For 5G topics discussed in 5G Job Interviews, check out the complete playlist below :) 🌐5G Interview Topics 💡ruclips.net/p/PL4OXTttOk9WiLsz4fR62lpPcT3Wx3l5OP
Dear Ali, two questions here. 1), why we used example of 4 RE for csi-rs? It is either 8. 16, 24, 32 2)NR can use SS-RSRP OR CSI-RS RSRP / SINR for mobility, but I couldn't find pdsch rsrp for decisions. Would you please refer us to 3gpp for this? How many REs are used in case rsrp of PDSCH, otherwise it's mammoth grid. Do we really have echo system for such calculations. Many thanks
There are implementations which can use 4 RE CSI as well. For Massive MIMO units, mostly it is 8 or more! There are no measurements on PDSCH RSRP. As per specs, the measurements should be from SS and CSI-RS. But, there are many UEs that use PDSCH SINR as well. Note: UEs do need to know the PDSCH SINR during demodulation anyways so some UEs might decide to use it for link adaptation as well.
@@OurTechPlanet and DMRS can not be use for data transfer. So mainly the DL LA or Tbs allocation base on DMRS is good enough I think why us to monitor PDSCH ? From UE perspective it may cause power consumption too. is it right？
Really Good. and it gave me insight. but let me ask you a question. when you explaint about 5G SS SINR, you mentioned that SSS instead of PBCH DMRS. I think UE calculate SS SINR thru PBCH DMRS and PBCH DMRS location is based on PCI mod 4. so when we compare LTE CRS SINR and 5G SS SINR in the same site density, I think 5G SINR would be better than LTE SINR even SSB block locations are same across the cell. What do you think of this? I might be wrong :)
From what i understood since there is no RS in 5G and the block will always happen at the same time then why we have to respect mod3 ? Collision will happen anyway?
Firstly, for 5G, mod3 is not that important but since there will always be collision so a different permutation or a different randomization can help in better decoding. So, a mod3 can help in that regard while mod4 can help in randomization of the DMRS in the PBCH part of the SSB. But again, both these mod3/mod4 are not found to be service impacting so more of a theoretical scenario.
Thanks a lot for all your valuable contents and for sharing your knowledgeI I'd have one question: why do we assume that SSB is always in the same location for different PCI? In LTE PSS/SSS/PBCH are always in the central frequency of the channel, but in NR has been added the flexibility to have SSB (in frequency domain) in different locations. Thanks!
Yes indeed, the SSB can be in different locations but then it will cause inter-frequency channels as the SSB frequency is used for all mobility events. So, to avoid this, the normal plan is to use SSB on same location
@@OurTechPlanet Thanks that was a good question, just to add we faced the same issue of very poor SINR though throughput was fine, so just as a trial , we set different positions for SSB for three sectors Sector-1 Lower part of Band , sector-2 Middle of the band & sector-3 Upper portion of the band , but SSB-SINR was still degraded , i don't understand why
Can we have the SSBs across cell at different times (Slots/SYMs) but keeping the Frequency location same? Just like we do in intra cell multiple SSBs.@@OurTechPlanet
One question often bothers me, may be you could guide on this , upon ENDC connection Establishment, NSA 3X model specifically , Bearer is split at SgNB & DL/UL data is transferred to UE either via F1-U interface ( 5G NRcell to UE ) or X2-U interface via MeNB or both X2-U & F1-U both simultaneously , question is how MeNB decides when to send data ( S1-U) simultaneously via both interfaces ?
Thanks a lot for listing down the difference. Can you suggest a 5G Phone that can be used to see the details of the channel estimations and call flow. Basically, looking for something that can be used for the initial 5G field testing.
That depends which drive test tool you are going to use. Usually mobile with qualcomm chipsets are good as they are compatible with most of the logging tools
CSI-RS is 5g technology specific,right ? If i have two bands, lower band for coverage and sub 6ghz for capacity then CSI RS existing st for both bands, right ? Wanted to confirm this.
