D2D-LoRa Latency Analysis: An Indoor Application Perspective

LoRaWAN is one of the popular Internet of Things (IoT) wireless technologies due to its versatility, long transmission range, and low power communication capabilities. In LoRaWAN, the data from the source to the destination is routed through the gateways, increasing the communication latency. The higher latency being a barrier in real-time applications has prompted researchers to employ the physical (PHY) layer of the LoRaWAN protocol -commonly termed as LoRa, which utilizes the Device-to-Device (D2D) based communication techniques to minimize the communication latency. However, an extensive analysis of the D2D-LoRa is needed for optimizing and better designing the network, which is missing in the current literature. To address the void, this paper analyzes the latency performance of the D2D based LoRa by varying Spreading Factors (SF) and bandwidths and explores the trade-offs with experimental deployment in a 110 m long indoor environment. The evaluation shows that with SF 7 and bandwidth 500 kHz, the communication latency is minimum which is 33.67 ms at 0 m and 53 ms at 110 m for the data packet of 13 bytes for each of the cases.