Generation Passive Optical Networks Research Articles

Investigation of 16 × 10 Gbps mode division multiplexed enabled integrated NGPON–FSO architecture under wired-wireless link losses

Abstract To enhance the transmission capacity for energy consumption and low cost system, mode division multiplexing (MDM) using mode 0 and mode 1 is proposed and investigated. A pair of eight downlink and uplink wavelengths is transmitted by using each MDM mode in an integrated bidirectional next generation passive optical network and free space optics (NGPON–FSO) system at 10 Gbps per channel transmission rate under the impact of FSO–fiber links impairments. Simulation results indicate that received power of −21.2 dBm with 0.2 dB power penalty can be obtained over 1 km FSO and 100 m multimode fiber under unfavourable turbulent effects. The system provides extended FSO link range, and fiber range of 150 km and 600 m respectively at threshold limit of 10−3. Besides, the mathematical analysis depicts the receiver sensitivity and splitter power budget of 42 dBm and 18 dB, respectively, for the proposed system. The system offers finest performance than other pre-existing systems.

Traffic prediction assisted wavelength allocation in vehicle-to-infrastructure communication: A fiber-wireless network based framework

The advent of the next generation of connected and autonomous cars offers immense opportunities for both users as well as service providers. In particular, fiber-wireless (FiWi) based vehicle-to-infrastructure (V2I) network can facilitate some of the stringent requirements of sixth-generation (6G) vehicular networks, including higher capacity, lower delay, and ubiquitous connectivity. FiWi based V2I network integrates the next generation passive optical network 2 (NG-PON2) with IEEE 802.11p based V2I network. In this work, we first review the various kinds of vehicular data traffic and their desired key performance indicators (KPIs), namely throughput, delay, and reliability. Depending on the KPI requirements, the V2I traffic is classified among four classes and assigned to different transmission containers (T-CONTs) of the optical network unit (ONU). Further, in order to minimize the delay of the network, we propose a machine learning (ML) based T-CONT priority assignment wavelength allocation algorithm that minimizes the number of wavelength switching instances in the PON. The performance of the proposed ML-based wavelength allocation algorithm is compared with the other approaches, namely random and equal T-CONT based wavelength allocation algorithms. Simulation results demonstrate the efficiency of the proposed algorithm vis-a-vis other approaches in terms of end-to-end (e2e) delay, throughput, and reliability.

Wheel‐based 5G fronthaul/backhaul hybrid MDM‐NGPON/FSO system under Gamma‐Gamma turbulence and weather effects

SummaryThis work presents the bidirectional and symmetric 40 Gbps wheel architecture comprising 16 channels‐based bidirectional hybrid next generation passive optical network with free space optics (NGPON/FSO) system using mode division multiplexing (MDM) scheme. The system incorporates a low‐cost high bandwidth and integrated time and wavelength division multiplexing with orthogonal frequency division multiplexing (TWDM‐OFDM) for data transmission over mixed fiber‐FSO links to various end users at donut modes 0 and 1. This system enhances the fifth generation (5G)‐based networks reliability, survivability, and flexibility, especially in rural places where the core fiber link may be damaged/destroyed under diverse turbulent and weather conditions. The obtained results depict the faithful multimode fiber range of 100 km with fixed FSO range of 100 m at −17 dBm receiver sensitivity and low power penalty of 0.2 dB at 10−9 bit error rate. Maximum FSO range of 2800 m under weak‐to‐strong Gamma‐Gamma turbulence and the effect of fog, rain, snow, and snow with rain can be obtained successfully with fixed 50 km fiber length. Also, the proposed wheel architecture provides superior performance over hybrid ring‐mesh architecture with high split ratio of 1:64. Moreover, the system can sustain up to 70 remote nodes at symmetric 10 Gbps throughput providing high gain, high optical signal‐to‐noise ratio, and low noise figure. The comparative literature work also reveals that the proposed architecture offers high bandwidth, security, long‐reach, and cost‐effectiveness in 5G fronthaul/backhaul networks.

