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Enhancing IoT Network Reliability through Antenna Diversity in Real-World Scenarios
Marco Niederberger, Yanick Schoch, Michel A. Nyffenegger, Christian Gwerder, Hans-Dieter Lang
TL;DR
Fixed orientations and nearby objects can degrade IoT wireless links, motivating practical ways to improve reliability. The paper measures antenna diversity in real-world indoor conditions and reports substantial received-signal-strength gains, including with PCB-only antennas.
Problem
Fixed device orientations, misalignment, and nearby objects can degrade IoT wireless-link quality and reliability, motivating simple remedies such as dynamically selecting among antennas.
Source: §II · p. 1, §VI · p. 5Method
The study measures IoT network performance using multiple differently polarized antennas, comparing antenna configurations in indoor real-world conditions.
Source: §I · p. 1, 3) Test Procedure and Conditions · p. 3, §VI · p. 5Results
Received signal strength gains reached 34 dB overall and 17 dB with two PCB antennas, while a 5% throughput increase was observed.
Source: §VI · p. 5, B. Antenna Diversity Gain in Terms of… · p. 5Takeaways & Limitations
The experiments suggest antenna diversity may justify added hardware and software complexity for demanding IoT applications requiring reliable connections.
Source: §VI · p. 5Further research is needed to assess link reliability statistically using factors such as packet loss.
Source: B. Antenna Diversity Gain in Terms of… · p. 5
Abstract
from arXiv · showhide
Antenna diversity in Internet of Things (IoT) devices is explored to address challenges associated with fixed device orientation and interference from nearby metallic objects, which can degrade wireless network performance. Integrating multiple antennas with different polarizations can significantly enhance signal quality and network reliability. Experiments demonstrated significant improvements in link quality, with gains exceeding 30 dB in received signal strength for specific scenarios. Already the addition of a second PCB-based antenna alone, resulted in a 17 dB improvement. These findings suggest that the added complexity in hardware and software to incorporate antenna diversity could well be justified by the resulting enhancements in network stability for real-world applications.
I. INTRODUCTION
IoT applications such as healthcare monitoring and industrial automation depend on reliable connectivity. This paper examines whether simple antenna diversity can address installation and environmental conditions that degrade wireless links.
I. INTRODUCTION
- Healthcare monitoring and industrial automation require reliable, efficient connectivity to support functionality, safety, and data integrity.Source: §I · p. 1
- The paper investigates practical use of differently polarized antennas in IoT devices, complementing prior theoretical and hardware-design work with real-world measurements.It focuses on improving wireless-link performance and reliability in IoT networks.Source: §I · p. 1
II. PROBLEM STATEMENT
- Fixed installations may prevent repositioning devices, while misalignment, nearby metal, and changing surroundings can degrade wireless-link quality and reliability.Relocating devices after installation may be impossible or costly.Source: §II · p. 1, Figure 1 · p. 1
- The study asks whether two orthogonal PCB antennas with switching suffice, or whether a third antenna is needed for full polarization freedom.Exploring antennas with different radiation patterns is outside the study’s scope; full MIMO is described as infeasible for short-range IoT mesh networks given chip and standards support.Source: §II · p. 1
III. RELATED WORK
Prior work covers antenna diversity through indoor IoT tests, polarization experiments, and antenna designs. This paper addresses practical measurements in stationary IoT mesh networks, where the literature review found relatively limited exploration.
III. RELATED WORK
- Antenna diversity is established in mobile communications, but its practical exploration for stationary IoT mesh networks is relatively limited.The review also identifies theoretical work on multihop IoT mesh networks that is difficult to compare with this practical study.Source: §III · p. 2
- Indoors, Silicon Labs found nodes without diversity needed 6 dB more transmit power to achieve comparable Packet Error Rates.Its approach selected the best antenna during the protocol preamble for the payload; outdoors, improvement was minimal.Source: §III · p. 2
- In an anechoic chamber, co- versus cross-polarized received power differed by up to 22 dB; in a reverberation chamber, the difference was around 15 dB.Multiple paths in the reverberation chamber mitigated polarization-mismatch effects.Source: §III · p. 2
- Ramirez et al. reported up to 11 dB improvement from switching among three orthogonal polarizations and a 4.3 dB median gain with a Wilkinson combiner.Their work also found sensitivity to antenna-placement variations of approximately λ/10; this study instead integrates antennas onto a flat PCB.Source: §III · p. 2
- Qorvo reported a 7 to 12 dB link-budget improvement for indoor point-to-point connections using hardware-based receive diversity.Its application differs from this paper’s focus on mesh networks.Source: §III · p. 2
2) Antennas:
The developed IoT nodes combine orthogonal antennas and sensors with a low-power mesh-network test setup. The software supports antenna control and performance monitoring.
