[awelkie]

Sure, but the probability would be low-ish of that happening, and the other system could either switch frequencies or beamform a null in the direction of the interferer if they were also a phased array.

Maybe the EIRP shouldn't be unlimited, but I still think it would be beneficial to encourage spatially selective systems.

[adrian_b]

In an unlicensed band, everyone may have receivers and transmitters, so the probability of other receivers in the same direction as yours is not low at all, but it is very high, unless you live in the middle of nowhere, so you do not have neighbors.

There is no justification for imposing additional costs for others in order to accommodate your desires that do not matter for them.

Nobody stops you to use a phased array antenna only to obtain a higher gain for reception, in order to increase the communication range.

Even without phased array antennas, using just classic directive antennas that are placed on high masts, it is possible to communicate through WiFi at tens of km (but only at low bit rates and not in all countries, as some have more severe EIRP limits).

The problem of directive antennas is that they are usable only for fixed positions of access points and wireless stations.

Phased array antennas are not enough to enable mobility, because initially a mobile wireless station must discover the direction of the AP and the AP must discover the direction of the station, by using omnidirectional transmission, which limits the range to what can be achieved without phased array antennas.

To use a mobile wireless network that works at distances greater than possible with omnidirectional antennas requires much more sophisticated equipment than just the phased array antennas. You also need means to determine the coordinates of each station (and of the access points, if they are also mobile) and maps with the locations of the access points so that a station that wants to associate with them will know in what direction to transmit. You also need a protocol different from standard WiFi, e.g. the access point may need to scan periodically all directions in order to allow new associations from distant stations.

[Dylan16807]

> so the probability of other receivers in the same direction as yours is not low at all, but it is very high

But on average, even with unlimited EIRP, I'll see 1/n as many interfering signals that are each n times as strong. That's not a bad tradeoff.

But having a moderate EIRP increase for focused signals would make things better for everyone. Let's say a signal that's 10x as focused can have 3x the EIRP, and everyone switches their equipment over. That drops the total power output by 3.3x, and interference drops significantly for almost everyone.

> initially a mobile wireless station must discover the direction of the AP and the AP must discover the direction of the station, by using omnidirectional transmission, which limits the range to what can be achieved without phased array antennas

You can do discovery at a lower bit rate to get a big range boost.