Low Power Wide Area Networks (LPWAN) are a category of RF communication systems which trade speed for low power consumption and increased transmission distance. Lower power consumption is ideal for battery powered devices if they have very low data bandwidth requirements. Examples include smart water meters, data loggers, lighting control, agriculture sensors and actuators and other low data volume applications. Battery life can be up to 10 years however in practice, it’s less than that.
In addition the transmission distance is significantly increased as does the penetration through walls, concrete slabs and other media. It’s not unusual to see a non-LPWAN system able to communicate one or two floors underground in a carpark (say) yet a LPWAN system will communicate an additional one or two floors further underground in the same carpark. Similarly open air (unobstructed) distance is greatly improved when using LPWAN networks.
Sigfox is another LPWAN platform. It’s a paid subscription and there is coverage in capital, cities, semi major cities and it’s part of a world wide network. It offers similar benefits to the other platforms – penetration, transmission distance, battery life etc. Operation is packet based similar to NB-IoT and LoRaWAN. Technically it’s worth considering however Sigfox’s previous history of financial woes in overseas markets is a concern to long term viability.
Solutions
Solutions are many and varied. Here at Electronics By Design we have designed bespoke circuit board (PCB) solutions for all of the above platforms starting from a clean sheet of paper to a finished product fully approved and ready to sell. This solution does incur significant R&D costs however.
There are many other ways to implement the same solution. Commercial of the shelf (COTS) PCBs are available which carry all the approvals and are ready to use. They can be integrated into existing products and interface through USB or serial port connections or SPI. On many occasions we’ve sourced and integrated such solutions into customer products however they do come at a higher piece price.
The next step up is boxed solutions – modems and gateways – which connect the same way. These are suitable for larger products such as vending machines, parking stations etc.
What is the best option?
If you have a number of LPWAN devices (such as sensors in a building) the best solution is LoRaWAN. You install the sensors and a single private gateway on the premises. The gateway has “free” internet connectivity through the building’s LAN. The cost of the gateway is amortised across many sensors and hence of minimal financial consequence.
If however you only have minimal LPWAN devices (say one or two), the gateway has a significant amortised cost, and hence is not feasible. In this case you need a standalone solution such as NB-IoT. The downside is the requirement for a monthly SIM subscription. This can be as low as 50c for 1K+ quantities or as much as $3 for a few off. Alternatively Sigfox can also be used. No SIM is required and the subscription cost is very affordable.
LoRaWAN can also be used to allow connection to a paid public network but check the coverage maps and spot test it to ensure you have coverage. Each device communicates to the network and is effectively standalone ie a private gateway is not required.
A word of advice – do not use free LoRaWAN networks also called community networks unless your project can tolerate potentially frequent or long term outages. Many gateways on these networks are set up by private individuals residing in houses and they are liable to turn them off when they feel like it. If it’s the only gateway your device has access to, it will lose connectivity.
LoRaWAN public networks that can be used reliably are council and government networks. Newcastle and Gold Coast LGAs have LoRaWAN networks to promote the Smart City concept. Any LoRaWAN device can connect to them and coverage is very good.
