scholarly journals Complimentary code keying of spectral amplitude coding signals in optical buffering with increased capacity

Author(s):  
Kai-Sheng Chen ◽  
Wien Hong
Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1117 ◽  
Author(s):  
Chen ◽  
Chen ◽  
Wu

Buffering management is a crucial function in current optical packet switching (OPS) networks. To avoid packet blocking due to competition for the same switched path, optical buffering is required to queue packets after a router makes the forwarding decision. In this paper, the author proposed a buffering scheme based on optical code-division multiple access (OCDMA), where each packet is encoded with an optical signature code. An optical coding technique combining spectral-amplitude coding (SAC) and two-code keying (TCK) is introduced to advance the buffering performance regarding packet loss probability. In TCK, the payload bits “1” and “0” of a stored packet are respectively converted to a SAC signal and its complementarity. As the Hamming distance between the coding signals of bits “1” and “0” is extended, the existing drawback that the OCDMA-based buffer capacity is limited by the decoder noise increased with the number of queued SAC packets is resolved. Moreover, an encoder consisting of a fiber Bragg grating (FBG) array is applied for simplifying the system design. A SAC signal and its complementary counterpart can be generated simultaneously without the need of an extra encoder.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Majidah H. Majeed ◽  
Riyadh Khlf Ahmed

AbstractSpectral Amplitude Coding-Optical Codes Division Multiple Access (SAC-OCDMA) is a future multiplexing technique that witnessed a dramatic attraction for eliminating the problems of the internet in optical network field such as multiple-user access and speed’s growth of the files or data traffic. In this research article, the performance of SAC-OCDMA system based on two encoding–decoding multidiagonal (MD) and Walsh Hadamard (WH) codes is enhanced utilizing three different schemes of dispersion compensating fiber (DCF): pre-, post- and symmetrical compensation. The system is simulated using Optisystem version 7.0 and Optigrating version 4.2. The performance of the proposed system is specified in terms of bit error rate (BER), Q-factor and eye diagram. It has been observed that the compensated system based on MD code is performs much better compared to the system based on WH code. On the other hand, the compensated SAC-OCDMA system with symmetrical DCF has the lowest values of BER and largest values of Q-factor, so it is considered the best simulated scheme contrasted with pre- and post-DCF.


Author(s):  
C. B. M. Rashidi ◽  
S. A. Aljunid ◽  
F. Ghani ◽  
M. S. Anuar ◽  
H. Al-Khafaji ◽  
...  

2018 ◽  
Vol 39 (2) ◽  
pp. 215-221 ◽  
Author(s):  
Manisha Bharti ◽  
Manoj Kumar ◽  
Ajay K. Sharma

AbstractThe main task of optical code division multiple access (OCDMA) system is the detection of code used by a user in presence of multiple access interference (MAI). In this paper, new method of detection known as XOR subtraction detection for spectral amplitude coding OCDMA (SAC-OCDMA) based on double weight codes has been proposed and presented. As MAI is the main source of performance deterioration in OCDMA system, therefore, SAC technique is used in this paper to eliminate the effect of MAI up to a large extent. A comparative analysis is then made between the proposed scheme and other conventional detection schemes used like complimentary subtraction detection, AND subtraction detection and NAND subtraction detection. The system performance is characterized by Q-factor, BER and received optical power (ROP) with respect to input laser power and fiber length. The theoretical and simulation investigations reveal that the proposed detection technique provides better quality factor, security and received power in comparison to other conventional techniques. The wide opening of eye in case of proposed technique also proves its robustness.


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