Yes you are right, the RSRP shared in measurement reports and measurement configuration are in positive values. In 5G, we subtract 156 from it to convert it into actual effective RSRP. I explained this in the following video (around 7min into the video) ruclips.net/video/VSdc74DS3FA/видео.html
There is PCI-4 issue as well with PBCH RS Symbols, how much will it impact and they are used for what purpose? Reason for using Secondary SS RSRP & SINR for Coverage & Mobility and not Primary SS? And how much it will impact Coverage & Mobility decisions because of fixed position of SSS? There is even PDCCH SINR as well similar objective like PDSCH SINR which is again better for scheduling PDCCH Resources
Originally PCImod4 was discussed for PBCH but no impact was seen so it was not considered further. The SSS was taken by specs. Most probably either because of its structure or because at PSS, the UE is unaware of phase information.
@@OurTechPlanet So PBCH exist but they are not any cause for concern and are not used in any decision making? Secondly how much SSS will impact Coverage & Mobility decisions because of fixed position of SSS since you mentioned those symbols have a higher interference floor
@@coolmunzir Yeah correct, PBCH will not impact any decision making. The entity used for mobility and accessibility decisions is SS RSRP which is not impacted by interference. The SS SINR will be impacted but it does not really have that much of an influence when it comes to the coverage and mobility.
Well there will be many. LTE In Bullets is good. You may also go through my blog which has LTE basics and advanced articles as well. ourtechplanet.com/category/telecom/
Since PCIs will differ between cells so RS will also move. If all the LTE RS are at same position, then they will increase RS to RS interference and thus, a lower RS SINR will be observed
@@hitendramalik3093 CSI-RS are used to estimate the CQI and Rank while DMRS are used to demodulate the PDSCH itself. So, CSI-RS occur after a few frames like 20ms or 40ms or 80ms and they are used for all the UEs to estimate their CQI/Rank/PMI while DMRS are specific to every UE i.e. every UE that gets a PDSCH allocation will get a DMRS inside that PDSCH allocation
For 5G topics discussed in 5G Job Interviews, check out the complete playlist below :)
🌐5G Interview Topics
💡ruclips.net/p/PL4OXTttOk9WiLsz4fR62lpPcT3Wx3l5OP
Dear Ali, two questions here.
1), why we used example of 4 RE for csi-rs? It is either 8. 16, 24, 32
2)NR can use SS-RSRP OR CSI-RS RSRP / SINR for mobility, but I couldn't find pdsch rsrp for decisions. Would you please refer us to 3gpp for this? How many REs are used in case rsrp of PDSCH, otherwise it's mammoth grid. Do we really have echo system for such calculations.
Many thanks
There are implementations which can use 4 RE CSI as well. For Massive MIMO units, mostly it is 8 or more!
There are no measurements on PDSCH RSRP. As per specs, the measurements should be from SS and CSI-RS. But, there are many UEs that use PDSCH SINR as well.
Note: UEs do need to know the PDSCH SINR during demodulation anyways so some UEs might decide to use it for link adaptation as well.
@@OurTechPlanet follow up if UE to measurement the PDSCH SINR is any impacr the DL Tpt ? is any RE be reserved for PDSCH like LTE RS ?
@@allenzhang9695 Nopes, there is no impact on throughput as PDSCH SINR is based on actual Data and PDSCH DMRS which already exist
@@OurTechPlanet and DMRS can not be use for data transfer. So mainly the DL LA or Tbs allocation base on DMRS is good enough I think why us to monitor PDSCH ? From UE perspective it may cause power consumption too. is it right？
Really nice! Easy to understand! Thanks a lot!
