scholarly journals Histogram Based Clustering for Nonlinear Compensation in Long Reach Coherent Passive Optical Networks

2019 ◽  
Vol 10 (1) ◽  
pp. 152 ◽  
Author(s):  
Ivan Aldaya ◽  
Elias Giacoumidis ◽  
Geraldo de Oliveira ◽  
Jinlong Wei ◽  
Julián Leonel Pita ◽  
...  
Keyword(s):  
Maximum Likelihood ◽  
Optical Networks ◽  
High Speed ◽  
Clustering Algorithm ◽  
Single Channel ◽  
Direct Detection ◽  
Digital Signal ◽  
Passive Optical Networks ◽  
Spatial Density ◽  
Signal Processors

In order to meet the increasing capacity requirements, network operators are extending their optical infrastructure closer to the end-user while making more efficient use of the resources. In this context, long reach passive optical networks (LR-PONs) are attracting increasing attention.Coherent LR-PONs based on high speed digital signal processors represent a high potential alternative because, alongside with the inherent mixing gain and the possibility of amplitude and phase diversity formats, they pave the way to compensate linear impairments in a more efficient way than in traditional direct detection systems. The performance of coherent LR-PONs is then limited by the combined effect of noise and nonlinear distortion. The noise is particularly critical in single channel systems where, in addition to the the elevated fibre loss, the splitting losses should be considered. In such systems, Kerr induced self-phase modulation emerges as the main limitation to the maximum capacity. In this work, we propose a novel clustering algorithm, denominated histogram based clustering (HBC), that employs the spatial density of the points of a 2D histogram to identify the borders of high density areas to classify nonlinearly distorted noisy constellations. Simulation results reveal that for a 100 km long LR-PON with a 1:64 splitting ratio, at optimum power levels, HBC presents a Q-factor 0.57 dB higher than maximum likelihood and 0.21 dB higher than k-means. In terms of nonlinear tolerance, at a BER of 2×10 − 3 , our method achieves a gain of ∼2.5 dB and ∼1.25 dB over maximum likelihood and k-means, respectively. Numerical results also show that the proposed method can operate over blocks as small as 2500 symbols.

Simulation and Analysis of different CMOS Full Adders for Delay Optimisation

2021 ◽  
Vol 9 (9) ◽  
pp. 66-70
Author(s):  
Nakul C. Kubsad
Keyword(s):  
Power Dissipation ◽  
High Speed ◽  
Digital Signal ◽  
Full Adder ◽  
Digital Signal Processors ◽  
Transmission Gate ◽  
Logical Operations ◽  
Recent Advancement ◽  
Voltage Swing ◽  
Signal Processors

Abstract: Full adder circuit is one among the fundamental and necessary digital part. The full adder is be a part of microprocessors, digital signal processors etc. It's needed for the arithmetic and logical operations. Full adder design enhancements are necessary for recent advancement. The requirement of an adder cell is to provide high speed, consume low power and provide high voltage swing. This paper analyses and compares 3 adders with completely different logic designs (Conventional, transmission gate & pseudo NMOS) for transistor count, power dissipation and delay. The simulation is performed in Cadence virtuoso tool with accessible GPDK – 180nm kit. Transmission gate full adder has sheer advantage of high speed, fewer space and also it shows higher performance in terms of delay. Keywords: Delay, power dissipation, voltage, transistor sizing.

Ethernet Passive Optical Networks

2009 ◽  
pp. 482-488
Author(s):  
Mário M. Freire ◽  
Paulo P. Monteiro ◽  
Henrique J.A. da Silva ◽  
José Ruela
Keyword(s):  
Optical Networks ◽  
High Speed ◽  
Low Cost ◽  
Optical Network ◽  
Cost Effective ◽  
Passive Optical Networks ◽  
Multipoint Control ◽  
Upstream Direction ◽  
Working Groups ◽  
Ethernet Passive Optical Networks

Recently, Ethernet Passive Optical Networks (EPONs) have received a great amount of interest as a promising cost-effective solution for next-generation high-speed access networks. This is confirmed by the formation of several fora and working groups that contribute to their development, namely the EPON Forum (http://www. ieeecommunities.org/epon), the Ethernet in the First Mile Alliance (http://www.efmalliance.org), and the IEEE 802.3ah working group (http://www.ieee802. org/3/efm), which is responsible for the standardization process. EPONs are a simple, inexpensive, and scalable solution for high-speed residential access capable of delivering voice, high-speed data, and multimedia services to end users (Kramer, Mukherjee, & Maislos, 2003; Kramer & Pesavento, 2002; Lorenz, Rodrigues, & Freire, 2004; McGarry, Maier, & Reisslein, 2004; Pesavento, 2003). An EPON combines the transport of IEEE 802.3 Ethernet frames over a low-cost and broadband point-to-multipoint passive optical fibre infrastructure connecting the optical line terminal (OLT) located at the central office to optical network units (ONUs) usually located at the subscriber premises. In the downstream direction, the EPON behaves as a broadcast and select shared medium, with Ethernet frames transmitted by the OLT reaching every ONU. In the upstream direction, Ethernet frames transmitted by each ONU will only reach the OLT, but an arbitration mechanism is required to avoid collisions. This article provides an overview of EPONs focused several issues: EPON architecture, multipoint control protocol (MPCP), quality of service (QoS), and operations, administration, and maintenance (OAM) capability of EPONs.

scholarly journals DSP-Based 40 GB/s Lane Rate Next-Generation Access Networks

2018 ◽  
Vol 10 (12) ◽  
pp. 118 ◽  
Author(s):  
Jinlong Wei ◽  
Ji Zhou ◽  
Elias Giacoumidis ◽  
Paul Haigh ◽  
Jianming Tang
Keyword(s):  
Optical Networks ◽  
High Speed ◽  
Digital Signal ◽  
Pulse Amplitude ◽  
Network Capacity ◽  
Access Networks ◽  
Next Generation ◽  
Efficient Manner ◽  
Continuous Growth ◽  
Modulation Format

