Yuka Okamoto;Hirotaka Ujikawa;Kenji Miyamoto;Tatsuya Shimada;Tomoaki Yoshida
According to the 3rd Generation Partnership Project, it is necessary to keep end-to-end latency to less than 5 ms in 5G mobile networks to achieve remote applications that replace on-site work and operations. The challenge here is that the bursty traffic (e.g., video) abruptly changes on a short timescale. Bursty traffic has an instantaneous high bitrate, which can exceed the link rate of the mobile midhaul (MMH) and thereby cause congestion, leading to an increase in latency. We propose a proactive congestion control method that performs parallel prediction of distributed unit (DU) traffic and fast switchover of the central unit (CU) and optical path in the MMH. Since the processing load of traffic analysis increases in accordance with the number of DUs, the CPU used for prediction becomes overloaded when many DUs are aggregated. This leads to concerns that the prediction cannot be completed in advance, that the timing of control is shifted, and that congestion occurs when switching is performed, thereby increasing the latency. The key idea of the proposed method is to optimize the number of CPU cores and threads for parallel prediction of the DU. To evaluate its feasibility and effectiveness, we experimentally optimized the number of CPU cores, thread allocations, and prediction periods and then estimated the maximum number of simultaneous predictions. The experimental results for a simple condition where video traffic and background traffic are mixed show that our prototype controller successfully achieved a latency at the MMH as low as 1 ms with appropriate congestion control. Our findings demonstrate the latency reduction effect of the proposed congestion control method for MMH in an aggregated DU configuration for applications with severe latency requirements such as remote control.
{"title":"Proactive congestion control for fast switchover and optical path at mobile midhaul utilizing optimized parallel traffic prediction with multi-thread and multi-processing procedures","authors":"Yuka Okamoto;Hirotaka Ujikawa;Kenji Miyamoto;Tatsuya Shimada;Tomoaki Yoshida","doi":"10.1364/JOCN.563719","DOIUrl":"https://doi.org/10.1364/JOCN.563719","url":null,"abstract":"According to the 3rd Generation Partnership Project, it is necessary to keep end-to-end latency to less than 5 ms in 5G mobile networks to achieve remote applications that replace on-site work and operations. The challenge here is that the bursty traffic (e.g., video) abruptly changes on a short timescale. Bursty traffic has an instantaneous high bitrate, which can exceed the link rate of the mobile midhaul (MMH) and thereby cause congestion, leading to an increase in latency. We propose a proactive congestion control method that performs parallel prediction of distributed unit (DU) traffic and fast switchover of the central unit (CU) and optical path in the MMH. Since the processing load of traffic analysis increases in accordance with the number of DUs, the CPU used for prediction becomes overloaded when many DUs are aggregated. This leads to concerns that the prediction cannot be completed in advance, that the timing of control is shifted, and that congestion occurs when switching is performed, thereby increasing the latency. The key idea of the proposed method is to optimize the number of CPU cores and threads for parallel prediction of the DU. To evaluate its feasibility and effectiveness, we experimentally optimized the number of CPU cores, thread allocations, and prediction periods and then estimated the maximum number of simultaneous predictions. The experimental results for a simple condition where video traffic and background traffic are mixed show that our prototype controller successfully achieved a latency at the MMH as low as 1 ms with appropriate congestion control. Our findings demonstrate the latency reduction effect of the proposed congestion control method for MMH in an aggregated DU configuration for applications with severe latency requirements such as remote control.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 11","pages":"E60-E69"},"PeriodicalIF":4.3,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The introduction of optical circuit switches (OCSs) has enabled the implementation of capacity- and energy-efficient networks in production data centers. To correctly operate optical-circuit-switched data center networks (OCS DCNs), fibers between pairs of terminals (e.g., servers or top-of-rack switches) and OCSs should be verified before starting operations; otherwise, unexpected failures during operations could occur. However, this task is difficult because OCSs cannot use topology discovery or link-monitoring functions, which are only available on electrical packet switches. We thus studied a fiber-topology and quality verification (FTQV) problem for OCS DCNs. Though a previous study inspected fibers between pairs of OCSs in hierarchical OCS DCNs using only one dedicated tester for fiber probing, making the process time-consuming, we consider verifying fibers between pairs of terminals and OCSs by using the digital diagnostic monitoring (DDM) function at multiple terminals. We thus developed new theories, to the best of our knowledge, for correctly carrying out FTQV even when parallel probes are sent and then designed an algorithm that efficiently solves the FTQV problem with near-optimal inspection steps. We also theoretically analyzed the conditions of detectable and undetectable malfunctioning fibers given the maximum measurement error of the DDM function. Experimental results indicate the correctness of our theoretical analysis and superior performance of our algorithm; it completes FTQV at most 93.0 times faster than a baseline algorithm. The feasibility of our algorithm was also demonstrated through evaluations on an actual network.
