Long-reach optical access networks: A survey of research challenges, demonstrations, and bandwidth assignment mechanisms

TLDR

Long‑reach optical access promises broadband for many customers while lowering capital and operational costs for operators. The paper surveys the evolution of access networks and identifies technology and business drivers for high‑bandwidth, low‑cost solutions. It reviews physical‑layer component requirements, topological protection schemes, global demonstrations, and evaluates dynamic bandwidth‑allocation algorithms to counteract increased control‑plane latency in extended‑reach networks.

Abstract

Long-Reach optical access is a promising proposal for future access networks. This technology can enable broadband access for a large number of customers in the access/metro area, while decreasing capital and operational expenditures for the network operator. First, the paper reviews the evolutionary path of access networks and shows the drivers from technology and business perspectives for high bandwidth and low cost. A variety of research challenges in this field is reviewed, from optical components in the physical layer to the control and management issues in the upper layers. We discuss the requisites for optical sources, optical amplifiers, and optical receivers when used in networks with high transmission rate (10 Gbps) and large power attenuation (due to large split, transmission over 100 km and beyond, and propagation), and the key topological structures that allow to guarantee physical protection (tree-and-branch, ring-and-spur). Then, some relevant demonstrations of Long-Reach Optical Access Networks developed worldwide by different research institutes are presented. Finally, Dynamic Bandwidth Allocation (DBA) algorithms that allow to mitigate the effect of the increased control-plane delay in an extended-reach network are investigated.