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Title: WDM/SCM PON incorporating a novel CWDM uplink combiner
Author: Ha, J. Y.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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There is currently much interest in the use of passive optical networks (PONs) for applications such as fibre to the home, fibre to the curb and fibre to the building. Some of these schemes use time division multiple access (TDMA), this enabling many users to share an optical channel with a bandwidth of typically up to 10-Gb/s. However, high speed implementations involve high bandwidth components at the customers’ premises, and require ranging and scheduling on the uplink to avoid interference induced by multiple users simultaneously transmitting in the same optical channel. Leveraging recent advances in high speed RF technologies, subcarrier multiplexing (SCM) has been proposed as an alternative to time division multiplexing and code division multiplexing access technologies for PON applications. The proponents of SCM have cited advantages of flexible protocol transmission (where different channels can therefore be used for different services), easy upgradeability of present access networks and good fibre transmission performance. However, significant disadvantages have been acknowledged including in particular the generation of optical beat interference (OBI) between uplink sources. In this PhD dissertation, therefore, a bandwidth symmetric wavelength division multiplexed (WDM)/SCM-PON architecture incorporating a novel uplink combiner as a solution to remove OBI and provide large bandwidths (> 1-GB/s) to the home is proposed. Here, the virtually-passive uplink combiner allows the simple and linear combination of SCM channels from multiple local users and inexpensive user components. In the proposed scheme, binary phase shift keying (BPSK), quadrature phase shift keying (QPSK) and 16 quadrature amplitude (16QAM) modulations are used as base-band modulation schemes respectively. In order to enable a spectrally efficient (> 1-bit/s/Hz) multi optical user network, the QPSK and 16QAM SCM PON are studied in detail. A proof-of-principle experimental demonstration of a dual channel multi-user optical network using SCM-QPSK and 16 QAM modulation for high spectral efficiency is reported. In order to show the potential of feasibility of a 1-Gb/s BPSK, QPSK, and 16QAM SCM PON, computer simulation using a time domain model is performed, showing that each optical channel is respectively capable of supporting 10 x 1-Gb/s QPSK and 20 x 1-Gb/s 16QAM dedicated links, and so serving 400 users and 800 users simultaneously when using 40 dense WDM (DWDM) channels.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available