Low-Power Wide Area Networking (LPWAN) technology offers long-range communication, which enables new types of services. Several solutions exist; LoRaWAN is arguable the most adopted. It promises ubiquitous connectivity in outdoor IoT applications, while keeping network structures, and management, simple. This technology has received a lot of attention in recent months from network operators and solution providers. Yet, the technology has limitations that need to be clearly understood to avoid inflated expectations and disillusionment. This article provides an impartial and fair overview of what the capabilities and the limitations of LoRaWAN are. We discuss those in the context of use cases, and list open research and development questions.

Providing low power and long range (LoRa) connectivity is the goal of most Internet of Things networks, e.g., LoRa, but keeping communication reliable is challenging. LoRa networks are vulnerable to the capture effect. Cell-edge nodes have a high chance of losing packets due to collisions, especially when high spreading factors (SFs) are used that increase time on air. Moreover, LoRa networks face the problem of scalability when they connect thousands of nodes that access the shared channels randomly. In this paper, we propose a new MAC layer-RS-LoRa-to improve reliability and scalability of LoRa wide-area networks (LoRaWANs). The key innovation is a two-step lightweight scheduling: 1) a gateway schedules nodes in a coarse-grained manner through dynamically specifying the allowed transmission powers and SFs on each channel and 2) based on the coarse-grained scheduling information, a node determines its own transmission power, SF, and when and on which channel to transmit. Through the proposed lightweight scheduling, nodes are divided into different groups, and within each group, nodes use similar transmission power to alleviate the capture effect. The nodes are also guided to select different SFs to increase the network reliability and scalability. We have implemented RS-LoRa in NS-3 and evaluated its performance through extensive simulations. Our results demonstrate the benefit of RS-LoRa over the legacy LoRaWAN, in terms of packet error ratio, throughput, and fairness. For instance, in a singlecell scenario with 1000 nodes, RS-LoRa can reduce the packet error ratio of the legacy LoRaWAN by nearly 20%.

LoRa-E is a new physical layer developed by Semtech to increase the capacity of LoRaWAN in dense and congested deployments. It has also been designed to address extremely long-range and large-scale communication scenarios with a focus on reaching gateway devices installed on satellites. Thanks to its design principles, it finely manages packet transmission, enabling Quality-of-Service policies on a per-packet basis. The core of LoRa-E is a Fast Frequency Hopping Spread Spectrum Modulation (FHSS) that uses frequency hopping sequences in which ∼50 ms fragments are transmitted. Given the notorious adoption of LoRaWAN in the IoT application landscape, this article is a reference for understanding how exactly LoRa-E works, what performance it offers, and what its limitations are.

The 433 MHz band is gaining relevance as an alternative to the 2.4 GHz band for machine-to-machine communications using low-power wireless technologies. Currently, two standards are being developed that use the 433 MHz band, DASH7 Mode 2 and IEEE 802.15.4f. The article presents propagation models based on measurements conducted at the 433 MHz and 2.4 GHz bands that can be used for link budget calculations in both outdoor and indoor environments depending on node height. The results obtained show that the 433 MHz band has a larger communication range in both indoor and outdoor environments despite the negative effects of having a larger Fresnel zone. In addition, indoor propagation measurements are conducted in line-of-sight and nonline-of-sight conditions to determine the suitability of channel hopping to combat the effects of multipath propagation. Contrary to the 2.4 GHz band, the results show that channel hopping at 433 MHz does not provide any link robustness advantage because the channel coherence bandwidth is larger than the whole band bandwidth, and thus, all channels are highly correlated.

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