Phase-induced Intensity Noise Research Articles

Performance enhancement of incoherent spectral amplitude encoding-optical code division multiple access (SAE-OCDMA) by using dispersion compensation fiber Bragg grating (FBG)

Incoherent spectral amplitude encoding optical code division multiple access (SAE-OCDMA) based on fiber Bragg grating (FBG) is one promising technique aim to improve local area networks to have longer span telecommunication network type. In this study, the performance enhancement incoherent SAE-OCDMA is achieved when a dispersion compensation fiber Bragg grating (DCFBG) and erbium doped fiber amplifier (EDFA) are used in optical link. Though, the results can be obtained, these components give good indicator on system performance. In the design, DCFBG is introduced as the dispersion compensation to eliminate the effect of the positive dispersion. This leads to reduce multiple access interference (MAI). While EDFA, is used to compensate loss in conventional single mode fiber (SMF). As a result, the maximum bit error rate (BER) reaches 10-9 and 10-6 for 3 and 7 users, respectively without DCFBG and EDFA at 40 km, respectively, but with DCFBG, the maximum BER reaches 10-21 and 10-10 for 3 and 7 Users, respectively, at the same distance. In this presence case, EDFA and DCFBG are together in optical channel, the maximum BER reaches 10-22 and 10-12 for 3 and 7 users respectively at the same distance (40 km). So that, the transmission distance is improved to 160 and 140 km for 3 and 7 Users, respectively. Simulation results presented in this study are obtained using Opti system and Opti Grating Softwares. Key words: Spectral amplitude encoding-optical code division multiple access (SAE-OCDMA), dispersion compensation fiber Bragg grating (DCFBG), multiple access interference (MAI), phase induced intensity noise (PIIN), Walsh hadamard code (WH code).

Performance Analysis of Diagonal Eigenvalue Unity (DEU) Code Using NAND Subtraction and Spectral Direct Detection Techniques and Its Use with Triple-Play-Services in SAC-OCDMA

In this paper, we investigate the performance of optical code division multiple access system using the diagonal eigenvalue unity (DEU) code as a promising code for future optical networks. A comparison between the utilization of the NAND subtraction detection technique and the spectral direct detection (SDD) technique is presented to investigate which one provides better performance with the DEU code. In addition, a complete mathematical analysis for the two cases is presented. The performance of the two techniques is evaluated in terms of signal to noise ratio, bit error rate (BER), the effective received power, and phase induced intensity noise. Also, the variable weight DEU code is discussed. It demonstrates success for triple-play services (audio, video, and data) using the SDD technique to provide different quality of service (QoS) values to users. The results show that the SDD technique supports a larger number of users, reduces the receiver complexity, and provides better performance than the NAND subtraction technique. For a minimum acceptable BER of 10?9 for a telecommunication system, the direct detection technique supports 265 users, while the NAND subtraction supports 150 users only for (weight W = 3). Also, with variable weights in a single system, the performance of users with high weight is always better compared to that of lower weight users.

New design of optical zero correlation zone codes in quasi-synchronous VLC CDMA systems

Direct-sequence optical code division multiple access technology is one efficient and simple way to reduce the multiple access interferences that existed in visible light communication system due to its ease implementation by simply turning the light-emitting diodes (LEDs) on and off. To overcome the multi-path effect and non-perfect clock impairment, an optical zero correlation zone code set is proposed in visible light communication quasi-synchronous optical code division multiple access system. Bit error rate performance is evaluated while taking into account the effects of phase-induced intensity noise, shot noise, and thermal noise. Based on the proposed optical zero correlation zone codes, the multiple access interference and phase-induced intensity noise can be eliminated finally; therefore, a better bit error rate can be obtained.

