Low-Latency and Energy-Efficient Frame Forwarding for vRAN Traffic

Researchers have been investigating ways to implement signal processing functionality in radio access network with software in general-purpose servers, which is called virtualized Radio Access Network (vRAN). In implementing software in vRAN servers, the performance and efficiency gap between dedicated hardware and software in a general-purpose server must be considered to save power while meeting strict latency requirements. In this paper, we design and implement a frame forwarding system for vRAN traffic to meet three requirements: (A) low latency, (B) energy efficiency, and (C) microsecond-scale responsiveness, which means that low-latency and energy-efficiency solutions are reactive and effective for a microsecond time slot in vRAN traffic. In the proposed system, a user-space thread receives frames with busy polling to achieve low latency and can sleep to reduce power consumption when no frame arrives. In addition, a polling thread in our system reduces the overhead of waking up to keep up with vRAN traffic even when it is woken up just after starting to sleep. Our experiments show the proposed system meets latency requirements at a level comparable with an existing busy polling system and can reduce the power consumption more than the existing busy polling system for most traffic.