Load Testing: An important function in Open RAN deployment

VIAVI Solutions has added load testing to its 5G network test equipment, but load testing is just one part of interoperability and compliance testing of the Open RAN. In the video below, 5GTW interviewed VIAVI’s Owen O’Donnell to learn about testing Open RAN.

The concept of open radio access networks (O-RANs) has taken hold as network operators look to add services and reduce costs. As with all network functions, operators and equipment manufacturers (hardware or software) need to test their product under simulated network conditions. Network test-equipment maker VIAVI Solutions has added load testing to its set of network test functions. In this case, the load testing covers segments of the radio-access network not previously accessible before Open RAN.

“Open” refers to open interfaces between RAN functions achieved through the disaggregation of a cell tower’s baseband unit (BBU) shown in Figure 1. Without the disaggregation, the functions inside the BBU remain proprietary, inaccessible, and fixed.

Figure 1. A single baseband unit connects a cellular base station’s radio directly to a central office. Image: VIAVI Solutions

Open RAN divides the BBU into functions called radio unit (RU), distribution unit (DU) and centralized unit (CU) where network operators can pick and choose these functions, supplied by multiple companies. The interfaces between the RU, DU, and CU are now standardized by the O-RAN Alliance. That’s the “open” part. Figure 2 compares a 4G network configuration to a 5G Open RAN architecture.

Figure 2. A 5G network that uses Open RAN disaggregates network functions when compared to traditional 4G (or 5G) networks. Image: VIAVI Solutions.

With the additional functions now accessible and provided by multiple companies, the need for compliance, interoperability, and load test of each network component becomes essential. In the video, VIAVI’s Owen O’Donnell explains what’s needed to test these network functions and who will perform the tests. To that end, the company has expanded its TeraVM 5G network test suite (Figure 3) to support load testing of the CU according to O-RAN specifications.

Figure 3. TeraVM from VIAVI Solutions tests 5G Open RAN network functions.

The test suite lets you simulate traffic to and from RUs, DUs, and CUs so you can test each of these functions individually, under load (Figure 4).

Figure 4. TeraVM emulates network function, letting you test a centralized unit, part of an Open Ran 5G network. Image: VIAVI Solutions.

In addition to discussing the network test suite (at the end of the video), O’Donnell clarifies the Open RAN network functions and how they interoperate with each other. He brings us up to date on the state of Open RAN.