Low-power wide area networks (LPWANs), Zigbee and Wi-Fi are radio communication technologies using licensed and license-free bands of the radio waves frequency range in the electromagnetic spectrum and are especially developed for the IoT applications and Local Area Networks (LANs).
Zigbee and Wi-Fi are technologies for short-range wireless data transmission within the IEEE 802.15.4 and IEEE 802.11 families of standards. Zigbee covers 50 metre typically but can vary between 10m and 100m and Wi-Fi is usually designed for short-range up to 100m (although long-distance Wi-Fi with a range of several kms is also possible). LPWANs are medium- to long-range cellular radio networks devised especially for IoT applications.
LPWANs and ZigBee are designed for small data transactions with data transmission rates in the region of 100 bps and 250 kbps respectively. The extremely low data rate and use of a very narrow transmission band are the two main features of LPWANs achieving a very long range covering a wide area. The data transmission rates of Wi-Fi can theoretically reach several Gbps. In real life situation however, they range from 3.3 Mbps to 9.8 Mbps (13 to 39 times that of ZigBee) depending on internal attenuation and interferences in a building.
Analogous to the small data rates of LPWANs and ZigBee their devices have a low power consumption by enabling long battery life ranging from months to years. For example, the energy use per hour for a hub connected to ZigBee is 20 mJ which corresponds to 0.56 * 10-5 watt, whereas the energy use per hour for a laptop connected to Wi-Fi is 2kJ which corresponds to 0.56 watt. Although, new low-power Wi-Fi modules have been introduced in the markets that support the IEEE 802.11 protocol.
An IoT application well-suited to LPWAN technology is the electricity smart reader fixed to the outside wall of my house enabling meter readings to be transmitted directly to my electricity provider without my interference. The remote temperature monitoring device in my kitchen is a good example of a ZigBee system where the sensor outside sends data of outside temperature and air pressure to the display interface in the kitchen. Also, my friend uses a ZigBee hub at home as a translation gateway between his broadband router and cameras inspecting the boundaries of his property. The infrastructure mode Wi-Fi network of a hospital enables patients and their visitors to gain access to the internet.