{"title":"Efficient verification algorithm for topology and quality of optical fibers in optical-circuit-switched data center networks","authors":"Kazuya Anazawa;Takeru Inoue;Toru Mano;Ryotaro Taniguchi;Yoshiaki Sone;Eiji Oki","doi":"10.1364/JOCN.563868","DOIUrl":"https://doi.org/10.1364/JOCN.563868","url":null,"abstract":"The introduction of optical circuit switches (OCSs) has enabled the implementation of capacity- and energy-efficient networks in production data centers. To correctly operate optical-circuit-switched data center networks (OCS DCNs), fibers between pairs of terminals (e.g., servers or top-of-rack switches) and OCSs should be verified before starting operations; otherwise, unexpected failures during operations could occur. However, this task is difficult because OCSs cannot use topology discovery or link-monitoring functions, which are only available on electrical packet switches. We thus studied a fiber-topology and quality verification (FTQV) problem for OCS DCNs. Though a previous study inspected fibers between pairs of OCSs in hierarchical OCS DCNs using only one dedicated tester for fiber probing, making the process time-consuming, we consider verifying fibers between pairs of terminals and OCSs by using the digital diagnostic monitoring (DDM) function at multiple terminals. We thus developed new theories, to the best of our knowledge, for correctly carrying out FTQV even when parallel probes are sent and then designed an algorithm that efficiently solves the FTQV problem with near-optimal inspection steps. We also theoretically analyzed the conditions of detectable and undetectable malfunctioning fibers given the maximum measurement error of the DDM function. Experimental results indicate the correctness of our theoretical analysis and superior performance of our algorithm; it completes FTQV at most 93.0 times faster than a baseline algorithm. The feasibility of our algorithm was also demonstrated through evaluations on an actual network.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 10","pages":"900-913"},"PeriodicalIF":4.3,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ji Zhou;Kainan Wu;Haide Wang;Jinyang Yang;Weiping Liu;Junwen Zhang;Changyuan Yu;Xiangjun Xin;Liangchuan Li
Driven by ever-increasing capacity demands, the 50G passive optical network (PON) is maturing gradually. One of the main challenges for the 50G PON is implementing burst-mode digital signal processing (BM-DSP) for the burst upstream signal. This paper demonstrates a real-time BM-DSP for burst reception of a 25 Gbit/s on-off keying signal to meet the asymmetric-mode 50G PON demand. The real-time BM-DSP includes BM frequency-domain timing recovery and a BM frequency-domain equalizer, which can be fast converged based on the ${sim}42;text{ns}$ designed preamble. Meanwhile, the simplified implementations for fast Fourier transform, minimum mean square error, and decision-directed least-mean-square-error algorithms decrease the DSP resources by 28.57% compared to the conventional implementation without optimization, enabling the loading of real-time BM-DSP in a field programmable gate array with limited DSP resources. The real-time implementation of BM-DSP can guide the design of application-specific integrated circuits for 50G PON.
