Performance improvement of spectral amplitude coding-optical code division multiple access systems using NAND detection with enhanced double weight code

Abstract

The bit-error rate (BER) performance of the spectral amplitude coding-optical code division multiple access (SAC-OCDMA) system has been investigated by using NAND subtraction detection technique with enhanced double weight (EDW) code. The EDW code is the enhanced version of double weight (DW) code family where the code weight is any odd number and greater than one with ideal cross-correlation. In order to evaluate the performance of the system, we used mathematical analysis extensively along with the simulation experiment. The evaluation results obtained using the NAND subtraction detection technique was compared with those obtained using the complementary detection technique for the same number of active users. The comparison results revealed that the BER performance of the system using NAND subtraction detection technique has greatly been improved as compared to the complementary technique. #

Alleviation Noise Effect Using Flexible Cross Correlation Code in Spectral Amplitude Coding Optical Code Division Multiple Access Systems

“…and thermal noise 〉 〈 thermal i to evaluate the system performance. The proposed system is based on the NAND subtraction detection [10] with Fiber Bragg Grating (FBG) followed by a photo -detector. Signal to Noise Ratio (SNR) is calculated at the receiver side and only one photodiode accommodated for each user and I is denoted as the current flow through the photodiode.…”

“…The broadband pulse coming thru to the FBG as an incoherent light field is mixed and incident upon a photo-detector while the phase noise of the fields causes an intensity noise in term of the photo-detector output. The source coherence time c τ is given as [10]:…”

“…The proposed system was analyzed with transmitter and receiver, we used the same assumption that used in [10] and those are important for mathematical preliminaries simplicity. Since, to analyze the proposed system, we assume the following assumptions:…”

“…Based on the above assumptions, the proposed systems can easily analyze using the Gaussian approximation. The power spectral density of the received optical signals can be written as [10]:…”

“…(31) ℜ represents as the responsivity of the photo-detectors and is given by ℜ = ሺߟ݁ሻ/ሺℎ‫ݒ‬ ሻ where η is the quantum efficiency, e is the electron charge, h is the Planck's constant, and v c is the central frequency of the original broadband optical pulse [10]. By substituting Equation (29) into Equation (31), the photodiode current I can be written as follows:…”