RRH

RRH stands for Remote Radio Head, a radio frequency subsystem used in modern cellular networks. It is typically deployed at or near the cell site’s antenna and is a key element of distributed radio access networks. The RRH is connected to a baseband unit (BBU) or centralized unit (CU) through a high-bandwidth fronthaul link, using interfaces such as CPRI, OBSAI, or the newer eCPRI.

Functionally, the RRH handles RF signal generation, reception, and conditioning. It includes RF transceivers, front-end components like filters and duplexers, and power amplification and low-noise amplification stages. In many architectures, analog-to-digital and digital-to-analog conversion occurs within the RRH, while most baseband processing, including scheduling and digital signal processing, is performed in the BBU or CU/DU. The RRH thus serves as the RF front end of the radio access network, converting between downlink RF signals and digitally transmitted IQ samples.

Deployment in LTE and 5G networks enables flexible, scalable coverage and capacity. RRHs can support multiple frequency bands and antenna configurations, including MIMO, and are often mounted on towers, rooftops, or small cells. They contribute to reduced feeder losses, easier site maintenance, and the possibility of centralized management.

Challenges include the high requirements on fronthaul bandwidth and latency, precise synchronization, and environmental reliability at remote sites. Power and cooling management, as well as security and provisioning of numerous remote units, are also considerations in large networks. See also: C-RAN, fronthaul, eCPRI, RRU.