# Experimental Evaluation of the Packet Reception Performance of LoRa
## 1 Introduction
The reliability of communication between LoRa nodes can be improved by adjusting the physical layer parameters, which has been demonstrated in [21]. The authors indicated that in order to maintain reliable communication, SF and CR should be configured to the highest values (a higher value means a higher receiving sensitivity). The experiment of [PERSON] et al. [16], which deployed LoRa nodes on a forest farm, also obtained similar results. Meanwhile, other previous work has also tried to use a more sensitive parameter configuration to improve the reliability of communication and experimental results have shown that the packet reception ratio was improved. However, using the most sensitive parameter configuration will minimize the data rate, which will bring about an increase in the communication time and energy consumption, as well as shortening of the working time of the node. Obviously, designing a transmission scheme that minimizes the energy consumption while maintaining a high data rate, thereby balancing reliability, delay, and energy consumption, is essential for successful deployment in real-world scenarios. In this study, we conducted extensive experiments to study the reliability of the communication link between LoRa nodes when the channel is interfered by white Gaussian noise, and we propose a transmission scheme that can achieve a balance between reliability, delay, and energy efficiency. To begin with, we studied the relationship between physical layer parameters (SF, BW, and CR) and the packet reception performance of LoRa in a sufficiently wide SNR range (from \(-24\) to \(0\) dB) and obtained detailed experimental results. Our experimental results found that physical layer parameters have a great impact on the packet reception performance of LoRa, and based on this, the optimal parameter combination was discussed in relation to the packet reception performance of LoRa. Next, we conducted a theoretical analysis and extensive experiments to study the impact of the packet length on the packet reception performance of LoRa. Our experimental results show that the Packet Error Ratios of different packet lengths are nearly equal in areas where the Packet Error Ratio is less than 0.2, that is, different packet lengths hardly affect the packet reception performance of LoRa in these areas. However, in areas where the Packet Error Ratio is greater than 0.2, long packets reduce the packet reception performance of LoRa and drastically increase packet loss and corruption. It seems that a short packet transmission scheme would be a better choice. However, short packets mean more headers than long packets, and this cost should not be underestimated. Therefore, if a node needs to send a large amount of data, the transmission scheme should use long packets instead of short packets. Finally, in order to select the appropriate parameters to optimize the transmission scheme, we combined the previous experimental results with the retransmission mechanism to strike a balance between communication reliability, delay, and energy efficiency. The experimental results show that the time of successful communication between nodes is reduced by 50% compared with the traditional transmission scheme, and the energy consumption is also greatly reduced. The contributions provided in this article can be summarized as follows:  
1. We studied the influence of physical layer parameters on the reliability of communication links between LoRa nodes, and obtained detailed experimental results on the relationship between the two;
2. The influence of the packet length on the reliability of communication links between LoRa nodes was studied by a theoretical analysis and extensive experiments. It should be noted that it is not worth using short packets instead of long packets;
3.