Wide area networks get your data across a site or between sites. The ‘low power’ part means transmitters can be battery powered and still last for weeks or months.
New LPWAN technologies have become available that operate at low power, low cost compared to traditional mobile networks. There range varies from 2km to 1,000km depending on the technology. The caveat is that low power also means small amounts of data that are not sent very often. This means that while it’s great for sensing, it’s not suitable for sending media such as images and video.
LPWANs are either cellular or use unlicensed, free wireless frqeuencies. Cellular comes as either LTE category M1 and Narrowband Internet of Things (NB-IoT) offered by the traditional network operators. Being a commercial offering, it costs but is generally reliable. Wireless LPWANs use unlicensed frequency bands using open standard or proprietary protocols.
Sigfox and LoRa are the most common wireless LPWANs. Sigfox uses 868 MHz or 902 MHz bands and only one operator is allowed per country. Messages can reach 35-50km in open areas and 3-10km in cities areas. Sigfox is limited to 150 messages at 12 bytes per day. LoRa uses the 433 MHz, 868 MHz (Europe) and 915 MHz (North America) bands and has a range up to 10Km in open areas.
LoRa is particularly attractive to SMEs because there are no subscription fees and it doesn’t depend on a particular country’s rollout of NB-IoT and Sigfox that have been slow in many countries. Commercial nodes, modules and gateways are also readily available and relatively inexpensive. Unlike commercial services such as NB-IoT, the downside is that communication isn’t guaranteed because there can be contention for the same frequencies. This doesn’t matter for many implementations because if data isn’t received it’s usually received on the next future transmission. If you need guaranteed transmission you will need a commercial, subscription NB-IoT or Sigfox service.
Most LPWAN networks don’t work in isolation and tend to be used with other networking technologies such as Bluetooth, Ethernet and WiFi.