The transmission distance of LoRaWAN water quality sensor is affected by many factors such as device performance, signal propagation environment and network configuration, as follows:

1. Equipment factors

Transmission power: The higher the transmission power, the higher the signal strength and the farther the transmission distance. However, the increase of transmission power will lead to a corresponding increase in power consumption, so it is necessary to balance between power consumption and transmission distance.

Reception sensitivity: The higher the reception sensitivity, the lower the minimum effective signal power that the sensor can receive, and the more weak signals can be received from a distance, thus extending the transmission distance.

Antenna gain: Antenna gain is an indicator of the antenna's ability to concentrate input power radiation. A high gain antenna can transmit signals more concentrated or receive signals more efficiently, thereby increasing the transmission distance.

Spread factor: In LoRa technology, the larger the spread factor (SF), the higher the sensitivity and the farther the communication distance. For example, SF12 has higher sensitivity than SF7 and a longer transmission distance, but the data transmission rate is lower.

Modulation bandwidth: Increasing the signal bandwidth can improve the effective data rate and shorten the transmission time, but it will sacrifice the sensitivity and lead to a shorter communication distance.

2. Environmental factors

Obstacles: Structures such as buildings, walls, trees, and hills can obstruct, reflect, or scatter signals, reducing their strength and shortening transmission range. In urban environments with dense building clusters, LoRaWAN wireless sensors typically have a shorter transmission range of 2-5 kilometers. However, in suburban or open areas, the range can extend up to 15 kilometers or even further.

Weather conditions: Rain, fog, snow and other weather conditions will attenuate the signal, especially in heavy rain or thick fog, the transmission distance of the signal may be significantly affected.

Electromagnetic interference: Electromagnetic interference sources in the surrounding environment, such as telecom base stations, industrial equipment, high-voltage power lines, etc., will interfere with LoRaWAN signals, reduce signal quality, and thus affect the transmission distance.

3. Network factors

Gateway density: In LoRaWAN networks, the density and location of gateways have a significant impact on transmission distance. In areas with low gateway density, the distance between sensors and gateways may be far, and signal loss on the transmission path will also increase, thus affecting the transmission distance.

Channel occupancy: If multiple devices use the same channel for data transmission at the same time, channel competition and interference will occur, resulting in reduced signal transmission quality and shortened transmission distance.