{"title":"Real-time burst-mode digital signal processing for passive optical networks","authors":"Ji Zhou;Kainan Wu;Haide Wang;Jinyang Yang;Weiping Liu;Junwen Zhang;Changyuan Yu;Xiangjun Xin;Liangchuan Li","doi":"10.1364/JOCN.560191","DOIUrl":"https://doi.org/10.1364/JOCN.560191","url":null,"abstract":"Driven by ever-increasing capacity demands, the 50G passive optical network (PON) is maturing gradually. One of the main challenges for the 50G PON is implementing burst-mode digital signal processing (BM-DSP) for the burst upstream signal. This paper demonstrates a real-time BM-DSP for burst reception of a 25 Gbit/s on-off keying signal to meet the asymmetric-mode 50G PON demand. The real-time BM-DSP includes BM frequency-domain timing recovery and a BM frequency-domain equalizer, which can be fast converged based on the <tex>${sim}42;text{ns}$</tex> designed preamble. Meanwhile, the simplified implementations for fast Fourier transform, minimum mean square error, and decision-directed least-mean-square-error algorithms decrease the DSP resources by 28.57% compared to the conventional implementation without optimization, enabling the loading of real-time BM-DSP in a field programmable gate array with limited DSP resources. The real-time implementation of BM-DSP can guide the design of application-specific integrated circuits for 50G PON.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 10","pages":"891-899"},"PeriodicalIF":4.3,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The limitations of segmented and power-inefficient legacy optical networks underscore the need for a disaggregated, transparent multi-band optical continuum spanning access, aggregation, and metro domains. In this work, we demonstrate the first field trial, to our knowledge, of a disaggregated and transparent multi-band optical network interconnecting access, aggregation, and metro segments over both the C- and O-bands. The proposed architecture extends the optical continuum from antenna sites through O-band access links to aggregation hubs, and further into a C-band metro-core network, eliminating intermediate opto-electronic conversions. The data plane integrates SOA-based O-band switching for dynamic signal routing and loss compensation, while the control plane is realized through an innovative hierarchical SDN-based solution. This control plane orchestrates end-to-end transparent paths across multiple domains, spectral bands, and layers, leveraging standardized protocols and models for interoperability. Experimental validation shows the seamless multi-band interconnection, demonstrating effective multi-domain orchestration, optical transparency, and control scalability.
{"title":"Disaggregated and transparent multi-band optical continuum across access, horseshoe aggregation, and metro IPoWDM networks","authors":"Roberto Morro;Emilio Riccardi;Anna Chiado' Piat;Annachiara Pagano;Evangelos Kosmatos;Alexandros Stavdas;Chris Matrakidis;Shiyi Xia;Henrique Freire Santana;Nicola Calabretta;Pol Gonzalez;Luis Velasco;Andrea Sgambelluri;Jordi Ortiz;Enrique Fernandez;Pablo Pavon-Marino;Ramon Casellas;Oscar Gonzales De Dios;Filippo Cugini;Alessio Giorgetti","doi":"10.1364/JOCN.569327","DOIUrl":"https://doi.org/10.1364/JOCN.569327","url":null,"abstract":"The limitations of segmented and power-inefficient legacy optical networks underscore the need for a disaggregated, transparent multi-band optical continuum spanning access, aggregation, and metro domains. In this work, we demonstrate the first field trial, to our knowledge, of a disaggregated and transparent multi-band optical network interconnecting access, aggregation, and metro segments over both the C- and O-bands. The proposed architecture extends the optical continuum from antenna sites through O-band access links to aggregation hubs, and further into a C-band metro-core network, eliminating intermediate opto-electronic conversions. The data plane integrates SOA-based O-band switching for dynamic signal routing and loss compensation, while the control plane is realized through an innovative hierarchical SDN-based solution. This control plane orchestrates end-to-end transparent paths across multiple domains, spectral bands, and layers, leveraging standardized protocols and models for interoperability. Experimental validation shows the seamless multi-band interconnection, demonstrating effective multi-domain orchestration, optical transparency, and control scalability.