10-Gbps Software Implementation of Burst-Frame Synchronization Using Array-Access Bitshift and Dual-Stage Detection for Flexible Access Systems

摘要： The application of network function virtualization (NFV) and software defined networks (SDNs) to optical access systems is attracting attention in order to quickly and cost-effectively respond to various service requests. In order to maximize the merits of NFV/SDN, we aim at expanding the software-defined region of optical line terminals (OLTs) by focusing on physical-layer (PHY) functions for the flexible access system architecture (FASA). We have studied 10-Gbps software implementation of OLT PHY functions using general-purpose graphic processing units (GPUs) since they offer large computation resources. However, burst-frame synchronization, which is essential for upstream PHY, is the lowest function of OLT and is very difficult to process in software due to its high computational complexity. This paper proposes a bitshift implementation method using array access for our dual-stage detection algorithm. By accessing the data stream in units of m-bits, where m is determined by data type in the program, our proposal replaces all possible bitshift calculations with bitshift calculations ranging 0 to m (cid:0) 1 bit and array access to the calculated results. This reduces the computation complexity of burst-frame synchronization. Our novel proposal of array-access bitshift and dual-stage detection are implemented on a general-purpose server and its feasibility is evaluated for 10G-EPON application using an optical system. Evaluations show that the proposal realizes 10-Gbps real-time processing.