DWDM/OOC and large spectrum sources performance in broadband access network

In this paper, we investigate the feasibility of a 2 Dimensional Optical Code Division Multiple Access system (2DOCDMA), with electronic coding and decoding functions. We present a modified construction method of Multi-Wavelength Optical Orthogonal Codes (MWOOC) which permits high flexibility for the code parameters choice. Our objective is to evaluate the 2D code performance, with a Conventional Correlation Receiver (CCR) and a more complex one named Parallel Interference Cancellation receiver (PIC). For example, for a Bit Error Rate (BER)10-9, 30 simultaneous users and an electrical implementation, we show that contrary to the CCR, the use of a PIC receiver leads to workable 2D code solutions.

Many multiple access techniques have been proposed and demonstrated to provide flexible solutions for FTTH network configurations. The performance of this system suffers because of the correlation properties that contribute to a high level of Multiple Access Interference (MAI), low system capacity (users), and lower transmission rate. In this paper, we have proposed Optical CDMA (OCDMA) as a configuration solution for FTTH networks to improve the performance of this type of network. Full Text: PDF References. Z. Mateusz, M. Mariusz, On cost of the uniformity in FTTH network design, Conference on Transparent Optical Networks (2017), 87-90 CrossRef CEDRIC F. LAM, Passive Optical Networks- Principles and Practice, first ed., British Library, USA, 2007. DirectLink M.K. Abdullah, W.T. P'ng, P.W. Lau, E.R. Tee, FTTH access network protection using a switch, Asia Pacific Conference on Communications (APCC), 3(2003) 1219–1222. CrossRef J. Ronnakorn, S. Napat, L. Somkiat, Design and implement of GPON-FTTH network for residential condominium, Conference on Computer Science and Software Engineering, (2017), 333-339. CrossRef M. BOUREGAA, M. CHIKH-BLED, Comparative Study of Optical Unipolar Codes for Incoherent DS-OCDMA system, International Journal of Hybrid Information Technology, 6 (2013) 225-236. CrossRef M. BOUREGAA, M. CHIKH-BLED, The performance of a DS-OCDMA system using Orthogonal Optical Codes (OOC), European Scientific Journal, 9 (2013), 322-335 CrossRef M. Iwase, Y. Ishikawa, T. Komatsu, J. Kasahara, N. Hattori, M. Miura, N. Nakamura, K. Odaka, Optical transceiver modules for gigabit Ethernet PON FTTH systems, Furukawa Review, 28 (2005) 8-10. DirectLink

The performance of 2D wavelength/time optical code division multiple access (OCDMA) system is adversely affected by the presence of noise at its physical layer. It is present in the form of Multiple Access Interference (MAI) and beat noise in OCDMA systems and degrades its performance. In this paper an attempt has been made to determine as well as to mitigate the effect of noise using either Optical Hard Limiter (OHL) or Coherent detection technique for a system employing prime sequence permutations over time spreading optical orthogonal codes (OOCs). Investigations reveal that performance of system is severely affected by noise and it can be improved by using coherent detection as well as hard limiter. Specifically for this PC/OOC coding technique, it has been reported in the results that coherent detection for reducing the noise outperforms the use of optical hard limiter.

Optical CDMA systems have received much attention in fiber optic networks where the high-speed, the huge band width, the secure and immune communication, asynchronous and simultaneous access for multiple users on the same channel. Those features nominate strongly Optical CDMA for future optical multimedia networks. However, multiple access interference (MAI), which is originated from other simultaneous users, severely limits the capacity of the system. In this paper, an efficient transceiver architecture has been proposed using MAI cancellation to improve the performance of the existence simple transceiver without MAI cancellation. The strategy of the proposed transceiver is based on an estimation and cancellation of MAI in Optical CDMA system with employing a new spreading code named double padded modified prime code (DPMPC) and an efficient pulse-position modulation (PPM) scheme. In addition, for further improvement of the bit-error rate (BER) performance for the proposed transceiver Manchester coding (source coding) is used in signaling the transmitted data. The MAI estimation is achieved by pre-reserving one of optical spreading code sequences at the receiver based on the correlation property of the DPMPC. The proposed receiver estimates the interference and cancels it out from the received signal after the photo-detection process. The performance of the proposed transceiver architecture and its improvement will be compared with the performance of simple transceiver without MAI cancellation. The performance of various codes like modified prime code (MPC), new modified prime code (NMPC) are applied and compared with the proposed DPMPC to demonstrate its potential. An upper bound on the BER for the proposed system is derived and compared with a lower bound on the BER from the system without cancellation. The simulated computer results reveal that the performance, in terms of the BER, of the proposed system is significance improved compared with that of the system without cancellation.

