Electrical and Electronic Engineering - Theses

Permanent URI for this collection

Search Results

Now showing 1 - 1 of 1
  • Item
    Thumbnail Image
    Wired and wireless services over next generation WDM/TDM PON systems
    Feng, Hao ( 2016)
    Passive optical networks (PON) have been the most popular networking approach for fibre-to-the-home network deployments. The incorporation of wavelength division multiplexing (WDM) along with time division multiplexing (TDM), delivered over a PON with longer feeder network, has been studied as a promising solution. This is widely known as the Long Reach WDM/TDM PON and is considered as a suitable option for a cost effective access network offering higher bandwidth, potentially to a larger customer base compared to PON. Future access networks like this will be expected to support the increasing level of fixed mobile convergence in wireless communications by offering cost-effective backhaul for such access networks. Future access networks will also need to offer better support for peer-to-peer (P2P) networking between customers. Increasingly, these network alternatives need to offer improved energy efficiency to help lower the carbon footprint of future access networks. As future networks will support the increasing mix of fixed and mobile wireless access, network needs to consider better mechanisms for the management of medium access control (MAC) layer functions to deal with the complexity of delivering wired and wireless services over a WDM/TDM PON architecture. This thesis explores long-reach WDM/TDM PON networks with a view to answering the following key questions: (a) how to support wireless networks through MAC layer design, (b) how to provide P2P networking interfaces, (c) how to support energy efficient operation, and (d) how to offer low latency in such networks. To understand the performance of optically networked wireless base stations, the MAC layer performance of wireless networks was investigated using radio-over-fibre (RoF) and picocell based architectures. Through mathematic analysis and simulations, it is shown that picocell solutions offer better performance compared to RoF solutions. The performance effect of contention-based bandwidth request mechanisms in mobile networks (using WiMAX as an example) is studied. A rigorous analysis of MAC layer performance is formulated using an accurate Markov chain mode, including new parameters for maximum bandwidth request retries and three waiting states during this procedure. Traditional P2P overlay networks, which are built on top of the network hierarchy, lead to long transmission distance for P2P traffic, crossing core networks and several Internet Services Providers systems, even though the peer node is located very close or even in the same passive optical network. In this case, to improve the performance of P2P traffic, a new P2P network architecture employing channel combine/splitting module is proposed to implement a low latency, flexible and scalable P2P overlay network over long-reach WDM/TDM PON systems. P2P traffic is localized at a remote node, to avoid long roundtrip delays due to long-reach system. Through the experiment and simulation, it is shown the P2P overlay network has negligible physical performance degradation and P2P data transmission delay is reduced. Furthermore, the overlay network shows good flexibility in constructing optical virtual private networking. To enable energy-saving design of the optical line terminal (OLT) by activating the ‘sleeping mode’, a tunable grating-based monitoring technique in RSOA-based WDM PON systems is proposed to wake up the sleeping OLT when the subscriber is active and connected to the network. The experimental evaluation shows good feasibility, and the tunable grating-based technique shows a 10dB distance gain compared to the amplified spontaneous emission (ASE)-based technique. Moreover, to support cost-effective and energy efficient network deployment and operation, a remote channel combine/split (CCS) module for long-reach WDM/TDM PON systems was proposed to achieve a higher energy saving by adopting subscriber take-up rate and traffic adaptive power management. Through experimental evaluation and simulation, it is shown the proposed CCS module only causes 0.15dB negligible physical link performance degradation. Also, simulation shows up to 60% investment saving at the initial network deployment stage, and over 20% energy saving compared to traditional full operating systems. To achieve less registration latency during network transition, a contention-free low-latency handover scheme is proposed to implement the smooth transition of optical network units between different PON groups. Through the simulation, it is shown the proposed handover scheme produces only 3.2-ms handover delay, which is far below the stringent delay requirement for voice services and shows a negligible degradation on QoS performance and ONU’s buffer size. Moreover, to support an energy-efficient networks operation, a globalized OLT cluster structure with energy-aware dynamic wavelength and bandwidth allocation (EA-DWBA) algorithm was proposed to save the power consumption of the OLT cluster itself and the edge router in the central office. The simulation shows up to 40% power consumption saving of the OLT at the lower traffic load, and up to 30% power consumption saving on the edge router based on realistic proportional edge router technology.