2) Antennas:
- Each node uses two PCB inverted-F antennas and a central wire monopole, all orthogonally oriented and tuned to 2.4–2.48 GHz.A QPC8014Q switch selects antennas; the third, protruding wire monopole presents physical integration challenges.Source: 2) Antennas · p. 2
3) Sensors and Battery:
- Accelerometers and magnetometers support dynamic antenna selection based on node orientation and surrounding conditions, while rechargeable batteries support untethered operation.Source: 3) Sensors and Battery · p. 2
B. Software Design
- The mesh uses OpenThread, an IPv6-based protocol for low-power IoT, and a Raspberry Pi acts as the Border Router and iPerf client.iPerf measures network data rate; a browser interface supports antenna selection, RSSI monitoring, and network-layout visualization.Source: B. Software Design · pp. 2–3, Figure 3 · p. 3
1) Test Environment:
The study measures antenna-diversity performance in a six-node, two-story indoor network. It compares fixed-antenna baselines with PCB-only and full antenna diversity configurations.
1) Test Environment:
- The test network comprised six nodes in a two-story indoor setting, with nodes 15 to 25 m apart among metal beams, pipes, wooden walls, and equipment.Source: 1) Test Environment · p. 3
2) Node Deployment:
- Nodes were mounted without optimizing antenna alignment: some were fixed to concrete walls or metal beams, while another sat on a railing.Nodes D and f were on the lower floor; the rest were on the upper floor.Source: 2) Node Deployment · p. 3
3) Test Procedure and Conditions:
- RSSI was averaged across 10 measurements per node-and-antenna combination, with tests conducted at night to reduce external influences.Source: 3) Test Procedure and Conditions · p. 3
- Throughput tests compared A↔g and A↔D across antenna 1, antenna 2, best-PCB-antenna, and best-overall-antenna configurations.Raspberry Pis were placed near the final node to minimize the final link’s effect; the best-PCB configuration represents 2D diversity, while best overall represents full 3D diversity.Source: 3) Test Procedure and Conditions · p. 3
A. Antenna Diversity Gain in Terms of RSSI
Antenna diversity produced substantial RSSI gains in the test network, with the best link improving by 11 dB in the illustrated example. Using only the two PCB antennas still improved connections, despite the added complexity of the third antenna.
A. Antenna Diversity Gain in Terms of RSSI
- The RSSI matrices compare readings across antenna configurations, nodes, and orientations to visualize signal-strength variation.Fig. 6 shows the full connection matrix; Fig. 7 shows only connections via antennas 1 and 2.Source: A. Antenna Diversity Gain in Terms of… · p. 3, Figure 6 · p. 4, Figure 7 · p. 4
- 11 dB better RSSI was achieved on link g–A by switching from antenna 1 at both nodes to antenna 2 at A and antenna 3 at g.The initial RSSI was –83 dBm; the best link was –72 dBm.Source: A. Antenna Diversity Gain in Terms of… · p. 4
- 6–34 dB RSSI gains were measured with antenna diversity in this test network.The best improvement was 34 dB.Source: A. Antenna Diversity Gain in Terms of… · p. 4
- 3–17 dB connection improvements were achieved using only the two PCB-based antennas.The study gave special attention to this setup because the third antenna adds significant complexity.Source: A. Antenna Diversity Gain in Terms of… · pp. 4–5
B. Antenna Diversity Gain in Terms of Throughput
In the measured multi-hop network, antenna diversity produced only small throughput improvements overall, although the A–D connection spanning at least three hops increased by 5%. The authors conclude that diversity enhances reliability and robustness rather than throughput capacity.
B. Antenna Diversity Gain in Terms of Throughput
- 5% higher throughput was measured for the A–D connection spanning at least three hops, while the table results showed only small improvements overall.The authors conclude that antenna diversity improves reliability and robustness rather than throughput capacity.Source: B. Antenna Diversity Gain in Terms of… · p. 5, Table I · p. 5
- In a one-hop scenario, maximum achievable throughput strongly correlates with RSSI.In multi-hop connections, maximum throughput depends highly on the number of hops.Source: B. Antenna Diversity Gain in Terms of… · p. 5
- Further research is needed to assess link reliability statistically using factors such as packet loss, error rate, and latency.Source: B. Antenna Diversity Gain in Terms of… · p. 5
VI. SUMMARY & CONCLUSIONS
Indoor real-world measurements show that differently polarized antennas can address misalignment and surrounding-object interference while improving IoT link quality and reliability. The gains include stronger received signal, modest throughput improvement, and added design complexity that the authors consider likely justified for demanding applications.
VI. SUMMARY & CONCLUSIONS
- Indoor measurements used multiple antennas with different polarizations to address misalignment and interference from surrounding objects that degrade received signal quality and network reliability.Source: §VI · p. 5
- Up to 34 dB received-signal-strength diversity gain was measured for individual connections, with at least 6 dB per connection versus the worst-performing antenna configuration.The simpler two-PCB-antenna setup produced gains between 3 and 17 dB.Source: §VI · p. 5
- A 5% increase in data throughput was observed, although antenna diversity primarily improved reliability and robustness rather than throughput.Source: §VI · p. 5
- The authors conclude that improved signal quality and network reliability likely justify added hardware and software complexity, particularly for demanding IoT applications in dynamic, challenging environments.Source: §VI · p. 5