+Barış Volkan Yıldırım - Thanks a lot man. The series is not complete yet, it's just the beginning. Stay tuned for our upcoming videos. Happy Learning

The credits goes to our research team. We hope that we will be able to make even better videos in coming future. Happy Learning.

Wow! Thanks Petrut. That's a lot of nice words. Happy Learning.

Hi Josch. Thanks for the valuable feedback. We have tried using natural voice. But it seems weirder. That is why we are using Text to Speech converter. Hope in some near future you will hear human voice. We are trying our best. Till then stay with us. Happy Learning

Then just put some kind of filter to your natural voice signal that makes it less weird. The point is: A speech converter doesnt understand the concept of flow, the way humans pronounce words and adjust breaks between words to create a flowing sound that appears natural and smooth. The speech converter just puts words after each other and sounds terrible.

+Josch K we agreed and we already in process of preparing next video on Carrier Aggregation using our voice. Hope this will be less weird than today's voice. Thanks for valuable feedback. 😊

Hi Josch. We have finally started using human voice. Would you mind giving us your valuable feedback?

Sure! I just watched the video featured by the indian accent speaker and I think its great! The overall video quality improved tremendously in my eyes I enjoyed watching a lot. Take that and the high informational density of these clips and you just got yourself another fan of your channel! Thats a like and a subscription, very well done.

+Chuan Huang - Thanks buddy. We try our best. Watch the other videos and share your feedback. Happy learning

Thanks Pragyan. Happy Learning.

hello Luis! Thanks for the nice words. We will be making a video on Carrier aggregation but it will take some time. You can check the video- channel roadmap where we have mentioned the topics that we are going to cover. happy learning

+Sukhpreet Singh - Ok! We have moved on from text to speech convertor to real voice. We will keep the music low from next video.

Thanks Victor.

Happy Learning.

+Omidiji Rasheed A. - Thanks Omidiji. Don't forget to share it among your friends. Happy Learning.

Thanks Mohamed.

Please check #dwdmotnc#discreteoptical #Norteltn #Ciena32slot

@@nicholasroos3627 ok

That and background music... :-/

Thanks for your support. Happy Learning.

You are welcome Buddy. Don't forget to share it with your friends. Happy Learning.

Hello Aashwini. We will come to it eventually. But before that we need to explain the basics. You can check the video channel roadmap, where we have shown, what are the topics that we are going to cover.

The centre frequencies actually represent the OFDM subcarriers. As a single monochromatic frequency cannot carry any data(as bandwidth is required for that), OFDM subcarriers occupy a portion of bandwidth in a form of sinc wave which in turn is centred around the centre frequency..Data modulation(psk, qam) will neither impact the centre frequency nor the shape of the sinc function.. it just changes the amplitude and phase of sinc function. Again DC frequency is actually the centre point(zero) of a frequency graph(on x axis). Since it has no frequency or alternating component, it is also called DC(direct current). Also since the LTE spectrum consists of both positive and negative frequencies(frequencies with 180 degrees phase shift) it is basically centred around the DC.

You are welcome Robert. Happy Learning.

+SunSon29 guard bands in OFDMA are not between the subcarriers rather they are at the both ends of the OFDMA spectra.

+SunSon29 - The guard bands are at the begining and at the end. See the part 2 of OFDMA. At 5:12 there is an image. Hopefully that image will help you understand.

LTE thank you. Btw, in OFDM, the guard bands are between each channel, not each subcarriers, am I right on this ?? Thank you again.

please please share the slides

@@43SunSon There are no guard bands required in OFDM since all the subcarriers are orthogonal to each other. This is the beauty of OFDM that guards buands are not required between the sub carriers and hence the Bandwidth efficiency is highly improved.

Please check #dwdmotnc#discreteoptical #Norteltn #Ciena32slot

Time period is the reciprocal of frequency i.e T=1/f, Where T=Time Period f= Frequency. So, when frequency is 10khz the Time period =1/f=10^-4 sec or 100x10^-6 sec or 100 microsec

Orthogonal means that they don't interfere. That's what the word means; independentness. In LTE OFDM, orthogonality is provided by FFT transform. That's a key property of FFT. You take a bunch of numbers, make FFT to them, it makes a waveform. Make FFT again to the waveform, you get back the same numbers. Now change one of the numbers. The waveform changes and again you get numbers back from the other end. *Only the one number that you changed, changes.* That's orthogonality, that is what it means.

