Not sure if this is the right place or even the right question to ask, but googling did not get me much further, so here goes:
I'm trying to assess whether the power consumed by an IoT device, based on (future) 5G technology, will ever come close to the power used by a device based on (current) LoRa technology. For the purpose of this comparison, the use case would be a battery powered device that transmits one small packet per minute.
Experience tells me that there currently is a large difference between technologies. Peak current drawn and total energy used for sending a single packet with LoRa is almost an order of magnitude smaller than with NB-IoT, one of the 3GPP protocols that is promoted as "Ultra Low Power" and part of 5G (and currently part of 4G).
As any google search for power consumption on 4G/5G or LoRa will return mostly vague promises made by marketing people, I have tried to dive a little deeper. The fundamental difference between the technologies lies in the modulation scheme used: PSK/QAM vs CSS.
The way I understand it, CSS (Chirp spread spectrum) spreads the signal in time and frequency, in such a way that in demodulation the effective noise level is reduced significantly, allowing for communication below the noise floor. PSK/QAM requires a signal above the noise floor, plus some margin. This then should explain the difference in the observed power consumption.
As the benefits of CSS come at the cost of reduced spectral efficiency, it may not be a likely choice for the industry, given the high cost of licensed spectrum and the market demand for high datarates. Apart from that, integrating CSS-like modulation within the framework of 3GPP technologies may pose various other obstacles way beyond my limited knowledge. My assumption is that we will not see CSS(-like) modulation within 3GPP standards anytime soon.
So my question is: Do PSK/QAM modulators (e.g. 4G/5G) fundamentally use more power per packet than CSS modulators (e.g. LoRa)? And does that rule out that any 5G module in the foreseeable future will come close to the power consumption of LoRa modules? Am I missing relevant factors in my assessment of 5G/LoRa power consumption?