Antennas & Radio Units R&D
The Baseband Unit (BBU) functionality in 4G/LTE is split in 5G into a Centralised Unit (CU) and Distributed Unit (DU). The DU is generally located close to a RU (in 5G a RRU/RRH is referred to simply as RU), either on site or in an Edge Cloud/data centre. The CU however can be either located in the Regional Cloud/data centre (e.g. C-RAN), or with the DU (e.g. D-RAN).
The most appropriate location of the CU and DU is determined by many factors including – but not limited to: the expected latency requirements of applications/services, site lease costs, availability of backup battery/generator capacity, high capacity fronthaul availability, the location of data centres and bandwidth costs.
For 5G, each CU can connect to one or more DUs, each of which in turn can connect to one or more RUs. In Carrier Aggregation (CA) scenarios, a single DU connects to all the RUs of the carriers being aggregated. In Dual Connectivity (DC) scenarios, two DUs are present, and can be connected to either the same or different CUs.
For distributed units and centralised units therefore, the key issues for Open RAN are:
FRANC (Future RAN Competition) run by DCMS, has allocated up to £30 million of R&D funding to projects that support the goals of the government's 5G Supply Chain Diversification Strategy. The competition aims to help to incentivise industry to create new products and services to unlock the full potential of Open RAN. Several of these projects are exploring distributed units and centralised units:
FRANC academic partners in this area include:
Building a more competitive, innovative, and diverse supply chain for the global telecoms market.