Sangjo Park

Radio-over-fiber system using fiber-grating-based optical CDMA with modified PN codes

In this work, we propose the fiber Bragg grating (FBG)-based optical code-division multiple-access (CDMA) with the modified pseudorandom noise (PN) codes for the radio-over-fiber (ROF) systems, and we numerically analyze the characteristics of the proposed system. By the proposed FBG-based optical CDMA with the modified PN codes and spectrally uniform intensity light sources, it is possible to construct interference-free optical CDMA for ROF systems.

Performance Analysis for Optimizing Threshold Level Control of a Receiver in Asynchronous 2.5 Gbps/1.2 Gbps Optical Subscriber Network with Inverse Return to Zero(RZ) Coded Downstream and NRZ Upstream Re-modulation

We propose the performance enhancing method optimization of an asynchronous 2.5 Gbps/1.25 Gbps optical subscriber network with inverse RZ (Return to Zero) coded downstream and NRZ (Non Return to Zero) upstream re-modulation by adjusting threshold level control of a receiver. We theoretically analyze the BER (Bit Error Rate) performance by modeling the occurrence of BER by simulation with MATLAB according to the types of downstream data. The results have shown that the normalized threshold level in an optical receiver could be saturated at 1/3 as the SNR (Signal to Noise Ratio) increases. The needed SNR for obtaining the BER

WDM Passive Optical Networks with Symmetric Up/Down Data Rates using Manchester Coding based Re-modulation

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Performance Enhancement by Threshold Level Control of a Receiver in WDM-PON System with Manchester Coded Downstream and NRZ Upstream Re-Modulation

can be reduced by

Proposal Ultra-fast Multimedia Optical Subscriber Access Network to Guarantee the same Performance Regardless of Data Rates using Optical Frequency Domain CDMA Method

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Proposal of optical subscriber access network using optical CDMA method with optical switches

5 dB by optimizing the normalized threshold level at 1/3 instead of by using the conventional receiver with threshold level of 0.5. The proposed system can be a useful technology for asynchronous optical access networks with asymmetric upstream and downstream data rates, because the improved minimum receiving power could replace a light source with a source with lower power and lower cost in an OLT (Optical Line Termination).

An OCDMA Scheme to Reduce Multiple Access Interference and Enhance Performance for Optical Subscriber Access Networks

A re-modulation scheme with symmetric up/down data rates is proposed by using synchronization between Manchester coded downstream and re-modulated NRZ coded upstream. The signal transmission of 2.5 Gbit/s symmetric data rates was successfully demonstrated.

Optical CDMA transmitting apparatus and method for transmitting bipolar data

We propose and demonstrate a scheme enhancing the performance of optical access networks with Manchester coded downstream and re-modulated NRZ coded upstream. It is achieved by threshold level control of a limiting amplifier at a receiver, and the minimum sensitivity of upstream is significantly improved for the re-modulation scheme with 5Gb/s Manchester coded downstream and 2.488Gb/s NRZ upstream data rates.

Performance Analysis of Asynchronous 2.5 Gbps / 622Mbps Optical Subscriber Network with Manchester coded Downstream and NRZ upstream re-modulation

In this paper, we propose ultra-fast multimedia optical subscriber access network using optical frequency domain CDMA method in order to access the multimedia with multiple data rates. We numerically analyze the effects of spectral power distortion in the light source for the optical CDMA system modified PN codes and FBG(Fiber Bragg Grating)s. In the proposed multiple-rate multimedia access optical networks, the performances such as BER(Bit Error Rate) are the same for all data regardless of data rates in the case of the same number of simultaneous ONU. In the proposed ultra-fast multimedia optical subscriber access network, the performances for all data are much more improved than those in the conventional system.

Performance enhancement using the bipolar capacity of bipolar coded fiber Bragg gratings and balanced detection in the spectral encoded code-division-multiple-access systems

In this paper, we propose the ATM based Passive Optical Network (PON) using the optical CDMA scheme with optical switches and PN codes in time domain. We also propose the bipolar optical receiving correlator for PN codes. As optical CDMA is performed by driving directly an optical switch on-off switching with PN codes, the number of distinct code sequences can be increased and the flexibility in assigning PN codes can be improved. Finally we theoretically analyze the signal-to-interference -plus-noise ratio and the bit error probability of regenerated signal and compare the performance of proposed scheme compared with ATM based PON using conventional optical CDMA with optical delay lines.