Beamforming (used in MIMO, for example) explained beautifully. Basically it is about controlling the phases and amplitudes of antenna to maximize their sum gain at the location of user device.
Would the ever growing loops shown at 0:34 break down to " half wavelength loops as they move out? What is never mentioned in antenna radiation is whether or not the E/M loops being radiated do break down into loops of half wavelength as the loop try to grow in size with distance, In waveguides and cavity resonators it is common to show the stacking of " half wavelength E/M blocks to fit in the available space. A one megacycle wave, has a much larger loop than a 5 GigaHertz signal and though everyone talks about lobes, and directivity, and efficiency, and so on, no one talks about the "stacking of E/M blocks" the size of which depends on the frequency of transmission. So for a given frequency , how many stacked E/M loops exist in it as the wave moves out? I have thought about this for the last 80 years and it seems to me that when one has a directional antenna, or a phased array, all that is happening the system is cutting off and eliminating the peripheral blocks in the stack of E/M blocks in the lobe or in any omnidirectional antenna, I simulated this with a computer algorithm which, when the circumference ( wavefront) of the wave grew larger than a wavelength integers, then the " circumference would accommodate another loop half a wavelength long". The simulation works beautifully and the patterns that emerge make it so obvious, after I saw it, From a central location of the antenna, after the wave settles down, the patterns seems to change from a "polar diagram" to a cartesian diagram where the four symmetrical squares of cartesian coordinates, simultaneously move out their four quarters containing the same pattern of E/M loops as exist in rectangular waveguides contain the higher modes. When I plotted the B and the E field loops far from the antenna they came out to be exactly as occurs in rectangular waveguides with the B loops as normal, and the E loops are exactly the same as the E in the waveguide and the surface currents in a waveguide, It is exactly the same pattern, So it seems, that a centrally placed antenna as a source, will have the near E/M fields going through "a pushy transient pattern" then "a middle field pattern" which I call the settling down zone, and then the far field would resemble the pattern obtained in a rectangular waveguide excited with an electric probe or a magnetic probe as one desires. It is fascination to see the four quarters of cartesian coordinates moving out with additional loops being added as the distance increases, It is remarkable, This stacking of E/M blocks, the size of half a wavelength, in a radiating pattern, is interesting, and in a phased array or a directional antenna, it seems that all one does is to " phase out the peripheral E/M blocks and donate the power to the other half wavelength E/M blocks remaining in the " stacked lobe" There seems to be more going on in radiation than one thinks, and this "stacking effect" needs further discussion . An analogy may be used by looking at Chladni's figures in vibrating sheets or a Jelly block, and after all our radiating medium is not much different from a jelly or a rubber block with its "own impedance" in how it permits our signals to "accelerate " build and decay and reverse those the E/M loops the size of half a wavelength.ua-cam.com/video/wvJAgrUBF4w/v-deo.html
The AP calculates the location from the clients receiving signal. As you can imagine this calculation needs to repeated for every received packet to achieve consistent performance increase.
Dean Williams Ok thanks. But specifically how does it do this? I'm guessing it's to do with the received signal difference between antenna's but I'm still struggling to understand how an exact direction is determined? Does it beam form in a sweep then see if the client reports an increase in signal at known beamforming directions?
I would assume that the router will periodically (probably several times per second) tweak its delays to move the beam slightly and then get feedback from the receiver about whether doing so boosted or cut the signal. If there was a boost in one direction, then you move the beam that way. If you see a loss in both directions, then the receiver is already in the center of the beam so you leave it where it is.
Interference. You would be increasing the cell, increasing the probability of co-channel interference. Also, doubling the signal (EIRP) by boosting the transmit power, is more complicated than it sounds. You'll need more than double the electricity to power the transmitter to get the +3db. This can put more heat stress on the radio components.
-80 to -65dB? It is mathematically impossible. If those two beams form one stronger signal, the difference is only 3dB, hence it should be -77dB instead. Also, you shouldn't use dBm as it references to mW (milliwatt. That 'm' stands for milliwatt) of the output power. When you do the relative measurement, it should be dB.
I think you are forgetting about the cancellation effect. If your laptop is sitting in a spot where the phase of transmitter one is 180 degrees relative to transmitter 2, you can't recieve anything in theory...
Of course. That's why a beam-forming access point can't just use static parameters. It needs to constantly get feedback from receivers and tweak the delays such that the receivers are kept on-beam. If there are multiple receivers, it is going to need to perform these calculations and change the delay factors on a per-packet basis so each receiver is on-beam for his packets (we don't care if he can receive anyone else's packets) I assume any access point (or AP controller for an enterprise system) is going to have a user limit, since each receiver is going to use up some amount of memory and CPU cycles to manage this and at some point there won't be enough left to add any new receivers to the algorithm.
that strange, both my router and my laptop has 802.11ac(with beamforming tech) and 802.11N(no beamforming). Yet I get much stronger signal with 802.11N :P
This is by far the best explanation of beamforming I've been able to find on UA-cam. Well done!
Beamforming (used in MIMO, for example) explained beautifully. Basically it is about controlling the phases and amplitudes of antenna to maximize their sum gain at the location of user device.
Would the ever growing loops shown at 0:34 break down to " half wavelength loops as they move out?
