Optical Line Terminal Research Articles

Investigation of laser phase noise tolerance in simplified coherent PON with subcarrier multiplexing

In this paper, we experimentally investigate the laser phase noise tolerance for a 100 Gb/s/λ coherent passive optical network (PON) with simplified optical network units (ONUs) transceivers when distributed feedback (DFB) laser is used as the local oscillator (LO). In the proposed scheme, the digitally subcarrier-multiplexed (DSCM) signals are generated in the coherent transmitter at the optical line terminal (OLT) side based on Alamouti encoding in two polarizations and received by a single-polarization heterodyne receiver at the ONU side. The experimental results show that the power budget can achieve 34.2 dB and 33.9 dB after a 25 km standard single-mode fiber (SSMF) link when external cavity laser (ECL) and DFB lasers are used as the LOs at the ONU side. Polarization and carrier phase tracking schemes for the DSCM systems based on frequency domain pilot tones were used in digital signal process (DSP). At the same time, the frequency offset estimation and phase noise compensation algorithms are conducted using residual carriers. By choosing an appropriate width for the low-pass filter, the optimal performance for the phase noise compensation can be achieved. The pre-equalization operation at the OLT side is also verified for the subcarrier-multiplexed signals to provide better and flatter performances.

Coherent time- and wavelength-division multiplexed point-to-multipoint optical access network using low-cost DFB lasers enabled by a frequency comb

Coherent reception, along with time- and wavelength-division multiplexing (TWDM), is a promising concept to simultaneously support multiple services in future high-speed point-to-multipoint passive optical networks (PONs). The next-generation PON 2 (NG-PON2) standard describes a TWDM-PON based on IM/DD intensity modulation and direct detection (IM/DD) which employs tunable-lasers and optical filters such as tunable optical filters or cyclic arrayed-waveguide gratings. Here, we investigate what we believe to be a novel coherent TWDM-PON architecture based on a frequency comb source in the optical line terminal (OLT), and thermally-tuned distributed-feedback (DFB) lasers in the optical network units (ONUs). For downstream operation, we broadcast multiple copies of two 25 GBd dual-polarization quadrature phase shift keying (DP-QPSK) signals, resulting in a total PON downstream capacity of 200 Gbit/s. The copies of the downstream signals are spanning ±2 nm (±250 GHz). In the ONUs, we align the wavelengths of the DFB lasers, which act as local oscillators (LOs), to one of the downstream signals by a thermal heater or by changing the direct current. In upstream, the already aligned DFB lasers act as transmit lasers and the frequency comb as LO. We demonstrate TWDM upstream by emulating two ONUs with 25 GBd DP-QPSK, resulting in a total PON upstream capacity of 200 Gbit/s.

Low-latency 100 Gb/s PAM-4 PON with a 42.5 dB power budget over the 20 km anti-resonant hollow-core fiber.

The surging growth in data traffic has necessitated the development of higher-speed, lower-latency intensity modulation and direct detection (IM/DD) passive optical networks (PONs) with higher power budgets. To address the inherent limitations of traditional silica-based solid-core fibers, anti-resonant hollow-core fibers have garnered significant attention from both academia and industry. In this Letter, we present an experimental demonstration of 100 Gb/s PAM-4 IM/DD PON transmission over a 20 km anti-resonant hollow-core fiber in the C band, utilizing low-complexity digital signal processing (DSP). The result achieves a record high power budget of 42.5 dB, facilitated by a 3-tap weighted lookup table (LUT) at the optical line terminal (OLT) side and a semiconductor optical amplifier used as a preamplifier at the optical network unit (ONU) side. This represents the highest power budget reported for IM/DD PON to date, to the best of our knowledge,and offers a promising alternative for the future evolution of PON systems.

Penerepan Analisis Optical Line Terminal (OLT) Dengan Rasio Spliter dan Pasif Spliter Pada 8 Optical Distribution Point (ODP)

This service aims to analyze the application of Optical Line Terminal (OLT) with splitter and passive splitter ratios at eight Optical Distribution Points (ODP) in the Fiber To The Home (FTTH) network. Through distance measurements, observations, and analysis of the power link budget and rise time budget, this research evaluates the performance of the FTTH network and determines the optimal configuration for the OLT and splitter. The results show that proper OLT settings and splitter ratios can significantly improve optical network performance. These findings provide practical guidance for internet service providers in designing efficient and reliable FTTH networks.

