Quality of service provisioning in optical burst switching network

Abstract

Future trend in communication system is to move to all-optical network. Optical Burst Switching (OBS) has been proposed as a new paradigm for switching and data transfer in all-optical network. One of the main challenges in deploying OBS network is to ensure QoS guarantee in minimising the contention and latency. The objective of this thesis is to develop OBS network that can ensure Quality-of- Service (QoS) by designing the ingress node that minimises delay and core node that minimises contention. In the ingress node, priority queueing (PQ) and burst assembly are deployed in differentiated service aware environment to decrease packet delay. Meanwhile, in the core node, integral of Fiber Delay Line, Wavelength Assignment and Wavelength Preemption (FDL-WA-WPremp) are proposed to minimise Burst Loss Probability (BLP) due to contention. In FDL, contending bursts are sent to travel over a longer fiber line and are, thus, delayed for a specific amount of time. In wavelength assignment, each traffic class has a pre-assigned wavelength for the transmission of bursts. Finally the wavelength preemption technique allows the higher priority traffic to preempt the lower priority traffic, when there is contention or, no available bandwidth for the transmission of the higher priority traffic. Three DiffServ class types that represent multimedia applications, including real time constant bit rate Expedited Forwarding (EF) traffic, real-time variable bit rate Assured Forwarding (AF) traffic and non-real time Best Effort (BE) traffic are investigated in the study. The proposed OBS network and traffic models have been developed using JAVA platform simulator and validated with mathematical analysis. The proposed OBS network performance parameters have been analysed based on BLP, packet end-to-end delay, bandwidth utilisation and throughput. The results show that the proposed OBS network with FDL_WA_WPremp, PQ and hybrid burst assembly; that is an event where burst is generated whenever the maximum assembling time is achieved or a minimum burst size is obtained, whichever occurs first, significantly improve the OBS network throughput by 10% compared to the technique without contention resolution. The proposed OBS network enhances the performance of EF, AF and BE traffic with BLP reduction of up to 70%, 42% and 34% respectively compared with OBS network with FDL only. In addition, the endto end delay performance of the EF and AF traffic deploying FDL_WA_WPremp with hybrid based assembly environment give 21.7% and 17.2% improvement compared to FDL_WA_WPremp with timer based. The overall findings prove that QoS provisioning can be guaranteed through FDL_WA_WPremp, PQ and hybrid burst assembly in OBS network. The proposed OBS network can therefore be deployed in the future all-optical network.