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 10","pages":"C170-C181"},"PeriodicalIF":4.3,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the generation and impact of optical DC leakage in upstream burst-mode coherent TDM-PON systems. In upstream burst transmission, the laser remains on to avoid wavelength drift even when the optical network unit (ONU) is inactive, leading to the generation of residual DC leakage caused by a limited modulator extinction ratio and bias drift from the null point. As the number of ONUs increases, the accumulated optical DC leakage becomes large. In a more extreme case, where the optical signal comes from a distant ONU and all the other inactive ONUs are located close to the optical line terminal, the accumulated DC power can even exceed the signal power, resulting in SNR degradation and increased quantization noise. To address these challenges, we propose a flipped-frequency heterodyne detection scheme combined with SCM signaling. This approach upconverts the DC tones from low-frequency regions to high-frequency regions, allowing DC leakage to be effectively filtered out by the bandwidth-limited receiver before analog-to-digital conversion. As a proof of concept, we analyze the impact of DC leakage in both the time and frequency domains, compare the DC tolerance of PAM and SCM under different detection schemes, and support our findings with both simulation and experimental results. Finally, a 200G upstream simplified coherent TDM-PON system is experimentally demonstrated, showing up to 18 dB improvement in DC leakage tolerance compared to a baseband PAM4 signal at the 29 dB N1 class loss budget.
本文研究了上游突发模相干TDM-PON系统中光直流泄漏的产生及其影响。在上游突发传输中，即使光网络单元（ONU）不工作，激光也保持开启状态以避免波长漂移，从而导致由于调制器消光比有限和零点偏压漂移而产生的残余直流泄漏。随着onu数量的增加，累积的光直流漏变大。在更极端的情况下，当光信号来自较远的ONU，而其他所有非活动ONU都位于光线路终端附近时，累积的直流功率甚至可能超过信号功率，导致信噪比下降，量化噪声增加。为了解决这些挑战，我们提出了一种结合单片机信号的倒频外差检测方案。这种方法将直流音调从低频区域上转换到高频区域，允许带宽有限的接收器在模数转换之前有效地滤除直流泄漏。作为概念验证，我们分析了直流泄漏在时域和频域的影响，比较了PAM和SCM在不同检测方案下的直流容差，并通过仿真和实验结果支持了我们的发现。最后，实验证明了一个200G上游简化相干TDM-PON系统，在29 dB N1类损失预算下，与基带PAM4信号相比，直流泄漏容限提高了18 dB。
{"title":"Simplified coherent TDM-PON in upstream burst-mode detection with enhanced DC leakage tolerance","authors":"An Yan;Renle Zheng;Penghao Luo;Yongzhu Hu;Junhao Zhao;Shuhong He;Aolong Sun;Xuyu Deng;Ouhan Huang;Jianyang Shi;Yingjun Zhou;Zhixue He;Nan Chi;Junwen Zhang","doi":"10.1364/JOCN.564562","DOIUrl":"https://doi.org/10.1364/JOCN.564562","url":null,"abstract":"This paper investigates the generation and impact of optical DC leakage in upstream burst-mode coherent TDM-PON systems. In upstream burst transmission, the laser remains on to avoid wavelength drift even when the optical network unit (ONU) is inactive, leading to the generation of residual DC leakage caused by a limited modulator extinction ratio and bias drift from the null point. As the number of ONUs increases, the accumulated optical DC leakage becomes large. In a more extreme case, where the optical signal comes from a distant ONU and all the other inactive ONUs are located close to the optical line terminal, the accumulated DC power can even exceed the signal power, resulting in SNR degradation and increased quantization noise. To address these challenges, we propose a flipped-frequency heterodyne detection scheme combined with SCM signaling. This approach upconverts the DC tones from low-frequency regions to high-frequency regions, allowing DC leakage to be effectively filtered out by the bandwidth-limited receiver before analog-to-digital conversion. As a proof of concept, we analyze the impact of DC leakage in both the time and frequency domains, compare the DC tolerance of PAM and SCM under different detection schemes, and support our findings with both simulation and experimental results. Finally, a 200G upstream simplified coherent TDM-PON system is experimentally demonstrated, showing up to 18 dB improvement in DC leakage tolerance compared to a baseband PAM4 signal at the 29 dB N1 class loss budget.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"18 1","pages":"A9-A18"},"PeriodicalIF":4.3,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145036847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The rapid evolution of wireless communication technologies has led to the development of Beyond 5G (B5G) networks, aiming to deliver ultra-low latency, high-capacity connectivity, and scalable deployments for applications including autonomous systems and immersive experiences. A critical challenge lies in efficiently designing the radio access network (RAN) and its transport infrastructure. The shift to open RAN (O-RAN) architectures, with disaggregated centralized units (CUs), distributed units (DUs), and radio units (RUs), offers a promising solution. However, optimal placement