PERANCANGAN DAN IMPLEMENTASI JARINGAN FTTH GPON DI CLUSTER GILIMANUK

This research aims to meet the target of building a homepass network of 512 homepasses from PT. PLN ICON PLUS in the North Bali UP3 area sector, namely the Gilimanuk Village area, Melaya District, Jembrana and the use of Huawei Optical Line Terminal (OLT) equipment with a total of 8 ports as well as the use of backbone network access that is already available in the Gilimanuk area. Gilimanuk demographically has an area of 56.01 km2 and consists of residential buildings inhabited by 2,451 families. To accommodate homepass from the Gilimanuk housing complex, this research offers a cascading scheme for Fiber To The Home (FTTH) with Gigabit Passive Optical Network (GPON) technology that is appropriate to use but still pays attention to the quality of the network provided. In determining the feasibility of the network design and determining the appropriate cascading scheme for the Gilimanuk Cluster, the parameters in network design and implementation are focused on measuring the power link budget in theory and implementation, then the rise time budget value in the network optisystem software simulation. The results of this research show that the 1:4 to 1:16 cascading scheme has better FTTH network system feasibility than the 1:8 to 1:8 cascading scheme with a Prx value of -18.42 dBm, which does not exceed the minimum Prx threshold value of the ITU-T G standard. 984, namely -28 dBm, then the rise time budget shows the system rise time value: 0.25537 ns, which does not exceed the maximum rise time limit, namely 0.292 ns, so the 1:4 to 1:16 cascading scheme is feasible to implement.

A deep learning based dynamic bandwidth allocation method for XG-PON based mobile fronthaul for CRAN

In the context of 5G and beyond era, the use of Time Division Multiplexed Passive Optical Network (TDM-PON) for mobile fronthaul (MFH) in centralized/cloud radio access network (CRAN) has proven to be an optimal solution for addressing low-latency requirements. While existing literature has predominantly focused on optimizing mobile fronthaul latency rather than end-to-end latency, this paper introduces an end-to-end latency model for TDM-PON, specifically within a 10-gigabit Passive Optical Network (XG-PON) based MFH for CRAN. The paper then proposes an Intelligent Dynamic Bandwidth Allocation (DBA) scheme to minimize end-to-end latency of the network. The proposed scheme predicts the buffer occupancy reports using deep learning techniques at optical network units (ONUs). Thereafter, optical line terminal (OLT) schedules the available bandwidth using conventional DBA schemes (Group-GIANT i.e., Ggiant, Optimized Round Robin, Dynamic Service Interval). Primarily, the proposed DBA scheme transforms conventional DBA schemes (Ggiant, Optimized Round Robin, Dynamic Service Interval) into Intelligent versions (Intelligent Ggiant, Intelligent ORR, Intelligent DSI), showcasing a reduction of 28.63 %, 45.86 %, and 48.60 % in end-to-end latency in the XG-PON-based MFH for CRAN. Further, the analysis of obtained results has confirmed the supremacy of the Intelligent DSI DBA scheme over the Intelligent Ggiant and the Intelligent ORR DBA scheme.

Multi-criteria model for selection of optical linear terminals based on FUZZY TOPSIS method

Optical networks are an integral part of modern telecommunication systems. Huge traffic and ever-increasing requirements for data transmission capacity and quality encourage the wider use of modern optical technologies in telecommunications. The rational choice of equipment for the design of optical networks is an urgent task at present. The subject of this study is the process of selecting optical line terminals, which is associated with the evaluation of possible options by a set of indicators. The OLT (optical line terminal) in PON technology implements the function of organizing subscriber lines and is also a node equipment - an L4 switch that combines the functions of routing (IP), traffic fragmentation (VLAN), switching (MAC), quality of service (QoS), and some necessary network service functions. The optimal structuring of PON access networks demands a judicious selection of software and hardware, guided by their tactical and technical characteristics, in view of the substantial information load they entail. One of the effective approaches to solving such problems is the use of MCDM (Multiple Criteria Decision Making) methods. Purpose: to construct a TOPSIS model of the optimal choice of optical linear terminals in the conditions of unclear information for different cases of aggregation of evaluations of decision makers. Task: to formalize the process of selecting optical linear terminals; develop a multi-criteria mathematical model for the effective selection of optical line terminals. Methods used in the study: The fuzzy TOPSIS method, four methods of aggregating the opinions of decision makers. The following results were obtained. Alternatives and criteria for their evaluation are defined. On the basis of interviews with decision makers, evaluations of the degree of importance of the criteria and alternatives to the criteria were determined. Linguistic changes were used to describe decision-makers’ evaluations, which were interpreted as triangular fuzzy numbers. During this study, four methods of aggregating the evaluations of decision makers were used. A fuzzy TOPSIS model for selecting an optical line terminal is constructed. The ranking of the selected optical line terminals is obtained and the best alternative is determined. The results of modeling with different methods of aggregating assessments of decision makers are compared. Conclusions. The use of the Fuzzy TOPSIS method for optimal selection of optical linear terminals is proposed. The influence of the methods of aggregation of evaluations of decision-makers is analyzed.

