Optical Access Networks Research Articles

Performance analysis of all optical contention detection circuit for high speed optical access networks

Performance analysis of all optical contention detection circuit for high speed optical access networks

30 Gbit/s PAM4 transmission using an 8-GHz directly modulated multi-section laser.

This paper describes the characterization of a novel directly modulated multi-section laser with a master-slave configuration. Amplitude and phase noise measurements show relative intensity noise values of around -150 dB/Hz and a 3-dB linewidth of around 3 MHz. The laser's suitability for optical access networks, enabled by the chirp reduction from the external injection locking, is shown by demonstrating unamplified 30 Gbit/s C-band transmission over 25 km and 50 km of single mode fiber using PAM4, as well as 30 Gbit/s PAM4 and PAM8 amplified transmission over 75 km.

Design and optimization of optical power splitters for optical access networks

This paper aims to study the design, simulation, and optimization of low-loss Y-branch passive optical splitters up to 64 output ports for telecommunication applications. For a waveguide channel profile, the standard material silica-on-silicon is used. The Y-splitters are designed and simulated at telecommunication operating wavelength, lambda = 1550 nm. Except for the lengths of the used Y-branches, and a core size of the waveguides, design parameters such as port pitch between the waveguides and simulation parameters for all splitters are considered fixed. The simulation results are analyzed to determine the optimum length of the splitters and the optimum core size. Based on this optimization the total length of the highest designed 1times 64 Y-branch splitter was reduced by 41.14 % for a waveguide core (5times 5) upmu mathrm{m}^2 compared to the length of splitter with a standard (6times 6) upmu mathrm{m}^2 core size.

Performance enhanced probabilistically shaped PAM4 signal based on nonlinear differential coding for IM/DD system

In this paper, the probabilistically shaped pulse amplitude modulation (PS-PAM) signal is proposed in intensity modulation and direct detection (IM/DD) system. For the traditional shaping scheme with constant composition distribution matcher (CCDM), there are several problems that high-precision algorithm for long block coding, the loss of information rate for short block coding. In addition, it can increase nonlinear interference. In order to reduce computational complexity and alleviate the influence of nonlinear interference on the system, the nonlinear differential coding (NLDC) scheme is used to realize PS, which can be better integrated with the cost-effective optical access network. This paper evaluates seven shaping spectrums obtained by different NLDC coding coefficients. As the coding coefficient increases, the performance of the system gradually improves. Moreover, this paper proposed the machine learning includes neural network (NN) and improved K-means clustering algorithm at the receiver. The results show that the PS-PAM4 signal is significantly better than the ordinary PAM4 signal in improving the channel bandwidth tolerance and signal transmission rate. Under the same data rate, using NLDC can save 5.8 GHz bandwidth for the system. For the bandwidth-limited system, the PS-PAM4 signal can obtain 19Gbit/s bit rate gain compared with the ordinary PAM4 signal. Compared with the typical shaping scheme using CCDM, this scheme can achieve 2.2 GHz band tolerance gain and 5Gbit/s rate gain in nonlinear fiber channel.

Optical access evolutions towards SDN and disaggregated hardware: an operator perspective [Invited

In this paper, we review recent advances of the optical access network in the path toward Cloud-computing-related technologies, software defined networking, and network function virtualization. We present the new network management architectures proposed by standardization bodies such as the Broadband Forum and non-profit organizations such as the Open Networking Foundation and propose to use today’s Orange-France Operation Support System as a baseline to discuss different evolution paths. We also provide a review of recent advances in the optical line terminal (OLT) hardware evolution, from white-box OLTs to general purpose hardware, and identify the remaining related challenges, such as energy consumption and interoperability. We also show how Cloud-computing technologies in optical access networks could remove the frontier between network segments (home local area network, optical transport network, and mobile network) by deeply improving the synergy among them.

High-security multi-level constellation shaping trellis-coded modulation method based on clustering mapping rules.

This paper proposes a high-security multi-level constellation shaping trellis-coded modulation (TCM) method based on clustering mapping rules, which is suitable for passive optical networks (PON) using three-dimensional (3D) carrier-less amplitude and phase modulation (CAP). This method combines the TCM mapping process with the constellation shaping and performs a multi-level mapping of the coded signal according to the classification label, so as to obtain better constellation shaping gain while expanding the coding gain of the TCM. The 3D constellation generated by the multi-level mapping adopts Chua's chaotic model for rotation encryption, which improves the ability of the optical access network to resist malicious attacks at the physical layer. Experiments show that 70 Gb/s (7×10 Gb/s) transmission is achieved on a 2 km weakly coupled seven-core fiber using the scheme proposed in this paper. At a bit error rate (BER) of 1 × 10-3, the difference in receiver sensitivity between the best and worst-performing cores is about 0.7 dB. The difference in receiver sensitivity between the cubic constellation and the chaotic spherical constellation is about 0.1 dB. The sensitivity of the chaotic spherical constellation receiver is about 6.98 dB higher than that of the 2D shaping constellation receiver. The experimental results show that the scheme has reliable security performance while improving the short-reach transmission capacity. It has broad application prospects in future short-reach communication research.

