在 LoRaWAN網路上提升應用層的資料傳輸成功率

Abstract

在現在LoRaWAN的系統架構下，雖然它有長距離、低功耗的優勢，但卻是用低流量、長間隔傳輸週期的代價換取來的。在封包傳輸間隔周期長這樣的情況下，單位時間內所能傳的封包數量很少，在這狀況下損失任何一個封包都會造成很大的損失。在我們為期一年的實際測量下，發現就算在LoRaWAN宣稱的有效距離內，仍舊還是會有相當高的遺失率，這對於使用LoRaWAN來收集重要感測資料的物聯網應用會造成很嚴重的問題。

本篇論文提出解決這個問題的兩個設計，我們修改LoRaWAN的後端網路設計，達成自我重送與透過其它節點轉送的目的。我們的實驗結果顯示，我們的設計可以在不增加太多網路頻寬成本的情況下，有效提升應用層資料傳輸的成功率。

The LoRaWAN network has the advantages of long-range transmission and low power consumption. However, it has the disadvantages of low throughput and long transmission duty cycle time interval. Caused by the long transmission duty cycle time interval, any packet lost cannot be recovered soon on the LoRaWAN network. In our experiments lasting for one year, we find that even though we place the devices in the effective range of LoRaWAN, the packet loss rates are still too high to be acceptable. It is a serious problem for IoT applications.

This thesis proposes two designs to solve the packet loss problem. We modify the IoT application to let the node retransmit lost data for itself and help transfer its neighboring node's data. Our approach can efficiently enhance the reliability of LoRaWAN with a low bandwidth overhead.