What is never mentioned in antenna radiation is whether or not the E/M loops being radiated do break down into loops of half wavelength as the loop try to grow in size with distance, In waveguides and cavity resonators it is common to show the stacking of " half wavelength E/M blocks to fit in the available space. A one megacycle wave, has a much larger loop than a 5 GigaHertz signal and though everyone talks about lobes, and directivity, and efficiency, and so on, no one talks about the "stacking of E/M blocks" the size of which depends on the frequency of transmission. So for a given frequency , how many stacked E/M loops exist in it as the wave moves out? I have thought about this for the last 80 years and it seems to me that when one has a directional antenna, or a phased array, all that is happening the system is cutting off and eliminating the peripheral blocks in the stack of E/M blocks in the lobe or in any omnidirectional antenna,
I simulated this with a computer algorithm which, when the circumference ( wavefront) of the wave grew larger than a wavelength integers, then the " circumference would accommodate another loop half a wavelength long".
The simulation works beautifully and the patterns that emerge make it so obvious, after I saw it, From a central location of the antenna, after the wave settles down, the patterns seems to change from a "polar diagram" to a cartesian diagram where the four symmetrical squares of cartesian coordinates, simultaneously move out their four quarters containing the same pattern of E/M loops as exist in rectangular waveguides contain the higher modes. When I plotted the B and the E field loops far from the antenna they came out to be exactly as occurs in rectangular waveguides with the B loops as normal, and the E loops are exactly the same as the E in the waveguide and the surface currents in a waveguide, It is exactly the same pattern,
So it seems, that a centrally placed antenna as a source, will have the near E/M fields going through "a pushy transient pattern" then "a middle field pattern" which I call the settling down zone, and then the far field would resemble the pattern obtained in a rectangular waveguide excited with an electric probe or a magnetic probe as one desires. It is fascination to see the four quarters of cartesian coordinates moving out with additional loops being added as the distance increases, It is remarkable,
This stacking of E/M blocks, the size of half a wavelength, in a radiating pattern, is interesting, and in a phased array or a directional antenna, it seems that all one does is to " phase out the peripheral E/M blocks and donate the power to the other half wavelength E/M blocks remaining in the " stacked lobe" There seems to be more going on in radiation than one thinks, and this "stacking effect" needs further discussion . An analogy may be used by looking at Chladni's figures in vibrating sheets or a Jelly block, and after all our radiating medium is not much different from a jelly or a rubber block with its "own impedance" in how it permits our signals to "accelerate " build and decay and reverse those the E/M loops the size of half a wavelength.ua-cam.com/video/wvJAgrUBF4w/v-deo.html
Best 3 minute video that I found explaining beamforming. Thank you
that was a cool illustration. i finally understand beamforming.
This was explained so well. Thank you.
good explanation
This is great. Thanks!
How does the router know the direction to beam form in? Is it able to use multiple antenna to sense too?
The AP calculates the location from the clients receiving signal. As you can imagine this calculation needs to repeated for every received packet to achieve consistent performance increase.
Dean Williams Ok thanks. But specifically how does it do this? I'm guessing it's to do with the received signal difference between antenna's but I'm still struggling to understand how an exact direction is determined? Does it beam form in a sweep then see if the client reports an increase in signal at known beamforming directions?
I would assume that the router will periodically (probably several times per second) tweak its delays to move the beam slightly and then get feedback from the receiver about whether doing so boosted or cut the signal. If there was a boost in one direction, then you move the beam that way. If you see a loss in both directions, then the receiver is already in the center of the beam so you leave it where it is.
Yes, I think it just use the same phase shift as whipe receiving.
@@Shamino0 there is no feedback from client about signal level.
Great explanation Thanks
great haircut
I was thinking the same thing. I really don't understand the point of beam forming. why run 2 transmitters at x power when you can run 1 at 2x power?
Interference. You would be increasing the cell, increasing the probability of co-channel interference. Also, doubling the signal (EIRP) by boosting the transmit power, is more complicated than it sounds. You'll need more than double the electricity to power the transmitter to get the +3db. This can put more heat stress on the radio components.
thank you.
good visual
-80 to -65dB? It is mathematically impossible. If those two beams form one stronger signal, the difference is only 3dB, hence it should be -77dB instead. Also, you shouldn't use dBm as it references to mW (milliwatt. That 'm' stands for milliwatt) of the output power. When you do the relative measurement, it should be dB.
Thanks for the video, it was very concise and helpful =)
I think you are forgetting about the cancellation effect. If your laptop is sitting in a spot where the phase of transmitter one is 180 degrees relative to transmitter 2, you can't recieve anything in theory...
Of course. That's why a beam-forming access point can't just use static parameters. It needs to constantly get feedback from receivers and tweak the delays such that the receivers are kept on-beam.
If there are multiple receivers, it is going to need to perform these calculations and change the delay factors on a per-packet basis so each receiver is on-beam for his packets (we don't care if he can receive anyone else's packets)
I assume any access point (or AP controller for an enterprise system) is going to have a user limit, since each receiver is going to use up some amount of memory and CPU cycles to manage this and at some point there won't be enough left to add any new receivers to the algorithm.
cool tech
how does the app know the location of the device
that strange, both my router and my laptop has 802.11ac(with beamforming tech) and 802.11N(no beamforming). Yet I get much stronger signal with 802.11N :P
AC is shit for range
11ac uses 5GHz band, while 11n uses 2.4GHz band. 5GHz band "penetrates" the surroundings much harder than 2.4GHz.
Beam forming was part of the 802.11n standard. This does not mean that every "n" device used it.
hey hackers im telling
susan