A Systematic Study on Open Radio Access Network: Components, Applications, and Future Directions

Yıl 2025, Cilt: 8 Sayı: 4, 1235 - 1244, 15.07.2025

Önem Yıldız

Öz

Open Radio Access Network (O-RAN) introduces a paradigm shift in mobile communications by promoting openness, multi-vendor interoperability, and software-defined networking capabilities as an alternative to traditional RAN architectures. This review study analyzes the architectural structure of O-RAN, its control plane components, and AI-driven network management frameworks. The roles of xApps and rApps operating on Near-Real-Time (Near-RT) and Non-Real-Time (Non-RT) RAN Intelligent Controller (RIC) architectures are examined in the context of resource management and policy-based control. Findings from the literature indicate that O-RAN can be effectively integrated not only into conventional mobile networks but also into emerging use cases such as private 5G networks, UAV-assisted platforms, and digital twin-based network monitoring. However, several technical challenges remain, including timing and synchronization sensitivity, security vulnerabilities, lack of real-world labeled datasets, and ongoing standardization gaps. As we move toward 6G, O-RAN is expected to serve as a foundational architecture supporting autonomous control loops, end-to-end slicing, and high-frequency communication systems. This work aims to provide comprehensive references for researchers and practitioners by consolidating recent developments and outlining future research directions in the O-RAN domain.

Anahtar Kelimeler

Open radio access network (O-RAN), 5G, 6G, Software-defined network, Artificial intelligence

Açık Radyo Erişim Ağı Üzerine Sistematik Bir İnceleme: Bileşenler, Uygulamalar ve Gelecek Perspektifleri

Öz

Açık Radyo Erişim Ağı (O-RAN), açıklık, çok tedarikçili yapı ve yazılım tanımlı ağ prensipleriyle geleneksel RAN mimarilerine alternatif sunarak mobil iletişimde önemli bir dönüşüm başlatmaktadır. Bu derleme çalışması, O-RAN’ın mimari yapısını, kontrol düzlemi bileşenlerini ve yapay zekâ ile bütünleşen ağ yönetim yaklaşımlarını incelemektedir. Yakın Gerçek Zamanlı (Near-RT) ve Gerçek Zamanlı Olmayan (Non-RT) RAN Akıllı Kontrolör (RIC) mimarileri çerçevesinde çalışan xApp ve rApp uygulamalarının rolleri, kaynak yönetimi ve politika tabanlı kontrol bağlamında incelenmiştir. Literatürdeki uygulama senaryoları, O-RAN’ın yalnızca mobil şebekeler değil, aynı zamanda özel 5G ağlar, uçan iletişim platformları ve dijital ikiz tabanlı ağ yönetimi gibi yenilikçi alanlara da entegre edilebildiğini göstermektedir. Bununla birlikte, zamanlama hassasiyetleri, güvenlik açıkları, sahaya dayalı veri eksiklikleri ve standardizasyon belirsizlikleri, mimarinin uygulanabilirliğini sınırlayan başlıca teknik zorluklar arasında yer almaktadır. O-RAN’ın 6G’ye geçiş sürecinde; otonom kontrol sistemleri, uçtan uca dilimleme ve yüksek frekanslı haberleşme altyapıları ile birleşerek temel bir yapı taşı haline gelmesi öngörülmektedir. Bu çalışma, O-RAN teknolojisine yönelik güncel araştırmaları bir araya getirerek, gelecekteki akademik ve endüstriyel çalışmalara kapsamlı bir referans çerçevesi sunmayı hedeflemektedir.

Anahtar Kelimeler

Açık radyo erişim ağı (O-RAN), 5G, 6G, Yazılım tanımlı ağ, Yapay zekâ

Etik Beyan

Bu araştırmada hayvanlar ve insanlar üzerinde herhangi bir çalışma yapılmadığı için etik kurul onayı alınmamıştır.

Destekleyen Kurum

Bu makale için herhangi bir maddi destek bulunmamaktadır.

