Realization of Wavelength-Time Modified Double Weight Codes Optical Code Division Multiple Access System

Abstract

Explosive growth of bandwidth demand together with advance in latest communication services and emerging applications have inspired interest in optical code division multiple access (OCDMA). The work focuses on analysis and demonstration of two-dimensional (2-D) modified double weight (MDW) OCDMA wavelength-time. The 2-D MDW uses balance-detection for mitigating multiple access interference. The property of cross-correlation results in optimum phase induces intensity noise suppression (PIIN). The proposed code achieves high scalability; below 10 -9 BER error floor the code cardinality reaches 254 simultaneous numbers of users which is double the 2-D PDC performance. The lowest effective power (P sr ) for minimum optical transmission requirement for smallest number of users is achieved at -17.5dBm. The 2-D MDW OCDMA simulation model is developed to validate the realization of the code for BER and distance performance. The 2-D MDW OCDMA code successfully suppresses PIIN and mitigating MAI which result in high cardinality, reduce P sr and improved distance. Various alternative approaches in OCDMA have been proposed to overcome PIIN reduction and improved system performance [3-9]. The 2-D hybrid codes with PIN suppression and MAI mitigation [5], Zou Wei et al. and Ghafouri Shiraz et al. [6] introduced fixed in-phase spectral

The effect of total noise on two-dimension OCDMA codes

“…The code also has the advantage of high cardinality and low effective transmitted power. The 2-D W/T MDW OCDMA code is derived from the 1-D MDW OCDMA [8,9]. The serious requirement in minimizing interference which is non-exclusive to all code groupings is the low crosscorrelation and high auto-correlation with low side flaps.…”

“…The average photocurrent output from the receiver is defined as the average output current of (PD0-PD1) minus (PD2-PD3) of the receiver and was expressed as [8,9]:…”