LoRa with UAVs: extending sub-GHz IoT coverage
October 2025
The paper Improving LoRa Signal Coverage in Urban and Sub-Urban Environments with UAVs (Dambal et al., 2019) measured how LoRa behaves when transmitters are mounted on drones instead of being limited to ground deployments. LoRa operates in the 920 MHz range in the US and Japan, a range shared with other sub-GHz technologies like IEEE 802.11ah (Wifi HaLow). The findings are therefore directly relevant to both LoRaWAN and HaLow deployments aiming for extended range or resilient coverage.
Indoor findings
Indoors, LoRa links worked reliably when gateway and node were in line of sight of a window or door. Within a single building, attenuation was significant across floors, with roughly 50 dB loss over two floors. Nodes located near glass or external openings sometimes performed better than closer nodes shielded by walls. Across buildings, reception only worked with high spreading factors, confirming that walls and glass heavily constrain coverage. For both intra- and inter-building cases, antenna placement relative to openings mattered more than distance.
UAV experiments in urban areas
With the transmitter mounted on a drone flying at 25 m and 50 m, the urban trials showed effective ranges up to ~2.9 km. Raising altitude beyond 25 m had little effect because tall buildings created dense multipath reflections, which dominated the channel. Antenna orientation was decisive: vertical-vertical alignment (VV) produced consistently stronger links, while horizontal transmitter placement (VH) often led to packet loss. The radiation pattern of the omnidirectional PCB antenna explains this — horizontal placement corresponds to a weaker lobe.
UAV experiments in suburban areas
Suburban deployments told a different story. Here, reflections are sparse and line of sight dominates. A transmitter on the ground at 1 m yielded no connectivity at distances over a kilometer. At 25 m, links were established but weak; at 50 m, reception improved by 5-7 dB and stable coverage was sustained to ~1.8 km. In suburban settings, therefore, UAV height was the critical factor for coverage, unlike in urban zones where multipath masked the effect.
Omni antennas and orientation
Though called “omnidirectional”, PCB trace antennas exhibit a torus-shaped pattern around the vertical axis. Vertical placement maximizes horizontal gain, while horizontal placement cuts effective link budget. The study demonstrated that UAVs carrying vertically oriented antennas could extend LoRa coverage by 1-3 km depending on the environment, while the same hardware misaligned lost range quickly.
Lessons for Wifi HaLow
HaLow shares the same sub-GHz propagation regime. Indoor attenuation across walls and floors, sensitivity to antenna orientation, and altitude-driven gains in suburban settings all carry over. The difference lies in receiver sensitivity: LoRa can decode signals at −130 dBm or lower, while HaLow typically needs −90 to −100 dBm depending on modulation. That gap implies that UAV-mounted HaLow nodes will extend range, but to shorter absolute distances: where LoRa reached nearly 3 km in urban tests, HaLow may sustain roughly 1-2 km with elevated transmitters. Still, the qualitative results align — sub-GHz coverage improves dramatically when nodes are lifted above clutter.
LoRa vs Wifi HaLow coverage comparison
To ground the discussion, the table below contrasts observed LoRa results from the UAV experiments with plausible Wifi HaLow ranges under the same environmental assumptions. LoRa benefits from extreme receiver sensitivity, while HaLow trades some distance for higher throughput.
| Environment | Ground-level (1 m) | UAV 25 m | UAV 50 m |
|---|
| LoRa - Urban | No reliable coverage | ~2.9 km (VV orientation) | ~2.9 km (VV orientation) |
| LoRa - Suburban | No coverage | ~1.1-1.4 km | ~1.8 km |
| Wifi HaLow - Urban | No reliable coverage | ~1.0-1.5 km (est.) | ~1.5-2.0 km (est.) |
| Wifi HaLow - Suburban | No coverage | ~0.5-1.0 km (est.) | ~1.5 km (est.) |
Rural and maritime expectations
While the measurements in Dambal et al. focus on urban and suburban areas, the same sub-GHz physics suggests different outcomes in rural and maritime settings. In open countryside with sparse structures, ground-level LoRa links already span several kilometers, and UAV-mounted nodes at 50-100 m have been reported to extend coverage to 10-15 km under clear line-of-sight conditions. HaLow, with its higher SNR requirements, is expected to reach 2-3 km in the same scenarios, potentially 4 km at lower data rates. Over water, the environment is even more favorable: ship-to-shore LoRa links exceeding 30 km have been documented when antennas are elevated, and UAV platforms could match this performance. HaLow would not reach the same extremes but may sustain 5-10 km depending on rate adaptation and antenna alignment. These figures are extrapolated from prior rural and maritime deployments rather than the controlled measurements of the paper, yet they highlight the outsized role of UAV elevation in open environments.
Key takeaways
LoRa gateways mounted on UAVs extended suburban links from zero reception at ground level to ~1.8 km at 50 m. In dense urban cores, UAVs reached ~2.9 km, though altitude mattered less than antenna orientation. For HaLow meshes, the same physics applies, albeit with shorter range expectations due to stricter SNR requirements: typically 1-2 km in urban tests and up to ~1.5 km suburban with UAV assistance.
In rural terrain, LoRa has demonstrated 10-15 km when elevated by UAVs, with HaLow sustaining 2-4 km depending on modulation. Maritime settings amplify this further: ship-to-shore LoRa has reached 30 km+ with mast-mounted antennas, while HaLow may support 5-10 km under favorable conditions.
The general lesson holds across all environments: sub-GHz coverage improves dramatically when nodes are lifted above clutter and oriented correctly, and UAV platforms provide a practical means to achieve this when fixed infrastructure is limited.