Enhanced authentication technology based on deep neural network in the physical layer of optical communication

To solve the problem of device identity security management in Passive Optical Networks (PON), this study proposes an enhanced authentication technique based on Deep Neural Network (DNN) in the physical layer of optical communication. By negotiating the device power and transmission distance used with legitimate Optical Network Units (ONUs), the Optical Line Terminal (OLT) can obtain a unique channel feature fingerprint for each legitimate device. These features are then identified and classified using a trained Deep Neural Network. Also, the method takes into account the substitution and fiber-splitting interception attacks. Simulation results show that the legitimate devices can be accurately identified using 64 neurons and 20 iterations, with a recognition accuracy of 100 %. Therefore, the method effectively improves the ability of the PON system to resist spoofing attacks at the physical layer and significantly improves the security level of the system.

Simultaneous upstream and inter optical network unit communication for long reach PON using single transmitter and self-phase modulation

The conventional passive optical network (PON) architecture requires optical line terminal (OLT) arbitration for communication between the optical network units (ONUs). This approach increases OLT processing load, it may also increase security hazards and causes higher communication latency. Moreover this also leads to wastage of bandwidth that can be saved if ONUs are able to communicate directly. The direct communication of ONUs without involving OLT is known as inter ONU communication (IOC). Earlier reported IOC proposals either do not support simultaneous upstream communication or require dedicated or tunable transmitters and receivers for simultaneous communication. This increases the overall cost of the system and also degrades the system performance because of additional tuning delays of the tunable transmitter and receiver. Therefore, this study proposes an IOC enabled physical layer design for PON that supports simultaneous upstream and IOC communication using single transmitter and self-phase modulation mechanism at each ONU. A 1310 nm wavelength, return to zero signal is generated by the transmitter which passes through the self-phase modulator resulting in an additional side lobe signal generation that carries the IOC data without impacting the upstream transmission. These two signals are coupled at the remote node where IOC signal gets reflected back, while the upstream signal gets transmitted through it towards the OLT at the same time. A long reach PON scenario is assumed by keeping the OLT at a distance of 80 km or more. The simulation results show that the proposed design supports a maximum reach of 118 km for upstream link between remote node and OLT with bit error rate of 1.52 × 10−12 for 25 Gbps and 90 km with bit error rate of 7.1 × 10−12 for 30 Gbps data rate. The IOC communication also works well up to a split ratio of 32 with a maximum distance of approximately 5 km between the ONUs and remote node with an end to end bit error rate of 8.60 × 10−12. for 25 Gbps and 7.1 × 10−12 for 30 Gbps. Overall, the proposed design shows acceptable performance, in compliance to ITU G 987.1 recommendations for a maximum end to end reach of 122 km.

Coexistence in future optical access networks from an operator’s perspective [Invited

In this paper, we address the challenges related to the simultaneous operation of legacy and future network technologies in passive optical networks (PONs) and point-to-point topologies. We explore the coexistence issues for various user categories, including residential, enterprise, factories, and mobile users. The future access networks will need to accommodate multiple technologies concurrently. Our paper demonstrates how G-PON, XGS-PON, and 50G-PON can coexist on the same optical distribution network using triple coexistence multi-PON modules. However, there are certain limitations that need to be considered, such as achieving a high optical budget and the associated costs, both in terms of monetary investment and CO2 emissions for technology deployment by operators. Additionally, we emphasize the significance of optical line terminals (OLTs) as crucial network components in the future. OLTs play a central role in supporting the traffic evolution with optimal efficiency in terms of throughput, latency, jitter, and adherence to CO2 emission constraints. Finally, we experimentally demonstrate the first assessment, to our knowledge, of a 50G-PON prototype with optical budget reaching 23.9 dB limited by the downstream (DS). Furthermore, we evaluate the potential limitations regarding coexistence by examining the effects of stimulated Raman scattering between the DS of 50G-PON and the upstream of XGS-PON for the first time with real PON systems.