Fully flexible remote node based energy-efficient and scalable hybrid WDM-TDM optical access network with broadcasting capability

Fully flexible remote node based energy-efficient and scalable hybrid WDM-TDM optical access network with broadcasting capability

Trusted distributed marketplace for virtual passive optical network sharing

Infrastructure sharing has always been a core aspect of telecommunications networks, especially in the access. The move towards resource-demanding services, which are part of the 5G evolution, further exacerbates its necessity, as the cost of ownership is often not matched by an increase in revenue. In parallel, the recent emergence of network function virtualization is creating new business opportunities and business models that challenge conventional centralized network ownership. In this work, we address the issue of optical access network sharing, addressing the challenging scenario of the untrusted broadband market. We propose, for the first time, to our knowledge, a distributed market scheme for capacity sharing that makes use of permissioned blockchain technology in multi-tenant passive optical networks. The blockchain is used as a verification mechanism that runs in parallel to shared, market-based capacity scheduling operations. To study the feasibility and performance of the proposed verification layer, we have developed a smart contract (chaincodes) using the Hyperledger Fabric permissioned blockchain platform that solves the high transaction cost and energy consumption concerns associated with permissionless blockchain solutions used in cryptocurrencies such as Bitcoin and Ethereum.

Dynamic Subcarrier Assignment in OFDMA-PONs Based on Deep Reinforcement Learning

Orthogonal Frequency Division Multiplexing Access Passive Optical Networks (OFDMA-PONs), a solution for the next-generation optical access network, allows multiple optical network units (ONUs) to dynamically share subcarriers (SCs) to support efficient bandwidth allocation. In uplink transmission, multiple ONUs can share orthogonal low bit rate SCs to transmit data at different time slots (TSs) during the transmission cycle. In this paper, the dynamic subcarrier allocation (DSA) scheme based on deep reinforcement learning (DRL) is proposed for various ONU bandwidth requests. The novel scheme jointly allocates time slots, subcarriers, and modulation formats in a dynamic and flexible manner. The ONU can save transmit power by using a lower order modulation format while meeting the delay requirement. The simulation part demonstrates how the proposed DRL-based DSA scheme can be adapted to various situations, including 1) variation in the size of ONU bandwidth requests, and 2) variation in the weight of different indicators. The extensive simulation results show that, for the first time, the proposed DRL-based DSA algorithm achieves optimal traffic latency with substantial power saving, compared with the traditional two-dimensional DSA algorithms.

Phase Carrier approach based on Optical Code Division Multiple Access Networks

A technique for optical code-division multiple-access (OCDMA) spectral amplitude coding is proposed and analyzed. The proposed approach is based on combining both OCDMA systems over a phase carrier. Compared with conventional OCDMA systems, this approach exhibits numerous advantages such as simplicity in the system design and cost efficiency. The phase shift based on phase modulation is adopted in the proposed system, and the orthogonal function based on the random diagonal code is applied. The proposed scheme is considered cost-effective because only one laser source is used; which minimizes interference for access network passive optical network applications and improves the system performance of bit-error rate (BER 10-12).

Bypass/backup-link switchable coherent point-to-multipoint configured WDM-PON system with shared protection.

A disaster-resistant, point-to-multipoint network configuration that connects distributed optical terminals to a centralized optical terminal, through an exclusive fiber link, is required in edge computing strategies such as 5G, IoT applications, ultrareliable and low latency applications, high-performance content delivery, artificial intelligence applications, and hyperconverged infrastructure. Therefore, we introduce a shared link orientation that fully connects the distributed optical terminal side to the centralized optical terminal side represented by the conventional optical access network. We also propose a method that switches a fully-coupled or half-split network to the centralized optical terminal on the optical switch aggregation station side. We report a verification experiment on the proposed method to confirm the operation of wavelength conversion/optical path switching when a link failure occurs, achieving < 2 dB penalty with small back reflection in wavelength collision-free secondary link transmissions with primary link failure. The unique point of this research is that the centralized optical terminal can easily change from the link-occupancy-oriented network to the link-sharing-oriented network. This work will lead to development of a novel disaster-resistant network configuration for wavelength division multiplexing-based coherent passive optical network systems.

