O-RAN Interview Questions

In this post, we have put most asked interview questions about Open RAN/O-RAN in various Telecom Companies/Service Provider who are developing Open RAN systems.

1. What is Open RAN, OpenRAN and ORAN?​
2. What is O-RAN ALLIANCE?
3. What is Open RAN Policy Coalition?
4. what C-RAN, Virtual RAN (vRAN) and OpenRAN?
5. What is Near RT RIC ?
6. What is Non-Near RT RIC?
7. Non Real-Time RIC is connected with the Near Real Time RIC on which interface ?
8. Function of 5G NR F1 Interface.
9. Explain Reference Architecture for O-RAN.
10. Explain about O-RAN working Group.
11. What is an Open DU? Explain its architecture.
12. What is an Open RU? Explain its architecture.
13. What is the difference between Category A and Category B Open RU?
14. What is Open Fronthaul?
15. Which Workgroup is responsible for CUS plane specifications?
16. What are the Plane available on Open Fronthaul?
17. Explain Sync topologies for O-RAN Fronthaul.
18. What is is PTP, and How it works?
19. What is PTP IEEE standard and what are available profile for PTP?
20. What is Xapps?
21. What do you mean by Open RAN inter-operability?
22. What are the test tools available for Open RAN interoperability testing

O-RAN Overview & Basics

1. What is the full form of O-RAN and what is its main objective?
2. Briefly describe the journey from traditional RAN to O-RAN.
3. What motivated the creation of the O-RAN Alliance?
4. Name at least three founding members of the O-RAN Alliance.
5. Explain how O-RAN promotes multi-vendor interoperability.
6. What are the three main pillars of O-RAN?
7. Define the term “open interfaces” in the O-RAN context.
8. What is the difference between open RAN and virtualized RAN (vRAN)?
9. Explain the importance of “disaggregation” in O-RAN.
10. How does O-RAN impact vendor lock-in for operators?
11. What is the difference between proprietary RAN and O-RAN?
12. Describe the O-RAN approach to RAN intelligence and automation.
13. How does O-RAN support innovation and ecosystem growth?
14. List two major global operator groups actively driving O-RAN adoption.
15. What role does open-source software play in the O-RAN ecosystem?
16. How does O-RAN drive down the cost of 5G deployments?
17. What is “white-box” hardware and why is it important for O-RAN?
18. How does O-RAN facilitate the deployment of small cells?
19. Explain the term “RAN sharing” and how O-RAN enhances it.
20. What is the relationship between 3GPP and O-RAN specifications?

O-RAN Architecture & Functions

1. What are the main building blocks of O-RAN architecture?
2. What is the primary function of the O-RU (Radio Unit)?
3. What is the O-DU (Distributed Unit) responsible for?
4. What are the O-CU (Centralized Unit) main roles?
5. What is the SMO (Service Management and Orchestration) in O-RAN?
6. Describe the role of the RAN Intelligent Controller (RIC).
7. Differentiate between Near-RT RIC and Non-RT RIC.
8. What are xApps and where do they run?
9. What are rApps and what is their purpose?
10. Which O-RAN node interfaces directly with user equipment (UE)?
11. Which O-RAN node is responsible for MAC/PHY layer functions?
12. Which node typically handles RRC and SDAP processing?
13. What is the role of the Network Management System (NMS) in O-RAN?
14. Explain the hierarchy between SMO, RIC, and DU/CU.
15. What is the function of the Management Plane (M-Plane)?
16. What is the CUS-Plane and what are its sub-planes?

O-RAN Interfaces

1. Explain the purpose of the O1 interface.
2. What is the O2 interface and its role?
3. What is the E2 interface used for?
4. What is the A1 interface and between which nodes does it run?
5. What are the standard interfaces between O-RU, O-DU, and O-CU?
6. Explain the function and structure of the open fronthaul interface.
7. What protocol is commonly used over the open fronthaul (O-DU to O-RU)?
8. What is eCPRI and why is it preferred over CPRI in O-RAN?
9. What are the Control, User, and Synchronization Planes (CUS) in O-RAN?
10. Explain the responsibilities of the M-Plane in O-RAN.
11. What protocols are used for M-Plane management?
12. Describe the use of NETCONF/YANG in O-RAN.
13. What is SSH used for in O-RAN M-Plane communications?
14. What is the function of the O-RU “Call Home” feature?
15. O-RAN Functional Splits & Timing
16. What is a functional split in O-RAN?
17. List all 3GPP-defined functional split options and their split points.
18. What is the most widely adopted split option in O-RAN and why?
19. Describe Option 7-2x split and its main advantages.
20. Compare high-layer and low-layer functional splits.
21. What are the main data flows in Option 7-2x split?
22. What are the trade-offs between Option 2 and Option 7-2x splits?
23. How does functional split impact fronthaul bandwidth requirements?
24. What data flows are exchanged on the User Plane (U-Plane)?
25. How are IQ samples transmitted in the O-RAN fronthaul?
26. Control/User/Synchronization Planes
27. What is the Control Plane (C-Plane) responsible for in O-RAN?
28. What are the main functions of the User Plane (U-Plane)?
29. Describe the Synchronization Plane (S-Plane) and its importance.
30. What is the role of an IEEE 1588 Grand Master in O-RAN?
31. What is the purpose of the S-Plane protocol stack?
32. What timing parameters must be managed for C-Plane and U-Plane coordination?
33. What is Tcp_adv_dl and why is it important?
34. Explain how C-Plane and U-Plane transmission windows are aligned.
35. How does O-RAN handle PRACH IQ data transfer?
36. What is Data Flow 1a, 1b, and 1c in U-Plane?

