{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,13]],"date-time":"2026-05-13T14:22:12Z","timestamp":1778682132697,"version":"3.51.4"},"reference-count":34,"publisher":"Optica Publishing Group","issue":"4","license":[{"start":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:00:00Z","timestamp":1774915200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/doi.org\/10.1364\/OA_License_v2#VOR"},{"start":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:00:00Z","timestamp":1774915200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/opg.optica.org\/policies\/opg-tdm-policy.json"}],"funder":[{"name":"MEXT\/JSPS KAKENHI","award":["JP24K17276"],"award-info":[{"award-number":["JP24K17276"]}]},{"name":"MEXT\/JSPS KAKENHI","award":["JP25K22800"],"award-info":[{"award-number":["JP25K22800"]}]},{"name":"MEXT\/JSPS KAKENHI","award":["JP25KF0055"],"award-info":[{"award-number":["JP25KF0055"]}]},{"name":"JST ACT-X","award":["JPMJAX22A8"],"award-info":[{"award-number":["JPMJAX22A8"]}]}],"content-domain":{"domain":["opg.optica.org"],"crossmark-restriction":false},"short-container-title":["J. Opt. Commun. Netw."],"published-print":{"date-parts":[[2026,4,1]]},"abstract":"<jats:p>To cope with the scalability limitations of conventional optical cross-connects (OXCs), previous studies have introduced a subsystem-modular OXC architecture, which comprises multiple low-port-count switch modules called OXC-subsystems. This architecture can employ an intra-node structure that connects OXC-subsystems sequentially within a node. While this architecture allows for low-port-count OXC-subsystems to be used, it includes redundant intra-node connections between OXC-subsystems to ensure high flexibility of intra-node routing, which can lead to an increase in the number of OXC-subsystems deployed. This paper proposes a node architecture that adopts unidirectional intra-node connections, aiming to reduce redundant intra-node fibers and improve the utilization efficiency of subsystem ports. In the proposed node architecture, OXC-subsystems are connected in one direction, which can help to avoid redundant bidirectional connections and enable more ports to be used for inter-node connections. We formulate the network model with the proposed node architecture as an integer linear programming problem. For large-scale problems, we develop heuristic algorithms for routing and wavelength assignment to cope with the constraints introduced by unidirectional intra-node connections. Numerical results demonstrate that the network with the proposed node architecture reduces the total number of OXC-subsystems compared to that with the benchmark architecture in static network design. The results also confirm that the proposed architecture achieves the same blocking performance as the benchmark system while reducing the number of OXC-subsystems by up to 17.4%.<\/jats:p>","DOI":"10.1364\/jocn.582560","type":"journal-article","created":{"date-parts":[[2026,3,3]],"date-time":"2026-03-03T13:00:18Z","timestamp":1772542818000},"page":"378","update-policy":"https:\/\/doi.org\/10.1364\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Node architecture with unidirectional intra-node connections for subsystem-modular optical cross-connects"],"prefix":"10.1364","volume":"18","author":[{"given":"Chenhao","family":"Chang","sequence":"first","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02kpeqv85","id-type":"ROR","asserted-by":"publisher"}]}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7991-4109","authenticated-orcid":true,"given":"Ryuta","family":"Shiraki","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02kpeqv85","id-type":"ROR","asserted-by":"publisher"}]}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2177-5027","authenticated-orcid":true,"given":"Eiji","family":"Oki","sequence":"additional","affiliation":[{"id":[{"id":"https:\/\/ror.org\/02kpeqv85","id-type":"ROR","asserted-by":"publisher"}]}]}],"member":"285","published-online":{"date-parts":[[2026,3,31]]},"reference":[{"key":"jocn-18-4-378-R1","doi-asserted-by":"publisher","first-page":"2174","DOI":"10.1109\/LPT.2015.2455931","type":"journal-article","volume":"27","author":"Simmons","year":"2015","journal-title":"IEEE Photonics Technol. Lett."},{"key":"jocn-18-4-378-R2","first-page":"Mo3K_1","article-title":"Optical switching for inter and intra computing center networks","volume-title":"Conference on Lasers and Electro-Optics Pacific Rim","author":"Deng","year":"2024"},{"key":"jocn-18-4-378-R3","doi-asserted-by":"publisher","first-page":"1009","DOI":"10.1364\/JOCN.7.001009","type":"journal-article","volume":"7","author":"Tanaka","year":"2015","journal-title":"J. Opt. Commun. Netw."