Search

A new two-dimensional (2-D) optical code division multiple access (OCDMA) scheme to increase the achievable system capacity is proposed. The code exhibits good cross-correlation property time and wavelength shift. Performances are analyzed on code size and correlation properties affecting two important system parameters, bit error rate (BER) as a function of cardinality generated and optical power transmission requirement. The proposed system can effectively suppress phase-induced intensity noise (PIIN) and has multi-access interference (MAI) cancellation property. Results in a good agreement indicate that 2-D modified double weight (MDW) offers 163.7% and 336.2% larger cardinality compare to 2-D perfect difference code (PDC) and 2-D modified quadratic congruence (MQC) code. By increasing spatial code (N) and keeps similar code length system performance can be further optimized. 2-D MDW (M = 45, N = 18) accommodates 252.2% and 18.3% cardinality increment and low effective transmitted power (Psr) at −17.9 dBm, compare to 2-D MDW (M = 247, N = 3) and (M = 84, N = 9) at 10−9 BER error floor. The architecture of the spectral/spatial MDW OCDMA system with property of MAI cancellation is presented.

This paper presents the review of Double Weight (DW) codes family from perspective of codes evolution since beginning until now. First generation focuses on one-dimensional (1D) code which spreading has been carried out in time. Later, the second generation was introduced known as two-dimensional (2D) code where the encoding of data bit has spread in both wavelength and time domain. Codes construction and variety of detection techniques scheme used in DW codes family are also discussed. In this paper we focus on structure of among DW codes family as all the design of code sequence aim to eliminate Multiple Access Interference (MAI). Previous papers of DW codes family show a good quality of transmission and satisfactory the standard quality of Bit Error Rate (BER) above 10−9.

This paper analyzes the performance of the OS-CDMA system using OFDM technique to enhance the channel data rate, to save power and increase the number of user of OSCDMA systems. This system compared with previous hybrid subcarrier multiplexing/optical spectrum code division multiple-access (SCM/OSCDMA) system. The average received SNR with the nonlinearity of subcarriers is derived. The theoretical results have been evaluated based on BER and number of users as well as amount of power saved. The proposed system gave better performance and save around −6 dBm of the power as well as increase the number of users twice compare to SCM/OSCDMA system. In addition it is robust against interference and much more spectrally efficient than SCM/OSCDMA system. The system was designed based on Flexible Cross Correlation (FCC) code.

A new class of code called Flexible Cross-Correlation (FCC) for Spectral-Amplitude Coding Optical Code-Division Multiple-Access (SAC-OCDMA) systems has been de-veloped. The FCC code has advantages, such as flexible cross-correlation property at any given number of users and weights, as well as effectively reduces the impact of Phase-Induced Intensity Noise (PIIN) and Multiple-Access Interference (MAI) cancellation property. The results revealed that the FCC code can accommodate 150 users, where FCC code offers 66%, 172%, 650% and 900% improvement as a contrast to 90, 55, 20 and 15 numbers of users for Dynamic Cyclic Shift (DCS), Modified Double Weight (MDW), Modified Frequency Hoping (MFH) and Hadamard codes, respectively, for a permissible Bit Error Rate (BER) of 10−9 •

Various two-dimensional (2-D) OCDMA codes have been introduced in recent years due to their capabilities in enhancing cardinality, suppressing phase induced intensity noise (PIIN) and eliminates multiple access interference (MAI). This paper presents our new proposal of 2-D spectral/spatial Extended Enhanced Double Weight (2-D Extended-EDW) code. This code is designed to enhance cardinality and effective transmitted power. In other word, it effectively reduces noise and increasing simultaneous users. From our numerical analysis, we found that 2-D Extended-EDW code has a significantly better performance, in terms of the cardinality and effective transmitted power when compared with 2-D M-Matrices code.

Two-dimensional Optical Code Division Multiple Access (2-D OCDMA) has gained great interest among researchers in optical communication systems. This work is aimed to present an alternative way of formulating the spectral/spatial incoherent two-dimensional Extended Enhanced Double Weight (2-D Extended-EDW) code. This code is proposed to suppress the phase induced intensity noise (PIIN) by using multiple access interference (MAI) cancellation property. The numerical analysis shows that 2-D EDW code has a better performance, in terms of bit error rate (BER) and the cardinality compared with one-dimensional Enhanced Double Weight (1-D EDW) code. In comparison with different combinations of spatial and spectral code length for 2-D Extended-EDW code, we found that by increasing the number of time chip, it significantly enhances the performance of the system.

A 2-Dimensional (2-D) Wavelength/Time (W/T) scheme is proposed for spectral amplitude coding OCDMA network system. The new hybrid codes are utilizing Flexible Cross Correlation (FCC) and Modified Double Weight (MDW) codes which both codes have good correlation properties and capable to suppress multiple access interference (MAI). From the numerical calculation, it has been shown that this new hybrid code effectively suppresses the phase Induced Intensity Noise (PIIN) and eliminates MAI. Furthermore, the cardinality of this proposed code accommodates 150% and 275% improvement compared to 2-D PD code and 2-D M-Matrices code respectively at the BER=10−9. As a result, the performance of the system can be improved as well as support much more simultaneous users compared to Perfect Difference (PD) and M-matrices codes.

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.

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 (P sr ) 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.

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.

This paper presented the novel of optical code for Optical Code Division Multiple Access (OCDMA) system using Spectral Amplitude Coding. A new class of code, called Modified Non-Zero Cross Correlation Code (MNZCC). MNZCC code has minimum length, can be constructed easily for a given number of users, weights and any desired cross correlation (λmax). The MNZCC code was observed by OptiSys. 6.0 software. The MNZCC code has shown superior performance in term reducing the effect of MAI, with better bit error probability. The results obtain for the MNZCC were compared with others existing optical codes such as DW code.