Virtual Network Function Development for NG-PON Access Network Architecture

Modern networks urge agility, flexibility, and capacity to cope with the growing demand for media content and applications increasingly oriented toward data consumption. The Central Offices (CO) of telecommunication providers, being a vital aggregator of different access networks, such as optical and mobile, need to be prepared to deal with these demands. The Open Broadband-Broadband Access ion (OB-BAA) architecture fits into the initiative to modernize the Information Technology (IT) components of broadband networks, more specifically the COs. This paper discusses the development of a Virtualized Network Function (VNF) in the context of network security to be integrated as a component of an OB-BAA architecture guided by the Software-Defined Network paradigm. More specifically, the authentication and authorization of network equipment within the IEEE 802.1X protocol are applied to Next Generation Passive Optical Networks. The VNF development is based on the Golang language combined with gRPC programmable interfaces for communication between the various elements of the OB-BAA architecture, and then the components were “containerized” and inserted in the Docker and Kubernetes virtualization frameworks of a multinational telecommunications operator. Finally, performance metrics such as computational resource usage (CPU, memory, and network I/O) and execution time of VNF processes were analyzed in usage tests with multiple supplicants and distinct operational modes, to attest to the most promising virtualization scenarios.

Investigation of 2.24Tbps full-duplex integrated multi-beam FSO/MDM-next generation PON under diverse atmospheric conditions

A full-duplex 2.24Tbps mode division multiplexing (MDM) based integrated multi-beam free space optics (FSO) and next generation passive optical network (NGPON) system to mitigate the atmospheric turbulence and fiber dispersion with enhanced network scalability as well as efficiency is proposed. In emergency scenarios the utilization of polarization shift keying (PolSK) and dual polarization (DP)-differential quadrature phase-shift keying (DQPSK) modulation in system offers high spectral efficiency, coherent detection, minimum link dispersion and less noise. The simulation results demonstrate the faithful MDM-FSO/NGPON signals transmission over 40 km fiber with 500 m multi-beam FSO links at −8 dBm received power and 2 dB maximum power penalty. Also, the maximum fiber & FSO range can be expanded upto 160 km and 1500 m respectively, considering fiber impairments and diverse weather conditions. The system also supports simultaneous 200 end users having 23–47 dB total channel loss. High optical to signal noise ratio of 36 dB in downlink and 44 dB in uplink is acquired successfully. The comparison of the designed system with other systems signifies its superiority to others.

Integrated long reach and energy-efficient NGPON-VLC system with OCDM/WDM for smart green buildings

Smart green buildings (SGBs) are composed of numerous services and offer hopeful solutions to the world's continuous and rapid urbanization. Conventional data transmission systems are insufficient to deliver acceptable services because to the sudden surge in high-quality information transmission requirements over long distance for numerous linked residents in SGBs. Consequently, a hybrid next generation passive optical network (NGPON) along with visible light communication (VLC) indoor/outdoor broadcast network is presented in this work to increase the reliability with intelligence, exalted overall efficiency, cost efficiency, and security of SGBs. Bidirectional PON-VLC system incorporates the time and wavelength division multiplexing (TWDM), wavelength division multiplexing (WDM) and optical code division multiplexing (OCDM) techniques. In order to improve system performance, various OCDM codes are used in this work at 10/2.5 Gbps per channel throughput via fiber-VLC channels. According to the simulation results, the modified new zero cross-correlation (MNZCC) code performs better than previous codes and supports 200 active residents at reliable 100 km fiber along with 5 m VLC range. Furthermore, by expanding the received aperture diameter to 25 cm, VLC coverage may be increased till 10 m. Moreover, it provides adequate receiver sensitivities of − 13 to − 12 dB in uplink with − 9.8 to − 6 dBm in downlink for 200 to 600 fields of view angles compared to 00 view angle having sensitivity of − 15 dBm. Additionally, the numerical analysis and comparison performance show that PON-VLC outperforms fiber-VLC link-based scenarios when it comes to noise and channel impairments.

Next generation PON architecture using PD-NOMA employing OAM and WDM multiplexing

In this paper, we propose and experimentally demonstrate the efficacy of a next-generation passive optical network (PON) architecture for free space optical link, which utilizes power domain (PD) non-orthogonal multiple access (NOMA) along with simultaneous orbital angular momentum (OAM) mode and wavelength-division multiplexing (WDM) techniques. In this proposed architecture, many optical network units (ONUs) are accommodated by clustering them based on their power budgets and their data streams are allocated with different powers accordingly. The clustered ONUs are served with multiple OAM modes over multiple wavelengths to maintain high capacity, low latency, and increased reliability. As a proof-of-principle experimental demonstration of the proposed architecture, we have experimentally emulated two ONU clusters having a power ratio of (near:far)−3.17dB for implementing the PD-NOMA system for downlink. Each ONU cluster uses three 50 GHz spaced WDM channels, where each WDM channel carries two multiplexed OAM modes having opposite topological charge (l=±1 and ±2) values. Each cluster’s six ONUs is delivered with a 10 Gbps On-Off Keying (OOK) signal. We have demonstrated that all users can achieve a pre-forward error correction (pre-FEC) bit error rate (BER) below the 7% overhead-FEC (OH-FEC) BER limit of 3.8×10−3. We have also measured the x-talk due to WDM and mode multiplexing, and it has been revealed that the main contribution to the power penalty (relative to the no cross-talk condition) comes from OAM mode cross-talk.