},{"key":"jocn-18-4-378-R4","first-page":"Mo3K_2","article-title":"Design of large-scale OXC for the next-generation ROADM","volume-title":"Conference on Lasers and Electro-Optics Pacific Rim","author":"Ye","year":"2024"},{"key":"jocn-18-4-378-R5","doi-asserted-by":"publisher","first-page":"476","DOI":"10.1364\/JOCN.8.000476","type":"journal-article","volume":"8","author":"Sato","year":"2016","journal-title":"J. Opt. Commun. Netw."},{"key":"jocn-18-4-378-R6","doi-asserted-by":"publisher","first-page":"1435","DOI":"10.1109\/JLT.2018.2800082","type":"journal-article","volume":"36","author":"Hashimoto","year":"2018","journal-title":"J. Lightwave Technol."},{"key":"jocn-18-4-378-R7","first-page":"WeIII3-3","article-title":"Cost effective and resilient optical network that offers seamless network expansion via subsystem modular OXCs and inter-node interconnection optimization","volume-title":"International Conference on Photonics in Switching","author":"Sato","year":"2015"},{"key":"jocn-18-4-378-R8","doi-asserted-by":"publisher","first-page":"A18","DOI":"10.1364\/JOCN.9.000A18","type":"journal-article","volume":"9","author":"Niwa","year":"2017","journal-title":"J. Opt. Commun. Netw."},{"key":"jocn-18-4-378-R9","doi-asserted-by":"publisher","first-page":"H27","DOI":"10.1364\/JOCN.532594","type":"journal-article","volume":"16","author":"Hasegawa","year":"2024","journal-title":"J. Opt. Commun. Netw."},{"key":"jocn-18-4-378-R10","doi-asserted-by":"publisher","first-page":"5994","DOI":"10.1364\/OE.23.005994","type":"journal-article","volume":"23","author":"Tanaka","year":"2015","journal-title":"Opt. Express"},{"key":"jocn-18-4-378-R11","doi-asserted-by":"publisher","first-page":"17982","DOI":"10.1364\/OE.25.017982","type":"journal-article","volume":"25","author":"Yamakami","year":"2017","journal-title":"Opt. Express"},{"key":"jocn-18-4-378-R12","doi-asserted-by":"crossref","DOI":"10.1109\/ICTON.2013.6602914","article-title":"An efficient add\/drop architecture for large-scale subsystem-modular OXC","volume-title":"15th International Conference on Transparent Optical Networks","author":"Ishida","year":"2013"},{"key":"jocn-18-4-378-R13","first-page":"TS7-2","article-title":"Subsystem-modular optical cross-connect architecture with unidirectional intra-node connections","volume-title":"Asia-Pacific Network Operations and Management Symposium","author":"Chang","year":"2025"},{"key":"jocn-18-4-378-R14","doi-asserted-by":"publisher","first-page":"896","DOI":"10.1109\/JLT.2020.3022375","type":"journal-article","volume":"39","author":"Ma","year":"2020","journal-title":"J. Lightwave Technol."},{"key":"jocn-18-4-378-R15","doi-asserted-by":"publisher","first-page":"22","DOI":"10.3390\/photonics4020022","type":"journal-article","volume":"4","author":"Wang","year":"2017","journal-title":"Photonics"},{"key":"jocn-18-4-378-R16","doi-asserted-by":"crossref","first-page":"Th1I.2","DOI":"10.1364\/OFC.2014.Th1I.2","article-title":"N-degree ROADM architecture comparison: broadcast-and-select versus route-and-select in 120 Gb\/s DP-QPSK transmission systems","volume-title":"Optical Fiber Communication Conference","author":"Filer","year":"2014"},{"key":"jocn-18-4-378-R17","doi-asserted-by":"publisher","first-page":"14796","DOI":"10.1364\/OE.23.014796","type":"journal-article","volume":"23","author":"Takashina","year":"2015","journal-title":"Opt. Express"},{"key":"jocn-18-4-378-R18","doi-asserted-by":"publisher","first-page":"B58","DOI":"10.1364\/JOCN.4.000B58","type":"journal-article","volume":"4","author":"Li","year":"2012","journal-title":"J. Opt. Commun. Netw."},{"key":"jocn-18-4-378-R19","first-page":"80","article-title":"Cascadability performance of continuous spectrum WB\/WSS at 10\/40\/160 Gb\/s","volume-title":"International Conference on Transparent Optical Networks","author":"Sygletos","year":"2006"},{"key":"jocn-18-4-378-R20","doi-asserted-by":"publisher","first-page":"15838","DOI":"10.1364\/OE.25.015838","type":"journal-article","volume":"25","author":"Ishikawa","year":"2017","journal-title":"Opt. Express"},{"key":"jocn-18-4-378-R21","doi-asserted-by":"publisher","first-page":"99","DOI":"10.1364\/JOCN.384140","type":"journal-article","volume":"12","author":"Hashimoto","year":"2020","journal-title":"J. Opt. Commun. Netw."