Next-generation Passive Optical Network Research Articles

A hybrid next-generation passive optical network and visible light communication for future hospital applications

The advancement in the latest healthcare technologies have shown a growing interest in 10/10 Gbps per channel hybrid next generation passive optical network (NG-PON) and visible light communication (VLC) networks to achieve the aim of future hospital applications. This paper investigates the use of hybrid time and wavelength division multiplexing PON (TWDM-PON), wavelength division multiplexing optical code division multiple access PON (WDM-OCDMA PON) using zero cross-correlation (ZCC) code and VLC for the hospitals scenario. The proposed bidirectional system is investigated for four TWDM, six WDM-OCDMA and three VLC information channels in terms of variable fiber length, bit rate, different OCDMA codes and multi-hospital systems. It is investigated that upstream channels performs better than downstream channels and provides the successful 10/10 Gbps hybrid system over 50 km fiber and 10 m VLC link serving 53 users in single hospital system. It also provides the high eye-height, optical signal to noise ratio (OSNR) and received power. Moreover, the performance of the proposed system can be further enhanced by using modified quadratic congruence (MQC) code and high transmission power. Also the comparative analysis with existing systems show the superiority of the hybrid NG-PON/VLC system using fiber/wireless links over the conventional radio access networks in healthcare applications.

5G-Enabled Tactile Internet Resource Provision via Software-Defined Optical Access Networks (SDOANs)

Emerging research trends in smart healthcare, smart manufacturing, and Industrial Internet-of-Things (IIoT) applications are based on 5G services, which can achieve ultra-reliable and low-latency communication networks. In such fields of application, haptic applications have gained importance. The invention of 5G wireless communication networks and advances in Tactile Internet (TI) technology, which provides controlled communications through the transmission of touch and actuation in real-time, have been envisioned as promising enablers of TI services. This study introduces TI-based smart hospital healthcare applications to enhance the alignment of services provided to patients. The existing telesurgery system has high communication delay and overhead, which limit its applicability. To alleviate these problems, we analyze and provide insights into the communication architecture for 5G-enabled low-latency telesurgery in a smart hospital. We then propose a new TI-software-defined optical access networking (TI-SDOANs) framework in Next-Generation Passive Optical Network 2, which includes cloud-based human-to-machine steering servers and supports multiple cloud-based applications. We further propose the implementation of an effective TI-dynamic wavelength and bandwidth allocation (TI-DWBA) resource provisioning scheme that meets the quality of service requirements of TI services. Simulation results show that the proposed scheduling schemes can significantly improve the Quality of Service (QoS) performance in terms of the packet delay, jitter, throughput and packet drop.

Polarization multiplexing and hybrid modulation based bandwidth efficient NG-PON2 coexisting with GPON and XG-PON

Bandwidth efficiency is an important design parameter for next-generation passive optical network stage 2 (NG-PON2). In this paper, two optical line terminal (OLT) designs based on the polarization split state are proposed for NG-PON2. The first method doubles the data rate per wavelength by separate amplitude modulation of both polarization states, whereas, in the second method, differential phase-shift keying (DPSK) modulates another data stream on each amplitude-modulated state; this approach increases the data rate per wavelength fourfold. The proposed system provides NG-PON2 access while coexisting with a gigabit passive optical network (GPON) and 10 GPON (XG-PON). The proposed system design serves 1024 NG-PON2 opitcal network units (ONUs), 128 GPON ONUs, and 128 XG-PON ONUs. The transmission performance of the system is verified by evaluating the bit error rate (BER) for varied received power. An acceptable BER level of less than ${{1}}{{{0}}^{- 9}}$ is considered in this work.

Effect of four-wave mixing on the loss budget of four-channel multiplexing NG-PON systems

In this study, the loss budget for adopting non-return-to-zero (NRZ) and four-level pulse amplitude modulation (PAM4) in next-generation passive optical networks (NG-PONs) was investigated by simulation and experiment. Through simulation, the signals are distorted by four-wave mixing (FWM) when the zero-dispersion wavelength locates in the middle of the channels. For 25-Gb/s NRZ, a maximal loss budget of approximately 32.5 dB is obtained. For 50-Gb/s PAM4, the bit error rate cannot reach 1 × 10−3. While, the impact becomes negligible whens the zero-dispersion wavelength stays away from the middle of the channels, and the loss budget is 36 and 25.7 dB for NRZ and PAM4 systems. Therefore, at least a 32.5-dB loss budget ise obtained in a 4 × 25G NRZ system. While, the loss budget cannot reach the basic requirement of 29 dB in the 4×50G PAM4 system. The experimental resultso verify this conclusion.

