4 ms·

It also wouldn't be trivial from the hardware side. LoRa/NB-IoT/long-range low-speed low-power protocols generally use ISM band of 915 MHz in US and 800 somethi

It also wouldn't be trivial from the hardware side. LoRa/NB-IoT/long-range low-speed low-power protocols generally use ISM band of 915 MHz in US and 800 something MHz, with some using 400 ish MHz. That will physically require a completely separate RF path than the 2.45 GHz and 5.8 GHz which WiFi uses. (No, even "integrated wideband transceivers" like AD936x have 1) unusably bad isolation and 2) filtering requirements) This is also disregarding that "a few extra modulation schemes" is costly to implement. Narrow band schemes (like GMSK) are incompatible with wide band protocols like LoRa or WiFi with spread spectrum/chipping or OFDM. (at least if you are interested in the same performance to price ballpark) Of course many things nowadays use digital baseband so it's in theory flexible, but the front end is still a major limiting factor, unless you use many-GHz RFADC/DAC which still suffer from wide vs narrow band problems. Also, most long range protocols are meant for ultra low power applications like smart-ag or energy harvesting which WiFi does not support. Considering the existing amount of congestion with WiFi, if we want to increase range further, we'd likely need more chipping codes to fit in the same frequency allocation, which will increase the noise floor for everybody, thus reducing the range... etc

londons_explore 3y ago
You'd run the whole thing over the same 2.4G/5G 20/40/80 Mhz channels as wifi, but probably using a gold-code scheme. You'd pre-arrange what code you'll use (perhaps derived from the base station mac address so there aren't collisions even across a city). Simulations would have to be done of high bandwidth close-by unencoded and low bandwidth long distance coded users coexisting, and defining a fairish sharing scheme between them. The whole thing could probably be implemented with only custom firmware (ie. no hardware changes). All modern GPS's do below-noise-floor reception of GPS signals entirely in software - this would be the same. You might want custom hardware to avoid the rather huge power costs of leaving the main high bandwidth receivers being turned on the whole time though! You could use the same MIMO mechanisms to get a better channel gain and increase the total amount of data users can transfer in a given city-sized area.

londons_explore 3y ago

You'd run the whole thing over the same 2.4G/5G 20/40/80 Mhz channels as wifi, but probably using a gold-code scheme. You'd pre-arrange what code you'll use (perhaps derived from the base station mac address so there aren't collisions even across a city). Simulations would have to be done of high bandwidth close-by unencoded and low bandwidth long distance coded users coexisting, and defining a fairish sharing scheme between them. The whole thing could probably be implemented with only custom firmware (ie. no hardware changes). All modern GPS's do below-noise-floor reception of GPS signals entirely in software - this would be the same. You might want custom hardware to avoid the rather huge power costs of leaving the main high bandwidth receivers being turned on the whole time though! You could use the same MIMO mechanisms to get a better channel gain and increase the total amount of data users can transfer in a given city-sized area.