AbstractsComputer Science

Subcarrier multiplexing for next-generation optical access networks

by Jonathan Buset




Institution: McGill University
Department: Department of Electrical and Computer Engineering
Degree: PhD
Year: 2015
Keywords: Engineering - Electronics and Electrical
Record ID: 2063347
Full text PDF: http://digitool.library.mcgill.ca/thesisfile130366.pdf


Abstract

The advent of the Internet in the 1970s has led to an unprecedented level of global connectivity enabling communication across continents and oceans. Over the last ten years, its continuous commercialization and adoption by mainstream consumers has led to tremendous growth in global traffic which is stressing the capacity of all current network layers. This trend is expected to continue as the technology permeates deeper into our lives through affordable mobile devices and high bandwidth services such as on-demand streaming audio and video services, high-definition television and remote cloud storage. To meet these projected traffic demands, experts anticipate that fiber-to-the-home access networks based on single mode optical fibers will provide a future-proof upgrade pathway to replace the existing copper-based infrastructure. By employing mature technologies from transport networks, wavelength-division multiplexed passive optical networks (WDM PONs) are a leading candidate technology to achieve the projected 10 Gbit/s s service rates of next-generation access networks. However, their commercial viability hinges on the availability of low cost and wavelength-independent client side transceivers to meet the economic constraints set by the service providers. Bidirectional single feeder WDM PONs with reflective semiconductor optical amplifier (RSOA)-based uplink transmitters are a well researched solution, but in general their performance has been limited by two key factors: 1) bidirectional impairments due to scattering, reflections and inter-channel crosstalk; and 2) the RSOA's limited modulation bandwidth.This thesis proposes using a combination of radio frequency subcarrier multiplexing (SCM) and digital signal processing (DSP) to address these challenges. We develop three generations of SCM WDM PON architecture to increase the bandwidth efficiency and the symmetric transmission bit rates as compared to previous SCM solutions. We also implement DSP-based techniques to compensate for the bandwidth-limited RSOA-based transmitter. In each case we experimentally realize the system's operation and verify its bit error rate performance over a 20 km single feeder WDM PON with bidirectional transmission and wavelength reuse. To demonstrate the architecture's economic viability, we intentionally limit the electronic and optoelectronic hardware to 10 GHz of electrical bandwidth. The evolution of the three architectures leads to 2.5 Gbit/s, 5 Gbit/s and 10 Gbit/s symmetric line rates. We successfully demonstrate the operation of a 10 Gbit/s SCM WDM PON using pulse shaped higher-order quadrature amplitude modulation (QAM) channels with cost effective intensity modulation and direct detection optoelectronic transceivers. We further optimize the system parameters and characterize its symmetric operation for different QAM orders and channel spectral efficiencies. Ultimately, we successfully demonstrate that SCM WDM PONs are a viable and flexible solution for next-generation optical access networks operating at 10…