Kaynakça

• Abdalla AS, Upadhyaya PS, Shah VK, Marojevic, V. 2022. Toward Next Generation Open Radio Access Networks: What O-RAN Can and Cannot Do! IEEE Netw, 36(6): 206-213.
• Alam K, Habibi MA, Tammen M, Krummacker D, Saad W, Renzo MD, Melodia T, Costa-Pérez X, Debbah M, Dutta A, Schotten HD. 2024. A Comprehensive Tutorial and Survey of O-RAN: Exploring Slicing-aware Architecture, Deployment Options, Use Cases, and Challenges. IEEE Open J Commun Soc, pp: 264.
• Arslan H, Yılmaz S, Sen S. 2023. Dynamic MAC Scheduling in O-RAN using Federated Deep Reinforcement Learning. 2023 International Conference on Smart Applications, Communns Netw (SmartNets): 1-8.
• Beerten R, Girycki A, Pollin S. 2022. User centric cell-free massive MIMO in the O-RAN architecture: Signalling and algorithm integration. 2022 IEEE Conference on Standards for Communications and Networking (CSCN): 181-187.
• Beerten R, Ranjbar V, Guevara AP, Pollin S. 2024. Mobile Cell-Free Massive MIMO: A Practical O-RAN Based Approach. IEEE Open J Commun Soc.
• Bertizzolo L, Bonati L, Demirors E, Al-Shawabka A, D’Oro S, Restuccia F, Melodia T. 2020. Arena: A 64-antenna SDR-based ceiling grid testing platform for sub-6 GHz 5G-and-Beyond radio spectrum research. Comput Netw, 181: 107436.
• Breen J, Buffmire A, Duerig J, Dutt K, Eide E, Hibler M, Johnson D, Kasera SK, Lewis E, Maas D, Orange A, Patwari N, Reading D, Ricci R, Schurig D, Stoller LB, Van Der Merwe J, Webb K, Wong G. 2020. POWDER: Platform for Open Wireless Data-driven Experimental Research. Proceedings of the 14th International Workshop on Wireless Network Testbeds, Experimental evaluation & Characterization, 17-24.
• Bonati L, D’Oro S, Basagni S, Melodia T. 2021a. SCOPE: An open and softwarized prototyping platform for NextG systems. Proceedings of the 19th Annual International Conference on Mobile Systems, Applications, and Services, 415-426.
• Bonati L, D’Oro S, Polese M, Basagni S, Melodia T. 2021b. Intelligence and learning in O-RAN for data-driven NextG cellular networks. IEEE Commun Mag, 59(10): 21-27.
• Bonati L, Johari P, Polese M, D’Oro S, Mohanti S, Tehrani-Moayyed M, Villa D, Shrivastava S, Tassie C, Yoder K. 2021c. Colosseum: Large-scale wireless experimentation through hardware-in-the-loop network emulation. 2021 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN): 105-113.
• Bonati L, Polese M, D’Oro S, Basagni S, Melodia T. 2022. OpenRAN gym: An open toolbox for data collection and experimentation with AI in O-RAN. 2022 IEEE Wireless Communications and Networking Conference (WCNC): 518-523.
• Bonati L, Polese M, D’Oro S, Basagni S, Melodia T. 2023. OpenRAN Gym: AI/ML development, data collection, and testing for O-RAN on PAWR platforms. Comput Netw, 220: 109502.
• Campana R, Amatetti C, Vanelli-Coralli A. 2023. O-RAN based non-terrestrial networks: Trends and challenges. 2023 Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit): 264-269.
• Choudhary A, Srivastava G, Jha MK. 2024. Technicalities of O-RAN for 5G and B5G. 2024 International Conference on Knowledge Engineering and Communication Systems (ICKECS): 1-5.
• Chu Y, Rahmani M, Shackleton J, Grace D, Cumanan K, Ahmadi H, Burr A. 2025. Testbed Development: An Intelligent O-RAN based Cell-Free MIMO Network. arXiv preprint arXiv:2502.08529.
