I always feel like optimization of both precoding matrixec(dig beamforming) and analog phase delays(analog beam) is lead to same conclusion but in more complex manner. Only codebook precoding make sense for me: If you found the best PMI (precode matrix) already, try to make it even better with analog beamforming ''fine tunning".
Hi, Sir. About the second picture (fully-connected hybrid antenna array), in many published papers, especially the papers about MU-MIMO, the "analog beamformer/beamforming" and ''digital beamformer/beamforming" are termed as "analog precoder/precoding" and "digital precoder/precoding", respectively. Is that OK/rational?
Yes, "precoding" is a generic term for this, but it can sometimes confuse people because "coding" is normally associated with digital encoding (either source coding or channel coding).
Do I understand right, you can sum the phases from the 2 streams together (lower picture) and still get the desired beams? Without that summation it is clear that you get 2 beams to the 2 users. Thank you.
When the two "individual beams" are summed together it produces a single "overall beam shape", but the fact that it was constructed in this particular way means that the two data streams are effectively being "beam formed" within the "overall beam shape" (intuitively speaking).
Thank You. In the RF chain bettween the digital- and the analog-beamformer, there needn't to be a mixer? I believe tthat I have seen mixers in similar pictures -> to mix the signal to the transmission frequency prior to the analog beamforming. Obviously there are also cases without that.
Yes, you're right, I didn't show the mixers. Typically we tend to do most of our thinking at "baseband", since the up-conversion and down-conversion are generally simple direct operations that don't change the "digital signal" characteristics (at least that's the typical case). See these videos for more details: "How are Complex Baseband Digital Signals Transmitted?" ua-cam.com/video/0lkRJgnywkg/v-deo.html and "What is a Baseband Equivalent Signal in Communications?" ua-cam.com/video/etZARaMNN2s/v-deo.html
Hi professor, thank you for the video. Is the second pic actually describing the concept of Zero forcing BF concept but in a specific implementation view of hybrid BF? The ZF precoding matrix seems to be decomponented into two parts: first part is the digital weghts precoding for each stream input and multiple ant outputs. second part is the sum of the precoded ant outputs as shown by analog part. Is my understanding correct?
Not really. This structure limits what you can achieve in the precoder (since you don't have the full degrees of freedom in the digital part). It doesn't have to be ZF that you are trying to implement. It's the same for other precoder types as well. See: "How are Matched Filter (MF), Zero Forcing (ZF), and MMSE Related?" ua-cam.com/video/U3qjVgX2poM/v-deo.html and "How are Beamforming and Precoding Related?" ua-cam.com/video/iMIqEpzxN9Y/v-deo.html
Thank you for the good lecture! I have two questions. Should I use the upper example only for single user beamforming? (why the below structure is for multi users?) Unlike analog beamforming, digital beamforming doesn't make sense easily. Is it impossible to visualize it easily?
Yes you're right, you could use the upper structure for sending to multiple users (as well as the bottom structure), but for the same number of antennas, you have more restricted beam shape possibilities. And yes, "digital beamforming" is a topic that's already on my "to do" list. I just need to find the time. 😥
They are phase changes of 0, 180, 90 and -90 degrees respectively. Hopefully this video helps: "How do Complex Numbers relate to Real Signals?" ua-cam.com/video/TLWE388JWGs/v-deo.html
Analog beamforming only allows the phases of each antenna to be varied, which limits the range of beam patterns that can be formed, compared to digital beamforming which can vary both the phase and the amplitude and allows more beam pattern design options.
Please, don’t do that again. I was more worried at you not paying attention at the road than anything else. Humanity can’t afford to lose the likes of you! 😉😂 Thanks for the video!!!
I always feel like optimization of both precoding matrixec(dig beamforming) and analog phase delays(analog beam) is lead to same conclusion but in more complex manner.
Only codebook precoding make sense for me:
If you found the best PMI (precode matrix) already, try to make it even better with analog beamforming ''fine tunning".
Nicely explained
please could you make a video about Egalisation aveugle base CAM
Hi, Sir. About the second picture (fully-connected hybrid antenna array), in many published papers, especially the papers about MU-MIMO, the "analog beamformer/beamforming" and ''digital beamformer/beamforming" are termed as "analog precoder/precoding" and "digital precoder/precoding", respectively. Is that OK/rational?