},{"key":"jocn-18-4-378-R22","doi-asserted-by":"crossref","DOI":"10.1109\/ICTON.2015.7193526","article-title":"On scaling transport networks for very high nodal degree ROADM nodes using state-of-the-art optical switch technology","volume-title":"17th International Conference on Transparent Optical Networks (ICTON)","author":"Pedro","year":"2015"},{"key":"jocn-18-4-378-R23","doi-asserted-by":"crossref","DOI":"10.1109\/ICTON.2017.8024880","article-title":"ROADM express layer design strategies for scalable and cost-effective multi-fibre DWDM networks","volume-title":"19th International Conference on Transparent Optical Networks (ICTON)","author":"Pedro","year":"2017"},{"key":"jocn-18-4-378-R24","doi-asserted-by":"publisher","first-page":"A263","DOI":"10.1364\/JOCN.9.00A263","type":"journal-article","volume":"9","author":"Sato","year":"2017","journal-title":"J. Opt. Commun. Netw."},{"key":"jocn-18-4-378-R25","doi-asserted-by":"publisher","first-page":"679","DOI":"10.1587\/transcom.2019EBP3148","type":"journal-article","volume":"E103b","author":"Ganbold","year":"2020","journal-title":"IEICE Trans. Commun."},{"key":"jocn-18-4-378-R26","doi-asserted-by":"publisher","first-page":"79","DOI":"10.1364\/JOCN.378370","type":"journal-article","volume":"12","author":"Ahmed","year":"2020","journal-title":"J. Opt. Commun. Netw."},{"key":"jocn-18-4-378-R27","first-page":"380","article-title":"Dynamic RMSA in spectrum-sliced elastic optical networks for high-throughput service provisioning","volume-title":"IEEE International Conference on Computing, Networking and Communications (ICNC)","author":"Zhang","year":"2013"},{"key":"jocn-18-4-378-R28","doi-asserted-by":"publisher","first-page":"1065","DOI":"10.1109\/SURV.2011.101911.00023","type":"journal-article","volume":"14","author":"Rahbar","year":"2012","journal-title":"IEEE Commun. Surv. Tutorials"},{"key":"jocn-18-4-378-R29","doi-asserted-by":"publisher","first-page":"478","DOI":"10.1364\/OE.21.000478","type":"journal-article","volume":"21","author":"Iwai","year":"2013","journal-title":"Opt. Express"},{"key":"jocn-18-4-378-R30","doi-asserted-by":"publisher","first-page":"1765","DOI":"10.1109\/JSAC.2011.111002","type":"journal-article","volume":"29","author":"Knight","year":"2011","journal-title":"IEEE J. Sel. Areas Commun."},{"key":"jocn-18-4-378-R31","doi-asserted-by":"publisher","first-page":"691","DOI":"10.1137\/0205048","type":"journal-article","volume":"5","author":"Even","year":"1976","journal-title":"SIAM J. Comput."},{"key":"jocn-18-4-378-R32","first-page":"184","article-title":"On the complexity of time table and multi-commodity flow problems","volume-title":"16th Annual Symposium on Foundations of Computer Science","author":"Even","year":"1975"},{"key":"jocn-18-4-378-R33","doi-asserted-by":"publisher","first-page":"3043","DOI":"10.1109\/JLT.2013.2278572","type":"journal-article","volume":"31","author":"Hamzeh","year":"2013","journal-title":"J. Lightwave Technol."},{"key":"jocn-18-4-378-R34","volume-title":"Network Recovery: Protection and Restoration of Optical, SONET-SDH, IP, and MPLS","author":"Vasseur","year":"2004"}],"container-title":["Journal of Optical Communications and Networking"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/opg.optica.org\/viewmedia.cfm?URI=jocn-18-4-378&seq=0","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,13]],"date-time":"2026-05-13T13:58:57Z","timestamp":1778680737000},"score":1,"resource":{"primary":{"URL":"https:\/\/opg.optica.org\/abstract.cfm?URI=jocn-18-4-378"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,31]]},"references-count":34,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026]]},"published-print":{"date-parts":[[2026]]}},"URL":"https:\/\/doi.org\/10.1364\/jocn.582560","relation":{},"ISSN":["1943-0620","1943-0639"],"issn-type":[{"value":"1943-0620","type":"print"},{"value":"1943-0639","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,31]]},"assertion":[{"value":"Optica Publishing Group","name":"publisher","label":"This article is maintained by"},{"value":"https:\/\/doi.org\/10.1364\/JOCN.582560","name":"articlelink","label":"Crossref DOI link to publisher maintained version"},{"value":"research-article","name":"content_type","label":"Article type"},{"value":"Screened by Similarity Check","name":"cross_check","label":"Similarity check"},{"value":"Yes","order":0,"name":"peer_reviewed","label":"Peer reviewed","group":{"name":"peer_review","label":"Peer review"}},{"value":"Single blind","order":1,"name":"review_process","label":"Review process","group":{"name":"peer_review","label":"Peer review"}},{"value":"24 October 2025","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"1 March 2026","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"31 March 2026","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}},{"value":"\u00a9 2026 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.","name":"copyright","label":"Copyright"}]}}