Radio over fiber broadband access networks architectures based on wavelength division multiplexing techniques

摘要

The recent remarkable growth in bandwidth of both wired optical and wireless accessnetworks supports a burst of new high bandwidth Internet applications such as: peer-topeerfile sharing, cloud storage, on-line gaming, video streaming, etc. Within thisscenario, the convergence of fixed and wireless access networks offers significantopportunities for network operators to satisfy user demands, and simultaneously reducethe cost of implementing and running separated wireless and wired networks.The integration of wired and wireless network can be accomplished within severalscenarios and at several levels. In this thesis we will focus on converged radio over fiberarchitectures, particularly on two application scenarios: converged optical 60 GHzwireless networks and wireless overlay backhauling over bidirectional colorlesswavelength division multiplexing passive optical networks (WDM-PONs).In the first application scenario, optical 60 GHz signal generation using externalmodulation of an optical carrier by means of lithium niobate (LiNbO3) Mach- Zehndermodulators (MZM) is considered. The performance of different optical modulationtechniques, robust against fiber dispersion is assessed and dispersion mitigation strategiesare identified. The study is extended to 60 GHz carriers digitally modulated with data andto systems employing subcarrier multiplexed (SCM) mm-wave channels.In the second application scenario, the performance of WDM-PONs employingreflective semiconductor optical amplifiers (RSOAs), transmitting an overlay orthogonalfrequency-division multiplexing (OFDM) wireless signal is assessed analytically andexperimentally, with the relevant system impairments being identified. It is demonstratedthat the intermodulation due to the beating of the baseband signal and wireless signal atthe receiver can seriously impair the wireless channel. Performance degradation of thewireless channel caused by the RSOA gain modulation owing to the downstreambaseband data is also assessed, and system design guidelines are provided.