1. Device and Hardware Performance (Transmitter & Receiver)

The specifications of the hardware determine the inherent signal strength:

• Transmit Power (Tx Power): Higher transmit power from the end device (water meter) results in greater range, typically constrained by local radio regulations.

• Antenna Gain:

• Gateway Side: High-gain fiberglass omnidirectional antennas can significantly increase coverage.

• Terminal Side: Due to the compact size of water meters, the type of antenna (spring antenna, FPC antenna) and its tuning state have a massive impact on radiation efficiency.

• Receiver Sensitivity: A major advantage of LoRa technology is its extremely high receiver sensitivity  improvement in sensitivity can theoretically double the transmission range.

2. Physical Environment and Propagation Path (Path Loss)

Energy attenuation during signal propagation is the primary cause of range limitations:

• Obstacle Blocking: LoRa utilizes UHF bands, which have limited diffraction capabilities. Reinforced concrete walls, metal pipes, and dense building clusters cause significant signal attenuation.

• Installation Depth (Underground Environments): Water meters are often installed under metal manhole covers or in basements. Deep burial leads to severe "shielding effects" when signals attempt to penetrate ground layers and metal covers.

• Fresnel Zone: If there is insufficient line-of-sight (LoS) between the gateway and terminal, obstacles cause multipath interference due to reflection and refraction, reducing communication range.

3. LoRa Modulation Parameters (Link Configuration)

Link-layer settings directly impact the link budget:

• Spreading Factor (SF):

• Higher SF: Results in slower transmission speeds but higher resistance to interference and better receiver sensitivity, extending communication range.

• Lower SF: Faster transmission and lower power consumption, but limited range.

• Signal Bandwidth (BW): Narrower bandwidth improves receiver sensitivity and range, though it reduces tolerance to frequency offsets.

• Coding Rate (CR): Higher coding rates improve resistance to burst interference, increasing reliability in complex environments at the cost of additional overhead.

4. External Interference and Environmental Noise

• Co-channel Interference: LoRaWAN operates in unlicensed bands (e.g., $470\text{MHz}$, $868\text{MHz}$, $915\text{MHz}$). The presence of walkie-talkies, wireless data modules, or other base stations in the vicinity raises the noise floor, reducing the signal-to-noise ratio (SNR).

• Weather Conditions: Highly humid air or heavy rainfall can cause scattering and attenuation of high-frequency electromagnetic waves.

Fengbo ultrasonic water meters support LoRaWAN version 1.0.4, feature ADR (Adaptive Data Rate) capabilities, and can be customized with an external antenna.