Bin-Packing-Based Online Dynamic Bandwidth and Wavelength Allocation Algorithm in Super-PON

Super passive optical network (Super-PON) is a next-generation Ethernet PON (NG-EPON) candidate that is envisaged to provide high data rate and low latency. For NG-EPON, there are two types of algorithms that manages bandwidth and wavelength scheduling, namely offline and online. The latter method is more scalable and efficient than the former method. Several online algorithms exist that propose schemes to manage wavelength and bandwidth scheduling. However, these algorithms lack in efficient wavelength utilization and switching. In this work, we propose a novel online bin-packing based dynamic bandwidth and wavelength allocation (DBWA) algorithm for Super-PON, namely updated best fit bin-packing (UBF-BP). This algorithm limits the wavelength switching per cycle, and uses the modified version of best fit bin-packing (BF-BP) technique for optimal wavelength allocation. Simulation results show that the proposed DBWA algorithm has a low complexity and overcomes the inefficiencies of wavelength utilization and switching. This results in lower network delay and higher channel utilization than the state-of-the-art DBWA. Furthermore, to verify the correctness of the proposed algorithm, we propose an analytical model and validate these simulation results with the analytical results.

Polarization-Discriminated RSOA–EAM for Colorless Transmitter in WDM–PON

The integrated reflective semiconductor optical amplifier (RSOA) and electro-absorption modulator (EAM) is viewed as an appealing solution to the colorless transmitter on the optical network unit (ONU) side of wavelength-division multiplexed (WDM) passive optical networks (PONs), for its broad modulation bandwidth and high optical gain. However, the conventional RSOA–EAM usually exhibits a poor upstream signal eye-diagram because it can hardly simultaneously saturate the downstream signal and boost the upstream signal as required. By exploiting the polarization-depended RSOA gain, we propose a polarization-discriminated RSOA–EAM to improve the quality of the upstream signal eye-diagram. In this device, the transverse electric polarized downstream signal is saturated by the high gain in the RSOA active region made of compressively strained multiple quantum wells, whereas the upstream signal is linearly amplified after polarization rotation. We find that, as the quality of the upstream signal eye-diagram improves with an increased polarization rotation angle, its power drops, which indicates that there exists an optimized rotation angle to reach a compromise between the upstream signal integrity and power. Simulation results show that the dynamic extinction ratio and output power of the upstream signal can reach 8.3 dB and 11 dBm, respectively, through the proposed device with its rotation angle set at an optimum value (80°), which exceeds the specification (6 dB and 4 dBm) of the upstream transmitter as required by the next-generation PON stage two. The quality of the upstream signal eye-diagram measured in Q-factor is improved by 10 dB compared to the conventional RSOA–EAM design without polarization rotation introduced.

Self-Adjusting DBA Algorithm for Next Generation PONs (NG-PONs) to Support 5G Fronthaul and Data Services

In this article, we propose a novel dynamic bandwidth allocation (DBA) algorithm for NG-PON networks to jointly support 5G fronthaul and best-effort data services in the same PON channel. The proposed self-adjusting DBA adjusts dynamically the allocation intervals to the current required fronthaul throughput based on the requests reported from the ONUs. It is suitable for dynamic 5G scenarios where, for energy efficiency reasons, the fronthaul connections are dynamically set up and torn down over time: when a new 5G fronthaul connection is set up, the maximum latency of the current connections is guaranteed while when a current 5G fronthaul connection is torn down, the freed transmission resources become available for data services. The only requirement is that the capacity of the channel in the NG-PON network is enough for the throughput of all 5G fronthaul connections supported by the channel. In this way, the proposed self-adjusting DBA algorithm has the advantage of requiring a much lower management coordination between the 5G infrastructure and the NG-PON infrastructure than the one required when the throughput of the 5G fronthaul connections is supported as a guaranteed service.

