Why is Subcarrier Spacing Bigger in 5G Mobile Communications?
Vložit
- čas přidán 11. 09. 2024
- Explains why there are bigger OFDM subcarrier spacings in the 5G standard, compared to the 4G standard. Explains the effect of using mm-wave frequency bands and the potential for 5G to be delivered over Low Earth Orbit (LEO) satellites.
Related videos: (see: iaincollings.com)
• Why is the OFDM Symbol Prefix Shorter in 5G Mobile and 802.11ac WiFi? • Why is the OFDM Symbol...
• What are Doppler Shift, Doppler Spread, and Doppler Spectrum? • What are Doppler Shift...
• How are OFDM Sub Carrier Spacing and Time Samples Related? • How are OFDM Sub Carri...
• OFDM and the DFT • OFDM and the DFT
• What is a Cyclic Prefix in OFDM? • What is a Cyclic Prefi...
• How does OFDM Overcome ISI? • How does OFDM Overcome...
• What are Flat Fading and Frequency Selective Fading? • What are Flat Fading a...
Full categorised list of videos with pdf Summary Sheets: iaincollings.com
Hello Iain, just a quick comment - in the Release 17 a new subcarrier spacings were added, mostly to accommodate NTN links. Now the highest possible subcarrier spacing is 960kHz, not as you mentioned 480kHz.
Interesting. Thanks.
Any other disadvantage using wide subCarrier spacing, except computation power?
Isnt its mean that we cant properly address frequency selective fading?
Because you get your performance averaged across more then one RB(relative to 30KHz SCS), aka you sending pilot once in RB which is disaster or at least sub-optimal.
Thank you very much, this one was enourmously informative!
It depends on how frequency selective the channel is.
Really an informative video! Please continue the good work...we learn a lot from your videos.
Thanks so much for your nice comment. It's great to hear from people who are finding the content useful.
Great video! I have a question though:
In a given bandwidth, if you double the SCS you essentially halve the PRBs. This in turn will reduce the amount of data you can transmit in that band in a given slot.
But at 5:45 you mention that since each subcarrier is wider, you can have a higher data rate in each subchannel.
Can you clarify?
Thank you very much
A wider subcarrier corresponds to a shorter symbol period, which means you send more symbols per unit of time.
A super lovely explanation angle of combining the theory in the textbook with the real industrial design concern. This will help students build the connection between theory and practical, definitely. Thanks, professor, for your sharing.
Thanks for your nice comment. I'm glad you liked the video.
Wonderful video ian.
Glad you enjoyed it
Hello Iain! Could you please share any reference text books for reading about 5G?
Thank you!
You're welcome!
Hi, what happens when one is at stationary condition , will v = 0 or close to 0 , in that case what will be the fd (dopler spread) , whether stationary or moving at 100 kmph we are using the same SCS in 5G , could not understand this part Could you help to explain a little bit ?
Many thanks !!
The Doppler spread depends on the relative change in path difference across all the paths. When the mobile is not moving, the paths could still be changing path-length, if the scatterers are moving. More details here: "What are Doppler Shift, Doppler Spread, and Doppler Spectrum?" czcams.com/video/LLr3-kotbz4/video.html
hello sir long time hope you are doing well,
great video sir, more over have question related to CFO if there is effect of CFO than each of the subcarrier is shifted by (del(f) = cfo) than why is that intercarrier interference is taking place , so my doubt is that if there is shift due to carrier frequency than each of the subcarrier will be shifted and there will be again equal spacing between the subcarriers than why is there ICI (intercarrier interference between the subcarriers)
i
Sorry, I don't understand your question. Yes, when there is carrier frequency offset, it will disrupt the orthogonality of the subcarriers.
amazing explanation
Glad it was helpful!
Can you explain the law of total probability but for the continuous case please ?
Thanks for the suggestion. I've put it on my "to do" list.
I wish I could have been in your class during my university days.
Thanks for your nice comment. I'm glad you're liking my videos now anyway.
hi sir!!. does a wider subcarrier spacing improve cell coverage?? for example if you have 50 MHz BW you get all the power spread over 138 PRBs with 15 KHz spacing, but with 60 KHz spacing you share the power among half of RBs.
Is it like this or the wider subCarrier spacing should also impact in noise so that you dont really get to improve coverage?
The overall SNR across the whole bandwidth determines the coverage.
@@iain_explains thanks for answering!!
May I also ask, what if it is a single building scenario?
Do you need to calculate the link budget based on overall power or based on power per subcarrier?
For example, if you have 50 dbm power
Do you need to use 50 dbm In link budget or 50-10log(number of subcarriers)?
I was wondering that because I guess if you use 50 dbm you are implying that all the power is used in a single subcarrier
It depends on what you're comparing your link budget to. If you're comparing it to the noise power across the entire band, then you need to calculate the signal power (in your link budget) across the entire band. If you are comparing it to the noise power in just a single subcarrier, then you only do your link budget for a single subcarrier.
@@iain_explains thank you very much sir
I totally got it
Now it makes sense absolutely sense to me
Sir please do an exclusive video on 5g
5G is a big topic. Is there anything in particular you'd like to know about it?
@@iain_explains yes sir. What is the underlying technology that meakes it superior to 4g. Why 5g has higher bandwidth and data rates.
This is why the police were enforcing drivers with 5G to drive at reduced speed in order to minimise the spread of the doppler shifting and thus increasing channel capacity < fd = +/- fc (v of driver/c) > that was a joke LOL
It certainly would make mobile-communications-engineers' jobs easier if everyone always did things in ways that optimised the communication link! 😁