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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

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 2y ago
> 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.
- adrian_b 2y ago
  For a radio receiver it is irrelevant how many interfering signals exist. The only things that matter are the radiant intensity (i.e. power per solid angle) of the interfering transmitter and the percentage of the time when that transmitter is active. A single interfering transmitter with high radiant intensity (a.k.a. EIRP) will blind the radio receiver for all the time when it is active. Doing discovery at a low bit rate is fine, but that means that your fancy phased array antenna cannot achieve any higher distance for communication than an omnidirectional antenna, but it can only increase the achieved bit rate at a given distance. That would be OK, except that it is achieved by interfering with your neighbors, exactly like when using a transmitter with a higher total power than allowed. Limiting EIRP is the right thing to do in order to limit the interference that you can cause to your neighbors. The law does not stop you to use a phased array antenna or any other kind of directive antenna, with the purpose of lowering the power consumption of your transmitter, while maintaining the same quality for your communication and the same interference for your neighbors. What you want to do, i.e. increase the interference for your neighbors, is the wrong thing to desire. If that were allowed, your neighbors would also increase the radiant intensity of their transmitters and then everybody would have worse reception conditions and you would gain nothing. The hope that only you will increase your radiant intensity and your neighbors will not, is of course illusory.
  - Dylan16807 2y ago
    > For a radio receiver it is irrelevant how many interfering signals exist. > The only things that matter are the radiant intensity (i.e. power per solid angle) of the interfering transmitter and the percentage of the time when that transmitter is active. And if a transmitter isn't pointed at you, then it isn't an interfering transmitter. This is a crucial factor in the math. Or for a more realistic analysis of directionality, the radiant intensity is only high for a small fraction of observers, and is very low for the rest of them. In the first scenario I talked about, total interference is probably the same. In the second, total interference is almost always much less. > A single interfering transmitter with high radiant intensity (a.k.a. EIRP) will blind the radio receiver for all the time when it is active. If a moderate boost blinds the receiver, then the alternative is being almost blind for much longer (because there are more interfering transmitters), so I'm not convinced that's a problem. > Doing discovery at a low bit rate is fine, but that means that your fancy phased array antenna cannot achieve any higher distance for communication than an omnidirectional antenna, but it can only increase the achieved bit rate at a given distance. I don't understand what you mean. If you don't care about speed, the maximum distance is the same for both antennas, and is defined by obstacles alone. You can always slow down to compensate for a lack of gain. And it's a proportional slowdown, not very expensive. Especially when you only need to send a beacon that's a few bytes long to initiate contact. Just some example numbers: Your functional requirements are 1Mbps of bandwidth with pretty tight focus. You send the few bytes of initial omnidirectional contact at 1Kbps. Your slow omnidirectional signal actually reaches further than your fast focused signal. > Limiting EIRP is the right thing to do in order to limit the interference that you can cause to your neighbors. If your only concern is the worst case of everyone being pointed at the same spot, yes. In normal situations the average level of interference matters more. > The law does not stop you to use a phased array antenna or any other kind of directive antenna, with the purpose of lowering the power consumption of your transmitter, while maintaining the same quality for your communication and the same interference for your neighbors. The law says that I can maintain quality and decrease interference, but I don't gain any real benefit because I'm only saving half a watt. So I'm not very motivated to do so. I'd prefer if it was legal to split the difference between increased signal quality and somewhat decreased interference. > What you want to do, i.e. increase the interference for your neighbors, is the wrong thing to desire. Where do you think I said that? Edit: > your neighbors would also Here, I'll elaborate on a scenario. Originally, me and my 6 neighbors are all transmitting omnidirectionally and causing 1 unit of interference to each other person. Everyone gets 6 units of interference. I want to lower my transmit power but double my EIRP. I am entirely selfishly motivated, and just want a better signal to my devices. As a consequence I will now cause 2 units of interference to a single neighbor, and 0.1 units of interference to all other neighbors. What happens when everyone thinks this way and does the same thing? Well now the neighborhood receives 2.5 units of interference on average instead of 6. Even with a bit of variance as devices move around, everyone is better off now. I love that my neighbors did the same thing I did.