Performance analysis of erbium-doped fiber amplifier (EDFA) and hybrid optical amplifier in NG-PON2 based on TWDM-PON system

One of the milestones in the optical access network evolution is the Next-Generation Passive Optical Network Stage 2 (NG-PON2) that has 40 Gbps as minimum upstream/downstream capacity. The optical amplifiers have to implement to combat the power degradation in the transmission line. This research aims to analyze the performance of EDFA boosters and hybrid optical amplifiers, which are implemented on TWDM-PON systems based on NG-PON2. Our work used 80 Gbps data speed, which each channel had 10 Gbps on eight channels with a channel space of 100 GHz. The optical link used in this simulation was 60 km with the Erbium-Doped Fiber Amplifier (EDFA) and Hybrid Optical Amplifier (HOA). The performance analysis is based on the variation of ONU and amplifier. Based on the results, the best value in the downstream is the transmission line using EDFA with the received power of - 19.184 dBm, Q Factor of 7.975, and BER of 5.852 x 10−16. In upstream transmission, the best value obtained was a hybrid optical amplifier with a received power value of 9.025 dBm, Q Factor of 69.64, and BER of 0. The optical amplifier increased the system performance when implemented on TWDM-PON systems based on NG-PON2.

Digital-Analog Hybrid Optical Access Integrating 56-Gbps PAM-4 Signal and 5G mmWave Signal by Spectral Null Filling

A bandwidth-efficient and low-cost spectral-null-filling scheme simultaneously delivering a 56-Gbps 4-level pulse amplitude modulation (PAM-4) digital signal and a 10 × 400-MHz analog radio frequency (RF) signal on a single wavelength is demonstrated for high-capacity wired and wireless optical access networks. The data rate of the PAM-4 signal is consistent with the next-generation passive optical network (PON), and the PAM-4 signal inherently provides a spectral null at 28 GHz, which can be filled with the RF signal exactly at the 5G-specified millimeter wave (mmW) band. Since pulse shaping is not essential in this hybrid transmission system, a low-cost 2-bit digital-to-analog converter (DAC) is adopted for the PAM-4 signal generation. Volterra nonlinear equalizer is adopted to effectively eliminate the analog-to-digital crosstalk without reserving a frequency gap in between. The digital-analog hybrid signal is simultaneously transmitted over a 25-km standard single-mode fiber in telecom C-band and the impact of chromatic dispersion on the number of supported mmW bands is analyzed. In addition, three types of hybrid transmitters are experimentally demonstrated, among which the first-time proposed IQ-modulator-based hybrid transmitter shows the best performance.

Transceiver technologies for passive optical networks: past, present, and future [Invited Tutorial

This paper provides an overview of transceiver technologies to be used for current and next-generation passive optical networks (PONs). The uninterrupted scaling of PONs to higher bitrates in a cost-effective way to meet future bandwidth demands will drive the need for continuous improvement in PON transceiver technologies. In this paper we try to analyze the requirements needed and the impact on this for next-generation transceiver technologies based on past and present PON transceiver designs.

Seven-channel 1 Gbps TWDM coexistence architecture supporting 65 Gbps optical link for next-generation passive optical network 2–based FTTX access networks

Abstract In this paper, we have presented the design and simulation of a 7-channel next-generation passive optical network (NG-PON2) network for the deployment of Fiber-to-the-X (FTTX) access network. Coexistence architecture is proposed, designed and simulated for the implementation of NG-PON2 access network. In a coexistence architecture approach, legacy PON networks like Gigabit passive optical network (GPON) PON, 10GPON, etc. and wavelength division multiplexing (WDM)-PON supporting point-to-point connectivity are designed and simulated together. A 4 × 4 WDM-PON in which each channel carrying data at 2.5 Gbps data rate is capable of supporting a throughput channel capacity of 65.5 Gbps. NG-PON2 network is designed and simulated at 187.1, 187.2, 187.3 and 187.5 to 187.8 THz wavelengths in downstream direction for different link distances from 40 to 80 km looking into the requirement of reach of access network for future cities. The network performance parameters such as bit error rate (BER), quality factor (Q-factor), signal-to-noise ratio using the Optisystem-16 simulator at above data rates and link distances. Further, channel capacity estimation is done for single-mode fiber channel coexistence NG-PON2 configuration up to 80 km supporting BER e-13 and Q-factor 7 for WDM link and BER e-12 and Q-factor 7 for a legacy network supporting almost-1 Gbps data rate to 65 users and 100 Mbps to 512 user.