Enhancing Energy Efficiency of the Doze Mode Mechanism in Ethernet Passive Optical Networks Using Support Vector Regression

An Ethernet passive optical network (EPON) is an optical access network that allows a higher data rate with low power consumption. To improve energy savings for an EPON, the sleep and doze modes for the optical network units (ONUs) play a pivotal role. Many prediction schemes have been proposed to control these modes. To increase the prediction accuracy, this study proposes an energy-efficient approach that uses a support vector regression (SVR) model. A dynamic bandwidth allocation (DBA) scheme called SVR-DBA is designed to allocate bandwidth to ONUs more efficiently and fairly. To determine the effectiveness of the proposed scheme, simulations are performed. The simulation results show that the proposed scheme decreases energy consumption for ONUs by up to 47% and fulfills the quality-of-service (QoS) requirements in terms of delay, jitter, and packet loss.

Guest editorial: Smart communications and networking: architecture, applications, and future challenges

Guest editorial: Smart communications and networking: architecture, applications, and future challenges

Guest Editorial: Next-Generation Optical Access Networks to Support Super-Broadband Services and 5G/6G Mobile Networks

We are pleased to introduce to our readers the following Special Issue (SI) on Next-Generation Optical Access networks to support Super-Broadband Services and 5G/6G Mobile Networks in IEEE Network. In recent years, optical access networks have been playing a growing role in mobile networks and will become even more prominent with 5G/6G due to the demand for extreme bandwidth, coverage, synchronization, and low latency. The success of future mobile networks will not just be about new radio access technologies. The deployment of future wireless technologies will be dependent on the ability of optical access networks to seamlessly connect to radio access networks (RANs) and edge/cloud computing resources. Many technologies are currently being developed for optical networks for convergence and access to increase throughput, improve energy efficiency, and simplify network design, deployment, and operation. This SI is intended to provide recent advances in optical networking technologies, concentrating on optical access networks and the convergence of integrated fiber and wireless access technologies.

Architectural Design and Life Cycle Management of Network Slicing for Software-Defined Optical Access Networks

Optical access networks (OANs) with passive optical network technology have been globally deployed on a massive scale, serving as the fundamental information infrastructure of teleCommunication networks. Some telecom service providers are re-architecting their networks based on cloud central office with software-defined networking and network functions virtualization capabilities to provide service agility, intelligence, and scalability. In this article, we present a synthesized analysis of the inherent value and practical use cases of access network (AN) slicing in the context of software-defined OANs. A novel hierarchical abstraction model and a workflow of end-to-end network slicing are presented to illustrate the support of multi-service and multi-tenancy applications over a converged OAN platform by enabling automatic life cycle management of AN slicing. Two successful trials utilizing the model and the workflow are also demonstrated.

TDM-PON-Based Optical Access Network for Tactile Internet, 5G, and Beyond

An optical access network plays a critical role in accommodating explosive new services such as augmented reality (AR), virtual reality (VR), machine-to-machine, and human-to-machine interaction applications. Continuous expansion of capacity as well as low latency in the optical access network are very important issues to avoid loss of connectivity for 5G and Tactile Internet. A time-division multiplexing passive optical network (TDM-PON) is an attractive solution to provide optical connectivity to end users in residential, business, and mobile applications since multiple remote nodes with simple optical power splitters give us easy-to-use optical connection anywhere in an optical distributed network. This article reviews TDM-PON-based optical access technologies for bandwidth-intensive as well as low-latency services, and introduces a recent feasibility demonstration of a Tactile Internet testbed. Technical challenges faced by TDM-PON for future networks in terms of capacity, latency, and virtual-izationlslicing are also discussed.

Global-Local AI Coordinated Learning over Optical Access Networks for Scalable H2M/R Collaborations

