物聯網閒置模式中最小化資源消耗

Abstract

物聯網(Internet of Things, IoT)未來將成為各國資訊通訊產業重要的發展項目，而且未來的物品裝置不再侷限於固定位置，而是有移動的能力，因此物品裝置的位置管理以及呼叫物品裝置(Paging)方法是很重要的，而且它們與DRX週期之間是有互相影響且關係密切的。

許多相關的研究都是以使用者或物品裝置為出發點，雖然提出的方法對使用者或物品裝置可能有許多好處(如較省電)，但對於營運商來說，可能提出的方法需要硬體設備的升級，使得營運成本大幅的提升。因此，本篇論文是以營運商的為觀點，利用模擬物品裝置的移動速率和資料來臨率的方式找出最佳的DRX週期長度，使得Tracking Area Update (TAU)與呼叫物品裝置(Paging)所產生的資源消耗量總合可以達到最低，當物品裝置剛建立連線，與MME做註冊的時候，MME根據建立好的資料庫，就可以配給物品裝置最佳的DRX週期長度，使營運商的營運成本可以獲得控制。

Machine-to-Machine (M2M) communication, which is also known as Internet of Things (IoT) or Machine-Type communications as well, is expected to be a major trend in mobile communication such as LTE Advanced Networks. M2M communications enables devices to be controlled via internet. Currently, LTE networks are primarily designed and optimized for human-to-human (H2H) communications. Nevertheless, some designs such as paging for a device in Idle Mode are not suitable for M2M communications.

In this thesis, we first discover the paging issue for M2M communications. Furthermore, we investigate that there is trade-off between paging and Tracking Area Update (TAU). In addition, both paging and TAU are affected by the length of DRX cycle. The longer length of the DRX cycle is, the more paging cost will be. However, when the DRX cycle length becomes longer, the TAU cost will be smaller. Therefore, we discuss how DRX cycle length impacts the paging and TAU. Finally, we propose an easy and effective solution to minimize the signal resource consumption by adjusting the length of DRX cycle from the operators’ point of view. In performance evaluations, the optimal DRX cycle length we proposed can save more power and signal resources than the DRX cycle lengths defined in LTE specification (e.g., 32, 64, 128 or 256 millisecond).