Dynamic OC2DMA Communication Systems in a Noisy Environment

Title: Dynamic OC2DMA Communication Systems in a Noisy Environment

Author        : Reda El-Sheshtawy Mohamed

Collection   : Ph.D. Electric

Abstract:

The optical orthogonal code division multiple access (OOCDMA) has been widely used in both one dimensional (1D) and two dimensional (2D) wavelengths hopping/time spreading (CDMA) systems. This thesis give an overview on time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA). It discusses optical CDMA techniques, optical CDMA devices, and types of OCDMA. The types of optical CDMA receivers have been studied. Also, we demonstrate optical orthogonal codes, mark position differences, and noises in optical systems, especially shot and thermal noises.

Proposing a new code called OC²DMA and a new implementation for dynamic OC²DMA transmitter and receiver. The probability of error for a dynamic noiseless optical system with different codes (1D OCDMA, 2D OCDMA, and OC²DMA), using 15 active users, 31 wavelengths and code lengths between (9 to 25) and (25 to 49) chips, have been analyzed. The effect of shot noise and of shot and thermal noises together, on the performance of 1D OCDMA, 2D OCDMA, and OC²DMA wavelength hopping/time spreading dynamic noisy systems is analyzed.

Also the probability of error is calculated for general systems employing asymmetric prime-hop codes (APHCs). A comparison is held between the performance of dynamic [1D OCDMA (0.90 × 10^-2), 2D OCDMA (0. 97 × 10^-2), and OC2DMA (0.20× 10^-5)] correlation receivers under the effect of both shot and thermal noises. The analysis reveals that the performance of the dynamic noisy OC²DMA correlation receiver is better than both dynamic noisy 1D CDMA correlation receiver and dynamic noisy 2D OCDMA correlation receiver.

In addition, a comparison is held between the performance of both idealized and noisy dynamic [1D OCDMA (0.9× 10^-8), 2D OCDMA (0. 55× 10^-8), and OC2DMA (0.5× 10^-12)] correlation receivers. The comparison reveals, in general, that the performance of the dynamic OC²DMA correlation receiver is better than both dynamic 1D OCDMA correlation receiver and dynamic 2D OCDMA correlation receiver.