3 ms·

But if they are limited the same radiated power (an important caveat placed on the "free for all", in the form of a class license) the MIMO system will be able

by femto 6y ago

But if they are limited the same radiated power (an important caveat placed on the "free for all", in the form of a class license) the MIMO system will be able to get more power focused on its receiver, and within that spatial region overpower the omnidirectional interferer. The omnidirectional transmitter will lose more by not being MIMO than the MIMO system will lose from the interference. MIMO isn't expensive these days with the availability of integrated chip sets, and the cost is only dropping. It will get to the point where apart from broadcasters no one runs a non-MIMO system because the cost of not being MIMO (loss of channel capacity) will exceed the cost of the MIMO hardware.

gruez 6y ago
>The omnidirectional transmitter will lose more by not being MIMO than the MIMO system will lose from the interference. The problem is that you're not competing against another laptop/router that wants to maximize throughput, you're competing against a IoT device (eg. smart fridge, surveillance camera, lowend tablet, etc.) that doesn't give a shit about throughput and will happily tolerate a 50Mb/s (or slower) connection, while taking up the same timeslice/radiative power as every other device.
- femto 6y ago
  Granted that there will be some impact on the MIMO from the Iot device, but it will be lopsided as the MIMO can null out the IoT transmission. It can be looked at in a couple of ways: the IoT is having to spread its power more thinly than the MIMO, so the IoT tx will have less influence on the MIMO receiver than the MIMO tx will, or the MIMO's spatial coding gives a degree of isolation which benefits both the IoT and MIMO devices. There will be a problem if there are a large number of close by IoT devices up against the MIMO, as their smallish contributions will sum up to something big. In that case the MIMO would need to improve its isolation from the IoT device by increasing its number of antennas or the quality of its processing. As a side issue (doesn't really negate your argument), excessive transmission power is a cost for battery powered devices, so at least some of this IoT devices will be motivated to use their transmitted power more wisely. To raise a new front in the argument :-), there is a case to be made that the ability of a device to cause interference isn't actually dominated by the power of its transmission, but by the information content of its transmission. Low information content means the signal is easier to predict and a smart enough receiver can predict the signal and cancel it out, leaving only the desired signal.

by femto 6y ago

gruez 6y ago

>The omnidirectional transmitter will lose more by not being MIMO than the MIMO system will lose from the interference. The problem is that you're not competing against another laptop/router that wants to maximize throughput, you're competing against a IoT device (eg. smart fridge, surveillance camera, lowend tablet, etc.) that doesn't give a shit about throughput and will happily tolerate a 50Mb/s (or slower) connection, while taking up the same timeslice/radiative power as every other device.

femto 6y ago
Granted that there will be some impact on the MIMO from the Iot device, but it will be lopsided as the MIMO can null out the IoT transmission. It can be looked at in a couple of ways: the IoT is having to spread its power more thinly than the MIMO, so the IoT tx will have less influence on the MIMO receiver than the MIMO tx will, or the MIMO's spatial coding gives a degree of isolation which benefits both the IoT and MIMO devices. There will be a problem if there are a large number of close by IoT devices up against the MIMO, as their smallish contributions will sum up to something big. In that case the MIMO would need to improve its isolation from the IoT device by increasing its number of antennas or the quality of its processing. As a side issue (doesn't really negate your argument), excessive transmission power is a cost for battery powered devices, so at least some of this IoT devices will be motivated to use their transmitted power more wisely. To raise a new front in the argument :-), there is a case to be made that the ability of a device to cause interference isn't actually dominated by the power of its transmission, but by the information content of its transmission. Low information content means the signal is easier to predict and a smart enough receiver can predict the signal and cancel it out, leaving only the desired signal.