Recent years have seen the rapid development of long-range wide area network (LoRaWAN) operating in region-specific sub-GHz frequency bands (e.g., 868 MHz in Europe and 915 MHz in North America). To achieve global deployment, LoRaWAN has been extended to operate in the globally available 2.4 GHz unlicensed band. However, this shift exposes LoRaWAN to significant interference from coexisting Wi-Fi networks, which share the same band and typically transmit at much higher power levels. To address this problem, this article presents InMAC, an interference-aware medium access control (MAC) protocol designed to improve coexistence between LoRaWAN and Wi-Fi networks. To the best of our knowledge, InMAC is the first MAC protocol specifically tailored to mitigate Wi-Fi interference for 2.4 GHz LoRaWAN. InMAC enhances LoRaWAN communication by probabilistically exploiting the silent time in Wi-Fi traffic, leveraging a Wi-Fi traffic profiling mechanism at LoRaWAN gateways and a packet length adaptation strategy at end devices. In addition to mitigating external interference from Wi-Fi, InMAC also tackles internal interference caused by signal collisions among LoRaWAN end devices. It incorporates a novel channel access mechanism based on channel activity detection (CAD), a carrier-sensing technique adapted specifically for LoRaWAN. Experimental results demonstrate that InMAC reduces both external Wi-Fi interference and internal LoRaWAN collisions, achieving up to a 111% throughput boost over existing approaches.

In long-range wide area network (LoRaWAN), end devices located in urban environments (e.g., deep inside buildings or basements) frequently suffer from poor network connection due to signal attenuation and blockages, causing dramatic reduction of LoRaWAN coverage. To solve this problem, existing solutions resort to additional efforts from multiple LoRaWangateways, multiple antennas at a gateway, or a third-party transmitter. However, these types of network architecture incur increased hardware costs and are hard to be implemented in all LoRaWAN use cases. In this paper, we propose iLoc to improve LoRaWAN coverage in a zero-effort manner by only leveraging a single-antenna gateway. At the heart of iLoc is a novel technique that exploits the redundancy of chirps in a LoRa signal to enhance the demodulation of signals transmitted over weak links. Experimental results show that iLoc can introduce more than 40% improvement of LoRaWAN coverage in practice. © 2025 IEEE.

This paper proposes a heterogeneous carrier-sense multiple access (CSMA) protocol named LoHEC as the first research attempt to improve energy fairness when applying CSMA to long-range wide area network (LoRaWAN). LoHEC is enabled by Channel Activity Detection (CAD), a recently introduced carrier-sensing technique to detect LoRaWAN signals even below the noise floor. The design of LoHEC is inspired by the fact that existing CAD-based CSMA proposals are in a homogeneous manner. In other words, they require LoRaWAN end devices to perform identical CAD regardless of the differences of their used network parameter - spreading factor (SF). This causes energy consumption imbalance among end devices since the consumed energy during CAD is significantly affected by SF. By considering the heterogeneity of LoRaWAN in terms of SF, LoHEC requires end devices to perform different numbers of CAD operations with different CAD intervals during channel access. Particularly, the number of needed CADs and CAD interval are determined based on the CAD energy consumption under different SFs. We conduct extensive experiments regarding LoHEC with a practical LoRaWAN testbed including 60 commercial off-the-shelf end devices. Experimental results show that in comparison with the existing solutions, LoHEC can achieve up to 0.85 x improvement of the energy fairness on average.

As a compelling wireless networking technology for the Internet of Things, long-range wide area network (Lo-RaWAN) has been newly designed to exploit the 2.4 GHz unlicensed band instead of the traditional sub-GHz bands. However, this makes LoRaWAN frequently suffer from communication failures caused by the signal interference from coexisting Wi-Fi networks using the same 2.4 GHz band. To mitigate this problem, this paper presents a physical-layer solution to directly extract LoRaWAN data out of Wi-Fi interference. This is achieved by exploiting the correlation of the signal demodulation results between the preamble and the payload of a LoRa (the physical layer of LoRaWAN) signal. Experimental results show that in comparison with existing approaches, our proposed technique can achieve up to 83% reduction of LoRa packet error rate. © 2024 IEEE.

Long-range wide area network (LoRaWAN) has been newly designed to exploit the 2.4 GHz unlicensed band instead of the traditional sub-GHz bands. However, this makes LoRaWAN frequently suffer from wireless communication failures caused by the cross-technology interference (CTI) from coexisting Wi-Fi networks using the same 2.4 GHz band. As a physical-layer solution to this problem, this paper presents CoWiL to combat the CTI from Wi-Fi to LoRa (the physical layer of LoRaWAN) in the 2.4 GHz band for better coexistence between LoRaWAN and Wi-Fi networks. Existing approaches address this problem by sacrificing Wi-Fi transmission performance or assuming that Wi-Fi interferes with only a small portion of LoRa signals. Unlike them, CoWiL does not affect normal Wi-Fi communications and is workable regardless of the degree of the CTI. This is achieved by implementing CoWiL at a LoRa receiver to directly extract LoRa data out of the CTI from Wi-Fi. Specifically, CoWiL exploits the correlation of the signal demodulation results between the preamble and the payload of a LoRa signal. A novel frequency bin mask is generated based on the demodulated preamble and then applied to the following payload for data decoding. Experimental results in various real-world environments show that in comparison with the existing solutions, CoWiL can reduce the packet error rate of LoRa transmissions by up to 96% under the CTI from Wi-Fi. © 2024 IEEE.

The last few years have witnessed the prosperity of low-power wide area networks (LPWANs) operating in the region-specific sub-GHz frequency bands. In particular, as one of the representatives of LPWANs, long-range WAN (LoRaWAN) has been newly developed to exploit the 2.4 GHz worldwide unlicensed band for region-independent LoRaWAN development. However, this makes LoRaWAN susceptible to signal interference caused by coexisting Wi-Fi networks that also use the 2.4 GHz band with a higher transmission power than LoRaWAN typically. As a medium access control (MAC)-layer solution to this problem, this paper proposes BeLow to enable better coexistence between LoRaWAN and Wi-Fi networks. To our best knowledge, BeLow is the first-ever LoRaWAN-oriented MAC protocol to mitigate the impact of Wi-Fi interference on LoRaWAN. Overall, BeLow seeks to exploit the silent time of Wi-Fi traffic for LoRaWAN communication. This is achieved in a probabilistic manner via a Wi-Fi traffic profiling technique at LoRaWAN gateways and a packet length adaptation approach at LoRaWAN end devices. On the other hand, BeLow also aims to avoid signal collisions among LoRaWAN end devices by including a novel channel access protocol based on Channel Activity Detection, a carrier-sensing technique tailor-made for LoRaWAN. Experimental results show that BeLow can avoid both Wi-Fi interference and LoRaWAN signal collisions well with a throughput boost of up to 120% compared to the best of our benchmark approaches. © 2024 IEEE.