CSAT‐FRMET: An energy‐efficient hybrid FiWi network‐based 5G model

AbstractHybrid fiber wireless (FiWi) access networks seek to combine the vast amount of bandwidth that is available for optical networks and wireless network mobility; hence, it favors larger bandwidth request but cause the highly nonlinear lagrangian dual problem that decrease energy‐efficient network resilience. Hence, a novel Ceplato‐SAT3 model has been proposed in which the SAT3 algorithm locates the optical network unit (ONU) in an optimal position with high‐speed cost‐efficient placement and weight factor introduced into the position update to improve the exploitation and exploration capability of the algorithm. To prioritize the large bandwidth request during resource allocation, gradient priority justifier requests (GPJR) has been utilized and a novel messaging technique termed flow‐random‐message‐exchanger‐topology (FRMET) provides the index for these prioritized requests depending on QoS parameters such as notification control, reflective QoS attribute (RQA), flow bit rates and maximum packet loss rate thereby decreasing the overhead and eliminate nonlinear langrage dualand perform O2U scheduling to reduce network resilience however synchronization between different ONU clocks may cause upstream data fatal crash at the optical line terminal (OLT). Hence, curl‐trio‐opt control mechanism has been proposed in which the minimization problem is transformed into a joint optimization problem of energy consumption, traffic demand, network requests, and service flow requests by the Lyapunov technique thereby minimizing the upstream data fatal lash. The proposed model has been implemented in Python and the output obtained showed better performance in terms of ONU arrangement, throughput, energy consumption, computation, latency, and error.

Demonstration of an 800G CDM-SDM coherent PON utilizing weakly coupled multicore fibers with CDM tributary manipulation

In this Letter, we present an experimental demonstration of downstream signaling in a 16 × 50 Gbit/s coherent passive optical network (CPON) using the code and space division multiplexing (CDM-SDM) approach. We realize optical SDM through the utilization of a 4-core weakly coupled multicore fiber (WC-MCF), enhancing the total available optical launch power at the optical line terminal (OLT). This enhancement significantly improves the power budget for CPONs that connect with a large number of optical network units (ONUs). At the second stage of the CPON, four CDM-assigned ONUs are connected to individual cores of the WC-MCF, thereby supporting the connectivity of up to 16 ONUs. Through experiments, we have noted substantial disparities in the downstream signaling performance among individual CDM-assigned ONUs, particularly as the capacity is increased to 800 Gbit/s. To address this issue, we have employed an innovative approach by leveraging space–time coding techniques to manipulate the CDM tributaries, to achieve a balanced reception performance for all ONUs within the CPON. We believe that the proposed CDM-SDM CPON scheme, complemented by the advanced DSP flow chart, holds significant promise for future PON systems characterized by substantial capacity and extensive connectivity.

Installation and Activation of Fiber To The Home (FTTH) Networks and Macrobending Problems in the Feeder Cable Segment

Macrobending is a form of disturbance in Fiber To The Home (FTTH) networks that occurs due to macro-level bending of the cable caused by damage to the fiber optic. Macrobending frequently occurs in FTTH networks within the feeder cables. Feeder cables serve as connectors between the Optical Line Terminal (OLT) and Optical Distribution Cabinet (ODC) in the FTTH system. The occurrence of macrobending in feeder cables affects the quality of the FTTH network. In this study, the impact of macrobending is analyzed based on curvature diameters of 50 cm, 25 cm, and 5 cm on feeder cables before and after FTTH network activation. Before FTTH network activation, the High Super Luminescent Diode (HSL) is used as the input power source, whereas after activation, the input power source comes from the OLT using Small Form-factor Pluggable (SFP) modules. The attenuation (loss) before activation due to macrobending, with curvature diameters of 50 cm, 25 cm, and 5 cm, is found to be 0.02 dB, 0.05 dB, and 0.26 dB, respectively. After activation, the attenuation with the same curvature diameters is measured as 0.01 dB, 0.02 dB, and 0.20 dB, respectively. It is observed that as the curvature diameter decreases, the attenuation increases. The comparison of attenuation before and after network activation doesn't show a significant difference because the input power doesn't affect macrobending, rather it is influenced by the curvature diameter.

