Optical burst switched access networks with dynamic bandwidth allocation

Laburpena

The research on this thesis was conducted to develop new access optical networks architectures based on Optical Burst Switching (OBS). OBS is a promising technology which is focused actually on optical core networks, providing an all optical transmission without optical/electrical/optical conversion by using large optical data bursts. In this thesis OBS is introduced in access networks and, to handle the optical resources, a Medium Access Control (MAC) protocol is defined for access, providing also Quality of Service (QoS). The MAC uses a Dynamic Bandwidth Allocation (DBA) module to manage the available bandwidth. This DBA is extended to merge access networks and metro networks proposing a new all-optical access-metro network interface based on Optical Burst Switching (OBS). First of all, a Hybrid Wavelength Division Multiplexing/Time Division Multiplexing (WDM/TDM) access architecture with Reflective-Optical Network Units (R-ONUs) or ONUs with light source, Arrayed Waveguide Grating (AWG) at outside plant and a tunable laser/photodiode stack at the Optical Line Terminal (OLT) is presented as a solution for the Passive Optical Network (PON). By means of OBS and a DBA algorithm, which polls the ONUs, the available access bandwidth is managed. All the network intelligence and costly equipment is located at the OLT, where the DBA module is centrally implemented; and, with prioritizing data bursts queuing, the DBA provides besides QoS. To scale this access network, an Optical Cross-Connect (OXC) is afterward employed to attain a large number of ONUs by the same OLT. Next, the hybrid WDM/TDM structure is extended towards the Metropolitan Area Network (MAN) by introducing the concept of Optical Burst Switching Multiplexer (OBS-M). The network element OBS-M bridges the MAN and access networks by offering all-optical cross-connection, wavelength conversion and data signaling. The proposed innovative OBS-M node yields a full optical data network, interfacing access and metro with a geographically distributed access control. The resulting novel access-metro architectures are non-blocking and, with an improved signaling, provide scalability and very low latency. Finally, prioritizing data bursts queuing is introduced and analyzed in order to offer QoS for Differentiated Services (Diffser) in the DBA protocol. Several queuing disciplines are considered and evaluated: Strict Priority (SP), Modified Strict Priority (MSP) and Earliest Deadline First (EDF). Numerical analysis and simulations demonstrate the traffic performance of the proposed access schemes, DBA module, queuing disciplines and all-optical access-metro interface and architectures.