Optical and Wireless Networks Research

Integrated Wireless-PONs Access Architectures

The research questions and solutions associated with the application  of radio-over-fibre (RoF) to transparently integrate currently deployed  passive optical networks (PONs) and LTE/WiMAX to demonstrate extended  features of these networks, beyond current deployments, have been the  study of our group.

The LTE/WiMAX potential to transparently inter-operate with NG-PONs  offers sufficient backhaul capacity for high-end bandwidth intensive  rich media wireless services with efficient network administration and  management, delivering high-capacity LTE/WiMAX broadband with low cost  per connection.

Also, RoF transmission over multi-wavelength splitter-PON topology  was investigated in order to enhance signal to noise ratio (SNR) at  remote radio heads (RRH) and meet stringent requirements for downlink  adjacent channel leakage ratio (ACLR).

Data Link Layer Modelling for Optical and Wireless Convergence

Our group also concentrates on the development of architectures demonstrating the consolidation of NG-PON2 and LTE-A for the public access network. Individual tasks with particular relevance to the development of LTE-A features such as coordinated multi-point (CoMP) transmission in order to enable interference cancellation in up-link are studied. An evaluation of such an architecture based on system level simulations is performed to establish the network propagation characteristics.

Developed system level model simulation platform takes into consideration practical LTE scenarios to appropriately model interference from high number of wireless cells. This is essential in modelling cell-edge effect in order to established performance gained by CoMP

Convergence of PON and wireless access networks

Work in this area concentrates on the system level design of the converged network, spanning in reach into the aggregation area, exploiting the full centralisation of processing functionalities at the network centre.

It is believed that the results of this programme will support further development of novel NG-PON topologies that will enable an efficient signal routing between base stations to enhance performance of advance wireless features investigated in previous research program.

Coarse WDM Wavelength-routed Passive Optical Networks

To allow even higher bandwidth, greater coverage and penetration than the currently deployed standards, various potential research paths for building next-generation PONs have been studied by our group, with a common aim to support new bandwidth-hungry online services and further reduce the cost for delivering the existing ones.

Towards this direction the application of coarse wavelength division multiplexing (CWDM) to route communications to and from reflective optical network units (ONUs) incorporated in time and wavelength division multiplexed PONs has been investigated. The concept of coarse and dense WDM grid integration and its adaptation in access networks to map selective closely-spaced wavelengths into coarse passband windows of Gaussian and flat-top arrayed waveguide gratings (AWGs), exhibiting coarse-fine grooming, is developed. This is followed by the identification of a new network architecture combining multiple PONs, using a coarse AWG to form a next-generation access network.