Unidirectional Ring-Based WDM Fiber Network for Both Downlink and Uplink Signal Access

In the paper, a dual-bidirectional ring-type wavelength-division-multiplexing (WDM) access network with downlink and uplink signal access simultaneously using a single fiber backbone in clockwise and counterclockwise directions, respectively. The proposed network architecture is simple and easy to implement via the designed remote node (RN) and optical line termination (OLT) modules, but it also can double the downlink traffic using the original WDM downlink wavelengths. The presented ring-type WDM network can also avoid the Rayleigh backscattering (RB) beat noise when the same wavelengths are applied as downlink and uplink channels concurrently. In the measurement, 50 km long-reach and 15 km short-reach fiber transmission lengths are achieved for the symmetrical 10 and 28 Gbit/s on-off keying (OOK) data access, respectively. In addition, based on the obtained power budgets of eight downlink WDM signals and network design at the forward error correction (FEC) threshold, 16 optical network units (ONUs) can be supported simultaneously.

Flexible PON systems enabling optical virtual private network and upstream channel upgrade

With the rapid growth of peer-to-peer (P2P) traffic in the access network, the capability to implement inter-optical network unit (ONU) communication (IOC) has become a fundamental requirement for the underlying passive optical network (PON). The conventional IOC is realized electronically on layer 2 or layer 3 and relies on the transfer operations in the optical line terminal (OLT), thus resulting in high transmission latency and excessive bandwidth consumption. To achieve an efficient IOC, the optical virtual private network (OVPN) is proposed to establish direct optical layer links among ONUs by adding some auxiliary optical components to the existing PON system. However, in previously reported OVPN schemes, the added devices are only used for IOC and cannot fulfill other network functions, which leads to poor flexibility. To improve the reconfigurability of the whole PON system, we present two simple modifications that can not only achieve a high-bandwidth OVPN but also increase the upstream channel capacity. The proposed schemes introduce a new wavelength as the OVPN channel to refrain from changing the physical configuration of the normal upstream and downstream. One scheme retrofits the optical line terminal (OLT) with a fiber Bragg grating (FBG) based reflection module, while the other employs an additional short-length distribution fiber for each ONU to redirect IOC traffic. In both schemes, optical switches (OSWs) are used to control the added OVPN wavelength and the original upstream wavelength so that the two wavelengths can transmit IOC traffic and upstream traffic flexibly. According to the states of OSWs, PON systems will form multiple working modes adapted to different network conditions. To evaluate the improvement in flexibility of wavelength usage, the throughput performances of proposed schemes were analyzed theoretically under varying offered loads and IOC traffic proportions. In addition, the feasibility of both schemes was verified through physical layer simulations, where the optical spectra and bit error rates (BERs) of signals on different wavelengths were investigated.

Software defined networking agent demonstration to enable configuration and management of XGS-PON architectures

This paper describes the design and implementation of an OpenFlow software defined network (SDN) agent that manages and configures 10-gigabit-capable symmetric passive optical network (XGS-PON) architectures. Acting as an OpenFlow switch, the SDN agent communicates with an SDN controller using OpenFlow, while holding direct communication with the optical line terminal (OLT) through the chipset manufacturer-specific application programming interface, eliminating the need for emulating SDN layers in hardware devices. The proposal was evaluated through experiments conducted on a White Box XGS-PON OLT using the Open Network Operating System. The results demonstrate that the proposal facilitates a real-time SDN configuration of various Internet services, successfully fulfilling different quality of service requirements. Due to its ease of deployment, low complexity, smooth learning curve, scalability, and flexibility in integrating services, the proposal has significant potential. As a result, it offers a rapid SDN solution for configuring and testing new functionalities with minimal programming changes required in specific layers of the developed SDN agent.

A Distance-Weighted Dynamic Bandwidth Allocation Algorithm for Improved Performance in Long-Reach Passive Optical Networks for Next Generation Networks