of these components and transport network design remains a challenge, especially in diverse and cost-sensitive environments. This paper proposes a comprehensive optimization framework for B5G network design, jointly optimizing the placement of O-RAN components and optical transport networks using Mixed Integer Linear Programming (MILP). By integrating geographic information system (GIS) data, the framework considers real-world constraints, including terrain, infrastructure, user distribution, coverage requirements, and capacity requirements, enabling practical and cost-effective designs. The proposed optimization framework allows exploration of the optimal planning solutions under diverse configurations, which helps analyze different network deployment approaches for their scalability and efficiency. The evaluation results demonstrate the effectiveness and versatility of the framework in reducing costs under diverse deployment scenarios while meeting performance and coverage requirements, offering valuable insights for network operators and planners.
{"title":"Cost-optimal network planning for converged optical X-haul in Beyond 5G networks","authors":"Brianna Laird;Julien Ugon;Chathurika Ranaweera","doi":"10.1364/JOCN.567406","DOIUrl":"https://doi.org/10.1364/JOCN.567406","url":null,"abstract":"The rapid evolution of wireless communication technologies has led to the development of Beyond 5G (B5G) networks, aiming to deliver ultra-low latency, high-capacity connectivity, and scalable deployments for applications including autonomous systems and immersive experiences. A critical challenge lies in efficiently designing the radio access network (RAN) and its transport infrastructure. The shift to open RAN (O-RAN) architectures, with disaggregated centralized units (CUs), distributed units (DUs), and radio units (RUs), offers a promising solution. However, optimal placement of these components and transport network design remains a challenge, especially in diverse and cost-sensitive environments. This paper proposes a comprehensive optimization framework for B5G network design, jointly optimizing the placement of O-RAN components and optical transport networks using Mixed Integer Linear Programming (MILP). By integrating geographic information system (GIS) data, the framework considers real-world constraints, including terrain, infrastructure, user distribution, coverage requirements, and capacity requirements, enabling practical and cost-effective designs. The proposed optimization framework allows exploration of the optimal planning solutions under diverse configurations, which helps analyze different network deployment approaches for their scalability and efficiency. The evaluation results demonstrate the effectiveness and versatility of the framework in reducing costs under diverse deployment scenarios while meeting performance and coverage requirements, offering valuable insights for network operators and planners.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 11","pages":"E50-E59"},"PeriodicalIF":4.3,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145036848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multi-constraint routing is a crucial problem in optical networks, as establishing a lightpath must account for multiple constraints, including bandwidth demand, transmission delay, and quality of transmission (QoT). However, the problem-solving complexity increases exponentially due to the addition of constraints such as wavelength contiguity and optical nonlinearity as the network scale increases. Therefore, it is difficult to find a path that satisfies all optical constraints within 10 ms in large-scale topologies. To address these challenges, this paper proposes a QoT-aware multi-constraint routing (QaMcR) algorithm for large-scale optical networks. The algorithm utilizes a contraction hierarchy structure to simplify the topology and employs an enhanced Dijkstra strategy during the routing process, which comprehensively considers transmission delay, bandwidth requirements, and GSNR. Additionally, QaMcR dynamically updates bandwidth usage within the network with low overhead through the time-efficient propagation chain. We simulate both classical and 274-node topologies, using GNPy for physical layer modeling and QoT estimation. A total of $5 times {10^8}$ simulations were conducted, exploring nearly a billion shortest paths. The results show that the QaMcR algorithm can find the path with the shortest delay that satisfies multi-constraints within 2 ms, reducing routing time by 95%, while ensuring low delay and low blocking rate.
