author        = "Rodes López, Guillermo Arturo and Otín Acín, Aránzazu",
      title         = "{Optical switching for dynamic distribution of
                       wireless-over-fiber signals in active optical networks}",
      year          = "2012",
      note          = "The ever growing demand of bandwidth by end users has put
                       a lot of pressure on access networks. Access networks,
                       mainly employing wireless technologies, are turning to
                       optics to support such large bandwidth requirements.
                       Depending on the requirements and features of the end
                       users, optical access networks have evolved in different
                       directions. In residential and urban environments, users
                       demand fix connections with high capacity at low price.
                       Passive optical networks (PON) have fulfilled these
                       requirements and are the operators chosen technology. In
                       business environments, in which quality assurance and
                       security are key issues, active optical networks (AON) have
                       found their niche, providing flexibility, adaptability and
                       high throughput while supporting tight management systems. 
                          Vendors are now turning their eye to new markets where
                       optics can be used effectively. Mobile backhaul is a target
                       market, since mobile traffic is growing exponentially –
                       new gadgets along with killing applications are fueling
                       such growth.     Baseband technologies can support mobile
                       backhaul effectively at current rates. However, due to the
                       location of new license-free available frequency bands and
                       the development of radio-over-fiber (RoF) technologies –
                       allowing generation, distribution and reception of micro-
                       and millimeter wave band signals optically, migration
                       towards wireless-over-fiber scenarios are likely.
                       Furthermore, concerns on security and high mobility seem to
                       indicate active solutions may be in favor of system
                       designers, provided that cost and energy consumption are
                       maintained within reasonable limits.     In this thesis, an
                       optical access network based on radio-over-fiber
                       technologies was designed. An active optical switch based
                       on active components (semiconductors optical amplifiers
                       (SOAs)) was used as main building block; the rest of the
                       network was designed according to the channel distribution
                       over the optical spectra required by the optical switch. An
                       experimental validation was conducted. The experiment
                       consisted in the implementation of a four channel system
                       operating on a worldwide interoperability for microwave
                       access (WiMax) frequency band, and employing an orthogonal
                       frequency-division multiplexing (OFDM) modulation at 625
                       Mbit/s per channel, transmission of the data over 20 km of
                       optical fiber, and active switching in a one-by-sixteen
                       active optical switch. The results show a negligible power
                       penalty on each channel, for both the best and the worst
                       case in terms of inter-channel crosstalk. The system meets
                       the requirements for an AON for wireless-over-fiber for
                       optical access networks (OAN).",