In this paper, the spectrally encoded hybrid WDM-OCDMA network employing 60 Gbps non-return to zero/differential quadrature phase shift keying (NRZ/DQPSK) orthogonally modulated data signal operating over 100 km SMF+DCF has been proposed. In proposed hybrid WDM-OCDMA network, the orthogonal modulation formats are used to enhance per channel capacity and the spectral amplitude optical coding for enhancing the confidentiality of data from unauthorized user or eavesdropper. The impact of input power, transmission distance and energy per bit to noise power spectral density ratio ( E b /N 0 ) on the performance of WDM-OCDMA network in terms of output optical power, timing diagram, BER, Q-factor and probability of error free code detection has been investigated. It can also be determined that orthogonal modulation formats are promising option to increase per channel capacity as compared to conventional modulation format and these are less vulnerable to chromatic dispersion (CD) and polarization mode dispersion (PMD). Meanwhile, the performance of proposed hybrid network is compared with existing OCDMA network which show the feasibility of proposed WDM-OCDMA network in future generation optical networking.

Performance analysis of spectrally encoded hybrid WDM-OCDMA network employing optical orthogonal modulation format against eavesdropper

The focus of this work is to consolidate a review of accomplished research in the field of optical code division multiple accesses (OCDMA), to outline the state-of-the-art comparison, and to recognize the prominent trends as well as limitations. Code division multiple access (CDMA) has prospered as a vital solution for numerous applications such as cellular mobile communication-based wireless network technology and wired/wireless local area networks that include areas of unlicensed industry, medicine, and science. Due to the commercial utilization of the various advantages of CDMA, it has raised the matter of whether optical technology reliant communications provide the noteworthy advantages to optical networks as well as what are the technologies that facilitate optical chip-based (code division) networks. Aforementioned matter has been addressed in the context of the incorporation of OCDMA in the systems through several experiments of laboratory-based test-bed investigations, field trials, and simulation analysis of multiple users in the recent research works. The performance of OCDMA has an edge over wavelength division multiplexing and offers an unmatched capacity that is seen through simulations. To cater the explosive expansions in internet application, different spectral amplitude codes have been proposed till now. We present a review of the different spectral amplitude codes based on the reported works in spectral amplitude code OCDMA systems. For the purpose of state-of-the-art comparison, parameters considered are data speeds, advanced modulation formats, bit error rate, extinction ratio, decision algorithms, photonic efficiencies of photodetectors, frequency bands, signal-to-noise ratio, forward error correction, photodetector noises, etc., and simulations are carried out in similar input environments. We explore the advantages/limitations of the spectral amplitude codes, recent progress in the technology, practical works on spectral amplitude coding (SAC) throughout the world, encryption–decryption techniques, all-optical methods, literature comparison, future scope, and applications of the SAC-OCDMA codes.

https://www.spiedigitallibrary.org/journals/optical-engineering/volume-57/issue-11/116102/Review-on-developments-in-all-optical-spectral-amplitude-coding-techniques/10.1117/1.OE.57.11.116102.pdf

Review on developments in all-optical spectral amplitude coding techniques

In this paper, a hybrid system is introduced using orthogonal frequency division multiplexing (OFDM) technique with spectral amplitude coding optical code division multiple access (SAC-OCDMA). In this system, the AND subtraction detection is used with the modified double weight (MDW) and enhanced double weight (EDW) codes, in addition to the single photodiode detection with the diagonal double weight (DDW) code. The proposed system achieves performance enhancement in the performance enhancement concerning the maximum allowable number of users, signal to noise ratio and (minimum) bit error rate (BER) $${\Re}$$. The proposed codes that used with AND subtraction detection techniques are: MDW and EDW, while the DDW codes are used with single photodiode detection (SPD). Detection techniques are investigated to reduce the effect of both the multiple access interference and phase induced intensity noise. A comparison is performed between the conventional SAC-OCDMA systems and OFDM with SAC-OCDMA. The obtained results reveal that OFDM with SAC-OCDMA gives better performance than conventional SAC-OCDMA. OFDM with SAC-OCDMA using DDW code with SPD detection can support a high bit rate up to 10 Gbps for 70 users with a BER of 10–9.

MDW and EDW/DDW codes with AND subtraction/single photodiode detection for high performance hybrid SAC-OCDMA/OFDM system

Free space optics (FSO) communication is a very recent mechanism. It is mainly needed when physical connection between the transmitter and the receiver is practically impossible and when high bandwidth data transmission is expected. This paper walks through the investigation of the performance of FSO communication adopting spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems at different weather scenarios. The suggested system uses enhanced double weight codes as signature codes by 3 clients, simultaneously. To eliminate multiple access interference and phase induced intensity noise, two different detection schemes are used; single photodiode (SPD) and modified-AND subtraction detection schemes. Furthermore, a comparison between PIN and APD detectors is performed. The performance is evaluated through its propagation distance, received power, Q-factor and bit error rate (BER). The obtained numerical results reveal both Q-factor and BER are modified by 30%. Accordingly, the system performance is enhanced by 30%, when using SAC-OCDMA-FSO with SPD detection technique compared with modified-AND subtraction technique.

SAC-OCDMA-FSO communication system under different weather conditions: performance enhancement

Development of ZCCC for multimedia service using SAC-OCDMA systems

A new code structure for spectral amplitude coding optical code division multiple access systems based on double weight (DW) code families is proposed. The DW has a fixed weight of two. Enhanced double-weight (EDW) code is another variation of a DW code family that can has a variable weight greater than one. The EDW code possesses ideal cross-correlation properties and exists for every natural number n. A much better performance can be provided by using the EDW code compared to the existing code such as Hadamard and Modified Frequency-Hopping (MFH) codes. It has been observed that theoretical analysis and simulation for EDW is much better performance compared to Hadamard and Modified Frequency-Hopping (MFH) codes.

Abdullah, , M.K

Papers

Spectral amplitude coding ocdma systems using enhanced double weight code