###### Abstract  
Low-power wide area network (LPWAN) technologies as part of IoT are gaining a lot of attention as they provide affordable communication over large areas. LoRa and Sigfox as part of LPWAN have emerged as highly effective and promising non-3 GPP unlicensed band IoT technologies while challenging the supremacy of cellular technologies for machine-to-machine-(M2M)-based use cases. This paper presents the design goals of LoRa and Sigfox while throwing light on their suitability in congested environments. A practical traffic generator of both LoRa and Sigfox is introduced and further interpolated for understanding simultaneous operation of 100 to 10,000 such nodes in close vicinity while establishing deep understanding on effects of collision, re-transmissions, and link behaviour. Previous work in this field have overlooked simultaneous deployment, collision issues, effects of re-transmission, and propagation profile while arriving at a number of successful receptions. This work uses packet error rate (PER) and delivery ratio, which are correct metrics to calculate successful transmissions. The obtained results show that a maximum of 100 LoRa and 200 Sigfox nodes can be deployed in a fixed transmission use case over an area of up to 1 km. As part of the future scope, solutions have been suggested to increase the effectiveness of LoRa and Sigfox networks. LoRa; Sigfox; Packet Error Rate; LPWAN +
Footnote †: journal: _Sensors_  
0000-0001-6000-0000-0000-0000-0000-0000-0000-0000-0000-0000-0000-0000-0000-0000  
low bandwidth using unlicensed bands. LoRa uses chirp spread spectrum (CSS), which provides strong resistance against noise, interference, and multipath fading effects. LoRa and Sigfox provide a platform for numerous widespread use cases such as smart agriculture, positioning, wearable, and other smart city applications replacing conventional mobile networks like 2G, 3G, 4G, and 5G, which consume higher energy and are capital intensive due to higher spectrum costs [12]. LoRa, developed by Semtech, uses the CSS technique to spread a narrow band signal over the full channel bandwidth, while Sigfox uses differential binary phase-shift keying (DBPSK) in industrial, scientific, and medical (ISM) radio bands. Both techniques increase the distance of signal while reducing power consumption as they are narrow band and thus sacrifice on data rate to enable larger distances with longer battery life [13; 14]. LoRa uses LoRAWAN at the medium access control (MAC) layer, which makes use of ALOHA as a random access technique, while Sigfox uses random frequency time division multiple access (RFTDMA) for channel access. Both techniques transmit in a random and uncoordinated fashion, thus any increase in the number of IoT devices will lead to an exponential increase in collisions. LoRa and Sigfox technologies promote fair usage of ISM band [15]. Sigfox is both the manufacturer and network operator for its devices [16]; its network is currently deployed in Europe. LoRa, on the other hand, has been deployed across continents as the MAC of LoRa can be operated by telecommunication service providers (TSP). Multiple configurable parameters of LoRa, such as spreading factor (SF), bandwidth (BW), coding rate (CR), transmission power (TP), and message length, can be tweaked in order to decrease the packet error rate (PER), thus providing a reliable communication environment for successful transmission. Figure 1 depicts the deployment of LoRa and Sigfox, wherein sensors are connected to LoRa/Sigfox nodes and sensor data are transmitted to the LoRa/Sigfox gateway through the radio network. Since LoRa/Sigfox are not just connected to a single gateway, multiple gateways are able to receive this communication, which is then forwarded to the LoRa server maintained by the telecommunications company, or LoRaWAN. At this point, duplicate copies of the same message are filtered out and finally passed to the application server maintained by the network provider.