M.N. Junita

Phase-induced intensity noise suppression wavelength-time modified double weight codes optical code division multiple access systems

The wavelength-time modified double weight (MDW) optical division multiple access (OCDMA) scheme to reduce multiple access interference (MAI) and compensate bit error rate (BER) and phase-induced intensity noise (PIIN) in incoherent OCDMA systems is proposed. The analysis permits thorough understanding of PIIN, shot and thermal noises effect on 2-Dimensional (2-D) MDW OCDMA system performance. PIIN is the dominant noise factor in the OCDMA time-spreading scheme. The 2-D MDW code shows better tolerance to PIIN in comparison to others with enhanced system performance. We prove by numerical analysis that the PIIN is maximally suppressed by the proposed code through minimizing property of cross-correlation in comparison to the 2-D PDC and 2-D MQC OCDMA code.

Modeling and simulation of variable weight zero cross correlation code in optical access network

In this paper, we demonstrate a novel architecture of variable weight Zero Cross Correlation code in the family of Spectral Amplitude Coding(SAC) Optical Code Division Multiple Access (OCDMA) to be utilized in the triple play services of OCDMA applications based on the end users demand and requirements. This is achieved by adapting multiple weights of Zero Cross Correlation (ZCC) code onto one system to accommodate different Quality of Service (QoS) requirements. The results are characterized by bit error rate (BER) and eye pattern simulated using OptiSystem software. Results proved a successful transmission of this scheme over 20km distance thus offering flexibility of independent QoS. It is also revealed that the performance is always better for users with larger number of code weight compared to those assigned with smaller code weight.

New design of Zero Cross Correlation Codes for Spectral Amplitude Coding in OCDMA systems

A new design code structure for Spectral Amplitude Coding with zero cross- correlation in Optical Code Division Multiple Access (OCDMA) has been proposed in this paper. The proposed code called Modified Zero Cross Correlation Code (MZCC). MZCC code provides much easier code construction, given any number of users K and weights to have minimum code length. MZCC code will be demonstrated using OptiSys 6.0. The results indicated that MZCC code is truly performs better in term of noise performance compared with existing Optical CDMA codes.

Dispersion compensation dense wavelength division multiplexing (DC DWDM) for nonlinearity analysis at various propagation distance and input power

Dense wavelength division multiplexing system is a system for coupling and transmitting the optical signals at different wavelength through the single fiber. Such technology is important in order to increase the capacity in optical communication system and to meet the growing demands of bandwidth. However, there are some limiting factors related to the data rate and capacity in this system. These limiting factors can be linear or nonlinear. Theoretically, the nonlinearities in fiber arise as the number of data channel, transmission length, data rate and input power level increase. In this project, the objective is focused towards analyzing on the nonlinearities effect by compensating the linear effect in the fiber. Dispersion Compensation Fiber (DCF) and linear loss EDFA compensation have been used in single mode fiber (SMF) channel to ensure the communication quality for the design. The proposed dispersion compensation DC-DWDM transmission system with 16 and 32 channels for 10Gbps with a channel spacing of 0.8nm was designed and simulated. The BER performance with various input power levels in the range of -10dBm up to 10dBm, and fiber length greater than 50km are analyzed. It has been shown that for fixed length of the fiber, the only variable that can be manipulated to lower the nonlinear contribution is the input power. The higher the input power the higher the nonlinear contribution. However, if the input power is low, the bit rate should be low to maintained transmission at the expected BER (BER <; 10-12).

Study of rain attenuation with diversity of wavelengths propagation transmission in tropical rainforest region

This paper examine about the selecting of wavelength in effecting the laser transmission over the free space spatial under the rain circumstances. The wavelengths used in these computation experiment theory are 780 nm, 850 nm, 1550 nm and 10000 nm. Comparison of the experiment result is measured in various types of rain such as drizzle, light rain, medium rain, heavy rain, cloudburst, extreme rain and very extreme rain. Visual range and scattering coefficient of rain is depending on wavelength utilize. This observation is based on an extensive literature search and from Mie scattering calculation.

Design and demonstration of a novel flexible cross correlation (FCC) code for an evasion of PIIN in OCDMA system

A detailed of code construction for an Optical Code Division Multiple Access (OCDMA) system with flexible cross correlation is presented to reduce the effect of interference thus optimizing the code length. In this paper, the proposed code called Flexible Cross Correlation (FCC) code. The FCC code can be constructed using a simple tridiagonal matrix compared to other OCDMA codes such as MDW and DCS codes thus the FCC code possesses various advantages including easy code construction and less complexity of encoder/decoder design. As a result, OCDMA system performance significantly improved by using FCC code with flexible cross correlation instead of fixed cross correlation such as MDW, MFH and DCS codes.

Hybrid subcarrier multiplexing Wavelength Division Multiplexing using laser and LED spectral slicing architecture

This paper demonstrates a novel architecture of hybrid subcarrier multiplexing Wavelength Division Multiplexing network combining laser and light emitting diodes (LED) as the light sources. The performances are simulated using Optisys software and analyzed based on bit error rates (BER) and the eye pattern of the received signals. Results proved that the combination of the laser and LED light sources in one system can be considered an effective way to maximize system capacity and at the same time, reduce implementation cost of hybrid SCM WDM network architecture.

Spectral efficiency improvement using subcarrier multiplexing in OCDMA system

This paper analyses the spectral efficiency of hybrid subcarrier multiplexed (SCM) Optical Code Division Multiple Access (OCDMA) and conventional OCDMA based on AND Subtraction technique. We compared the spectral efficiency of SCM and the conventional OCDMA with respect the number of weights and number of users. Results indicate that the SCM OCDMA is more efficient compared to conventional OCDMA.

Performance of hybrid subcarrier multiplexed — optical CDMA system based on different detection methods

In this article, a subcarrier-multiplexed Optical CDMA system utilizing the direct and AND subtraction method in receivers detection is explored. The OCDMA part exploits the Recursive Combinatorial (RC) code for its algorithm. The two different designs are then simulated and the performances are compared. Results indicate that the hybrid SCM/OCDMA system using direct detection technique could transmit to a longer distance of up to 50 km with better quality than that with AND subtraction detection for acceptable communication error rate of BER of 10-9.

APD impact on spatial/spectra modified double weight codes optical code division multiple access systems

In this paper, an improvement of achievable system capacity Avalanche photodiode (APD) performance of spatial/spectral modified double weight (MDW) code for cardinality, bit error rates (BER) and noise interference is analyzed. The results in very good agreement indicate that 61% cardinality improvements compare to 2-D MDW code with PIN. The effective transmitted power (Psr) for 2-D MDW-APD (M=135, N=3) improves by 8.5dBm at 10-9 error floor. At low gain BER value is mitigated through suppressing PIIN. Apparently, performance of the proposed system improves substantially with APD.