I would like to address an aspect of Low-Power, Wide-Area (LPWA) networking that is extremely important yet receives little attention:  capacity.   Capacity is a measure of how many devices a piece of networking infrastructure may support and/or how rich of a data model a network can provide to those devices.

Below are LPWA technology comparisons that either ignore capacity entirely, or use unjustified vendor claims that are often simply based on the amount of addressing space supported.

http://frankrayal.com/2016/06/11/comparative-look-at-lpwa-performance/

http://lora.multitech.com/white-papers/lpwa_white_paper_86003000_2016-06-13.pdf

http://www.eejournal.com/archives/articles/20150907-lpwa/

http://www.eetimes.com/document.asp?doc_id=1328365&page_number=3

These comparisons spend much of their attention on supported link data rates, thus missing the point fundamentally on what a wide area network (WAN) is supposed to do.   A WAN in general is not about delivering data rates to a single endpoint, rather, it is fundamentally about providing high-capacity connectivity to a large number of endpoints.

Here’s an analogy. When you order a pizza, would you be comfortable understanding a range of size of individual pizza slices you might receive (analogous to range of data rates), but giving the pizza parlor full control of the number of slices that they will deliver as well as the sizes of those slices (as long as they are within the stated pizza slice range)?   If this pizza slice scenario makes perfect sense, then these “data rate centric” frameworks are for you.  But, if you’re like me, and prefer ordering a pizza based on the size of the pizza, then you would likely be more comfortable with a different measure – one that examines the “capacity” of the system.  Just as the size of a pizza is indicative of the number of hungry family members that can be satiated (or often over-satiated), capacity is a measure of how many IoT devices may be served by a network based on their data needs.  We should probably have colored the circles more pizza-colored for clarity.  As you can imagine, insufficient capacity means not being able to build a profitable network…or analogously, whether that pizza parlor can stay in business.

If you would like to understand the details behind these calculations,  please check out Appendix A through C of How RPMA Works:  The Making of RPMA.

On a side-note, I was surprised to see RPMA represented as inferior coverage in this framework. We work through the link budget calculations in Section 2.3 of the same document (How RPMA Works:  The Making of RPMA) and make the point that RPMA has a massive coverage advantage.