具低延遲及公平性之IEEE 802.15.4 動態排程機制

Abstract

IEEE 802.15.4 是一個針對低功率無線個人區域網路 (LR-WPAN)所設計的新的通訊協定。它針對低成本、低複雜 度、低能量消耗的固定或可攜裝置提供了一個低速的無線連 結。在此規格中的保證時槽 (GTS)功能中，提供了一個高優 先權的傳輸方式。此為一個保證各裝置有一段獨占的時間傳 輸資料的設計，可用來提供服務品質 (QoS)。一些應用例如 醫療儀器或者安全系統，由於這些資料極為重要且不能被遺 失或延遲，因此尤其需要這個服務的提供。我們提出了一個 新的保證時槽方法，是根據過去的保證時槽回應來提供更好 的服務品質，實驗結果證實我們的方法比規格上的不管在資 料延遲時間上，或者各裝置之間的公平性，都具有更好的效 能。

IEEE 802.15.4 is a new standard uniquely designed for low rate wireless personal area networks (LR-WPANs). It targets ultra-low complexity, cost, and power for low-datarate wireless connectivity among inexpensive fixed, portable, and moving devices. The standard allows GTS (Guaranteed Time Slots) for the optional use of high-priority transmissions, which provides the devices with high-priority data a specific duration of time to send their frames within a superframe. By using GTS, some applications such as medical alerts or security systems can benefit from the dedicated use of network bandwidth. Based on standard IEEE 802.15.4 GTS specification, we propose a new GTS scheduling scheme to support low-latency transmissions and to retain fairness among low and high prority transmissions. Performance evaluation shows that in terms of the delay time and fairness, our proposed scheme significantly outperforms the original scheme proposed in IEEE 802.15.4 standard.