Optical pulse width modulation based TDM-PON monitoring with asymmetric loop in ONUs

Abstract

We propose a time division multiplexing passive optical network (TDM-PON) monitoring scheme based on the optical pulse width modulation (OPWM) by using a simple asymmetric loop (AL) located near the optical network unit (ONU). Various pulse widths can be easily obtained by configuring the appropriate length of the patchcord used to generate the path difference between two branches of a 1 × 2 splitter. Different wavelengths can be assigned to the same pulse width, which can further increase the network size. The optimized parameters of the AL are investigated and analysis models are established. The calculation results show that the proposed scheme has smaller correlation distance (CD) and lower multiple-customers interference probability (MCIP) than the periodic coding (PC) scheme. A simplified PON system with 8 ONUs is set up to experimentally demonstrate the feasibility of the proposed scheme. The network recognition processing used to identify the reflected monitoring signals in the proposed scheme is simple, especially compared with the reduced complexity maximum likelihood sequence estimation (RC-MLSE) used in the typical PC scheme.

A PON Monitoring Scheme for Online Fault Detection and Localization

“…It is known that optical-time-domain reflectometry (OTDR) techniques are widely used in point-to-point (P2P) networks. However, it has major limitations in tree topology or point-tomultipoint (P2MP) network like PONs [15], [16]. In P2MP networks the OTDR trace at the central office (CO) is aggregation of the backscattered and reflected powers from all the network branches [17].…”

“…It is difficult for the CO network manager to distinguish the events in one branch from those in others. Due to the failure of OTDR in P2MP networks, many PON monitoring schemes have been widely presented to improve the service reliability [15]- [19]. Mainstream PON monitoring schemes usually focus on centralized monitoring, and most of them can take into account factors such as cost, difficulty of implementation, and effectiveness.…”

Interference Solutions for the Deployed 2D Optical Coding PON Link Health Detection System With Massive Densely Distributed Customers

“…However, the superposition of the reflection signals will be serious in high-density PONs since only one wavelength is used for monitoring. In [19], an optical pulse width modulation based TDM-PON monitoring scheme utilize an asymmetric loop located in front of the optical network unit (ONU) to generate pulse codes. However, the encoder is located at the customer side in this scheme and a variety of encoders need to be prepared separately, which increase the deployment difficulty and system cost.…”