藍牙網狀網路多個中繼節點傳輸下提高長封包抵達率之研究

Evaluation of Long Packet Arrival Rate in Bluetooth Mesh Multiple Relay Transmission

黃文良(Wen-Liang Huang)

指導教授 ： 魯大德

健行科技大學/電資學院/資訊工程系碩士班/碩士(2020年)

摘要

隨著物聯網的進步，低功耗藍牙也隨之演進，藍牙網狀網路傳輸方式是以洪泛(Flooding)進行通訊相較傳統藍牙點對點配對傳輸方式，洪泛的傳輸方式的優點是不考慮路徑的將訊息發送到附近所有能傳送到的裝置，並且透過中繼節點來延伸藍牙傳輸距離，改善藍牙受限短距離的傳輸及單一節點故障導致無法傳輸等問題。
藍牙運作可透過封包切割與組合的方法來達到長封包的傳輸，提升藍牙封包傳送的能力，但這代表著在單次的傳輸行為中會發送數筆切割封包，在中繼的傳輸過程中將會產生更多的封包碰撞而導致封包丟失或是傳送遲滯。
在藍牙技術文件中當下層傳輸Protocol Data Unit (PDU)送出後，將會開始等待確認訊息封包，然而對於長封包切割，預設的等待時間是不夠的，所以會啟動分段傳輸計時器( segment transmission timer)來計算等待確認訊息封包的補償時間，
本研究將調整分段傳輸計時器進而提出會談補償時間的公式並應用於長封包的接收上，在實驗中將透過在不同的中繼次數下傳輸切割筆數不同的封包做為比較並統計長封包抵達率，在實驗數據結果顯示，透過本研究提出的會談補償公式針對不同中繼次數及長封包切割筆數不同的封包，中繼20次時傳送兩筆切割封包的抵達率提升了8%；中繼25次傳送三筆切割封包的抵達率提升了10%。

關鍵詞：藍牙低功耗、藍牙網狀網路、洪泛、長封包、封包抵達率

關鍵字

藍牙低功耗 ； 藍牙網狀網路 ； 洪泛 ； 長封包 ； 封包抵達率

並列摘要

Evaluation of Long Packet Arrival Rate in Bluetooth Mesh Multiple Relay Transmission

Student：Huang,Wen-Liang Advisors：Prof. Lu, Ta-Te

Department of Computer Science and Information Engineering
Chien Hsin University of Science and Technology

Abstract
Bluetooth mesh network transmission is using flooding to send packets to all nearby devices without considering the path communication. The flooding behavior can extend the Bluetooth transmission distance through relay nodes. The Bluetooth operation can achieve long packet transmission through packet cutting and recombination process. However, too many cutting packets transmitting in mesh network causes more packet collisions to occur. Therefore, long packets transmissions result in packets lost or delayed transmission.
In the Bluetooth technology, the lower layer transmission Protocol Data Unit (PDU) is sent, and the segment transmission timer will be started to wait for the confirmation message packet (segment transmission timer). The preset segment transmission timing (10 sec) is not enough for long packet transmission. In this study, we add the session compensation time to the segmented transmission timer to extend the transmission timing for long packet transmission.
In the experiment, we test the arrival rate of long packets by transmitting and cutting different packets under different relay times. According to the experimental data results, through the compensation of segment transmission timer method proposed in this research, for packets with different relay times and different numbers of cuts, the long packet arrival rate of sending two cut packets after 20 relays increased by 8%, and three cut packets after 25 relays increased by 10%.

Keywords: Bluetooth Low Energy, Bluetooth mesh network, Flooding, Long packet, Packet delivery ratio.

並列關鍵字

Bluetooth Low Energy ； Bluetooth mesh network ； Flooding ； Long packet ； Packet delivery ratio

參考文獻

參考文獻

[1] Mesh Network Specifications

https://www.bluetooth.com/specifications/mesh-specifications/

[2] Diego Hortelano, “From Sensor Networks to Internet of Things. Bluetooth Low Energy, a Standard for This Evolution”, Sensors 2017, 17(2),pp.372

[3] Mohammad Ghamari, “Detailed Examination of a Packet Collision Model for Bluetooth Low Energy Advertising Mode”, IEEE Access ( Volume: 6 ),pp. 46066 – 46073,August 2018