A study of three-dimensional optical code-division multiple-access for optical fiber sensor networks

This study proposes a novel optical fiber sensor (OFS) network using three-dimensional (3-D) wavelength/time/spatial optical code-division multiple-access (OCDMA) scheme. The proposed 3-D modified quadratic congruence/M-matrix (MQC/M-matrix) coding scheme overcome the restriction of single pulse per row inherent in traditional three-dimensional codes and maintain a high signal-to-noise ratio even when source power is low. The 3-D system is implemented using optical switches (OSW), fiber-Bragg gratings (FBGs), optical splitter and optical combiner. The noises of phase-induced intensity noise (PIIN) and multiple access interference (MAI) in the decoding mechanism can be suppressed by using a spectral spreading scheme and balance-detection in the receivers. By constructing 3-D codes using bipolar pseudorandom (PN) codes rather than unipolar codes provides a significant increase in the maximum permissible number of active sensor nodes.

Eradication of Multiple Access Interference Using a Modified Multi-service Code for SAC–OCDMA

Phase induced intensity noise (PIIN) and multiple access interference (MAI) are the main parameters that affect the performance of optical code division multiple access (OCDMA) systems, leading to degradations in system performance and reduction in the number of active users. So, this paper presents an efficient modified multi-service (MMS) code that can be used for encoding the spectral amplitude of the optical source in OCDMA systems to avoid these limitations. The proposed code disposes the effect of MAI, PIIN, and gives better performance than the other traditional codes. It can support a large number of active users (80 at bit error rate of 10?9) with a small code weight (w = 4). Also, it achieves a practical code length with a simple receiver structure.

Reducing the Effect of Noise for SAC-OCDMA System by using OFDM Modulation

Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) system encounters several challenges because the MultipleAccess Interference (MAI) of the overlapping chips as number of simultaneous users’ increases. Objectives: Our objective is to develop SAC-OCDMA system with OFDM modulation, based on Flexible Cross Correlation (FCC) code to limit the effect of noises. Methods/Analysis: The average received signal to noise ratio (SNR) with the effects of total noise such as Phase Induced Intensity Noise (PIIN), shot noise and nonlinearity of subcarriers is derived. In addition to generated the Numerical analyses of proposed system. Findings: The results have been evaluated based on SNR, PIIN, shot noise and number of users as well as the amount of power received. The results show that the proposed system improve the capacity of system performance in term of users and suppress the system impairments, Furthermore, by using FCC code can effectively reduce the effects of total noise and mitigate the Multiple Access Interference (MAI). Therefore the applying of OFDM modulation with SAC-OCDMA system has been proven to be robust against the MAI and surely enhanced the system performance, in term of SNR and high number of user allocated, compare to SubCarrier Multiplexing (SCM)/ SAC-OCDMA system.

Modified multiphotodiode balanced detection technique for improving SAC-OCDMA networks

The aim of this study was to develop a feasible modified multiphotodiode balanced detection (MMBD) technique suitable for application in spectral-amplitude-coding optical code-division multiple-access networks, which could mitigate the effect of phase-induced intensity noise (PIIN). Because PIIN is related to the beating between optical signals with wavelengths arriving simultaneously at a balanced photodetector, combining spectral partitioning and an MMBD scheme facilitates reducing PIIN, which tends to dominate performance. Therefore, the system using the proposed scheme exhibited an enhanced performance.

Modified Single Photo-diode (MSPD) Detection Technique for SAC-OCDMA System

AbstractIn this paper, a new detection technique called modified single photo-diode (MSPD) detection for SAC-OCDMA system is proposed. The proposed system based on the single photo-diode (SPD) detection technique. The new detection technique is proposed to overcome the limitation of phase-induced intensity noise (PIIN) in SPD detection technique. However, the proposed detection is based on an optical hard limiter (OHL) followed by a SPD and a low-pass filter (LPF) in order to suppress the phase intensity noise (PIIN) at the receiver side. The results show that the MSPD detection based on OHL has a good performance even when the transmission distance is long, which is different from the case of SPD detection technique. Therefore, the MSPD detection technique is shown to be effective to improve the bit error rate (BER<10