Dylan16807 2y ago

> 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.

adrian_b 2y ago
For a radio receiver it is irrelevant how many interfering signals exist. The only things that matter are the radiant intensity (i.e. power per solid angle) of the interfering transmitter and the percentage of the time when that transmitter is active. A single interfering transmitter with high radiant intensity (a.k.a. EIRP) will blind the radio receiver for all the time when it is active. Doing discovery at a low bit rate is fine, but that means that your fancy phased array antenna cannot achieve any higher distance for communication than an omnidirectional antenna, but it can only increase the achieved bit rate at a given distance. That would be OK, except that it is achieved by interfering with your neighbors, exactly like when using a transmitter with a higher total power than allowed. Limiting EIRP is the right thing to do in order to limit the interference that you can cause to your neighbors. The law does not stop you to use a phased array antenna or any other kind of directive antenna, with the purpose of lowering the power consumption of your transmitter, while maintaining the same quality for your communication and the same interference for your neighbors. What you want to do, i.e. increase the interference for your neighbors, is the wrong thing to desire. If that were allowed, your neighbors would also increase the radiant intensity of their transmitters and then everybody would have worse reception conditions and you would gain nothing. The hope that only you will increase your radiant intensity and your neighbors will not, is of course illusory.
- Dylan16807 2y ago
  > For a radio receiver it is irrelevant how many interfering signals exist. > The only things that matter are the radiant intensity (i.e. power per solid angle) of the interfering transmitter and the percentage of the time when that transmitter is active. And if a transmitter isn't pointed at you, then it isn't an interfering transmitter. This is a crucial factor in the math. Or for a more realistic analysis of directionality, the radiant intensity is only high for a small fraction of observers, and is very low for the rest of them. In the first scenario I talked about, total interference is probably the same. In the second, total interference is almost always much less. > A single interfering transmitter with high radiant intensity (a.k.a. EIRP) will blind the radio receiver for all the time when it is active. If a moderate boost blinds the receiver, then the alternative is being almost blind for much longer (because there are more interfering transmitters), so I'm not convinced that's a problem. > Doing discovery at a low bit rate is fine, but that means that your fancy phased array antenna cannot achieve any higher distance for communication than an omnidirectional antenna, but it can only increase the achieved bit rate at a given distance. I don't understand what you mean. If you don't care about speed, the maximum distance is the same for both antennas, and is defined by obstacles alone. You can always slow down to compensate for a lack of gain. And it's a proportional slowdown, not very expensive. Especially when you only need to send a beacon that's a few bytes long to initiate contact. Just some example numbers: Your functional requirements are 1Mbps of bandwidth with pretty tight focus. You send the few bytes of initial omnidirectional contact at 1Kbps. Your slow omnidirectional signal actually reaches further than your fast focused signal. > Limiting EIRP is the right thing to do in order to limit the interference that you can cause to your neighbors. If your only concern is the worst case of everyone being pointed at the same spot, yes. In normal situations the average level of interference matters more. > The law does not stop you to use a phased array antenna or any other kind of directive antenna, with the purpose of lowering the power consumption of your transmitter, while maintaining the same quality for your communication and the same interference for your neighbors. The law says that I can maintain quality and decrease interference, but I don't gain any real benefit because I'm only saving half a watt. So I'm not very motivated to do so. I'd prefer if it was legal to split the difference between increased signal quality and somewhat decreased interference. > What you want to do, i.e. increase the interference for your neighbors, is the wrong thing to desire. Where do you think I said that? Edit: > your neighbors would also Here, I'll elaborate on a scenario. Originally, me and my 6 neighbors are all transmitting omnidirectionally and causing 1 unit of interference to each other person. Everyone gets 6 units of interference. I want to lower my transmit power but double my EIRP. I am entirely selfishly motivated, and just want a better signal to my devices. As a consequence I will now cause 2 units of interference to a single neighbor, and 0.1 units of interference to all other neighbors. What happens when everyone thinks this way and does the same thing? Well now the neighborhood receives 2.5 units of interference on average instead of 6. Even with a bit of variance as devices move around, everyone is better off now. I love that my neighbors did the same thing I did.