In this paper, we introduce the optimization of bit error rate (BER) in parallel cancellation of multiple access interference (PIC) using the bias compensation with a direct sequence unipolar optical code division multiple access (DS-OCDMA) system. This receiver is dedicated to mitigate Multi access Interference (MAI). The principle of our proposed receiver consists in reducing the output error by amplification of the interfering signals. We develop the PIC compensated theoretical error probability expression. The performance of such a technique is analyzed in a synchronous network using orthogonal optical codes (OOCs) and the results are compared with those for different receivers.

We compared the theoretical bit-error-rate (BER) and throughput performance limits of 2-D time-wavelength and coherent time-spreading optical code division multiple access (OCDMA) communication systems. The results show that the BER performance of the coherent time spreading OCDMA scheme is much superior to 2-D time wavelength scheme in the multiple access interference (MAI) noise limited case without considering beat noise, and the beat noise affects the system performance seriously and appears as a dominant source of noise for the two kinds of OCDMA systems. Nevertheless, the 2-D time wavelength scheme has better tolerance to beat noise than coherent time spreading OCDMA scheme, and the superiority is more apparent with the increasing of the code length N. While the coherent time spreading scheme has higher peak throughput, and it supports a higher throughput than the 2-D time wavelength scheme at higher offered loads.

Multiple Access Interference (MAI) is the major reason for the system degradation in the Optical Code Division Multiple Access (OCDMA). MAI increases with the number of simultaneous users, resulting in deterioration in the performance and limits the maximum number of simultaneous users. Optical Hard Limiter (OHL) is known to improve the performance of the conventional OCDMA system. However, in the present of other sources of noise, the improvement is not considerable. Moreover, the need for dynamic threshold value in the conventional OCDMA receiver to recover the data is very demanding requirement particularly in the high speed LANs. To overcome these limitations, some studies have been conducted on the Optical Parallel Interference Cancellation (OPIC) through this paper. OHL is placed in front of the receiver side to mitigate the effect of MAI. The study focuses on the lowest threshold value i.e. Th=1. The results are compared to the conventional OCDMA and it shows that, OHL is effective to reduce the power of MAI and a better performance can be obtained by selecting the smallest threshold value.

This manuscript deals with analysis of Spectral Amplitude Coding Optical Code Division Multiple Access (SACOCDMA) system. The major noise source in optical CDMA is co-channel interference from other users known as multiple access interference (MAI). The system performance in terms of bit error rate (BER) degrades as a result of increased MAI. It is perceived that number of users and type of codes used for optical system directly decide the performance of system. MAI can be restricted by efficient designing of optical codes and implementing them with unique architecture to accommodate more number of users. Hence, it is a necessity to design a technique like spectral direct detection (SDD) technique with modified double weight code, which can provide better cardinality and good correlation property.

A new architecture for Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) system based on two Dimensional Multi Diagonal (2D-MD) codes named 2D-MD SAC-OCDMA and utilizing a laser optical source is proposed for Long-Reach Passive Optical Network (LR-PON). In this work, a computer simulator tool is used, for the first time, as a SAC-OCDMA simulation set-up utilizing the unique combination of a coherent laser array and 2D-MD codes. In addition, the system performance is addressed numerically by taking into account Multiple Access Interference (MAI), optical coherent source noise, first, second and third order fiber dispersion, nonlinear effects and photo-detector noise. Simulation results indicate that for a single user (i.e., without considering MAI), the system can operate at a maximum bit rate of 55 Gb/s over 250 km of Single Mode Fiber (SMF), with a Bit Error Rate (BER) below 10−9 (Q-limit = 15.5 dB), when only first order fiber dispersion is considered. However, including the effects of second and third order fiber dispersion as frequency domain parameters, results in a reduction of the maximum bit rate to 40 Gb/s, while maintaining a Q-factor above the Q-limit under the same transmission distance. Furthermore, we demonstrate that the proposed architecture extends the SMF transmission reach up to 600 km and 480 km, when considering linear and nonlinear effects, respectively. Finally, we show that our proposed 2D-MD SAC-OCDMA system outperforms existing solutions presented in the literature for LR-PON configuration, in terms of both aggregate bit rate and transmission reach.