{"title":"QoT-aware multi-constraint routing in large-scale optical networks based on contraction hierarchies and propagation chains","authors":"Yingbo Fan;Yan Pan;Jiaxing Guo;Yajie Li;Yongli Zhao;Jie Zhang","doi":"10.1364/JOCN.568033","DOIUrl":"https://doi.org/10.1364/JOCN.568033","url":null,"abstract":"Multi-constraint routing is a crucial problem in optical networks, as establishing a lightpath must account for multiple constraints, including bandwidth demand, transmission delay, and quality of transmission (QoT). However, the problem-solving complexity increases exponentially due to the addition of constraints such as wavelength contiguity and optical nonlinearity as the network scale increases. Therefore, it is difficult to find a path that satisfies all optical constraints within 10 ms in large-scale topologies. To address these challenges, this paper proposes a QoT-aware multi-constraint routing (QaMcR) algorithm for large-scale optical networks. The algorithm utilizes a contraction hierarchy structure to simplify the topology and employs an enhanced Dijkstra strategy during the routing process, which comprehensively considers transmission delay, bandwidth requirements, and GSNR. Additionally, QaMcR dynamically updates bandwidth usage within the network with low overhead through the time-efficient propagation chain. We simulate both classical and 274-node topologies, using GNPy for physical layer modeling and QoT estimation. A total of <tex>$5 times {10^8}$</tex> simulations were conducted, exploring nearly a billion shortest paths. The results show that the QaMcR algorithm can find the path with the shortest delay that satisfies multi-constraints within 2 ms, reducing routing time by 95%, while ensuring low delay and low blocking rate.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 10","pages":"876-890"},"PeriodicalIF":4.3,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145027948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In higher-speed passive optical networks (HS-PONs), an upstream dedicated activation wavelength (DAW) is introduced to eliminate the latency caused by periodically creating quiet windows (i.e., time slots) for optical network unit (ONU) activation, thus supporting emerging time-sensitive services. As for the DAW, only part of the bandwidth is reserved for ONU activation, and the remaining bandwidth can still be used to transmit data frames of non-time-sensitive services. However, the existing dynamic bandwidth allocation mechanism tailored for PONs with a single wavelength cannot support cooperative bandwidth scheduling of working and activation wavelengths. In addition, even though transmitting data frames by the DAW can improve the performance in terms of latency and throughput, it brings high energy consumption, especially for the optical digital signal processing function being performed in ONUs. In this paper, we address the above problems by enhancing the existing scheduling protocols for HS-PONs with DAWs to enable bandwidth scheduling of two wavelengths in a unified way, based on which the maximum upstream latencies are further analyzed. Furthermore, we also propose an energy-efficient bandwidth and wavelength allocation scheme, in which the number of operating wavelengths can be reduced while meeting the services’ latency requirements. Simulation results show that the proposed scheme outperforms the benchmarks in terms of energy saving, without affecting the latency constraint, thus well satisfying services’ diverse requirements.
