The argument for LPWAN in the Internet of Things

Range, power consumption, data rate - pick any two...

 

There are laws of physics in play here and nobody breaks the laws of physics. Not even Einstein and certainly not IoT connectivity companies. The three basic parameters - power consumption, range and data rate - are interrelated. It’s an inconvenient truth but it’s reality and that's that.

 

Short range, low cost, long battery life

 

So what does the landscape look like? We have short range (metres) PAN and LAN technologies like Bluetooth and Wi-Fi offering very low power consumption and high data rates. Very good - but the Internet of Things (IoT) needs wide area connectivity - networks across cities, not across the office. Bluetooth and Wi-Fi might well become the dominant IoT connectivity tech for the home and office where connectivity above a few metres is unnecessary. For longer range applications, look elsewhere…

 

Long range, high cost, short battery life

 

How about GSM - GPRS, 3G, LTE, 5G? These technologies operate over several kilometres. They also offer high data rate comms so voice and video streaming are possible. Brilliant, if you need voice or video streaming. Hint: you almost certainly don’t. GPRS modems cost around US$10. 3G modems cost US$25 and LTE modems are up around US$50. And 

 

So how about the lower cost LTE-M variants? LTE-M Cat 1 networks and devices might be available in 2016 but they don’t get close to LPWAN for cost or power consumption. Wait for LTE-M Cat 0 then? Release 13 of the LTE-M specification will not be with us until at least 2017, more likely 2018. And it still won’t compete with LPWAN on either cost or power consumption. You can optimise a design forever and still not compete with a technology developed explicitly for the application – that’s why LPWAN makes sense now and in the future.

 

LPWAN, LP Want

 

And so we come to the third option, low power, wide area network (LPWAN) technology. You get signal propagation characteristics enabling networks with an urban range measured in kilometres married to power consumption figures that enable battery powered endpoints to carry on working for years, not days or weeks - a utopian Shangri-La! And then there’s the cost – it’s in the same ballpark as Bluetooth. Low cost endpoints, low cost base stations, low cost networks. And all because LPWAN is optimised for the IoT where data rate is less important than range, battery life or cost. A Weightless-N network will enable a mean data rate of 30kbits/s (higher peak) which exceeds the requirements of the majority of IoT use cases. 

 

It's no surprise then to find several LPWAN connectivity technologies emerging as contenders in the IoT space - all of them proprietary except for Weightless. We'll find out next week why that's important. And then we’ll look in detail at cost, range and battery life in a Weightless IoT system.

 

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