Implementation of Multi-Wavelength Source for DWDM-PON Fiber Optical Transmission Systems

Abstract Four-wave mixing (FWM) is one of the well-known nonlinear optical effects (NOE), and it is considered as an adverse impact in fibre optical communication lines. This nonlinear optical effect as a productive one can be used in fibre optical communication systems for various optical processing functions, like wavelength conversion, high-speed time-division multiplexing (TDM), pulse compression, fibre optical parametric amplifiers (FOPA), etc. In most of the fibre optical communication systems, each data transmission channel requires one light source (e.g., laser) as a carrier, which can make these transmission systems expensive. For example, to provide operation of 4-channel dense wavelength-division-multiplexed (DWDM) system four separate lasers at specific operation wavelengths are needed. On the contrary, through the FWM effect, which can be obtained in highly nonlinear optical fibre (HNLF) by using two high-power pump lasers, the generation of new multiple carriers forming the laser array or a multi-wavelength source is possible. Accordingly, within the present research, we investigate the latter approach for FWM light source implementation in DWDM passive optical networks (DWDM-PONs). We analyse up to 16-channel 50 GHz spaced DWDM-PON system with a bitrate of up to 10 Gbit/s per channel, constructed on the basis of two high-power continuous wave (CW) pump lasers. We evaluate the system performance against the number of its channels by changing it from 4 to 16 and in each case find the most optimal HNLF fibre length (for a 4-channel system it is 0.9 km; for an 8-channel system – 1.39 km; and for a 16-channel system – 1.05 km) and laser pump powers (for a 4-channel system it is 20 dBm; for an 8-channel system – 24.1 dBm; and for a 16-channel system – 26.3 dBm). These optimal parameters were found in order to get the highest system performance, respectively, the lowest BER (threshold BER≤10−10), and minimal power fluctuations among FWM generated carriers. The obtained results show that the proposed transmission system can be a promising solution for next-generation high-speed PONs.

All-optical encryption in 80-Gbps next-generation passive optical network stage 2

Passive optical network broadcasts extensive data to subscribers. However, they are vulnerable to various security attacks. The main objective of our work is to assess the information security aspects at the physical layer of next-generation passive optical network stage 2 (NG-PON2). Our paper focuses on the security issues faced by NG-PON2, and we propose an encryption method using the all-optical exclusive-OR gate. The proposed simulation architecture of symmetric 80-Gbps NG-PON2 is based on array waveguide grating. Further, we verified the inherent security of the NG-PON2 system through an eavesdropping attempt at an optical network unit (ONU). For this, we used a key exchange mechanism using the Diffie–Hellman algorithm for sharing individual unique keys between every ONU and the optical line terminal. The simulation results show that the presented technique provides secure broadband services in the access network. The transmitted data are encrypted to ensure confidentiality on the multipoint fiber connection. We have evaluated the transmission performance of the proposed set up and achieved acceptable results in terms of Q-factor (7.12 dB) and bit error rate of (5.26 × 10 − 13). The bits in the optical domain, which are sent to the first ONU, are also compared with the received optical bits at the receiving ONU. The correct reception of the bits at the intended ONU and the inability of malicious ONUs to eavesdrop the data of other ONUs validates the scheme.

Photonic Integrated Circuits for NGPON2 ONU Transceivers (Invited)

The development of photonic integrated circuits (PIC) for access network applications, such as passive optical networks (PON), constitutes a very attractive ecosystem due to PON’s potential mass market. The implementation of PIC solutions in this context is expected to facilitate the possibility of increasing the complexity and functionalities of devices at a potentially lower cost. We present a review addressing the prominent access network market requirements and the main restrictions stemming from its specific field of application. Higher focus is given to PON devices for the optical network unit (ONU) and the implications of designing a device ready for market by discussing its various perspectives in terms of technology and cost. The discussed PIC solutions/approaches in this paper are mainly based on indium phosphide (InP) technology, due to its monolithic integration capabilities. A comprehensive set of guidelines considering the current technology limitations, benefits, and processes are presented. Additionally, key current approaches and efforts are analyzed for PON next generations, such as next-generation PON 2 (NGPON2) and high-speed PON (HSP).