• Demir ÖT, Masoudi M, Björnson E, Cavdar C. 2024. Cell-free massive MIMO in O-RAN: Energy-aware joint orchestration of cloud, fronthaul, and radio resources. IEEE J Sel Areas Commun, 42(2): 356-372.
• Dik D, Berger MS. 2023. Open-RAN fronthaul transport security architecture and implementation. IEEE Access, 11: 46185-46203.
• D’Oro S, Bonati L, Polese M, Melodia T. 2022a. OrchestRAN: Network automation through orchestrated intelligence in the open RAN. IEEE INFOCOM 2022-IEEE Conference on Computer Communications, 270-279.
• D’Oro S, Polese M, Bonati L, Cheng H, Melodia T. 2022b. dApps: Distributed applications for real-time inference and control in O-RAN. IEEE Commun Mag, 60(11): 52-58.
• Garcia-Saavedra A, Costa-Perez X. 2021. O-RAN: Disrupting the virtualized RAN ecosystem. IEEE Commun Stand Mag, 5(4): 96-103.
• Gomez-Miguelez I, Garcia-Saavedra A, Sutton PD, Serrano P, Cano C, Leith DJ. 2016. srsLTE: An open-source platform for LTE evolution and experimentation. Proceedings of the Tenth ACM International Workshop on Wireless Network Testbeds, Experimental Evaluation, and Characterization, 25-32.
• Groen J, D’Oro S, Demir U, Bonati L, Polese M, Melodia T, Chowdhury K. 2024a. Implementing and evaluating security in O-RAN: Interfaces, intelligence, and platforms. IEEE Netw.
• Groen J, D’Oro S, Demir U, Bonati L, Villa D, Polese M, Melodia T, Chowdhury K. 2024b. Securing O-RAN open interfaces. IEEE Trans Mobile Comput.
• Groen J, Kim B, Chowdhury K. 2023. The cost of securing O-RAN. ICC 2023-IEEE Int Conf Commun, 5444-5449.
• Habibi MA, Han B, Fellan A, Jiang W, Sánchez AG, Pavon IL, Boubendir A, Schotten HD. 2023. Toward an open, intelligent, and end-to-end architectural framework for network slicing in 6G communication systems. IEEE Open J Commun Soc, 4: 1615-1658.
• Habibi MA, Han B, Yousaf FZ, Schotten HD. 2020. How should network slice instances be provided to multiple use cases of a single vertical industry? IEEE Commun Stand Mag, 4(3): 53-61.
• Hamdan MQ, Lee H, Triantafyllopoulou D, Borralho R, Kose A, Amiri E, Mulvey D, Yu W, Zitouni R, Pozza R. 2023. Recent advances in machine learning for network automation in the O-RAN. Sensors, 23(21): 8792.
• Huang Y, Sun Q, Li N, Chen Z, Huang J, Ding H. 2023. Validation of current O-RAN technologies and insights on the future evolution. IEEE J Sel Areas Commun, 42(2): 487-505.
• Kasuluru V, Blanco L, Vázquez MÁ, Vaca-Rubio CJ, Zeydan E. 2024. Minimizing power consumption under SINR constraints for cell-free massive MIMO in O-RAN. 2024 20th Int Conf Netw Serv Manag (CNSM), 1-7.
• Ko WH, Dinesha U, Ghosh U, Shakkottai S, Bharadia D, Wu R. 2023. EdgeRIC: Empowering real-time intelligent optimization and control in nextG networks.
• Lee H, Cha J, Kwon D, Jeong M, Park I. 2020. Hosting AI/ML workflows on O-RAN RIC platform. 2020 IEEE Globecom Workshops, 1-6.
• Liyanage M, Braeken A, Shahabuddin S, Ranaweera P. 2023. Open RAN security: Challenges and opportunities. J Netw Comput Appl, 214: 103621.
• Marinova S, Leon-Garcia A. 2024. Intelligent O-RAN beyond 5G: Architecture, use cases, challenges, and opportunities. IEEE Access, 12: 27088-27114.
• Nayebi E, Ashikhmin A, Marzetta TL, Yang H. 2015. Cell-free massive MIMO systems. 2015 49th Asilomar Conf Signals Syst Comput, 695-699.
• Nikaein N, Marina MK, Manickam S, Dawson A, Knopp R, Bonnet C. 2014. OpenAirInterface: A flexible platform for 5G research. ACM SIGCOMM Comput Commun Rev, 44(5): 33-38.