IP Routing by Phase Induced Intensity Noise Suppression in Optical CDMA Network

In this paper, we explore avenues to efficiently use spectral amplitude coding optical code-division multiple-access (SAC-OCDMA) technique as a solution to the Internet protocol (IP) routing bottleneck in the global internet access. This work reveals for the first time the authors proposed a novel class of codes called the flexible cross correlation (FCC) code to enhance the network capacity and achieve the highest performance possible through phase induced intensity noise (PIIN) evasion and eliminating multiple access interference (MAI). The results indicated good performance, where the FCC code can accommodate 150 simultaneous users and has an optimum receive power Psr = -25 dBm at the receiving plant. It is truly proved that, from the theoretical results, the SAC-OCDMA technique can be an excellent candidate for the future IP backbone.

Alleviation Interference Scheme Analysis Using Flexible Cross Correlation (FCC) Code for SAC-OCDMA Systems

This paper presents a new Alleviation Interference Scheme (AIS) for Spectral Amplitude Coding (SAC) - Optical Code Division Multiple Access (OCDMA) coding approaches. The AIS SAC-OCDMA systems is demonstrated by utilizing the Flexible Cross Correlation (FCC) code. 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 impacts of phase induced intensity noise (PIIN) and multiple-access interference (MAI). The results indicated good performance whereas the FCC code offers 100%, 207% and 471% percentage larger number of active users compared to MDW W=4, Hadamard and MFH W=8 codes, respectively. Finally, the FCC code has low receive power Psr = -18 dBm which is expected to be more significant for future SAC-OCDMA coding systems.

A new two-code keying scheme for SAC-OCDMA systems enabling bipolar encoding

In this paper, we propose a new two-code keying scheme for enabling bipolar encoding in a high-rate spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) system. The mathematical formulations are derived for the signal-to-noise ratio and bit-error rate (BER) of SAC-OCDMA system based on the suggested scheme using multi-diagonal (MD) code. Performance analyses are assessed considering the effects of phase-induced intensity noise, as well as shot and thermal noises in photodetectors. The numerical results demonstrated that the proposed scheme exhibits an enhanced BER performance compared to the existing unipolar encoding with direct detection technique. Furthermore, the performance improvement afforded by this scheme is verified using simulation experiments.

Cardinality enrichment of flexible cross correlation (FCC) code for SAC-OCDMA system by alleviation interference scheme (AIS)

In this paper, we propose an alleviation interference scheme (AIS) for spectral amplitude coding (SAC) – optical code division multiple access (OCDMA) coding system approaches. The AIS SAC-OCDMA systems is demonstrated by utilizing the new flexible cross correlation (FCC) code. The FCC code has advantages, such as flexibility in-phase cross-correlation at any given number of users and weights, as well as effectively reduces the impacts of phase-induced intensity noise (PIIN) and has the multiple-access interference (MAI) cancelation property. The results indicated good performance whereas the FCC (W=4, K=150) AIS SAC-OCDMA coding system offers 66%, 172%, 650% and 900% percentage of cardinality enrichments as a contrast to DCS (W=4, K=90), MDW (W=4, K=55), MFH (W=4, K=20) and Hadamard (W=8, K=15) codes, respectively. Finally, the FCC AIS SAC-OCDMA coding system has low effective receive power Psr=−21dBm which is expected to be more significant for future SAC-OCDMA coding systems without requiring any amplification at the receiving plant.

A new two dimensional spectral/spatial multi-diagonal code for noncoherent optical code division multiple access (OCDMA) systems

A new two dimensional codes family, namely two dimensional multi-diagonal (2D-MD) codes, is proposed for spectral/spatial non-coherent OCDMA systems based on the one dimensional MD code. Since the MD code has the property of zero cross correlation, the proposed 2D-MD code also has this property. So that, the multi-access interference (MAI) is fully eliminated and the phase induced intensity noise (PIIN) is suppressed with the proposed code. Code performance is analyzed in terms of bit error rate (BER) while considering the effect of shot noise, PIIN, and thermal noise. The performance of the proposed code is compared with the related MD, modified quadratic congruence (MQC), two dimensional perfect difference (2D-PD) and two dimensional diluted perfect difference (2D-DPD) codes. The analytical and the simulation results reveal that the proposed 2D-MD code outperforms the other codes. Moreover, a large number of simultaneous users can be accommodated at low BER and high data rate.