Comparative study of cost-effective coherent and direct detection schemes for 100 Gb/s/λ PON

As the capacity of the next-generation passive optical network (PON) is reaching 100 Gb/s and beyond, cost-effective transceivers have been widely discussed. In this work, we provide a comprehensive comparison of various simplified coherent and direct detection (DD) schemes operating at a 100 G b / s / λ 4-ary pulse amplitude modulation signal through numerical simulation. According to the cost, the coherent receivers can be divided into three levels: intensity-only coherent receivers and phase-insensitive and phase-sensitive complex-value coherent receivers. The received power sensitivity at back-to-back, influence of laser frequency offset, local oscillator power, laser linewidth, analog-to-digital convertor resolution, fiber dispersion, and hardware complexity are investigated and analyzed for each transceiver structure. The results show the following: (1) Transmitter-side optical amplification is suggested for DD and intensity-only coherent receivers to meet the 29 dB power budget requirement, and these schemes have a large dispersion penalty. (2) Compared with 3 × 3 coupler and 2 × 4 hybrid-based coherent receivers, 2 × 2 coupler and balanced-photodiode-based heterodyne detection exhibit similar performance with a simpler structure. (3) Both phase-insensitive and phase-sensitive complex-value coherent receivers have superior power budget and dispersion tolerance, and their application in PON would depend on the cost.

Low peak-to-average power ratio OFDM-PON system with multiprobabilistic shaping distribution

Higher flexibility and high peak-to-average power ratio (PAPR) are the main challenges for orthogonal frequency division multiplexing passive optical network (OFDM-PON) systems. For this purpose, we propose a low PAPR OFDM-PON system with a dynamic regulatory factor U, which can dynamically adjust the transmission capacity of the system according to the needs of users at optical network units and reduce PAPR at the same time. Dynamic regulatory factor U can assign different probabilistic shaping schemes to different subcarriers, thus improving the system flexibility and adjustability in both the time and frequency domains. Meanwhile, U can flexibly change the number of phase sequence groups in selecting mapping, which is a well-known effective PAPR reduction technique. Simulations of a back-to-back OFDM-PON transmission system with different bit rates are setup to verify the performance of the proposed scheme. It is demonstrated that the proposed scheme achieves effective PAPR reduction performance with considerably lower computational complexity and outstanding bit error performance. More importantly, our proposed OFDM-PON system can be flexible and adjustable in acquiring different and dynamic access bit rates, which suggests a prospective solution for the next-generation PON.

METAhaul framework of HPON for smart city access networks

ABSTRACTThis work presents, a novel, Mobile Evaluation Transport Architecture haul (METAhaul) of Hybrid PON (HPON), that integrates mobile backhaul (MBH), mobile fronthaul (MFH) and smart devices in one platform. It forms a unified analytical framework, that comprehensively accounts for both fiber/copper (FiCo) and METAhaul broadband access networking technologies, to accommodate the fifth generation (5G) Radio Access Network (RAN) evolution and smart sensor devices. Our framework is flexibly designed to roll out while adopting 5G into the smart city. HPON allows the coexistence of the Time Division Multiplexing Passive Optical Network (TDM-PON), Wavelength Division Multiplexing Passive Optical Network (WDM-PON), hybrid Time-Wavelength Division Multiplexing Passive Optical Network (TWDM-PON), multi-gigabit fast access to subscriber terminals (G.mgfast), and Radio over Fiber (RoF) architecture. It can reduce the power consumption by 78.13%, 79.62% at Sub-6GHz, and 77.7%, 79.21% at mmWave against Optical Transport Network (OTN) and Carrier Ethernet (CE), respectively. Specifically, HPON grants a higher Energy Efficiency Rating (EER) of 65.58%, 67.34% when compared to OTN, and CE each while deploying 15 Radio Units (RU). The proposed next-generation PON architecture can benefit the design and operation of smart city access networks, with its large capacity, multilevel of service, and energy saving.

