An Enhanced LoRa Wireless Mesh Networking System Supporting Immediate Transmission and Data Recovery

• Main Authors: LIANG, CHI-WEN, 梁綺文
• Other Authors: LEE, HUANG-CHEN
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/7r7hr4

碩士 === 國立中正大學 === 通訊工程研究所 === 106 === Monitoring of sensors distributed within large areas like a tall building or campus using 3G/4G networks or laying cables is costly and impractical for real-life applications. LoRa has been examined for long-range performance of wireless data transmission. Although LoRa shows good performance for long-range transmission in the countryside, its radio signals can be attenuated and interfered with by buildings, trees, and other radio signal sources. Wireless mesh networking is a solution for increasing communication range and packet delivery ratio without the need to install additional LoRa gateways. Based on the previous research which proposed a LoRa mesh networking, this study presents an enhanced LoRa mesh networking system for large-area monitoring of sensor applications supporting immediate transmission and data recovery for lost data. Emergency information by sending Non-Periodic Packet or NPP is supported to minimize the transmission delay. We deployed 20 LoRa nodes in the CCU campus and the proposed LoRa mesh networking system achieved an average 92.55% packet delivery ratio without data recovery mechanism and 99.99% with data recovery mechanism for periodical reporting data. For NPP, the averaged transmission delay achieved 2.58 seconds, 5.24 seconds and 8.04 seconds to deliver data to gateway, for one-hop, two-hops and three-hops scenarios respectively. This study further examines the received signal strength indicator (RSSI), the signal-to-noise ratio (SNR), the packet delivery ratio (PDR) to suggest alternative communication paths for better communication quality.