Real-Time Implementation of Coherent Receiver DSP Adopting Stream Split Assignment on GPU for Flexible Optical Access Systems

Abstract

We aim to maximize the flexibility of access networks by combining two trends: digital signal processing (DSP)-based physical (PHY) layer technologies and network function virtualization (NFV). We implement an advanced DSP-PHY on a general-purpose server. However, given that the server must handle high data transfer rate, the transfer time is a significant issue for softwarizing DSP-PHY. This article proposes a pipeline architecture that adopts split assignment of the transfer stream; it can execute data transfer and DSP-PHY calculation in parallel which significantly reduces the processing time. We implement on a graphic processing unit (GPU) a 5-Gbit/s coherent receiver DSP handling the output of a 40-Gbit/s analog-to-digital converter. As evaluated in an optical system, our proposal significantly relaxes the processing time requirement for DSP algorithm calculations; the processing time margin is 11.2 times greater than that of previous work. An additional digital filter is also successfully implemented in real time; it offers an optical power budget of 47.2-dB, a gain of 2-dB.