In recent years, there has been an increasing trend towards extending the coverage of passive optical networks (PONs) over large geographical areas. Long-reach PONs (LRPONs) are capable of extending the distance covered by PONs from 20 km to 100 km, leading to cost savings in the network operation by reducing the number of central offices. They have become widely deployed due to their ability to provide high-speed, long-distance data transmission over optical fibers. In addition, the next generation of optical access networks are expected to provide high-capacity mobile and wireless backhauling over a wide coverage area. However, this extended reach also requires the design of efficient dynamic bandwidth allocation (DBA) schemes to address the performance degradation caused by the increased propagation delay in LRPONs. The DBA schemes commonly used for upstream traffic transmission in traditional PONs are not well-suited for use in LRPONs due to their inefficiency in bandwidth utilization due to the increased round-trip time (RTT) between the optical line terminal (OLT) and the optical network unit (ONU). In this study, we present an efficient DBA algorithm, the Distance-Weighted Bandwidth Allocation DWDBA Algorithm, specifically enhanced for multi-wavelength LRPONs. Our DBA algorithm utilizes a scheduling policy that assigns weight vectors to Optical Network Units (ONUs) based on their distance from the Optical Line Terminal (OLT), sorting them accordingly without penalizing any ONU due to their distance. The DWDBA takes the laser tuning time into consideration. We conducted extensive simulations to evaluate the performance of the proposed algorithm under various scenarios and compared it to the IPACT algorithm. The results of the simulations show that the proposed algorithm outperformed the IPACT algorithm in terms of bandwidth utilization and queue delay.

A Novel 64 QAM-OFDM Optical Access System Based on Bit Reconstruction

This paper proposes a novel orthogonal frequency division multiplexing (OFDM) optical access scheme based on bit reconstruction. In this method, correlation is introduced into the data information of optical line terminals (OLT) through the logical coding circuits and partition mapping. Even after passing through the optical fibre channel, the strong correlation after bit reconstruction can still be used in the optical network unit (ONU) for reliable decoding. In the simulation experiments, a 60 Gbit/s bit reconstruction 64 quadrature amplitude modulation (QAM) OFDM signal was successfully transmitted over a 10/20 km single-mode fibre (SMF). The simulation results show that the proposed scheme can effectively achieve reliable transmission with gains of about 1.3 dB and 0.51 dB at a 20% soft decision-forward error correction (SD-FEC) threshold, respectively. The proposed scheme is a promising candidate for a next-generation passive optical network (NGPON) solution.

Construction of Fiber Optical Communication System Infrastructure for 3T (Terdepan, Terluar dan Tertinggal) Areas Using Fiber to the Area Network System

Distribution of telecommunications in Indonesia, the government is aggressively building telecommunications network facilities, especially for 3T areas (Frontier, Outermost and Disadvantaged). Because there are still many areas that have not received access to telecommunications services, the Fiber to The Area (FTTA) network is the right solution to meet the needs of the community in economic, environmental and technical aspects. This design will provide an expansion of Fixed Broadband services around the Tanjung Lesung Special Economic Zone (SEZ), Pandeglang Regency, Banten. Later this fiber optic access network will use a Fiber To The Area (FTTA) network topology that connects the CO (Central Office) as a Metro Ethernet and DWDM hub with the Mini OLT Shelter as an Optical Line Terminal (OLT) hub supported by NG-PON (Next-Generation) PON (Passive Optical Network) technology with 2 Stage architecture which involves two stages of sending information signals through optical fiber. This design must first be designed on Google Earth to determine the fiber optic cable path and to determine the feasibility of performance on the system the author uses several test components including: Link Power Budget (LPB) testing, Rise Time Budget (RTB), Signal to Noise Ratio (SNR), Bit Error Rate (BER), Quality Factor (Q-Factor) which is simulated on optisystem to be able to provide performance values that match the eligibility standards at PT Telkom Indonesia.

Robust Key Update With Controllable Accuracy Using Support Vector Machine for Secure OFDMA-PON

In this paper, we first propose a novel secret key update scheme only with a single support vector machine (SVM). To achieve robust and efficient key management for secure orthogonal frequency division multiple access-based passive optical network (OFDMA-PON). The key sequences required to be shared between multiple optical network units (ONUs) and optical line terminal (OLT) are converted into partial quadrature amplitude modulation (QAM) symbol phases, and then masked into the whole upstream signal using two-dimensional chaos. The session keys can be distributed in real-time without consuming exclusive secure channels and resulting in data rate loss. A well-trained support vector machine (SVM) implemented at the receiver enables error-free key decision. Moreover, the numerous cross validations are conducted to verify the superior generalization performance under various parameters including key length and modulation format. The 16-QAM, 32-QAM, and 64-QAM OFDM signal transmissions are successfully demonstrated over 25 km standard single mode fiber (SSMF) by an experiment. The results show that the controllable restored accuracy of key can be realized by regulating the pivotal algorithm parameter to flexibly adapt to different system conditions, thus this scheme can be a promising efficient key update technology for future secure PON.