The low power wide area networks (LPWANs) that have been emerging to support smart city and IoT services are in a fragmented state. The market recently seemed to be consolidating around two cellular options (NB-IoT and LTE-M) and two main unlicensed ones (LoRA and Sigfox), though some specialist choices like Wi-SUN are gaining ground too. But now Amazon threatens to throw a cat among the pigeons with the launch of Sidewalk, a LPWAN protocol to connect sensors over very wide areas, in the unlicensed 868/900 MHz spectrum (where most unlicensed LPWANs also operate). Amazon claims it will differentiate its technology from more established alternatives with its level of security, particularly when it comes to over-the-air updates, harnessing some of the…