Thank you for a nice article... The “energy per bit” is any day a better indicator of power efficiency than other metrics and this has been raised in other areas like design of high speed motherboards for 100Gb/s ethernet.
One issue that doesn't seem to have been addressed above with respect to power efficiency in a M2M context is the issue of multipath fading...
Drones are, in essence, flying autonomous vehicles. Pros and cons surrounding drones today might well foreshadow the debate over the development of self-driving cars. In the context of a strongly regulated aviation industry, "self-flying" drones pose a fresh challenge. How safe is it to fly drones in different environments? Should drones be required for visual line of sight – as are piloted airplanes? Join EE Times' Junko Yoshida as she moderates a panel of drone experts.