{"title":"Energy-efficient bandwidth and wavelength allocation in HS-PONs with a dedicated activation wavelength","authors":"Guanlun Sun;Jun Li;Xiang Lu;Rui Lin;Lena Wosinska","doi":"10.1364/JOCN.566096","DOIUrl":"https://doi.org/10.1364/JOCN.566096","url":null,"abstract":"In higher-speed passive optical networks (HS-PONs), an upstream dedicated activation wavelength (DAW) is introduced to eliminate the latency caused by periodically creating quiet windows (i.e., time slots) for optical network unit (ONU) activation, thus supporting emerging time-sensitive services. As for the DAW, only part of the bandwidth is reserved for ONU activation, and the remaining bandwidth can still be used to transmit data frames of non-time-sensitive services. However, the existing dynamic bandwidth allocation mechanism tailored for PONs with a single wavelength cannot support cooperative bandwidth scheduling of working and activation wavelengths. In addition, even though transmitting data frames by the DAW can improve the performance in terms of latency and throughput, it brings high energy consumption, especially for the optical digital signal processing function being performed in ONUs. In this paper, we address the above problems by enhancing the existing scheduling protocols for HS-PONs with DAWs to enable bandwidth scheduling of two wavelengths in a unified way, based on which the maximum upstream latencies are further analyzed. Furthermore, we also propose an energy-efficient bandwidth and wavelength allocation scheme, in which the number of operating wavelengths can be reduced while meeting the services’ latency requirements. Simulation results show that the proposed scheme outperforms the benchmarks in terms of energy saving, without affecting the latency constraint, thus well satisfying services’ diverse requirements.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 9","pages":"863-875"},"PeriodicalIF":4.3,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144916327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alfonso Sanchez-Macian;Nataliia Koneva;Marco Quagliotti;Jose M. Rivas-Moscoso;Farhad Arpanaei;Jose Alberto Hernandez;Juan P. Fernandez-Palacios
Model networks and their underlying topologies have been used as a reference for techno-economic studies for several decades. Existing reference topologies for optical networks may cover different network segments such as backbone, metro core, metro aggregation, access, and/or data center. While telecommunication operators work on the optimization of their own existing deployed optical networks, the availability of different topologies is useful for researchers and technology developers to test their solutions in a variety of scenarios and validate the performance in terms of energy efficiency or cost reduction. This paper presents an open-source tool, MoleNetwork, to generate graphs (backbone, metro core, and metro aggregation) inspired by real network topologies of telecommunication operators that can be used as benchmarks for techno-economic studies. A new topology, to our knowledge, Italy2k, is generated based on the structure of a real operator’s network. Then, the tool is tested by validating that the expected operator parameters are matched in the generated topology and by using the topology to forecast technical demands in a 10-year period in one of its metro regions (core and aggregation networks).
{"title":"Generating realistic optical topologies for techno-economic studies using MoleNetwork","authors":"Alfonso Sanchez-Macian;Nataliia Koneva;Marco Quagliotti;Jose M. Rivas-Moscoso;Farhad Arpanaei;Jose Alberto Hernandez;Juan P. Fernandez-Palacios","doi":"10.1364/JOCN.567964","DOIUrl":"https://doi.org/10.1364/JOCN.567964","url":null,"abstract":"Model networks and their underlying topologies have been used as a reference for techno-economic studies for several decades. Existing reference topologies for optical networks may cover different network segments such as backbone, metro core, metro aggregation, access, and/or data center. While telecommunication operators work on the optimization of their own existing deployed optical networks, the availability of different topologies is useful for researchers and technology developers to test their solutions in a variety of scenarios and validate the performance in terms of energy efficiency or cost reduction. This paper presents an open-source tool, MoleNetwork, to generate graphs (backbone, metro core, and metro aggregation) inspired by real network topologies of telecommunication operators that can be used as benchmarks for techno-economic studies. A new topology, to our knowledge, Italy2k, is generated based on the structure of a real operator’s network. Then, the tool is tested by validating that the expected operator parameters are matched in the generated topology and by using the topology to forecast technical demands in a 10-year period in one of its metro regions (core and aggregation networks).","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 9","pages":"847-862"},"PeriodicalIF":4.3,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144914179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juan Carlos Hernandez-Hernandez;David Larrabeiti;Maria Calderon;Ignacio Soto;Farhad Arpanaei