This paper presents the study of a receiver device for the optical code division multiple access (OCDMA) called the optical parallel interference cancellation (Opt-PIC). The performance of OCDMA system is known to be easily influenced by the multiple access interference (MAI) caused by other simultaneous users. To overcome this problem, there is a strong demand for the design of new detection scheme that will be efficient enough to improve the performance of the OCDMA system, while minimizing the effects of the MAI. In this paper, some studies have been conducted on the Opt-PIC specifically for the lowest threshold value. Studies have been carried out not only using the conventional method but also using a hard limiter. The results are compared to the previous techniques used to mitigate the effect of MAI.

In this paper, an adaptive parallel interference cancellation (PIC) receiver is introduced for asynchronous multicarrier code division multiple access based (MC-CDMA) communications systems. The multiple access interference (MAI) estimates are obtained using the bit estimates from the previous stage and the adaptive weights for the bit estimates. The adaptive weights are updated by minimizing the mean squared error between the received signal and its estimate based on the adaptation of the normalized least mean square (LMS) algorithm. The results from the simulations show that the performance of conventional PIC (CPIC) and adaptive PIC (APIC) can be different depending on the combining schemes used.

This paper proposes an integration of optical Code Division Multiple Access (OCDMA) with new catenated Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme. This effective combination based on Zero Cross Correlation (ZCC) code can enhanced the system capacity and increased spectral efficiency by fully utilizing the available electrical bandwidth. We investigate the performance of the proposed system for various number of user, number of weight and effective power. The performance assessment is carried out by means of the signal to noise ratio (SNR) and bit error rate (BER) for up to five catenated OFDM bands transmitted simultaneously through optical link at 622 Mbps. More specifically, mathematical expressions for SNR and BER performance are derived. The corresponding numerical results are presented and compared with traditional OCDMA-ZCC system to verified the feasibility of the proposed system. The results show that with OCDMA/catenated-OFDM based on ZCC code provides 86% more number of permissible user for SNR of 15 dB. In addition, this integration provides higher receiver sensitivity; an approximately –22.5 dBm for 20 number of user with 8 number of weight. It is also found that, to accommodate more user, the system requires higher effective power at the receiver.

In this paper, a comparison between direct-current-biased optical orthogonal frequency-division multiple-access (DCO-OFDMA) and synchronous one-dimensional (1-D) optical code-division multiple-access (OCDMA) is performed for optical wireless communication (OWC). Line-of-sight (LOS) channel conditions are considered in an indoor downlink scenario. The bit-error ratio (BER) performance is investigated in an additive white Gaussian noise (AWGN) channel under the conditions of equal spectral and power efficiency. For DCO-OFDMA and 1-D OCDMA, the negative-level clipping effect and multiple-access interference (MAI) are considered, respectively. For the OCDMA scheme, the categories of optical orthogonal codes (OOCs) and unipolar Walsh-Hadamard codes (WHCs) are employed. The time-division multiple-access (TDMA) is also represented in the context of synchronous OCDMA by the use of identity matrices. In order to enhance the 1-D OCDMA spectral efficiency, unipolar M-ary pulse amplitude modulation (M-PAM) is employed. The BER performance versus the average electrical signal-to-noise ratio (SNR) per bit is illustrated both for the single and the multiple-user communication using Monte Carlo simulations.

In this paper, a theoretical analysis is presented to evaluate the influence of polarization mode dispersion (PMD) on the bit error rate (BER) performance of direct sequence optical code division multiple access system. In this analysis, intensity modulation direct detection technique is employed in single mode fiber operating at 1550nm, and optical orthogonal codes are used as address sequence. Optoelectronic conversion is performed by an avalanche photodiode in an optical correlator receiver. The system BER performance is determined on account of receiver, optical amplifier, and multiuser access interference noises. The power penalty suffered by the system is evaluated at BER of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−9</sup> as a function of number of simultaneous users, chip rates, and PMD co-efficient. The system performance is found to degrade more at higher chip rate, and longer fiber length due to the PMD.

This paper suggests an enhanced performance of the 3-D optical code division multiple access (OCDMA) codes, a space/wavelength/time spreading family of codes. The initial codes are in the format wavelength hopping/time sequence (WH/TS), selected according to their performance requirements and the TS sequence is constructed to achieve a linear spacetime complexity. The asymmetric run length constraints are introduced in that regard, such that the positive bit positions align with the encoder/decoder frequency spacing pattern, yielding a 3-D WH/WS/TS. The selected 2-D OCDMA codes are one-coincidence frequency hopping codes (OCFHC) and optical orthogonal codes (OOC). As a time sequence code, the OOC code length is extended with a code rate of 0.04. The complexity and the bit error rate (BER) are herein given and compared with previous work. The results of the performance show not only an improvement in the number of simultaneous users due to the code length extension, but better correlation properties and hence a better signal-to-noise ratio.