While pre-fifth and fifth generation networks have been designed mainly to support machine-to-machine and human-to-human communications via data, audio, and video communications, a major thrust of beyond fifth generation Networks is the abutment of human-to-machine/robot (H2M/R) collaboration. Such collaborations are deeply anchored in the vision of Society 5.0, which promotes a human-centered society that integrates virtual and physical real spaces to resolve social problems, and Industry 5.0, which promotes intelligent manufacturing processes through collaboration between humans and cyber-physical systems. It is expected that real-time H2M/R collaborations will drive new technologies that facilitate the low-latency exchange of control signals and haptic feedback between humans and machines/robots. The low-latency constraints for real-time interaction will, however, place limits on deployable distance and the flexibility of adding new machines/robots to the system. The scalability of H2M/R collaborations across large geographical distances that also allow rapid onboarding of new machines/robots is therefore an open challenge. This article focuses on global-local AI coordinated learning (GLAD), a solution framework that supports the dynamic addition of new machines/robots and their rapid onboarding. The GLAD framework is based on learning the traffic characteristics and correlation of supported robots/machines at the local edge and global cloud. Harnessing data samples from a real H2M/R application for training and validation, GLAD enables human operators to remotely control machines/robots over extended distances through accurately forecasting their haptic feedback. By globally coordinating and sharing this learning across the network, up to 72 percent of the time can be saved when onboarding new machines/robots.

Research on optical sparse code division multiple access encoding technology based on a multi-core fiber.

Sparse code division multiple access (SCMA) technology is one of the main technologies of 5G (5th Generation Mobile Communication Technology). Applying SCMA technology to the field of optical communication has broad prospects, which solves the access problem of a large number of users in optical access network. In this paper, a transmission system based on SCMA over multi-core fiber is proposed. The SCMA coding signal transmission at 30 Gb/s is successfully implemented on a seven-core fiber, which four of seven-core is only used. Its bit error rate (BER) can achieve forward error correction (FEC) limit (BER is 3.8 × 10-3) when the received optical power is -10 dBm. And this experiment verifies the performance of the proposed scheme. In addition, we propose a scheme to reduce the complexity of message passing algorithm (MPA) at the receiver by using the core of fiber dimension. Compared with original MPA, this scheme reduces the number of users superimposed on the same resource block. From the second experiment, for a BER of FEC limit the SNR penalty is∼1 dB for the proposed MPA compared to original MPA. The research of this paper provides a feasible scheme for the next generation of optical access network.

Blockchain-Enabled Tripartite Anonymous Identification Trusted Service Provisioning in Industrial IoT

The integration of Internet of Things (IoT) and industry reveals the industrial manufacturing developments, resulting in Industry IoT (IIoT), which is to provide a general interconnect system for the access of various industry devices. However, as the amount and type of terminal increase, the creditability and privacy protection of terminal devices are hard to be guaranteed in IIoT, since the data and digital identity of access devices are nearly transparent for more devices in networks. It is a critical issue for the security of IIoT whether the access and service of device are trustworthy. In this article, we present a novel private blockchain-enabled trusted anonymous access (BlockTrust) architecture for IIoT, where the distributed cloud radio and optical access networks (C-RONs) are considered to provide a risk reduction of privacy leakage. Based on the BlockTrust architecture, a blockchain-enabled tripartite anonymous identification trusted service provisioning (TriTrustServ) scheme is further proposed to guarantee a balanced tradeoff among the credibility, confidentiality, and efficiency in IIoT, including digital identity generation, anonymous access identification, and trusted resource provisioning. Note that for the sake of a high credibility in IIoT networks, a tripartite authentication is presented in this article with the first time among device manufacturer, devices, and network operator for the access process of device in IIoT networks. The feasibility and efficiency of BlockTrust architecture are experimentally verified in the realistic testbed, and the performances of the TriTrustServ scheme are evaluated by comparing with two benchmark schemes in the terms of average mistrust rate, resource utilization, and identification cost.

4G to 6G: disruptions and drivers for optical access [Invited

The exponential growth of diverse smart mobile applications such as smart monitoring, holograms, and autonomous vehicles are driving mobile technologies toward a more intelligent and software-defined communication system. This growing demand has led to the next giant leap in next-generation wireless communication technology, i.e., sixth-generation (6G) mobile technology, which anticipates providing 1 Tbps data rates and ultralow latency over ubiquitous 3D coverage areas. However, the transport network, which connects hundreds of thousands of cell sites and the network core to enable intelligence, virtualization, and other key features of 6G, has not advanced enough to cater the dense cell deployment expected in future 6G networks. Because many aspects of 6G remain undefined, this provides us with the opportunity to take optical transport networks into design consideration to realize the benefits that 6G has to offer. To this end, in this paper, we present a comprehensive view on the role of optical access networks in supporting fourth-generation (4G), fifth-generation (5G), and beyond wireless technologies. In particular, we discuss design and deployment strategies and their challenges when using optical access as a transport solution during the evolution of wireless access technologies. For this purpose, we first identify how an optical access network is used to support high-capacity transport networks in 4G, followed by the challenges that 5G brought into optical transport networks and its diverse solutions. We conclude the paper by providing insights into how an optical transport network can be designed to support 6G.