You are welcome. Glad that you liked it :)
Really Good. and it gave me insight. but let me ask you a question. when you explaint about 5G SS SINR, you mentioned that SSS instead of PBCH DMRS. I think UE calculate SS SINR thru PBCH DMRS and PBCH DMRS location is based on PCI mod 4. so when we compare LTE CRS SINR and 5G SS SINR in the same site density, I think 5G SINR would be better than LTE SINR even SSB block locations are same across the cell. What do you think of this? I might be wrong :)
Mashalla and jazak allah khair for the amazing knowledge u r sharing
Thank you
You are most welcome :)
very clear explanation of difference of both SINR...Thanks a lot.
Thanks and welcome
From what i understood since there is no RS in 5G and the block will always happen at the same time then why we have to respect mod3 ? Collision will happen anyway?
Firstly, for 5G, mod3 is not that important but since there will always be collision so a different permutation or a different randomization can help in better decoding. So, a mod3 can help in that regard while mod4 can help in randomization of the DMRS in the PBCH part of the SSB. But again, both these mod3/mod4 are not found to be service impacting so more of a theoretical scenario.
Thanks a lot for all your valuable contents and for sharing your knowledgeI I'd have one question: why do we assume that SSB is always in the same location for different PCI? In LTE PSS/SSS/PBCH are always in the central frequency of the channel, but in NR has been added the flexibility to have SSB (in frequency domain) in different locations. Thanks!
Yes indeed, the SSB can be in different locations but then it will cause inter-frequency channels as the SSB frequency is used for all mobility events. So, to avoid this, the normal plan is to use SSB on same location
@@OurTechPlanet Thanks that was a good question, just to add we faced the same issue of very poor SINR though throughput was fine, so just as a trial , we set different positions for SSB for three sectors Sector-1 Lower part of Band , sector-2 Middle of the band & sector-3 Upper portion of the band , but SSB-SINR was still degraded , i don't understand why
Can we have the SSBs across cell at different times (Slots/SYMs) but keeping the Frequency location same? Just like we do in intra cell multiple SSBs.@@OurTechPlanet
@@syedmujahid596 Yes that is a possible implementation.
One question often bothers me, may be you could guide on this , upon ENDC connection Establishment, NSA 3X model specifically , Bearer is split at SgNB & DL/UL data is transferred to UE either via F1-U interface ( 5G NRcell to UE ) or X2-U interface via MeNB or both X2-U & F1-U both simultaneously , question is how MeNB decides when to send data ( S1-U) simultaneously via both interfaces ?
You may get your answer from here
ruclips.net/video/f-GSdoP2RsY/видео.html
😊The best explanation! Thanks bro 🙏
Glad it was helpful! You are welcome :)
Extremely good videos. But the advertisements just pops up exactly the wrong moments. Well I know it’s not in ur hands. Keep up the good work.
Yeah ads are something related to RUclips. But thanks for the comment :)
Thanks a lot for listing down the difference.
Can you suggest a 5G Phone that can be used to see the details of the channel estimations and call flow. Basically, looking for something that can be used for the initial 5G field testing.
That depends which drive test tool you are going to use. Usually mobile with qualcomm chipsets are good as they are compatible with most of the logging tools
It's really awesome. Thanks for your videos
Great to hear that. Thanks!
❤️❤️❤️❤️❤️ Brilliant effort 👌👌👌👌👌 Thankyou so much always. ❤️❤️
You are welcome! :)
Excellent Ali .. Can you also please elongate about SRS RSRP/ SRS SINR
Sure, I will add it in my To-Do List :)
CSI-RS is 5g technology specific,right ?
If i have two bands, lower band for coverage and sub 6ghz for capacity then CSI RS existing st for both bands, right ?
Wanted to confirm this.
Yes, both bands in your case will have CSI-RS. The number of ports may vary depending on the implementation.
Detailed explanation, Keep Going Bro
Thanks :)
Nice & Detailed Comparison with Pros & Cons
Thanks :)
RSRP and SINR shares the same Reference signal?
Yes, for instance, if we are talking about SSB RSRP and SINR then yes, it comes from the same REs.
but different PCIs doesn't have same RB to compare between them , the whole band is divided between cells (PCIs) in a cluster
I am not sure, if I got your question. The LTE CRS change location based on PCI.