Quantum key distribution (QKD) combined with quantum-safe encryption algorithms offers a practical path to future-proof communication security. Currently, the BB84 QKD protocol is mature and can be deployed over legacy optical fiber infrastructure using commercial products, with trusted key relaying as a workaround for its distance limitations. However, designing cost-effective QKD networks is essential for widespread adoption by end users and telecom operators (Telcos). To address this challenge, we propose and study a novel, to our knowledge, strategy: periodic time sharing of QKD transceivers. This strategy, especially cost saving at low and medium workloads, allows for generating keys for pairs of nodes at deterministic rates decided a priori. This work presents an offline solution for allocating and scheduling QKD transceivers that are shared by the aforementioned time-division multiplexing (TDM) scheme in a QKD network. We propose a mixed-integer linear programming (MILP)-based scheduling (MBS) method to solve this problem, which is computationally expensive, even for small network topologies. As an alternative, we introduce allocation-driven scheduling (ADS), an algorithm that internally breaks the problem into two steps: allocate first and schedule later. The scheduling can be handled by either a relaxed-MBS (rMBS) or a round-robin scheduling (RRS) approach (ADS-rMBS and ADS-RRS, respectively). Both methods yield results comparable to MBS for small networks. Furthermore, simulations illustrate that both ADS-rMBS and ADS-RRS enable a pay-as-you-grow model, reducing the initial capital expenditure in low-load scenarios. Compared with the non-TDM baseline (i.e., QKD transceivers are non-shared), the cost savings range from 30% to 50%, making QKD deployment more economically viable. Moreover, ADS-rMBS generally outperforms ADS-RRS, but requires a higher runtime, reaching up to 2500 s in large networks. Conversely, ADS-RRS maintains a stable 1 ms runtime across all conditions, making both approaches viable depending on the traffic matrix update interval.
{"title":"On offline scheduling for time-division multiplexing QKD networks","authors":"Juan Carlos Hernandez-Hernandez;David Larrabeiti;Maria Calderon;Ignacio Soto;Farhad Arpanaei","doi":"10.1364/JOCN.566174","DOIUrl":"https://doi.org/10.1364/JOCN.566174","url":null,"abstract":"Quantum key distribution (QKD) combined with quantum-safe encryption algorithms offers a practical path to future-proof communication security. Currently, the BB84 QKD protocol is mature and can be deployed over legacy optical fiber infrastructure using commercial products, with trusted key relaying as a workaround for its distance limitations. However, designing cost-effective QKD networks is essential for widespread adoption by end users and telecom operators (Telcos). To address this challenge, we propose and study a novel, to our knowledge, strategy: periodic time sharing of QKD transceivers. This strategy, especially cost saving at low and medium workloads, allows for generating keys for pairs of nodes at deterministic rates decided a priori. This work presents an offline solution for allocating and scheduling QKD transceivers that are shared by the aforementioned time-division multiplexing (TDM) scheme in a QKD network. We propose a mixed-integer linear programming (MILP)-based scheduling (MBS) method to solve this problem, which is computationally expensive, even for small network topologies. As an alternative, we introduce allocation-driven scheduling (ADS), an algorithm that internally breaks the problem into two steps: allocate first and schedule later. The scheduling can be handled by either a relaxed-MBS (rMBS) or a round-robin scheduling (RRS) approach (ADS-rMBS and ADS-RRS, respectively). Both methods yield results comparable to MBS for small networks. Furthermore, simulations illustrate that both ADS-rMBS and ADS-RRS enable a pay-as-you-grow model, reducing the initial capital expenditure in low-load scenarios. Compared with the non-TDM baseline (i.e., QKD transceivers are non-shared), the cost savings range from 30% to 50%, making QKD deployment more economically viable. Moreover, ADS-rMBS generally outperforms ADS-RRS, but requires a higher runtime, reaching up to 2500 s in large networks. Conversely, ADS-RRS maintains a stable 1 ms runtime across all conditions, making both approaches viable depending on the traffic matrix update interval.","PeriodicalId":50103,"journal":{"name":"Journal of Optical Communications and Networking","volume":"17 9","pages":"834-846"},"PeriodicalIF":4.3,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144909298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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