Yes, "precoding" is a generic term for this, but it can sometimes confuse people because "coding" is normally associated with digital encoding (either source coding or channel coding).
Do I understand right, you can sum the phases from the 2 streams together (lower picture) and still get the desired beams?
Without that summation it is clear that you get 2 beams to the 2 users. Thank you.
When the two "individual beams" are summed together it produces a single "overall beam shape", but the fact that it was constructed in this particular way means that the two data streams are effectively being "beam formed" within the "overall beam shape" (intuitively speaking).
Thank You. In the RF chain bettween the digital- and the analog-beamformer, there needn't to be a mixer? I believe tthat I have seen mixers in similar pictures -> to mix the signal to the transmission frequency prior to the analog beamforming. Obviously there are also cases without that.
Yes, you're right, I didn't show the mixers. Typically we tend to do most of our thinking at "baseband", since the up-conversion and down-conversion are generally simple direct operations that don't change the "digital signal" characteristics (at least that's the typical case). See these videos for more details: "How are Complex Baseband Digital Signals Transmitted?" ua-cam.com/video/0lkRJgnywkg/v-deo.html and "What is a Baseband Equivalent Signal in Communications?" ua-cam.com/video/etZARaMNN2s/v-deo.html
Hi professor, thank you for the video. Is the second pic actually describing the concept of Zero forcing BF concept but in a specific implementation view of hybrid BF? The ZF precoding matrix seems to be decomponented into two parts: first part is the digital weghts precoding for each stream input and multiple ant outputs. second part is the sum of the precoded ant outputs as shown by analog part. Is my understanding correct?
Not really. This structure limits what you can achieve in the precoder (since you don't have the full degrees of freedom in the digital part). It doesn't have to be ZF that you are trying to implement. It's the same for other precoder types as well. See: "How are Matched Filter (MF), Zero Forcing (ZF), and MMSE Related?" ua-cam.com/video/U3qjVgX2poM/v-deo.html and "How are Beamforming and Precoding Related?" ua-cam.com/video/iMIqEpzxN9Y/v-deo.html
Thank you for the good lecture! I have two questions. Should I use the upper example only for single user beamforming? (why the below structure is for multi users?)
Unlike analog beamforming, digital beamforming doesn't make sense easily. Is it impossible to visualize it easily?
Yes you're right, you could use the upper structure for sending to multiple users (as well as the bottom structure), but for the same number of antennas, you have more restricted beam shape possibilities. And yes, "digital beamforming" is a topic that's already on my "to do" list. I just need to find the time. 😥
thank you, sir !! you just save my final exam. :)
I'm glad you found the video helpful, and useful for your exam. That's great to hear.
I don't understand what 1, -1, j and -j really mean in precoding codebook ..
They are phase changes of 0, 180, 90 and -90 degrees respectively. Hopefully this video helps: "How do Complex Numbers relate to Real Signals?" ua-cam.com/video/TLWE388JWGs/v-deo.html
@@iain_explains
Thank you.. so 1 and -1 mean the two signals cancel out ?
Yes.
@@iain_explains
Thank you
Thanks, great video 👏
Glad you liked it!
Pl explain about beam forming Algorithms
Some details can be found here: "What are Spatial Diversity and Spatial Multiplexing in MIMO?" ua-cam.com/video/MNA0xn7EeyY/v-deo.html
Why must the "null" steering be accomplished in digital beamforming? Is it simply too complex to achieve any other way?
Analog beamforming only allows the phases of each antenna to be varied, which limits the range of beam patterns that can be formed, compared to digital beamforming which can vary both the phase and the amplitude and allows more beam pattern design options.
Thank you sir
My pleasure.
ترجمه
Please, don’t do that again. I was more worried at you not paying attention at the road than anything else. Humanity can’t afford to lose the likes of you! 😉😂
Thanks for the video!!!
Thanks for your concern. I appreciate it. 😁 Don't worry though - that road has lots of cyclists and almost no cars. I'm glad you like that videos.