Source-linked AI summary
Mitigating Inter-network Interference in LoRa Networks
Thiemo Voigt, Martin Bor, Utz Roedig, Juan Alonso
TL;DR
Interference between nearby LoRa networks motivates alternatives to constrained static transmission settings. The paper compares directional antennae with multiple base stations through calibrated simulation and finds that both improve performance, while multiple base stations clearly outperform directional antennae. Under a representative workload, three base stations raise DER from 0.24 to 0.56 versus 0.32 with directional antennae.
Problem
Nearby LoRa networks interfere, while transmission-parameter trade-offs and unsupported coordination make dynamic settings less practical.
Method
The paper evaluates directional antennae and multiple base stations using LoRaSim, a simulation environment based on experimental data and extended for directional transmissions.
Results
Three base stations improve DER from 0.24 to 0.56, while directional antennae increase it to 0.32 in a representative interference setting.
Takeaways & Limitations
Adding base stations is more efficient than equipping nodes with directional antennae for mitigating LoRa network interference.
Takeaways & Limitations
The evaluation reports only SN1 results because of space constraints, although simulations verified the same trends for other settings, including SN3.
Abstract
from arXiv · showhide
Long Range (LoRa) is a popular technology used to construct Low-Power Wide-Area Network (LPWAN) networks. Given the popularity of LoRa it is likely that multiple independent LoRa networks are deployed in close proximity. In this situation, neighbouring networks interfere and methods have to be found to combat this interference. In this paper we investigate the use of directional antennae and the use of multiple base stations as methods of dealing with inter-network interference. Directional antennae increase signal strength at receivers without increasing transmission energy cost. Thus, the probability of successfully decoding the message in an interference situation is improved. Multiple base stations can alternatively be used to improve the probability of receiving a message in a noisy environment. We compare the effectiveness of these two approaches via simulation. Our findings show that both methods are able to improve LoRa network performance in interference settings. However, the results show that the use of multiple base stations clearly outperforms the use of directional antennae. For example, in a setting where data is collected from 600 nodes which are interfered by four networks with 600 nodes each, using three base stations improves the Data Extraction Rate (DER) from 0.24 to 0.56 while the use of directional antennae provides an increase to only 0.32.
1 Introduction
Multiple nearby LoRa networks can interfere, while practical constraints limit static transmission settings as a solution. The paper compares directional antennae and multiple base stations and finds that both help, but multiple base stations are more effective.
- Multiple LoRa networks deployed in the same physical space create inter-network interference that must be managed.
- Static transmission settings remain common because parameter choices affect range, reliability, and energy consumption, while dynamic coordination requires unsupported protocol cooperation.
- Directional antennae improve receiver signal strength without increasing transmission energy cost, whereas multiple base stations improve the chance of decoding at least one receiver.
- Both approaches improve LoRa performance under interference, but adding base stations is more efficient than equipping nodes with directional antennae.
- Three base stations raise DER from 0.24 to 0.56, while directional antennae raise it to 0.32 for 600 nodes interfered by four 600-node LoRa networks.
2 Long Range (LoRa)
LoRa is a low-power spread-spectrum technology whose configurable transmission parameters trade off robustness, range, rate, duration, and energy consumption. Its wideband signaling provides resistance to noise and interference, but parameter choices have competing effects.
- LoRa is a proprietary spread-spectrum modulation technique derived from Chirp Spread Spectrum, encoding messages with frequency sweeps.
- Spreading the signal over a wide bandwidth makes LoRa less susceptible to noise and interference, while CSS resists Doppler effects and multipath fading.
- LoRa transceivers expose five runtime-adjustable parameters: TP, CF, SF, BW, and CR.
- Higher SF increases signal-to-noise ratio, receiver sensitivity, and range, but lowers transmission rate while increasing duration and energy consumption.
- Wider BW improves interference resilience and data rate but reduces reception sensitivity because it integrates additional noise.
3 LoRa Simulation Environment
The study uses LoRaSim, a calibrated discrete-event simulator extended to model directional transmissions. Its models capture communication range, sensitivity, collision behavior, and capture effects that determine whether packets decode under interference.
- LoRaSim places N LoRa nodes and M base stations in two-dimensional space and assigns nodes LoRa transmission parameters and behavior.
- The simulator models communication range as a function of TP, SF, and BW using testbed-derived LoRa link behavior.
- LoRaSim was extended to represent directional transmissions using the SPIDA electronically switchable directional antenna model.
- Successful reception depends on received power exceeding receiver sensitivity, with sensitivity determined by BW and SF and calibrated using Semtech SX1272 measurements.
- Collision decoding is modeled using carrier frequency, spreading factor, power, timing, and the LoRa capture effect.
4 Evaluation
The evaluation measures LoRa network performance with DER under inter-network interference, comparing directional antennae with multiple base stations. Both approaches improve DER, but multiple base stations provide the stronger improvement.
- Evaluation metric: DER is the ratio of correctly received messages to transmitted messages, with a message counted when at least one base station receives it.DER evaluates the network deployment as a whole and equals 1 when all transmitted messages arrive successfully.
- Evaluation setup: The study uses simulations based on the LoRaSim environment and evaluates a central network surrounded by interfering networks.LoRaSim was extended to model directional transmissions, and the experiments use DER as the performance measure.
- Inter-network interference: At 200m between base stations, DER reaches around 0.8, the maximum limited by interference within the network itself.Increasing distance reduces the number of interfering nodes; at 200m, interfering base stations cannot interfere.
- Inter-network interference: With 500 nodes per network, DER falls from 0.58 without interference to ca. 0.3 with interference from four networks.DER decreases significantly as the number of interfering networks increases, particularly when node counts are high.
- Directional antennae: Directional antennae increase DER by about 0.04 in most setups, while 8dBi antennae add another 0.04.The increased signal strength makes successful reception under collisions more likely through the capture effect.
- Additional base stations: With two base stations, the best separations are 33m–67m; for 600 nodes, DER rises from 0.35 to 0.53 at 50m–67m.Coincident base stations receive the same packets, while excessive separation can leave nodes out of range.
- Additional base stations: Three base stations generally achieve higher DER than two because their distribution keeps nodes within reach and increases opportunities for capture-effect reception.The improvement is especially pronounced at larger separations such as 97m.
- Comparison: Multiple base stations are more efficient than directional antennae for achieving high DER under interference.The paper's comparison identifies additional base stations as the more effective mitigation approach.
5 Related Work
Prior LoRa research covers link behaviour, scalability, and directional antennae, but does not address interference from co-located, noncooperating LoRa networks.
- Prior studies evaluate LoRa link behaviour, coverage, reliability, capacity, and scalability using open-space, indoor, theoretical, or empirical approaches.
- None of the cited previous efforts considers interference from co-located, noncooperating LoRa networks.
- SNOW supports concurrent transmissions through distributed OFDM, whereas this work assumes a more constrained base station that limits scalability.
- Directional antennae research in wireless networks reports performance improvements with minor protocol modifications and applications such as bulk transfers.
6 Conclusions
The paper evaluates inter-network interference in LoRa networks through simulations based on real experimental data. It finds that both directional antennae and multiple base stations improve performance, with multiple base stations outperforming directional antennae.
- Simulations based on real experimental data show that inter-network interference can drastically reduce LoRa network performance.
- Directional antennae and multiple base stations both improve LoRa performance under interference.
- Multiple base stations outperform directional antennae for improving LoRa performance under interference.