If you’re familiar with the Internet of Things, you know that there are an almost overwhelming number of IoT connectivity options. From Wi-Fi to Bluetooth, NB-IoT to CAT-M1, and LoRA to RPMA, it’s difficult to understand them all, let alone which is best for your specific IoT application.
Every IoT application has its own unique requirements, so the IoT connectivity option that’s amazing for one application may be awful for another. Your application may have thousands of remote sensors, so battery life is a critical consideration. Your application may need to send lots of data, like video, so high-bandwidth is essential. Or your application may involve life-or-death decisions, so time is the primary consideration. That’s why it’s crucial to choose the best IoT connectivity option for your specific needs.
In this series, we’ll provide the definitive guide to a class of IoT connectivity known as LPWAN (low-power wide-area networks). This first post will provide an overview of LPWAN, including what it is and the benefits of LPWAN technology compared to other IoT connectivity options. In subsequent posts we’ll take a deeper dive and examine the various LPWAN options and players in the space.
Ultimately, you’ll know whether LPWAN is right for your IoT application and, if it is, how to best move-forward.
The first thing to understand is that LPWAN (Low Powered Wide Area Network) is NOT a standard. It’s a broad term encompassing various implementations and protocols, both proprietary and open-source, that share common characteristics as the name suggests:
Low power: Operates on small, inexpensive batteries for years
Wide area: Has an operating range that is typically more than 2 km in urban settings
A physical limitation to achieve low power and wide range is small data size. Most LPWAN technologies can only send less than 1,000 bytes of data per day or less than 5,000 bits per second.
The above characteristics make LPWAN an excellent choice for the following classes of IoT applications:
Dense locations: cities or big buildings for smart lighting, smart grid, and asset tracking
Long term monitoring: sensors and meters to be installed and monitored over a long period of time (e.g. water metering, gas detectors, smart agriculture, and remote door locks).
Simply put, LPWAN technology works well in situations where devices need to send small data over a wide area while maintaining battery life over many years. This distinguishes LPWAN from other wireless network protocols like Bluetooth, RFID, cellular M2M, and ZigBee, shown below with regards to bandwidth and range capability.
Cellular networks suffer primarily from poor battery life and may have gaps in coverage. Another difficulty is technology sunsetting (when a technology is intentionally phased out): there are 30 million 2G endpoints in the US orphaned by sunsetting. Many of the IoT devices must remain on the network for 10 years. It doesn’t make economic sense if a cellular network is sunset and no longer supports the devices.
Most notable aspects of cellular LPWA are still under development. As mentioned with cellular networks above, technology sunsetting is a huge concern. Cat-0 was touted as a long-term solution, only to fall victim to sunsetting.
There’s active research into LTE-M, NB-IoT, EC-GSM, and 5G IoT, but none of them are cross-compatible and the jury is still out on whether they will be suitable for long-term IoT solutions. Initial versions of LTE-M are being rolled out now by AT&T and Verizon so the space is definitely heating up.
Mesh networks like ZigBee are being used in IoT applications. In fact, many home automation systems deploy ZigBee, but ZigBee isn’t an ideal fit for LPWA applications. Mesh networks are only useful at medium distances and don’t have the long-range capabilities of LPWAN technologies.
More importantly, mesh networks aren’t battery efficient because each node must constantly receive and repeat the neighboring RF signals. When sensors scale to the thousands, ZigBee or other mesh networks don’t adequately fit the needs of LPWA applications.
Local RF includes Bluetooth and NFC, but these options simply don’t have the range to be useful for many IoT applications.
Stay tuned for part 2! We’ll examine the various LPWAN technologies and players, providing an overview of their varying pros and cons.