Low Power Wide Area Networks: A Survey of Enabling Technologies, Applications and Interoperability Needs <s> 1) LoRaWAN <s> In addition to long battery life and low cost, coverage is one of the most critical performance metrics for the low power wide area networks (LPWAN). In this work we study the coverage of the recently developed LoRa LPWAN technology via real-life measurements. The experiments were conducted in the city of Oulu, Finland, using the commercially available equipment. The measurements were executed for cases when a node located on ground (attached on the roof rack of a car) or on water (attached to the radio mast of a boat) reporting their data to a base station. For a node operating in the 868 MHz ISM band using 14 dBm transmit power and the maximum spreading factor, we have observed the maximum communication range of over 15 km on ground and close to 30 km on water. Besides the actual measurements, in the paper we also present a channel attenuation model derived from the measurement data. The model can be used to estimate the path loss in 868 MHz ISM band in an area similar to Oulu, Finland. <s> BIB001 </s> Low Power Wide Area Networks: A Survey of Enabling Technologies, Applications and Interoperability Needs <s> 1) LoRaWAN <s> Low-power wide area networking technology offers long-range communication, which enables new types of services. Several solutions exist; LoRaWAN is arguably 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. However, 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 the capabilities and limitations of LoRaWAN. We discuss those in the context of use cases, and list open research and development questions. <s> BIB002 </s> Low Power Wide Area Networks: A Survey of Enabling Technologies, Applications and Interoperability Needs <s> 1) LoRaWAN <s> We propose analytical models that allow us to investigate the performance of long range wide area network (LoRaWAN) uplink in terms of latency, collision rate, and throughput under the constraints of the regulatory duty cycling, when assuming exponential inter-arrival times. Our models take into account sub-band selection and the case of sub-band combining. Our numerical evaluations consider specifically the European ISM band, but the analysis is applicable to any coherent band. Protocol simulations are used to validate the proposed models. We find that sub-band selection and combining have a large effect on the quality of service (QoS) experienced in an LoRaWAN cell for a given load. The proposed models allow for the optimization of resource allocation within a cell given a set of QoS requirements and a traffic model. <s> BIB003 </s> Low Power Wide Area Networks: A Survey of Enabling Technologies, Applications and Interoperability Needs <s> 1) LoRaWAN <s> Pure ALOHA would be one of the candidate techniques to realize low-power wide-area networks and various applications of Internet of Things with a huge number of low-cost end-devices (EDs) and sensors. No strict time-synchronization of pure ALOHA systems may reduce the hardware cost of sensors and system significantly. As such, this letter characterizes the performance of pure ALOHA systems in terms of throughput, access delay, and stability, and further proposes a particle-filter-based control algorithm for retransmission intervals of EDs to achieve near-optimal throughput performance. <s> BIB004
LoRa [39] stands for Long-Range, a physical-layer technology for long-range, low-power wireless communication systems invented by Semtech. LoRa, among other LPWA technologies such as SigFox and WiSUN  , is one of the most promising and widely adopted technologies BIB002 . Its robustness to interference and long-range coverage (more than 10 km) are made possible through the use of M-ary frequency-shift keying (FSK) modulation (symmetric for uplink (UL) and downlink (DL)) and chirp spread spectrum (CSS) modulation, a technique in which the signal is modulated by chirp pulses  . Real experiments by BIB001 have shown that LoRa can cover more than 15 km on the ground and close to 30 km on the water using the 868 MHz ISM band with a transmit power of 14 dBm and the maximum spreading factor (SF). LoRa is now available from mobile network providers around the world [39] . LoRa technology operates under the LoRaWAN protocol developed by the LoRa Alliance. LoRaWAN is designed for battery-based end devices. The end devices are connected to the central network server through a gateway (also called a concentrator or base station) in a star-of-stars topology. End devices make connections to one or more gateways using single-hop LoRa or FSK communication, whereas the gateways and network servers are connected using standard Internet protocol (IP) connections  . Figure 4 shows both LoRa and LoRaWAN. Different channels and data rates are utilized by end devices using unlicensed radio spectrum resources in the ISM band  . Studies have shown that sub-band selection and combination affect the quality of service (QoS) BIB003 . An adaptive data rate scheme facilitates per end device data rates and frequencies and maximizes the network capacity and battery life of end devices. LoRa can support data rates from 0.3 kbps to 50 kbps  . To mitigate interference, end devices select channels in a pseudo-random fashion for every transmission. They also ensure that the maximum transmit duty cycle and maximum transmission duration are suitable to the sub-band used and compliant with local regulations  . It has been revealed that unlike channel duty cycle limitation, the duration of receive window affects the throughput for small packet size, SF has a significant impact on the network coverage and LoRaWAN is similar to ALOHA in that its performance degrades rapidly as load increases  . A nearoptimal throughput was reported to be achieved by means of the pure ALOHA protocol and a proposed particle-filterbased retransmission control algorithm BIB004 . Figure 4 illustrates how LoRaWAN supports various applications through three bidirectional classes of communication, as described below  : Class A allows end devices to communicate bidirectionally. This class is supported by all LoRaWAN devices and is compatible with Class B and Class C. Class A operation requires the lowest power end devices. The end devices receive random windows on the DLs. Pure ALOHA is deployed for ULs by devices in this class. Class B end devices have received windows at scheduled times in addition to the random receive windows of Class A. Beacon is used for time synchronization with the server and 