A.M. Hill

Linear crosstalk in wavelength-division-multiplexed optical-fiber transmission systems

Design rules are given for overcoming the effects of optical crosstalk between digital PCM channels, when introducing wavelength-division-multiplexed (WDM) operation into optical-fiber systems. Power penalties are derived for two-, three-, and four-channel symmetric systems in the presence of interchannel interference, using a simple model for the recovery of the eye opening at a digital regenerator. The model is also extended to give a generalized, deterministic solution for the power penalties in asymmetric multichannel WDM systems, and the limitations of the model are discussed.

An experimental broadband and telephony passive optical network

An experimental passive optical network that demonstrates the integrated delivery of telephony and broadband services to a variety of business and residential customers over a typical local loop is described. Telephony is provided over a 112-way split at 1300 nm, and broadband services (asynchronous transfer mode and single-channel video at 155 Mb/s, and 2.2 Gb/s 32-channel video) are provided over a 28-way split. Two approaches to the addition of broadband services are used: coarse-grained WDM (wavelength-division multiplexing) with 20-nm channel spacing in the 1300-nm window, and high-density WDM with 1-nm spacing in the 1500-nm window. Optical technology solutions are described for providing different levels of service to various customer types, including a single-mode wavelength multiplexer with 1-nm channel spacing, a hybrid integrated demultiplexer/receiver with 20-nm channel spacing, and a tunable optical filter with 0.6-nm FWHM (full-width at half-maximum) bandwidth.<<ETX>>

One-sided rearrangeable optical switching networks

New and existing one-sided rearrangeable switching networks are described, which minimize the number of optical switches required to interconnect N optical terminals. Technical problems are identified. The potential size of one-sided rearrangeable networks, employing single-mode optical fiber, and the corresponding performance requirements of optical switches, are established.

Multiwavelength technology for local loop applications

Some of the possible options for the exploitation of wavelength division multiplexing (WDM) techniques in the local loop are illustrated. It is noted that few-wavelength systems will probably be the first systems to be exploited, and early practical realizations are discussed. It is further suggested that the fuller exploitation of the optical spectrum available will be via much more extensive high-density WDM. Techniques are described showing that these opportunities could rapidly follow from few-wavelength systems.<<ETX>>

Analysis of the maximum balanced load in Long-Reach PONs

Maximum balanced load is the load above which mean packet delay and packet loss ratio increase rapidly, queues start to build up and packets start to drop. In this paper, we propose theoretical formulas to analyse the maximum balanced load in Long-Reach Passive Optical Networks (LR-PONs). This is done for two algorithms, the GIANT algorithm and a proposed BwUpdate algorithm. We compare the expressions obtained with simulation studies and find the simulation results match the theory well. We compare the two algorithms as a function of the Assured Bandwidth Restoration Time (ABRT) and find that the BwUpdate algorithm increases the maximum balanced load, for assured bandwidth restoration times longer than 3.75 milliseconds.

Multi-service SDN controlled reconfigurable long-reach optical access network

The convergence of multiple service demands and different user types on a single physical layer can be enabled by dynamically reconfigurable time-division multiplexing (TDM) dense wavelength division multiplexing (DWDM) long-reach passive optical networks (PONs). In this paper we demonstrate two TDM-DWDM PON designs, the first one for densely populated urban areas and the second one better suited for rural deployment. Heterogeneous services and modulation formats, i.e. residential 10G PON channels, business 100G dedicated channel and wireless fronthaul are demonstrated experimentally coexisting on long reach TDM-DWDM PON systems, with at least 100km reach, 1024 users and emulated system load of 40 channels. End-to-end software defined networking (SDN) management of the access and core network elements is also implemented and integrated with the PON physical layer in order to demonstrate two service use cases: a fast protection mechanism with end-to-end service restoration in the case of a primary link failure; and dynamic wavelength allocation (DWA) in response to an increased traffic demand.