Calvin C. K. Chan

Novel network architectures for survivable WDM passive optical networks

In this paper, several considerations in designing survivable WDM-PONs will be discussed. Several feasible protection schemes and architectures for automatic traffic restoration upon any fiber cut in WDM-PONs will be reviewed.

Rayleigh noise mitigated 70-km-reach bi-directional WDM-PON with 10-Gb/s directly modulated Manchester-duobinary as downstream signal

A 70-km-reach bi-directional WDM-PON with 10-Gb/s downstream Manchester-duobinary signal and 1.25-Gb/s upstream re-modulated NRZ-OOK signals is demonstrated, with effective mitigation of Rayleigh backscattered noise.

Chapter 6 – Protection Architectures for Passive Optical Networks

Publisher Summary This chapter discusses the protection architectures for passive optical networks (PON). In a WDM-PON, each optical network unit (ONU) is served by a dedicated set of wavelength channels to communicate with the OLT and enjoys a dedicated bandwidth, which is also scalable according to its own need. However, with conventional PON architectures, which have limited protection feature, any component or fiber failure would lead to huge loss of data or even business. Thus, protection measures to enhance the network survivability are highly desirable to provide resilience against failures. This chapter also discusses several survivable network architectures for both conventional PONs as well as WDM-PONs, in both tree and ring topologies. Most of the conventional PONs, such as A-PON, B-PON, EPON, and G-PON, adopt a tree topology to provide point-to-multipoint connections. In tree typology, an optical power splitter is employed to split the received optical signal at the remote node (RN) to all outgoing distribution fibers. In ring typology, duplicated protection fibers are employed to provide redundant paths, and line or path protection switching is incorporated at both the OLT and the access nodes. In most of these schemes, the critical optical components are the OSWs to enhance the protection switching. Hence, optical switching technologies with low-cost and fast-switching responses would be very crucial and of high practical importance to enable wide deployments of the survivable PONs.

A passive surveillance scheme for passive branched optical networks

In summary, we have proposed and experimentally demonstrated a practical fibre link in-service surveillance scheme using fibre Bragg gratings (FBGs) for fault identification in branched optically amplified networks without requiring any extra light source.

Survivable architectures and optical multicast overlay for WDM passive optical networks

WDM passive optical network is a promising approach to realize high-capacity and flexible data delivery for access network subscribers. Due to the data-centric nature of the access network traffic, high network availability and flexible data delivery are highly desirable. In this paper, various survivable architectures and optical multicast overlay schemes for WDM PONs will be reviewed. The schemes provide feasible and practical options to enhance the network functionalities of WDM-PONs.

Multiwavelength optical access networks: architectures and enabling technologies

In this paper, we will discuss the network architectures and the enabling technologies to realize a robust multi-wavelength optical access network. Various network topologies employing the dense WDM or coarse WDM technique; as well as several network enabling technologies such as data re-modulation technique, fiber link protection and traffic restoration, etc. will be described. Besides, some future trends and applications of multi-wavelength optical access networks will also be discussed.

Optical performance monitoring and network diagnosis in reconfigurable optical networks

We review some of the recent developments of optical performance monitoring (OPM) in various aspects: (i) the enhancement of monitoring resolution, (ii) multi-impairment monitoring, and (iii) OPM network optimization. In particular, some of the studies on the optimization of performance monitoring networks to achieve the optimal monitoring locations and number of monitoring probes are discussed.

Novel WDM passive optical network with bidirectional protection

Passive optical networks (PONs) have recently emerged to be a promising approach to enhance the penetration of fiber towards the subscriber side, thus further enables delivery of higher data-rate services to the subscribers. They feature easy network maintenance as there is no active component at the remote node (RN). However, in conventional PONs, both upstream and downstream bandwidths have to be time-shared among all optical network units (ONUs). By applying WDM technique to PONs, the total system capacity can be further enhanced. Each ONU enjoys a dedicated bandwidth and resolves the ranging problem as in PONs. In both conventional PON and WDM-PON, little work has been done to offer protection capability though fiber fault detection methods have been extensively studied. We propose a novel network architecture for WDM-PON which offers 1:1 protection capability. In case of any fiber cut between remote node and ONUs, the affected ONU can re-route the wavelength channels via the adjacent ONU and can still maintain normal bidirectional traffic.

Physical-layer network coding in optical networks

Physical-Layer Network Coding (PNC) is a promising technique to improve the network throughput of full-duplex transmission in a wireless two-way relay channel. Here, we explore the application of PNC in optical systems and networks. Two transmitted optical signal frames are simply added together to form an optical PNC-coded composite frame, which shares the same network channel/resource. At their destined node, the composite signal is directly-detected, before being decoded by subtracting one of the two transmitted signal frames, which is either already known or stored locally, from the received PNC-coded composite frame.

Chromatic Dispersion Monitoring of Optical OFDM Signals in Flexible Optical Networks

A chromatic dispersion monitoring scheme for flexible optical OFDM networks is presented. Coded label subcarriers are added to the signal spectrum and dispersion monitoring is performed via direct detection, followed by electronic correlation procedures.