Publication:
Development of new two dimensional ZCC/MD spectral/spatial code for OCDMA system
Development of new two dimensional ZCC/MD spectral/spatial code for OCDMA system
Date
2019
Authors
Rima Matem
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Publisher
Research Projects
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Abstract
The expanding interest in traffic information has led to an increase of the capacity and functionality of communication systems. For this reason, various multiplexing techniques have been introduced with the purpose of allowing multiple users to share the same optical domain simultaneously. The basis of the system revolution is large bandwidth, the data transmission and security of transmitted information. Optical Code Division
Multiple Access (OCDMA) is the most popular multiplexing technique due to its advantages which include the ability to provide as high capacity, flexible bandwidth, and capacity to improve the systemβs security, large cardinality and scalable asynchronous access. In this technique, each user is assigned by a unique and specific address code. The OCDMA system can be affected by two major challenges which are Multiple Access
Interference (MAI) and Phase Induced Intensity Noise (PIIN). Thus, a suitable code with a good cross-correlation property is needed in order to suppress the effect of MAI and mitigate PIIN. Based on this assumption, many 1D codes have been developed in different domain (wavelength, time and space), but using 1D codes require a very long code length in order to increase the number of simultaneous users. However, twodimensional
codes have been introduced with the purpose of enhancing the system performance by increasing the number of simultaneous users with short code length compared to 1D codes. The 2D spectral/spatial is one of the developed schemes. In this thesis, a new 2D hybrid code is proposed for the spectral/spatial scheme called 2D Zero Cross-correlation/Multi-Diagonal (ZCC/MD) code to overcome the mentioned defies (MAI and PIIN). The development of the proposed code is based on ZCC and MD codes where the 1D ZCC code is used for the spectral encoding while 1D MD is used for spatial spreading. Due to this combination, the effect of MAI can be completely suppressed and the PIIN is mitigated and offer a developed code a good cross correlation property. In addition, the mathematical and simulation analysis have also been investigated. The mathematical equation derivation is presented in terms of SNR and BER by taking into consideration different noises at the receiver, and using the simulation software πππ‘πππ¦π π‘ππππ version 7.0 from πππ‘ππ€ππ£π for the validation. The theoretical findings show that 2D ZCC/MD exhibits a better performance than the 2D Flexible Crosscorrelation/ Modified Double (FCC/MDW) and 2D Diluted Perfect Difference Code (DPDC), in terms of cardinality. It was found that the new proposed 2D ZCC/MD code achieves a high cardinality and scalability whereby it attains 360 users at the standard BER with an improvement factor value of 240%. In addition, the decoder of the 2D
ZCC/MD system is characterized by simplicity, due to the direct detection technique used at the receiver. This study established that a 2D ZCC/MD spectral/spatial code can successfully improve the system performance, where the simulation finding validate that 2D ZCC/MD code can be used and exploited in the optical CDMA network.
Description
Doctor of Philosophy
Keywords
Optical Code Division Multiple Access (OCDMA),
Multiple Access Interference (MAI),
Phase Induced Intensity Noise (PIIN),
Two dimensional ZCC,
MD spectral,
Spatial code