Integrated Wireless-pon access Network Architectures Milos Milosavljevic

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Integrated Wireless-PON Access Network 
Architectures 
 
 
Milos Milosavljevic 
 
 
 
A thesis submitted in partial fulfilment 
of the requirements of the University of Hertfordshire 
for the degree of Doctor of Philosophy 
 
The programme of research was carried out in the Science and 
Technology Research Institute (STRI), University of Hertfordshire, 
United Kingdom. 
 
2010

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Abstract
Integrated Wireless-PON Access Network Architectures
 
i 
Abstract 
Next generation access networks should be able to cultivate the ongoing evolution in services 
and applications. Advancements on that front are expected to exhibit the transformation of high 
definition television (HDTV) and 2D services into ultra-HDTV and individual interactive 3D 
services. Currently deployed passive optical networks (PONs) have been certified to be able to 
deliver high quality video and internet services while in parallel broadband wireless standards 
are increasing their spectral efficiency and subscriber utilisation. Exploiting the benefits of both 
by providing an integrated infrastructure benefiting from the wireless mobility and ease of 
scalability and escalating bandwidth of next generation PONs are expected to offer service 
providers the business models justifying the evolved services. In this direction, this thesis deals 
with the means of transparent routing of standard worldwide interoperability for microwave 
access (WiMAX) signal formats over legacy PONs to and from wireless end users based on 
radio over fibre (RoF). The concept of frequency division multiplexing (FDM) with RoF is used 
for efficient addressing of individual base stations, bandwidth on-demand provisioning across a 
cell/sector, simple remote radio heads and no interference with the baseband PON spectrum. 
Network performance evaluation, initially through simulation, has displayed, in the presence of 
optical non-linearites and multi-path wireless channels, standard error vector magnitudes 
(EVMs) at remote radio receivers and bit error rates (BERs) of 1E-4 for typical WiMAX rates 
bidirectionally. To provide enhanced scalability and dynamicity, a newly applied scheme based 
on extended wavelength band overlay over the splitter, wireless-enabled PONs has been 
progressively investigated. This allows for the routing of multiple FDM windows to different 
wavelengths resulting in significantly reduced optical and electrical component costs and no 
dispersion compensation over the fibre. This has been implemented through the application of a 
dense array wave guide grating (AWG) and tuneable filter in the optical line terminal (OLT) 
and optical network unit/base stations (ONU/BSs) respectively. Although with the use of a 
splitter the distribution point of the optical network remains largely the same, vertical cavity 
surface emitting laser (VCSEL) arrays provide colourless upstream transmission. In addition, an 
overlapping cell concept is developed and adopted for increased wireless spectral efficiency and 
resilience. Finally, an experimental test-bed using commercially available WiMAX transceivers 
was produced, which enabled repetition of the simulation outcomes and therefore confirmed the 
overall network performance. 

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