Visualising Hybrid Beamforming Optimization

[@serrafayaz]

Thanks so much. Always useful 🌸 dear Professor, do you have any video for positioning AoA with regards to beamforming?

[@iain_explains]

The delays between antenna elements directly relate to the angle of arrival. Have you seen this video? "What is Beamforming?" kzbin.info/www/bejne/d2LRZnuerNmtbZo

[@michaelalex5235]

Thanks again Iain! By the way, it would be great to hear your explanation of LoRa communications - modulation and demodulation of chirp spread spectrum (CSS) signals. What I've found out there so far seems a bit murky... Thank you, Michael

[@iain_explains]

Thanks for the suggestion. It's on my "to do" list.

[@stellatauer761]

Thank you, a short question, please. How do we optimize the ABF in that case? I assume we need the channel matrix to both UEs (?) Perhaps we can work with the phase information in these channel matrices. With just one UE, it is clear, we have the phase shifts at every element and we just compensate it. But for more than one UE, I don't know - we have just one phase shifter at every element, so we cannot adapt 2 different phases.

[@iain_explains]

Good questions. Yes, the channel matrix needs to be known. And there need to be seperate phase shifters for each analog beam that needs to be formed - then they need to be added for each antenna. More details here: "What is Hybrid Beamforming?" kzbin.info/www/bejne/rHvVdaeQZ5l-bbM

[@georgepalafox5967]

Hi Sir! Excellent video! Thanks. Q: what are examples of elements in the first "dir" column vector? Meaning what could be contained as elements in thar matrix, e^j? Also, why don't the analog beamformers have an amplifiers? Is that a typical thing? Thanks.

[@iain_explains]

As the carrier frequency goes up, the matching antenna size comes down. Therefore you need more radiating elements to achieve the same overall radiating power. At some point it becomes impractical to implement seperate amplifiers for each radiating element (antenna element). That's when you need hybrid beamforming implementations. More details here: "What is Hybrid Beamforming?" kzbin.info/www/bejne/rHvVdaeQZ5l-bbM

[@jasminnadic2103]

Thanks, to the lower right side, we have this maxtrix operations and you say the first row of the last matrix is matched to the first column of middle matrix (ABF1). I cannot understand exactly how because we multiply the first line of the first matrix with the columns of the second matrix - the whole line w11*x1 w12 *x2 does not stay get to column ABF1, I assume. What do I miss? Thank you.

[@iain_explains]

The elements in the columns of the left hand matrix multiply the elements in the rows of the right hand matrix. This is just a property of general matrix multiplication. Perhaps if you write it out element-by-element, you'll see it.

[@Ticdou777]

Hello Professor, thank you for the video, I have 3 easy questions : Which mathematical method are used to compute ABF ? When ABF is computed and found, it’s values can be put in an analog way in the system (phased values) and how ? Dir 1 = [1 e^1phi1 e^2phi1 e^3phi1 e^(N-1)phi1] N the number of linear radiating elements used to create a beam ? Thank you ! An interested engineering student

[@pitmaler4439]

ABF is done by phase shifters - we just adapt the phase

[@Ticdou777]

@@pitmaler4439 I see, so any choice can be done in phased i imagine

[@pitmaler4439]

@@Ticdou777 yes

[@Ticdou777]

thanks @@pitmaler4439 :)

[@eswyatt]

General question: Can you attain a deep understanding of signal processing without complex analysis?

[@iain_explains]

I think you know the answer already, based on the way you phrased your question. The best way to attain a deep understanding is to watch the videos on my channel. 😁 ... and if you do that, you'll notice that I refer to complex numbers quite a bit. But you'll also find videos that explain the important aspects of complex analysis, as far as signal processing is concerned. It's all there at iaincollings.com