Matrix partitioning code family for spectral amplitude coding OCDMA

This paper presents a family of newly constructed codes to mitigate the multiple access interference (MAI) and phase-induced intensity noise (PIIN) in spectral amplitude-coding optical code division multiple access systems. The family of newly constructed codes, named matrix portioning (MP) code, is derived from arithmetic sequence, and their cross-correlation is not larger than one. In addition, the weight code can be any number which makes an MP promising code for future optical communication systems. We have also described detailed examples on how to construct this code family. The results reveal that the MP code is effective in reducing the MAI and PIIN, while maintaining a good signal-to-noise ratio and low bit error probability. Simulation results taken from a commercial optical system simulator, Virtual Instrument Photonic $$(\hbox {VPI}^{\mathrm{TM}})$$ ( VPI TM ) , are also demonstrated. The results obtained for MP code have shown significant improvement compared to other schemes that employ flexible cross-correlation, multi diagonal, dynamic cyclic shift, and random diagonal codes. It is shown that, when the effective power is large, the intensity noise specifies as the main factor that deteriorates the system performance. When the effective power is not sufficiently large, thermal and shot noise sources become the main limiting factors and the effect of thermal noise is more influential than that of shot noise.

Performance analysis of asynchronous optical code division multiple access with spectral‐amplitude‐coding

In this study, the performance of a spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) system in the asynchronous regime is evaluated using a Gaussian approximation of the decision variable for codes with fixed cross-correlation used in SAC-OCDMA systems. The authors consider the effect of phase-induced intensity noise (PIIN), thermal noise and shot noise. Moreover, the validity of the Gaussian approximation is confirmed by a Kolmogorov–Smirnov fitness test. For sake of comparison, the bit error rate (BER) of the asynchronous SAC-OCDMA system is also plotted numerically in comparison with the BER of the synchronous SAC-OCDMA. They show that a SAC-OCDMA system without any time management for the users, that is, the asynchronous regime, has a better performance than the synchronous SAC-OCDMA when PIIN effect exists.

Assessment of an Optical Burst Switched Core Node With a Restricted Number of Simultaneous Active Users Using the Burst Error Loss Rate

The technical superiority of spectral-amplitude coding optical code-division multiple-access (SAC-OCDMA) systems over traditional wavelength division multiplexing (WDM) systems in optical burst switched (OBS) networks is mainly attributed to the former’s better medium access control (MAC) layer performance. Nevertheless, in order to conduct an accurate comparison, a thorough study of the physical layer performance should be involved, especially because in many cases the physical layer noise would affect the maximum achievable number of simultaneously active users. Hence, in this work, we develop a novel assessment approach that combines both MAC and physical layer capabilities by introducing a new burst error loss rate parameter. In particular, the approach targets cases with limitations on the number of simultaneous active users. Next, as an example of a noisy physical layer, the effect of phase-induced intensity noise on the number of active users in OBS/SAC-OCDMA systems is analyzed. Our analysis shows that this effect introduces a burst error rate (BurstER) in the multiple-access interference cancellation operation (not investigated before). This BurstER is an increasing function of the number of active users and hence would suppress the system MAC layer performance. Finally, assuming an ideal WDM physical layer, we employ the developed approach to present an illustrative performance comparison between OBS/SAC-OCDMA and OBS/WDM systems. The results show that OBS/SAC-OCDMA performance outperforms that of OBS/WDM when the number of tolerated bits in error per burst exceeds a certain value.