Performance investigations on integrated MMF/FSO transmission enabled by OAM beams

This paper introduces a new hybrid system for high-bandwidth and high-transmission-capacity communication. The system integrates a multi-mode fiber (MMF) cable with free space optics (FSO) using orbital angular momentum (OAM) multiplexing. The proposed system uses a single wavelength to simultaneously transmit 40 Gb/s data on four distinct OAM beams ((LG0,0, LG0,17, LG0,40, and LG0,75)) with a symmetric circular shape. The performance of the system was evaluated with a fixed MMF length of 100 m and varying FSO ranges, according to extreme climate changes such as rain and fog, and atmospheric turbulences. The results indicate that the suggested system is capable of transmit up to 1250 m (100 m MMF length + 1150 m FSO range) under clear weather (CW) and weak turbulence (WT), with a minimum transmission distance of 440 m (100 m MMF length + 340 m FSO range) under heavy fog (HF). The performance of the system was also demonstrated based on actual meteorological data for two different cities, Alexandria, Egypt and Chandigarh, India, with different visibility ranges and geographical locations. Since Alexandria has a longer visibility range than Chandigarh, our proposed model could spread over a larger area than it could be in Chandigarh. The obtained ranges were within an acceptable bit error rate (BER) of less than 10−9. The system’s maximum range was 1200 m for Alexandria and 1100 m for Chandigarh. The proposed model can be suggested for use in next generation (NG) passive optical networks (PON) for supporting symmetric 40 Gb/s data.

50G-next generation passive optical networks stage 2 using millimeter wave over fiber technique under the ITU-T G.9804 standardization

50G-next generation passive optical networks stage 2 using millimeter wave over fiber technique under the ITU-T G.9804 standardization

Design of long‐reach symmetric 1.6 Tbps bidirectional NG‐PON2 using 2D spectral/spatial SWZCC code

AbstractIn this paper, a bidirectional symmetric 16 × 10 Gbps next generation passive optical network stage 2 (NG‐PON2) based time and wavelength division multiplexing PON (TWDM‐PON) has been designed. To satisfy the requirement for ever‐increasing demands for high‐security, high speed and long‐reach with high system capacity to handle the large number of users, two‐dimensional spectral/spatial single weight zero‐cross correlation code has been employed in TWDM‐PON. The results show that the proposed design can handle simultaneous users of 240 in downstream and 250 in upstream channels over 10 km transmission distance at symmetric 1.6 Tbps data rate. The transmission distance can be extended upto downlink 110 km and uplink 170 km, delivering receiver sensitivity of −45 and −46 dBm, respectively. Also, high optical signal to noise ratio of 62 dB in downlink and 72 dB in uplink is successfully achieved. Meanwhile, the proposed work is superior to the recent work.

A Comprehensive Framework For Itu Next Generation Pons

Due to the higher number of Optical Network Units (ONU), the power dissipation of Next Generation Passive Optical Network (PON) has gradually risen. Several energy energy-saving schemes have been proposed by the International Telecommunication Union (ITU) such as Cyclic Doze Mode (CDM) and Cyclic Sleep Mode (CSM). The performance of the small capacity devices (nodes) is relying on traffic advent or arrival rate and traffic threshold on which Local Wakeup Indication (LWI) ignited. Thus, an investigative model of ONU to review different CSM / CDM control schemes need extremely important and as well as becoming a hot topic among the scientific community. The state-of-the-art models do not use the sleep buffer parameter that yields lower performance assessment of the CSM process at limited traffic advent rates. They are incapable to acquire the CSM / CDM process at the above traffic rates. The proposed work boosts the current Discrete-Time Markov Chain (DTMC) established power exhibit taking into account a parameter i.e. sleep buffer at each ONU. Additionally, it governs the LWI events at the ONU and as well as Optical Line Terminal (OLT). Furthermore, the suggested exhibit precisely measures the ONU sojourn in every CSM / CDM state, energy savings, and power dissipation of ONU which depends on the advent rate of traffic. According to the recommended model, a CSM / CDM framework is also supplemented to configure all the parameters effectively under the given average delay constraints.

