Offset time compensation algorithm for OBS control channel

Abstract

Optical Burst Switching (OBS) has been proposed as an alternative switching technology for the next optical backbone network based on the current technology. OBS separates the control channel for the Burst Control Packet (BCP) and the data channel for data burst. BCP is transmitted ahead of data burst as the defined offset time in order to configure the switches along the route of burst. When the load increases in the control channel, the congestion occurs by heavily loaded traffic. The congestion makes the offset time variation. When the data burst enters the optical switching matrix before its BCP has been processed, the loss of the data burst happens. This problem is so called $\emph{"early arrival"}$. We focus on the control channel to resolve this matter and try to reduce the defects. This thesis proposes a new scheduling algorithm for the OBS control channel, Offset Time Compensation (OTC) algorithm. The core of this algorithm is the compensation of the difference between the defined offset time and the experienced offset time accumulated in the previous nodes. The more processing delay of BCP in the previous nodes, the prior service is provided in the current node. In OTC algorithm, we determine the offset time by existing static offset time scheme and proposed dynamic offset time scheme considering network condition. OTC can reduce the end-to-end delay variation of BCP and make the BCP arrive at the switching fabric of node at determined time. So it reduces the data burst loss rate due to early arrival. When we use the dynamic offset time scheme, data burst loss rate remarkably decreases and has the regular rate regardless of the offered load. In addition, we expend the OTC algorithm for service differentiation. The QoS-Aware (QA) OTC provides the controllable QoS differentiation in terms of data burst loss rate due to early arrival. The service objective of higher class is satisfied even in heavily loaded network. In comparison with traditional...