• Niknam S, Roy A, Dhillon HS, Singh S, Banerji R, Reed JH, Saxena N, Yoon S. 2022. Intelligent O-RAN for beyond 5G and 6G wireless networks. 2022 IEEE Globecom Workshops, 215-220.
• O-RAN Alliance. 2018. O-RAN: Towards an open and smart RAN. https://www.o-ran.org/o-ran-resources (accessed date: March 10, 2025)
• O-RAN Alliance. 2020. O-RAN use cases and deployment scenarios. https://www.o-ran.org/o-ran-resources (accessed date: March 10, 2025)
• Pham C, Fami F, Nguyen KK, Cheriet M. 2022. When RAN intelligent controller in O-RAN meets multi-UAV enable wireless network. IEEE Trans Cloud Comput, 11(3): 2245-2259.
• Polese M, Bonati L, D’Oro S, Basagni S, Melodia T. 2022. ColO-RAN: Developing machine learning-based xApps for open RAN closed-loop control on programmable experimental platforms. IEEE Trans Mobile Comput, 22(10): 5787-5800.
• Polese M, Bonati L, D’Oro S, Basagni S, Melodia T. 2023. Understanding O-RAN: Architecture, interfaces, algorithms, security, and research challenges. IEEE Commun Surv Tutor, 25(2): 1376-1411.
• Polese M, Bonati L, D’Oro S, Johari P, Villa D, Velumani S, Gangula R, Tsampazi M, Robinson CP, Gemmi G. 2024. Colosseum: The open RAN digital twin. IEEE Open J Commun Soc.
• Ramezanpour K, Jagannath J. 2022. Intelligent zero trust architecture for 5G/6G networks: Principles, challenges, and the role of machine learning in the context of O-RAN. Comput Netw, 217: 109358.
• Raychaudhuri D, Seskar I, Zussman G, Korakis T, Kilper D, Chen T, Kolodziejski J, Sherman M, Kostic Z, Gu X, Krishnaswamy H, Maheshwari S, Skrimponis P, Gutterman C. 2020. Challenge: COSMOS: A city scale programmable testbed for experimentation with advanced wireless. Proc 26th Annu Int Conf Mobile Comput Netw, 1-13.
• Reliance Jio, DTAG, KDDI, NVIDIA, Rakuten, SK Telecom, Bell, Tech Mahindra Ltd. 2023. O-RAN towards 6G. O-RAN next Generation Research Group (nGRG) Research Report No: RR-2023-01.
• Santos JF, Huff A, Campos D, Cardoso KV, Both CB, DaSilva LA. 2025. Managing O-RAN networks: xApp development from zero to hero. IEEE Commun Surv Tutor.
• SD-RAN. 2020. SD-RAN Docs 1.4.3 documentation. https://docs.sd-ran.org/master/index.html (accessed date: March 13, 2025)
• Sever O, Salan O, Hokelek I, Gorcin A. 2025. A practical demonstration of DRL-based dynamic resource allocation xApp using OpenAirInterface. arXiv preprint arXiv:2501.05879.
• Singh SK, Singh R, Kumbhani B. 2020. The evolution of radio access network towards Open-RAN: Challenges and opportunities. 2020 IEEE Wireless Commun Netw Conf Workshops (WCNCW), 1-6.
• Sucuoglu HS. 2025. Development of Real-Time Fire Detection Robotic System with Hybrid-Cascade Machine Learning Detection Structure. Processes, 13(6): 1712.
• Thiruvasagam PK, Venkataram V, Ilangovan VR, Perapalla M, Payyanur R, Kumar V. 2023. Open RAN: Evolution of architecture, deployment aspects, and future directions.
• Tsampazi M, D’Oro S, Polese M, Bonati L, Poitau G, Healy M, Melodia T. 2023. A comparative analysis of deep reinforcement learning-based xApps in O-RAN. GLOBECOM 2023-2023 IEEE Global Commun Conf, 1638-1643.
• Zhang CC, Nguyen KK, Cheriet M. 2022a. Joint routing and packet scheduling for URLLC and eMBB traffic in 5G O-RAN. ICC 2022-IEEE Int Conf Commun, 1900-1905.
• Zhang H, Zhou H, Erol-Kantarci M. 2022b. Federated deep reinforcement learning for resource allocation in O-RAN slicing. GLOBECOM 2022-2022 IEEE Global Commun Conf, 958-963.