Universal optical line terminal encoding and decoding architecture in two-code keying for noncoherent spectral amplitude coding optical code division multiple access systems

We propose a new code family, called extended shifted prime codes, and the universal encoding architecture for spectral amplitude coding optical code division multiple access systems using a two-code keying scheme. The proposed system can eliminate multiuser interference and suppress phase-induced intensity noise. In addition, we design the ESP codes to be an encoding/decoding architecture based on the array waveguide grating architecture and reduce the power loss and the complexity of the optical line terminal. The numerical results demonstrate that the proposed system with ESP codes outperforms the existing one-dimensional shifted prime codes system.

Intensity noise analysis of a fibre laser after passing through an optical mode cleaner

The intensity noise in a 1560 nm single frequency fiber laser after passing through an optical mode cleaner is analyzed both theoretically and experimentally. Experimental measurement shows that in addition to the evident suppression of intensity noise by the mode cleaner, there exist induced observable periodic fluctuations in the analyzing frequency range of 2 to 12 MHz, as well as the amplification of the intensity noise at low frequencies. The above results cannot be explained by the present mode cleaner model for noise suppression. In this paper, we propose a new theoretical model, in which the mode cleaner is considered equivalent to a delay line and through it the phase-noise of the fiber laser is partially converted to the intensity noise. The phase-induced relative intensity noise (RIN) amplitude is jointly determined by the laser linewidth, the mode cleaner linewidth, and the analyzing frequency. The theoretical analysis shows a very good agreement with the experimental results. The noise suppression effect of the acoustic optical modulator is further analyzed by inserting it into the setup and providing a frequency modulation for it. We have observed an evident improvement of the mode cleaner locking, while the bandwidth of the laser is slightly suppressed from 26 to 16kHz, and the degradation of the measured intensity noise after the mode cleaner is also moderate. The theoretical analysis according to our proposed model fits well with this result. This result further confirms that the phase-induced intensity noise has no direct connection to the mode cleaner locking quality. Through the above analysis, a complete theoretical mode for analyzing the noise suppression by a mode cleaner is built.

A Review on Successive Interference Cancellation Scheme Based on Optical CDMA Network

AbstractDue to various desirable features of optical code division multiple access (OCDMA), it is believed this technique once developed and commercially available will be an integral part of optical access networks. Optical CDMA system suffers from a problem called multiple access interference (MAI) which limits the number of active users, it occurs when number of active users share the same carriers. The aim of this paper is to review successive interference cancellation (SIC) scheme based on optical CDMA system. The paper also reviews the system performance in presence of shot noise, thermal noise, and phase–induced intensity noise (PIIN). A comprehensive review on the mathematical model of SIC scheme using direct detection (DS) and spectral amplitude coding (SAC) were presented in this article.

PERFORMANCE ANALYSIS OF SEVERAL QUASI-ORTHOGONAL CODES OPTICAL CDMA FOR RADIO-OVER-FIBER SYSTEM

An optical code-division multiple-access (OCDMA) network for radio-over-fiber (RoF) transmissions was proposed. The network encoders/decoders (codecs) were structured based on arrayed-waveguide-grating (AWG) routers coded using modified prime codes (MPCs). In the proposed system, the lower in-phase cross correlation could reduce the beating noise, and in the proposed study, its performance was compared with that of a conventional system that uses M-sequence and Walsh-Hadamard codes. The performance of both systems was numerically evaluated by analyzing the effect of phase-induced-intensity noise (PIIN). The results showed that the new code families that had lower cross correlation can suppress the intensity of the noise and effectively cancel out the multiple-access interference (MAI) in balanced detection processes, which improved system performance. By using the proposed MPC-coded OCDMA ROF network codecs, each network required only two AWG routers to accomplish the spectral coding of radio base stations (RBSs) and the decoding of control stations (CSs), resulting in a simple and low-cost system. Therefore, it is possible to produce interference- and crosstalk-free optical CDMA systems for RoF transmissions.