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2 September 2019

NGMN tackles 5G antenna size with RF cluster connector spec

New open source technologies and conventional standards are still needed to push 5G deployments forward from the current ‘phony war’ of conventional architectures and 4G cores, to something genuinely disruptive. Some of these are high profile and radical, like new low latency and high density aspects of 3GPP Release 16, due early next year, or the emerging open specifications from the ORAN Alliance.

Others, potentially like ONAP (Open Network Automation Protocol), risk being outdated before they are widely deployed – in the ever-receding horizon of true 5G, the definitions change all the time. ONAP seemed like something radical when AT&T donated the underlying code to the Linux Foundation – now it looks like a monster, an attempt to create a modern OSS (operations support system) for a virtualized world, when a fully cloud-native 5G network should be completely automated and not require an OSS at all.

And then there are the unglamorous, low level but essential standards and specs. For instance, last week, the Next Generation Mobile Networks (NGMN) Alliance decided on the cluster connector it recommends for integrated 5G antennas.

The challenge in 5G is that operators need very integrated antennas with a large number of RF ports because of the diversity of 5G spectrum bands – together with support for both active and passive antennas, and Massive MIMO, within the same units, this is leading to complex and expensive products, and the risks of proprietary lock-in. One challenge is to keep antenna size down, which means limiting the number of RF connectors – cluster connectors address this issue by integrating several RF ports in one unit.

The NGMN Alliance recommends RF cluster connector type C (MQ4/5) as a uniform spec, particularly for 8T8R MIMO arrays in unpaired (TDD) spectrum. Unlike 3G and 4G, 5G is initially being deployed mainly in TDD spectrum, especially around the 3.5 GHz band. In a new white paper, Recommendation for RF Cluster Connector for use in 5G NR 8T8R TDD Deployment, the Alliance describes its selection process, and sets out the features that are required for the best RF cluster connector in these early 5G scenarios.

The NGMN’s cluster connector project involved MNOs from different countries plus equipment, antenna and connector suppliers. The project was chaired by Tomas Sedlacek, a site infrastructure expert at Deutsche Telekom.

He said: “This cluster connector industry recommendation, aligning equipment suppliers towards using a common type of connector, will help operators to simplify logistics and reduce operations and maintenance expenditures.”

Dr Peter Meissner, CEO of the NGMN, added in a statement: “This will accelerate time-to-market and decrease installation costs. The selection of a cluster connector marks a significant step in this mission, and we are committed to continuing to work with the industry as we move forward towards the new era of connectivity that 5G is set to bring.”