A Security Detection Scheme Based on TTD for NG-PON2 Fiber Links

For improving the physical layer security of next generation passive optical network (NG-PON2), we propose a security detection scheme by detecting the terminal thermal distribution (TTD) at the optical fiber end face on the optical network unit (ONU), when the fiber link is tapped. The principle of the scheme is given that the thermal energy always exists in fiber links and the TTD at the optical fiber end face can be detected. When the link tapping occurs, the leaking light energy induced by bending converts into the thermal energy, which changes the TTD at the optical fiber end face on ONU of NG-PON2. The TTD models of core and cladding layers at the optical fiber end face owing to bending are built with the double cylindrical coordinate systems, based on the bending loss formula of optical fiber and thermodynamic coupling theory. Then, the simulations for the TTD models are carried out under the different conditions of input power, bending radius and distant of detected point from the center of optical fiber end face, respectively. The simulation results indicate three conditions above are the main factors affecting the TTD changes. Finally, we set up an experimental system in the lab, using a light-emitting diode at 1550nm, and a thermal microscope (Telops-FAST-IR). The experimental results show the TTD of core layer at the optical fiber (G.652D) end face changes 72.5% at the input power of 1dBm with the bending radius from 10mm to 5mm, and are consistent with the simulation ones.

A novel bidirectional entirely passive remote node design for ring topology based NG-PON2 with fiber faults protection capability

The service disruptions in passive optical networks (PONs) due to fiber or node failure is an important issue. In the conventional star topology time and wavelength division multiplexing (TWDM) based next generation passive optical network stage 2 (NG-PON2), there is no provision to restore the service if the fiber between remote node (RN) and optical network unit (ONU) fails. In this paper, we proposed a novel entirely passive node design for ring based NG-PON2 which provides fiber fault protection against any fiber break between RNs. The working of the proposed node is verified by simulating normal conditions and fault conditions. It is observed that in the case of fiber failure, the affected ONUs can still communicate with the optical line terminal (OLT). The performance of the system has been analyzed in terms of bit error rate (BER), and the BER <10−9 confirms the correct working of the system.

Efficient optical duobinary transmission for high-speed next generation passive optical networks

Efficient optical duobinary transmission for high-speed next generation passive optical networks

Enhanced Energy Savings with Adaptive Watchful Sleep Mode for Next Generation Passive Optical Network

A single watchful sleep mode (WSM) combines the features of both cyclic sleep mode (CSM) and cyclic doze mode (CDM) in a single process by periodically turning ON and OFF the optical receiver (RX) of the optical network terminal (ONT) in a symmetric manner. This results in almost the same energy savings for the ONTs as achieved by the CSM process while significantly reducing the upstream delays. However, in this study we argue that the periodic ON and OFF periods of the ONT RX is not an energy efficient approach, as it reduces the ONT Asleep (AS) state time. Instead, this study proposes an adaptive watchful sleep mode (AWSM) in which the RX ON time of ONT is minimized during ONT Watch state by choosing it according to the length of the traffic queue of the type 1 (T1) traffic class. The performance of AWSM is compared with standard WSM and CSM schemes. The investigation reveals that by minimizing the RX ON time, the AWSM scheme achieves up to 71% average energy saving per ONT at low traffic loads. The comparative study results show that the ONT energy savings achieved by AWSM are 9% higher than the symmetric WSM with almost the same delay and delay variance performance.

Generalized Multi-Access Dynamic Bandwidth Allocation Scheme for Future Generation PONs: A Solution for Beyond 5G Delay/Jitter Sensitive Systems

In this paper, we present a novel dynamic bandwidth allocation (DBA) scheme for future generation passive optical networks (PON) in order to meet the beyond 5G (B5G) and sixth generation (6G) stringent requirements. Our proposed algorithm is a generalized multi-access DBA (GMA-DBA) that exploits both orthogonal and non-orthogonal multi-access (MA) resources, resulting in a radical enhancement in the network performance. The proposed GMA-DBA algorithm is modeled as an optimization problem for which a closed form solution is derived. Results show that the GMA-DBA is capable of accommodating a network throughput higher than 1 Tbps while securing a latency and jitter below 100 &#x00B5;s and 10 &#x00B5;s, respectively. It can also maintain reliability, simplicity and energy efficiency. Therefore, using a non-orthogonal MA layer seems to be inevitable to achieve the stringent performance needed for the B5G and 6G next generation systems.