To address the continuous growth in high-speed ubiquitous access required by residential users and enterprises, Telecommunication operators must upgrade their networks to higher data rates. For optical fiber access networks that directly connect end users to metro/regional network, capacity upgrade must be done in a cost- and energy-efficient manner. 40 Gb/s is the possible lane rate for the next generation passive optical networks (NG-PONs). Ideally, existing 10 G PON components could be reused to support 40 Gb/s lane-rate NG-PON transceiver, which requires efficient modulation format and digital signal processing (DSP) to alleviate the bandwidth limitation and fiber dispersion. The major contribution of this work is to offer insight performance comparisons of 40 Gb/s lane rate electrical three level Duobinary, optical Duobinary, and four-level pulse amplitude modulation (PAM-4) for incorporating low complex DSPs, including linear and nonlinear Volterra equalization, as well as maximum likelihood sequence estimation. Detailed analysis and comparison of the complexity of various DSP algorithms are performed. Transceiver bandwidth optimization is also undertaken. The results show that the choices of proper modulation format and DSP configuration depend on the transmission distances of interest.

scholarly journals Optical Back-Propagation for Nonlinear Compensation in OFDM-Based Long Range-Passive Optical Networks

2020 ◽  
Vol 36 (1) ◽  
Author(s):  
Ngo Thi Thu Trang ◽  
Nguyen Duc Nhan ◽  
Bui Trung Hieu
Keyword(s):  
Optical Networks ◽  
Long Range ◽  
Direct Detection ◽  
Back Propagation ◽  
Fourier Method ◽  
High Rate ◽  
Passive Optical Networks ◽  
Ofdm System ◽  
Nonlinear Compensation ◽  
Optical Ofdm

In direct-detection optical OFDM system, the nonlinear impairment is the key factor that limits the system performance. The back-propagation techniques in digital and optical domains have been proposed to compensate the nonlinear effects, however they can be unsuitable for long-range passive optical networks (LR-PONs) due to their implementation at receiver. In this study, we propose an optical back propagation (OBP) approach for compensation of the nonlinear and dispersion distortions in direct-detection optical OFDM system. The proposed OBP using split-step Fourier method is implemented at transmitter that is suitable for high-rate OFDM-based LR-PONs applications. In this OBP, the fiber Bragg grating (FBG) is used as a step for dispersion compensation and the high-nonlinear fiber (HNLF) with a short length is used as a step for nonlinear compensation. The performance improvement based on our proposed approach has been demonstrated via Monte-Carlo simulations of the 100 Gbit/s direct-detection optical OFDM system with 80 km of standard single mode fiber link. The influence of optical conjugation process and launching conditions has been investigated. The obtained results show that the proposed OBP can improve remarkably the performance of system with the launched power range from -2 dBm to 6 dBm.

scholarly journals Programmable Adaptive S-BVTs for Future Optical Metro Networks Adopting SOA-Based Switching Nodes

2018 ◽  
Author(s):  
Laura Martín González ◽  
Sjoerd van der Heide ◽  
Xuwei Xue ◽  
John van Weerdenburg ◽  
Nicola Calabretta ◽  
...  
Keyword(s):  
Optical Networks ◽  
Direct Detection ◽  
Digital Signal ◽  
Cost Effective ◽  
Optical Amplifier ◽  
Limiting Factor ◽  
Bit Rate ◽  
Discrete Multitone ◽  
Key Factor ◽  
Metro Networks

Adaptive Sliceable-Bandwidth Variable Transceivers (S-BVTs) are key enabler for future optical networks. In particular, those based on Discrete MultiTone (DMT) modulation and Direct Detection (DD) can be considered a flexible solution suitable to address the cost efficiency requirement of optical metro networks. In this paper, we propose to use this cost-effective S-BVT option/implementation in optical metro networks adopting switching nodes based on Semiconductor Optical Amplifier (SOA) technology. Bit loading (BL) and power loading (PL) algorithms are applied to the Digital Signal Processing (DSP) modules, to maximize the performance and/or the capacity as well as enhance the flexibility and adaptability of the system. Our analysis considers switching nodes based on SOAs with and without filtering elements and fiber spans of 25 km. We present the results up to 100 km, with and without SOA-based nodes. Firstly, we analyze the adaptive BVT transmission using the Margin Adaptive (MA) BL/PL algorithm at a fixed bit rate of 28 Gb/s. The possibility of controlling the SOAs current is a key factor to face the transmission impairments due to the fiber and the filtering elements. We also analyze the system considering Rate Adaptive (RA) transmission at a fixed target BER of 3.8·10−3, showing that a maximum capacity above 34 Gb/s can be achieved for a single span of 25 km. Although the cascading of filtering elements still constitutes a limiting factor, we show that an improvement of the net bit rate performance can be obtained thanks to the combined use of S-BVT and SOA technology at the switching nodes, resulting in a promising approach for designing future optical metro networks.

High Speed Vedic Multiplier for Digital Signal Processors

2009 ◽  
Vol 55 (6) ◽  
pp. 282 ◽  
Author(s):  
Ramesh Pushpangadan ◽  
Vineeth Sukumaran ◽  
Rino Innocent ◽  
Dinesh Sasikumar ◽  
Vaisak Sundar
Keyword(s):  
High Speed ◽  
Digital Signal ◽  
Digital Signal Processors ◽  
Vedic Multiplier ◽  
Signal Processors
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