LoRaWAN A類效能分析

Abstract

長距離廣域網路(Long Range Wide Area Network，LoRaWAN)是新興的低功耗廣域網路(Low Power Wide Area Networks，LPWAN)技術其中之一。其主要目標是實現物聯網(Internet of Things，IoT)。由於它操作在工業、科學、和醫學(Industrial Scientific Medical Band，ISM)頻段上，因此對於封包傳送有嚴格的占空比規定。此外，Pure ALOHA是用於LoRaWAN A類設備之通道存取。之前的研究不是沒有考慮占空比問題，就是在分析中忽略封包若遭遇碰撞需要重新傳送的問題。因此，在本研究中，我們分析了LoRaWAN A類設備在網路中封包傳輸的延遲。在我們的分析中，將同時考慮了由於碰撞引起的封包重傳以及占空比之規定，並提出所對應的M / G / 1排隊模型，以計算封包延遲的平均值與延遲機率分布。我們以數值結果呈現分析的準確性。Long range wide area network (LoRaWAN) is one of emerging technologies for low power wide area networks (LPWANs). Its main objective is to realize Internet of things (IoTs). Since it operates on the ISM band, there is a strict rule of a duty cycle for packet transmissions. Besides, a pure ALOHA is used for a LoRaWAN class A device to access channels. Previous works either fail to address the issue of a duty cycle or neglect packet collisions in their analysis. In this thesis, we analyze the delay of a packet transmission in a LoRaWAN class A network. In our analysis, packet retransmissions due to collisions are considered and an M/G/1 queueing model taking into account the duty cycle is utilized to calculate not only the mean of packet delay but also its distribution. Numerical results are given to show the level of accuracy of our analysis.