Synchronization & Topology

1. How is time synchronization distributed in an O-RAN network?
2. What is SyncE and how is it used in O-RAN?
3. What are the compliant O-RAN timing topology configurations (LLS-C1 through LLS-C4)?
4. What are the reference points R1, R2, R3, R4, and Ra in O-RAN?
5. What are T12 and T34 delays in O-RAN?
6. How does the O-DU function as a Grand Master for synchronization?
7. What is the impact of excessive hops/switches on PTP performance?
8. What does Full Timing Support mean in O-RAN synchronization?
9. What are T-BC and T-TC switches and their relevance to O-RAN?
10. What issues may arise if O-DU and O-RU are not properly synchronized?

Management & Orchestration

1. What are the main FCAPS functions provided by the O-RAN M-Plane?
2. List the architectural models for M-Plane management (Hierarchical vs Hybrid).
3. Describe the O-RU bootup and startup sequence.
4. What is the function of SDaaS in O-RU integration?
5. What information is exchanged during NETCONF capability discovery?
6. What is the purpose of “Call Home” in O-RU management?
7. How is performance management activated at O-RU startup?
8. How is O-RU software upgraded and managed remotely?
9. What fault management procedures are performed by O-RU controller?
10. What is the role of the management system (NMS/SMO) in hybrid M-Plane models?

RIC, AI/ML, and xApps/rApps

1. What is the role of the Near-RT RIC in O-RAN?
2. What functions are performed by Non-RT RIC?
3. What are xApps, and what types of use cases do they support?
4. What are rApps and how are they different from xApps?
5. Describe the interaction between RIC and the E2 interface.
6. How can AI/ML models be integrated into RIC/xApps?
7. What is the A1 interface and what information does it convey?
8. How does the Near-RT RIC enable closed-loop automation?
9. List examples of RIC use cases for performance optimization.
10. What is the significance of O-RAN RIC openness for innovation?

Security, Performance & Testing

1. What are the security challenges specific to O-RAN architecture?
2. How is secure onboarding of O-RU achieved in O-RAN?
3. What protocols ensure secure communication across O-RAN interfaces?
4. How are authentication and authorization handled in O-RAN systems?
5. What role does SSH play in M-Plane security?
6. What are the risks of multi-vendor integration in O-RAN and how can they be mitigated?
7. How does O-RAN architecture affect latency performance?
8. What are the bandwidth requirements for Option 7-2x fronthaul?
9. How is jitter managed in the fronthaul network?
10. What are the typical throughput metrics for an O-RU and O-DU link?
11. How is Quality of Service (QoS) maintained in an open fronthaul deployment?
12. What KPIs are commonly used to evaluate O-RAN system performance?
13. Describe a typical testing environment for validating O-RAN fronthaul.
14. What tools are used for O-RAN protocol conformance testing?
15. What is the role of the O-RAN PlugFest and who participates?
16. How is inter-vendor interoperability validated in O-RAN?
17. What types of test cases are executed on the E2 interface?
18. What is a “golden device” in the context of O-RAN testing?
19. What are the typical failure modes in O-RAN functional split interfaces?
20. How does lab testing differ from field testing in O-RAN environments?

Deployment, Use Cases & Market

1. What are common O-RAN deployment models (greenfield vs brownfield)?
2. What are the top use cases driving O-RAN adoption globally?
3. How does O-RAN enable private 5G network deployments?
4. What are the benefits of using O-RAN in rural connectivity?
5. How can O-RAN help reduce Total Cost of Ownership (TCO)?
6. What cloud-native principles are used in O-RAN CU/DU implementations?
7. How is Kubernetes used in managing CU/DU or RIC components?
8. What hyperscalers are involved in O-RAN ecosystem support?
9. What challenges arise when integrating legacy networks with O-RAN?
10. What is vO-RAN and how does it differ from containerized O-RAN?
11. What role do system integrators play in O-RAN deployments?
12. What is the significance of TIP (Telecom Infra Project) in O-RAN?
13. Which global operators have completed commercial O-RAN rollouts?
14. What are the geographical regions leading in O-RAN adoption?
15. What are the projected growth trends for the O-RAN market?

Advanced Topics & Future Directions

1. What is 6G’s potential relationship with O-RAN architecture?
2. How is network slicing supported in the O-RAN framework?
3. How does O-RAN handle Massive MIMO and beamforming?
4. What is Zero-Touch Provisioning (ZTP) in O-RAN?
5. How does the concept of Digital Twins apply to O-RAN?
6. How can Digital RAN (vRAN) co-exist with O-RAN deployments?
7. What are the potential bottlenecks in scaling O-RAN?
8. What efforts are being made to reduce power consumption in O-RAN nodes?
9. What is the O-RAN Software Community and what does it develop?
10. What role does ONAP play in managing O-RAN components?
11. How do L1 accelerators (like FPGAs or ASICs) affect O-DU design?
12. What is the role of TSN (Time-Sensitive Networking) in O-RAN fronthaul?
13. What is meant by “Open F1” in the context of CU/DU split?
14. What’s the significance of LLS-C3 topology in high availability?
15. How is energy efficiency monitored and optimized in O-RAN?