広域同期型光スイッチ網における高精度時刻同期手法の検討

摘要

広域同期型光スイッチ網では，光パースト生成タイミングと光スイッチの切り替えタイミングを高精度で時刻同期された制御系により周期的に制御する.したがって，時刻同期誤差や温度変動による遅延推定誤差吸収のためにガードタイムが必要となる.これまでの研究では，最長パスおよび最大の温度変動を考慮した最悪値設計が用いられていた.本稿では，経路長に応じて設計を行う経路別設計，およびIEEE1588時刻同期プロトコルにより伝搬遅延時間を実際に測定する遅延測定設計について検討し，最悪値設計と比較した各設計の効果をシミュレーションにより評価する.%In a Grobally-Synchronized Optical Switching Network, the optical burst timing and the optical switching timing are controlled by the precisely synchronized control system. However, guard time is needed to compensate time synchronization error and propagation delay variation caused by temperature change. In previous work, the worst case design of guard time, which assumes the largest temperature change in the history and the longest path length in the network, is employed. In this paper, we introduce two alternate design of guard time; a path-by-path design and delay measurement design. The former method calculates guard time length by the transmission length of each path. The latter method measures the propagation delay of each path by using IEEE 1588 precision time protocol and only measurement error is reflected in guard time length design. Furthermore, we compared these proposed design with the worst case design and verified those efficiency through simulations.