A Performance Study of CPRI over Ethernet

There has been a debate on whether or not Ethernet, a highly cost effective technology, could meet the stringent latency and jitter requirements imposed by CPRI. To facilitate the discussion, we conducted simulations to understand how Ethernet performs when carrying CPRI traffic, with and without newly proposed Ethernet enhancements, namely Ethernet with preemption and Ethernet with scheduled traffic. Our simulation results led to three observations: 1) Ethernet alone, with or without newly proposed frame preemption enhancement, could not meet the jitter requirement of 65ns ; 2) the newly proposed Ethernet enhancement of scheduled traffic could lower or even completely remove jitter in most cases, but not always. Further, scheduled traffic appears intrusive, thus requires further careful examination. 3) Ethernet with frame preemption, combined with some jitter reduction methods such as edge based buffering, could potentially meet jitter requirements of CPRI.