5G/NGPON Evolution and Convergence: Developing on Spatial Multiplexing of Optical Fiber Links for 5G Infrastructures

ABSTRACTThe offering of demanding telecommunication services as promised by the 5G specifications raise the necessity for high capacity, flexible, adaptive, and power conserving fronthaul. Toward this goal, the role of the passive optical network which is responsible for interconnecting the central office (CO) with the cell-sites is crucial. Among the latest related technologies that need to be integrated in the context of the next generation passive optical networks (NGPONs), the most promising for increasing the provided bandwidth, is the optical spatial multiplexing. In this paper, we present the key 5G technologies, focusing on spatial division multiplexing, which constitutes the main innovation of the blueSPACE 5G Infrastructure Public Private Partnership (5G PPP) project. Exploiting the recent developments on multicore fibers (MCFs), optical beamforming networks (OBFNs), analog radio over fiber (ARoF), and spatial-spectral resources granularity in the context of Spectrally Spatially Flexible Optical Networks (SS-FONs), we describe a complete approach for the 5G fronthaul, emphasizing on the efficient allocation of optical resources while aiming at minimizing energy consumption. The modeled optimization problem is thoroughly presented, and the introduced scheme is evaluated through a real-world based simulation scenario, exhibiting quite promising results.

Resource Allocation and QoS Guarantees for Real World IP Traffic in Integrated XG-PON and IEEE802.11e EDCA Networks

Globally, there is a significant rise in the number of connected devices. Every device has an access to wide variety of telecom services among which voice, video and best effort (BE) contribute significantly. There is a noticeable growing trend towards upstream BE traffic besides real time e-services that demand high quality of service (QoS). Converged next-generation fiber-wireless (FiWi) access networks composed of next-generation passive optical network (XG-PON) and 802.11n based wireless local area network (WLAN) has emerged as a suitable choice to provide high quality and affordable e-services to plenty of subscribers as they possess both high bandwidth and flexibility. In this paper, we study the performance of the integrated network architecture which combines XG-PON and enhanced distributed channel access (EDCA) under real time bursty traffic derived from the current global IP traffic distribution. The joint tuning of various crucial parameters of both XG-PON and EDCA with incorporation of an efficient deficit dynamic bandwidth algorithm (DBA) at optical line terminal (OLT) is done by exhaustive simulations in network simulator-3 (NS-3). Through intensive simulations and tuning, we are able to achieve a end-to-end delay performance of <; 150 ms for voice, <; 500 ms for video and a few seconds for BE upto full capacity. Also, a packet loss ratio (PLR) of <; 3% and <; 6% is achieved for voice and BE respectively upto full load. For voice PLR is <; 1% upto 60% total offered load. Further, it is observed that the fine tuning of key parameters has also resulted in increased bandwidth for dominant BE services. Therefore, this optimized network architecture is 20% more fair to BE services as compared to the conventional integrated FiWi architectures.

Optical add/drop multiplexer for tree-based passive optical networks

Abstract A novel tree-based optical add/drop multiplexer (TOADM) that realises the flexible migration of embedding legacy passive optical networks (PONs) and point-to-point networks to next-generation PON 2 (NGPON2) is proposed. The TOADM comprises two four-port optical circulators (OCs), one three-port OC and two fibre Bragg gratings (FBGs). Such a passive component can be placed at any selected location along the trunk fibre of a tree-topology PON to multiplex/demultiplex optical wavelengths dynamically. Experimental results reveal that the insertion losses of the proposed device are smaller than those caused by a 1 × 2 optical splitter in downstream and upstream directions. Unlike the traditional OADM, the novel TOADM is developed to multiplex/demultiplex optical wavelengths for tree-topology networks instead of ring-topology networks. The wavelength routing function of the novel TOADM is more flexible than that of the commercial array waveguide grating or interleaver because the system manager can dynamically readjust the wavelength plan of a PON by modifying the FBG function of preinstalled TOADMs or embedding an extra TOADM in the proper location of the PON.