Nice explained, thanks
You are welcome :)
Please post how to calculate RSRP level . Like -156 that,, am not clear ..
Yes you are right, the RSRP shared in measurement reports and measurement configuration are in positive values. In 5G, we subtract 156 from it to convert it into actual effective RSRP. I explained this in the following video (around 7min into the video)
ruclips.net/video/VSdc74DS3FA/видео.html
@@OurTechPlanet thanku so much brother for kind heart ❤️❤️❤️❤️ Stay blessed 🙏🙏🙏❤️❤️❤️❤️
How can the UE estimate RI if there are no RS as in LTE, would the csi be enough for mimo rank indicator?
Yes, the CSI-RS are also spread over the whole bandwidth. And the UE uses CSI-RS and port information to estimate Rank.
There is PCI-4 issue as well with PBCH RS Symbols, how much will it impact and they are used for what purpose?
Reason for using Secondary SS RSRP & SINR for Coverage & Mobility and not Primary SS? And how much it will impact Coverage & Mobility decisions because of fixed position of SSS?
There is even PDCCH SINR as well similar objective like PDSCH SINR which is again better for scheduling PDCCH Resources
Originally PCImod4 was discussed for PBCH but no impact was seen so it was not considered further.
The SSS was taken by specs. Most probably either because of its structure or because at PSS, the UE is unaware of phase information.
@@OurTechPlanet So PBCH exist but they are not any cause for concern and are not used in any decision making?
Secondly how much SSS will impact Coverage & Mobility decisions because of fixed position of SSS since you mentioned those symbols have a higher interference floor
@@coolmunzir Yeah correct, PBCH will not impact any decision making.
The entity used for mobility and accessibility decisions is SS RSRP which is not impacted by interference. The SS SINR will be impacted but it does not really have that much of an influence when it comes to the coverage and mobility.
Simply beautiful! ♥♥🥰
Thanks!
good and clear explanation. Could you please suggest to me a good LTE Course and Book to get good and clear understanding of the LTE system .
Well there will be many. LTE In Bullets is good. You may also go through my blog which has LTE basics and advanced articles as well.
ourtechplanet.com/category/telecom/
valuable
Thanks. Glad to know that it helped :)
how is CSI-RS estimation whold BW 5G ?
Yes, CSI-RS are used for channel estimation so they are supposed to be distributed over the whole bandwidth
@@OurTechPlanet so the csi-RS vs LTE is more flexible and depending configuration possible position timer such as.
Hi, from where I could read more about this? any reference from the standard? thank you in advance
You can refer to 3GPP 38.211, 38.214, 38.331 for further study!
for lte if RSs is in the same locations , there will be no interference , as each pci is in different band ?? is that true !
Since PCIs will differ between cells so RS will also move. If all the LTE RS are at same position, then they will increase RS to RS interference and thus, a lower RS SINR will be observed
0h, very very thanks!!!
You are welcome! :)
What about DM-RS ? Is it what you refer as PDSCH ?
DMRS are incorporated in PDSCH allocation. They are used in helping to decode the PDSCH and thus can be used to estimate SINR of the PDSCH.
@@OurTechPlanet But PDSCH is for Data channels and for Data Channels we aer using CSI-RS
@@hitendramalik3093 CSI-RS are used to estimate the CQI and Rank while DMRS are used to demodulate the PDSCH itself. So, CSI-RS occur after a few frames like 20ms or 40ms or 80ms and they are used for all the UEs to estimate their CQI/Rank/PMI while DMRS are specific to every UE i.e. every UE that gets a PDSCH allocation will get a DMRS inside that PDSCH allocation
@@OurTechPlanet TQ so much .Your session are too good.Your language too easy too understand.I hope i will meet you and pass my regards.
Nice one
Thanks for watching
PCI is defining the location of DMRS in 5G
PCI defines location of reference signals in LTE