simulation results show that DB offers betters BER performance compared to CSRZ in high-speed WDM-FSO-PI system.


2015 ◽  
Vol 25 (2) ◽  
pp. 147
Author(s):  
Bui Trung Ninh ◽  
Nguyen Quoc Tuan ◽  
Ta Viet Hung ◽  
Nguyen The Anh ◽  
Pham Van Hoi

We present the results of investigation  for  influence of amplified spontaneous emission (ASE) noise, noise figure (NF) and  chromatic dispersion on the performance of middle-distance Dense-wavelength-division-multiplexing (DWDM) networks using low-power pumped distributed Raman amplifiers (DRAs) in two different pump configurations, i.e., forward and backward pumping. We found that the pumping configurations, ASE noise, and dispersion play an important role for improving network performance by decrease of noise figure and bit error rate (BER) of the system. Simulation results show that the lowest bit error rate and low noise figure were obtained, when using forward pumping configuration. Moreover, we have also compared ASE noise powers of the simulation with these of the experiment. These results conclude that DRA with low pump power  ($<1$~W) is the promising key technology for short-- and/or middle-distance DWDM transmission networks.


2019 ◽  
Vol 40 (3) ◽  
pp. 307-314 ◽  
Author(s):  
Rajat Kumar Giri ◽  
Bijayananda Patnaik

Abstract In this paper, we study the performance improvement of free space optical (FSO) communication system with spatial diversity techniques employing hybrid pulse position modulation-binary phase shift keying-subcarrier intensity modulation (PPM-BPSK-SIM). The involvement of multiple photo-detectors in diversity based FSO systems offers an effective way to overcome scntillation. In this paper, we have simulated the bit error rate (BER) with respect to different parameters like average SNR, link distance at various weather conditions. The simulation results are verified in Matlab environment with the mathematical analysis. The simulation results show that higher order single input multiple output (SIMO) system achieves better BER performance and hybrid PPM-BPSK-SIM has significant improved performance than the common modulation schemes like PPM, BPSK-SIM.


2008 ◽  
pp. 68-78

The channels contributed in creating new pulse during the four-wave mixing (FWM) process are a subject of two features: the first is the fact that all channels are not working with probability %100 , but with p probability. Second, the bits transmitted are not all "1". Therefore, the equation of power generated using these features should be corrected. On the other hand, the use of equally spaced channels wavelength divisionmultiplexing (ESC WDM) system cause an increase in the number of new components generated that interfere with the active channels and increase the bit error rate. In order to reduce these interferences, we have provided an unequally spaced channels wavelength division-multiplexing (USC WDM) system composed of several sets. Each set consists of only four channels, which locations have been selected to cause no interferences between them. Neighboring sets are separated by a frequency spacing which should be large enough to reduce the interferences between the sets, andsmall enough to increase the total number of channels of the system.


Author(s):  
Hiền

Phân phối khoá lượng tử QKD (Quantum Key Distribution) là giải pháp có khả năng đảm an ninh vô điều kiện nhờ áp dụng luật cơ lượng tử để phân phối khóa an toàn giữa hai bên hợp pháp với sự hiện diện của kẻ nghe lén. Sử dụng vệ tinh để phân phối khóa lượng tử tới các trạm mặt đất qua kênh quang không gian tự do FSO (Free Space Optic) là giải pháp hứa hẹn tạo ra một mạng QKD phạm vi toàn cầu. Tuy nhiên, do ảnh hưởng của kênh FSO, đặc biệt là nhiễu loạn khí quyển, tốc độ truyền khóa bí mật SKR (Secret Key Rate) của các hệ thống QKD hiện tại bị hạn chế. Do đó, nghiên cứu này đề xuất mô hình hệ thống QKD đa kênh dựa trên ghép kênh phân chia theo bước sóng WDM (Wavelength Division Multiplexing) và ghép kênh sóng mang phụ SCM (Sub Carrier Multiplexing) nhằm tăng SKR. Sử dụng phương pháp phân tích lý thuyết với các công cụ giải tích và xác suất, nhóm tác giả đã xây dựng các công thức tính toán SKR và tỉ lệ lỗi bit lượng tử của hệ thống đề xuất. Kết quả khảo sát hiệu năng cho thấy, hệ thống QKD đa kênh cho phép cải thiện SKR so với hệ thống đơn kênh trong khi vẫn đảm bảo yêu cầu về QBER (Quantum Bit Error Rate).


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