# Experimental Evaluation of the Packet Reception Performance of LoRa
## 2 Related Work  
In this section, we do our best to introduce related work on the impact of physical layer parameters on the performance of LoRa. In [22], the authors conducted extensive experimental research on the reliability of LoRa. At the same time, the authors also studied the influence of temperature on the performance of LoRa and found that high temperatures decrease the received signal strength and drastically increase packet loss and corruption for nodes at the edge of the communication range. However, the influence of several physical layer parameters (for example, SF8) on the performance of LoRa has not yet been determined. The paper [23] answered some common questions faced by system users and researchers regarding LoRa, and verified Semtech's commitments in terms of the transmission distance, node life, and capacity. We also noticed that some experimental results on the performance of LoRa are not as good as Semtech claims. [PERSON] et al. [16]measured the communication distance of LoRa on a forest farm and found that the actual communication range of LoRa was shorter than the theoretical communication range, and the reliability of the actual data was inconsistent with the report when employing different distances and physical layer parameter configurations. Additionally, the author also found that the Fresnel zone affects the LoRa network. The setting of physical layer parameters not only affects the performance of LoRa, but also the capacity of the LoRa network. The relationship between physical layer parameter settings and the capacity of the LoRa network is discussed in [24]. The researchers have shown, through simulation, that the choice of physical layer parameter settings affects the number of LoRa nodes that can access the channel at the same time, resulting in the limitation of the capacity of the LoRa network. Similar results were obtained in [14]. The work in [14] is also the first to propose the use of LoRa technology for health detection, and the authors have pointed out that if there are multiple devices in the same environment, there may be problems with the communication reliability. In [15], the author evaluates the communication performance of LoRa in a building by changing the transmit power, data rate, package length, and location of the wireless module. The experimental results show that the practical considerations of signal reliability in different building environments lead to certain limitations in practical applications. Therefore, it remains a challenge to improve the reliability while maintaining high data rates and low energy consumption. Meanwhile, LoRa technology uses different spreading factors to increase the number of nodes in the channel, which is the use of orthogonality of different spreading factors. However, the experimental results in [25] show that different spreading factors will also exhibit conflict and greatly reduce the performance of LoRa. Moreover, the author believes that the packet length is not a key factor affecting the performance of LoRa. Similarly, the results presented in this work show that there is no obvious difference in the Packet Error Ratio of using short packets or long packets, except at the edge of the communication link. Other works [21; 26; 27] have evaluated the performance of LoRa in different environments, and suggested using the most sensitive parameter configuration to improve the reliability of LoRa. However, they did not consider all parameter configurations, and important details on the relationship between physical layer parameters and the performance of LoRa are not sufficiently detailed and specific. In addition, although the transmission scheme they proposed has an improved reliability, the data rate and energy consumption have also increased accordingly. Different from previous work, this article expects to obtain important details on the impact of physical layer parameters and packet length settings on the packet reception performance of LoRa.