Optimized Joint Allocation of Radio, Optical, and MEC Resources for the 5G and Beyond Fronthaul

In 5G and beyond telecommunication infrastructures a crucial challenge in achieving the strict Key Performance Indicators (KPIs) regarding capacity, latency, and guaranteed quality of service, is the efficient handling of the fronthaul bottleneck. This part of the next generation networks is expected to comprise the New Radio (NR) access and the Next Generation Passive Optical Network (NGPON) domains. Latest developments load the fronthaul with computing tasks as well (e.g., for AI-based processes) in the context of Mobile Edge Computing (MEC). Towards efficient management of all resource types, this paper proposes a joint allocation scheme with three optimization phases for radio, optical, and MEC resources. This scheme, which has been developed in the context of the blueSPACE 5G Infrastructure Public Private Partnership (5G PPP) project, exploits cutting-edge technologies, such as radio beamforming, spatial-spectral granularity in optical networks, and Network Function Virtualization (NFV), to provide dynamic, adaptive, and energy efficient allocation of resources. The devised model is mathematically described and the overall solution is evaluated in a realistic simulation scenario, demonstrating its effectiveness.

Entirely passive remote node design and system architecture for bus topology based 80Gbps symmetrical NG-PON2

The next generation passive optical network stage 2 (NG-PON2) is a broadcast network in which a large number of optical network units (ONUs) can be served using various network topologies. In this paper, a purely passive remote node (RN) design based on fiber bragg grating (FBG) is presented for the bus topology of a high split NG-PON2 system. The performance of the proposed node has been analysed for a symmetric 80 Gbps NG-PON2 system serving 1024 ONUs in terms of bit error rate (BER) and optical signal to noise ratio (OSNR). The working of the proposed node has been explained with the optical frequency spectrums for downstream and upstream signals. The observed OSNR levels for the ONUs operating at the 1st RN is 84.8743 dB which decreases to 75.7973 dB for the ONUs connected to the 8th RN. The BER level < 10–9 for both upstream and downstream confirms the correct working of the proposed node in the NG-PON2 system.

Security enhanced dynamic bandwidth allocation algorithm against degradation attacks in next generation passive optical networks

The dynamic bandwidth allocation (DBA) algorithm is highly impactful in improving the network performance of gigabit passive optical networks (GPON). However, reports delineating its vulnerability to certain attacks can be found in the literature, thus raising concerns. A degradation attack manipulates the transmission control protocol (TCP) congestion control algorithm, which may impact the received bandwidth of targeted network users. Here, the absence of electronics within the passive splitter renders attack identification in GPONs a significant challenge. Therefore, the current study aimed to propose a secured DBA mechanism known as security enhanced DBA capable of overcoming this particular threat. A detection phase served as a critical component for sensing and subsequently mitigating any abnormal behaviors observed among optical network units (ONUs). Upon identification of the attacker, penalties were imposed to deter the next attack attempt and reestablish the fairness to previously attacked ONUs. The simulation findings revealed throughput improvement of up to 63% due to the security feature offered by the mechanism. Besides, significant improvements for the upstream delay performance recorded at 52%, 60%, and 65% for traffic containers (TCONT) TCONT2, TCONT3, and TCONT4, respectively, were observed in comparison to the non-secure DBA mechanism. Hence, the integration of the security mechanisms in DBA renders it possible to avoid any exploitation of GPON vulnerability in hacking other users’ bandwidth.

A performance investigation of SAC-OCDMA system based on a spectral efficient 2D cyclic shift code for next generation passive optical network

A two dimensional spectral/spatial cyclic shift (2D-CS) optical code division multiple access (OCDMA) systems is proposed for a potentially next generation passive optical network (NG-PON) implementation called (2D-CS NG-OCDMA-PON) system. The2D-CS proposed code is characterized by a high capacity and a zero cross correlation property leads to completely eliminating the multiple access interference (MAI) effect that is considered as the main OCDMA system drawback. Firstly, the 2D-CScode construction is investigated from 1D-CS code. Secondly, a system description is provided by exhibiting the transmitter and receiver architecture in the PON context. Analytical analysis reveals that our proposed 2D-CScode outperforms similar codes such as perfect difference (2D-PD) and dynamic cyclic shift (2D-DCS) codes in terms of spectral efficiency, simultaneous network subscribers and data bit rate. In addition, based on numerical analysis 2D-CS NG-OCDMA-PON system shows a good system performance by means of avery low BER and a high Q-factor values equal to $$10^{{ - 26}}$$ and 10.41 dB, respectively. Likewise, for four users and free-amplification the achievable reach ability distance of the NG-OCDMA-PON system is 63.21 km, 43.57 km and 33.2 km while Q-factor is equal to 6 dB at a bit rate of 622 Mb/s, 1 Gb/s and 1.5 Gb/s, respectively. On the other side, according to the system setup the number of single mode fiber (SMF) is reduced to the half compared to other 2D-OCDMA-PON systems based on enhanced multi diagonal (EMD) and single weight ZCC (SWZCC) codes.