Modern base stations (BS) utilize distributed architectures, wherein the BS functionalities are split between a radio unit (RU) and a distributed unit (DU), that are connected via a fronthaul link. Managing the overhead on this link within tolerable limits is challenging due to ever increasing uplink data traffic and limited fronthaul capacity. In the widely accepted O-RAN 7.2 split architecture, the RU performs combining and sends lower dimensional signals over the fronthaul, thereby reducing the overhead. This approach suffers from performance loss due to channel aging, since RU combining is based on older/aged CSI received from DU. An alternate, less explored approach for reducing overhead is to transmit low-resolution signals over the fronthaul, obtained via quantization of post-FFT samples at the RU. While quantization noise results in some degradation, this approach does not suffer from channel aging. To date, a realistic performance comparison between combining and quantization is not available in the literature. The present work fills this gap and explores the regimes where quantization is favorable in both performance and overhead compared with combining. Our results suggest that opportunistically switching from combining to quantization under favorable conditions achieves superior performance at reduced overhead.
Opportunistic Quantization for Fronthaul Overhead Reduction in Beyond 5G Distributed Base Stations
2024-06-24
636462 byte
Conference paper
Electronic Resource
English