Network energy saving (NES)

Energy efficiency for O-RAN radio units

Open RAN (O-RAN) is a transformative approach to telecommunications networks that advocates for:

• Disaggregation of hardware and software components
• Adoption of open interfaces
• Use of virtualization and cloud-native architectures.

O-RAN breaks down traditional proprietary silos and promotes interoperability between equipment from different vendors. This enables greater innovation, flexibility and efficiency in deploying and managing network services.

The technological gaps between traditional RAN and O-RAN are closing. Some O-RAN elements, such as non-complex macro radio units (RU) and cloud platforms, are ready for large-scale deployments.

5G data transmission is far more efficient than that of 4G, but energy consumption is expected to increase dramatically as cellular networks start supporting higher data rates. O-RAN radio units (O-RU) account for 60-80% of a 5G mobile network’s total energy consumption. As such, O-RU energy efficiency is a high priority for network operators. The overall objective is for O-RAN networks to be highly energy efficient without sacrificing O-RAN concepts such as cloudification and disaggregation.

Your network energy saving challenges

Each new generation of cellular technology is more efficient than the last. Since 2G, energy efficiency has improved considerably - thanks to new modulation techniques that improve the quality of the transmitted signal while using less energy per bit. 4G and 5G are at least five times more energy efficient than 3G, and 5G massive multiple input multiple output (M-MIMO) is at least three times more energy efficient than 4G M-MIMO. Without mitigation efforts, however, energy consumption is still expected to skyrocket because cellular networks are getting denser to support the increasingly higher data rates demanded by users.

Network densification means the deployment of many small base stations (or gNB in 5G) to increase network capacity by efficiently reusing frequencies. M MIMO takes advantage of large antenna arrays to create narrow spatial beams and simultaneously serve multiple users with the same time-frequency resources. Higher user throughput equates increased power consumption:

• New base stations and gNBs contribute to power consumption.
• Base stations can be equipped with large antenna arrays, and each of these antenna elements requires power-consuming hardware.

From a test and measurement perspective, the main challenges are:

• Monitoring voltage, current and power simultaneously with RF quality (performance) under different traffic load conditions
• Dynamic real-time monitoring
• Isolating network sub elements down to the chipset level
• Characterizing virtualized RAN (vRAN)

High-performance solutions for network energy saving

A power supply is the most economical solution for measuring RU and O RU power consumption. It also provides high measurement resolution and accuracy over longer time frames.

The R&S®NGP power supply series from Rohde & Schwarz provides a stable output to the device under test (DUT). The R&S®NGP accurately measures the overall power consumption with time resolutions of 8 ms.

Another option is to use an oscilloscope with current and voltage probes. For this, we offer:

• R&S®RTO6 oscilloscope: the best tool for correlating power consumption dynamics to changes in the transmitted RF signal
• MXO4 oscilloscope: ideal for monitoring dynamic power measurements even at fast load changes

Both instruments pair perfectly with the R&S®RT ZC31 current probe and R&S®RT ZHD07 high voltage differential probe. Depending on your application, you may also want to consider the R&S®RT ZVC high dynamic power probe, which is ideal for debugging the power consumption of individual O RU components.

We have also partnered with VIAVI Solutions to develop a fully automated test solution to verify O-RU energy efficiency. This setup includes the R&S®RTO6 oscilloscope and an R&S®NGP power supply with all necessary probes. The entire setup is controlled and turnkey-automated by VIAVI’s O-RU Test Manager Application (O-RU TMA), which executes the energy efficiency test scripts defined by the O-RAN ALLIANCE Fronthaul Working Group Conformance test specification (O-RAN.WG4.CONF.), test cases defined by ETSI (ES 202 706-1) or user specific test scripts.