Quality Of Service In The Optical Burst Switching Network

As a promising approach to build the next generation optical Internet, optical burst switching (OBS) networks have been receiving more and more attention. In this paper, we mainly discuss the resource reservation scheme and quality of service (QoS) in the OBS network.In chapter 1, popular all-optical switching technologies, such as optical circuit switching (OCS), optical packet switching (OPS) and optical burst switching (OBS) are discussed, and their advantages and disadvantages are analyzed. In chapter 2, firstly some traditional resource reservation schemes of OBS network are introduced. Then we have mainly discussed the guarantee of the QoS for Just-enough-time resource reservation scheme. Through the theoretical model and simulation, we find that Just-enough-time could allow service differentiation efficiently. In chapter 3, we firstly describe the basic architecture of the OBS network based on dynamic wavelength routing (DWR), under which the guarantee of the QoS in the DWR-OBS network is discussed. Then we focus on two aspects: the transmission latency of the data packets and the blocking probability, which lead to a quantitative description of the transmission latency and the size of the edge node buffer. We also propose a method called Dynamic preferred wavelength sets (D-PWS) to reserve the wavelength resource. Based on the D-PWS, an entire-candidate path sets (E-CPS) wavelength assignment algorithm is given. Finally, we make a simulation on the DWR-OBS network by using the D-PWS method and take a comparison with the static preferred wavelength sets (S-PWS). The simulation results show that our approach excels traditional ones in QoS guaranteeIn chapter 4, we propose a new QoS scheme, termed Leaky-Bucket Traffic Control Model (L-BTCM), to provide differentiated service for the Optical Burst Switching (OBS) network. Unlike existing approaches, which may bring extra transmission delay or suffer from low resource utilization, the L-BTCM could balance the weightiness of the blocking probability and the transmission delay very well and achieves high resource utilization. At the same time the L-BTCM could adjust the service contract of every link timely to accommodate dynamic traffic variations. To evaluate the performance, we conduct some simulations and compare the L-BTCM with the conventional QoS schemes used in the OBS network. Calculation results indicates that the L-BTCM could provide better support for QoS and achieve higher utilization of the network resource.In chapter 5, a dynamic resource allocation scheme based on transmission impairments, termed wavelength node scheme (WNS), is proposed. Through transforming the conventional topology of the network, the WNS can always find a lightpath with the minimum transmission impairments. In order to make the WNS more efficient, a BER calculation model is constituted in which all of the main transmission impairment factors are considered, such as crosstalk, polarization mode dispersion (PMD), amplified spontaneous emission(ASE) of optical amplifiers, and four wave mixing(FWM). Through the simulation, we conclude that the WNS can make the network performance more efficient than conventional resource allocation schemes.