O-RAN Tests

The Open Radio Access Network, commonly known as ORAN, has emerged as a significant trend in the telecommunications industry.
Due to its vast potential, networking professionals are actively exploring, testing, and implementing O-RAN solutions. The significance of O-RAN and its components, especially its fronthaul network, cannot be ignored.
The fronthaul network is a key component of O-RAN architecture and plays a critical role in its efficiency. It requires precise and reliable Time Synchronization to ensure the system's integrity, functionality, and performance.
       

O-RAN Fronthaul LLS-C2 (Option A)

In our tests, we took the liberty of making one major change to the O-RAN Fronthaul LLS-C2 (Option A) topology: We exchanged the Open Distributed Unit (O-DU) for a Boundary Clock.
Our setup consisted of one Grandmaster (T-GM), one Boundary Clock(T-BC ), and two separate timing paths branching from the T-BC. Each path had one Hub-Site Router (HSR) and one Cell-Site Router (CSR). Both CSRs were connected to a measurement tool to measure the relative time error between their outputs.
All three test runs with different vendor combinations passed the requirements for the maximum absolute time error and the maximum relative time error, as defined in O-RAN.WG9.XTRP-TST.0-R004-v05.00, section 9.1.5; however, we were unable to test 1PPS.

O-RAN Fronthaul LLS-C3 Configuration with GM from Fronthaul

Additionally, we executed a test to emulate an LLS-C3 scenario as per O-RAN.WG9.XTRP-SYN.0-R003-v05.00, where the GM was at the Fronthaul.
This test was executed once, with the Keysight Time Sync Analyzer serving as the emulated O-DU, O-CU, and O-RU and the Keysight IxNetwork as the traffic generator. The Ciena 8140 took the role of the HSR, and the Juniper ACX7100-32C of the CSR.
The maximum absolute time error was 2.344ns for the Ciena 8150 and 4.781ns for the Juniper ACX7100-32C, both incredibly low and well within the limits of ITU-T G.8273.2 Class D media converter pairs.