+José Ricardo Moyeda - you are welcome Jose. Send us your email id; we will mail it to you.

+Aqeel Ahmed - Thanks. Don't forget to share it with your friends.

You are welcome Zeinab. Did you see our other videos?

Please check #dwdmotnc#discreteoptical #Norteltn #Ciena32slot

+BlackLeg199 every time there is a service request from the UE, An ENB scheduler will allocate some PRBs. The number of PRBs depend on their availability, QoS demands of the radio bearer as well as on the radio parameters like RSRP and the LTE radio band, the user is latched upon. The number of subcarriers will be 12 times the Allocated PRBs.

let's say that i saw a signal at the oscilloscope, and recognize that it uses multi-carrier modulation. Is there a mathematical tool or any other way to find the number of modulated tones and their frequencies? Thank you for your help.

+BlackLeg199 I suppose you're asking about radio frequencies assigned to a particular user when it receives user plane data.. so first of all, the user data is sent over the downlink shared channel but before that, the ENB will inform the user about the Allocated resources I.e PRBs and the corresponding modulation scheme in the DCI(downlink control information) over PDCCH channel. Using the DCI, a UE is able to decode the frequencies which are carrying information specific to that user. So if you somehow convert the RF signal of a particular band from an ENB and feed it to an oscilloscope, you will get a composite signal ranging the whole Spectrum having data for all the users.. moreover this signal would be a analog wave which would require to be converted to digital discrete signal and once you do the FFT operation, you will see all the frequency components, now in order to find out frequency components for a particular user, you will have to read it's DCI.....this is done by every LTE receiver... Hope this helps and do see our next videos.. :)

Subcarrier along with time formed a resource element and further resource block. This group of resource block are given to user on demand as they requested. For example 1 subcarrier (15Khz) with 1 symbol (0.5second/6 or 7 symbol) make one resource element. Further 12 subcarrier (15x12=180Khz) with (6 or 7 Symbol = 0.5 Second) make one resource Block. This combination always there and assiged to user. Initially 1.6Mhz bandwidth assiged by default to handset which means around 6 resource block, which carries required data to be used by handset to make decisions and request further resource to start using service. I hope this is clear. Any doubt you can ask ? Happy Learning...!

LTE Thank you very much for answering. But if that is the case, then what about other users sharing same bandwidth? If I am not mistaken, at 20MHz downlink we get only 20/1.6=12 users only! If for example some video is sent to a particular user continuosuly, doesn't other users who are sharing the same bandwidth of 1.6MHz experience interference? Let me know if I have made mistake somewhere.

Yes indeed.....12 Users only....but that for only 0.5second time slot... But users can get chance in next 0.5 second and so on.... Apart from this one more things to be cleared, there are fixed resources and there are on dedicated resources which mapped on control channels and shared channel accordingly. User will always get resource, except network is fully congested and everyone is using it heavily. In that case some users have to be in queued and they will fill like buffering that is nothing but congestion in radio or in other word high physical resource utilization.

You should check our video on Throughput Calculation. May ve you can get better picture. kzfaq.info/get/bejne/q6-Ap6-jnbiVXYk.html

LTE Perfect! Thanks a lot!

+All Rounder - Thanks a lot. Happy Learning

+Alireza Mokhtari Doust - Do You mean to say the background sounds and the soothing track?

yeah, the background sound

+Alireza Mokhtari Doust - Ok we will keep that in mind. By the way, have you seen our other videos?

Yeah, all of them, i study Communications Engineering at TU Munich, your videos are perfectly matching to subjects like "System Aspects in Communications" and some other sujects. I will share your channel with my friends 100% 😉

+Alireza Mokhtari Doust - Aw that's so sweet of you. You can follow us on Facebook. The details is mentioned in the about section. For technical queries you can ask us on Quora as well. We use the same name for Quora i.e LTE. Thanks again for your support. Happy learning.

Hi! Rohit we have tried to keep a tempo so that people don't get bored. if you are having difficulty in understanding you can pause the video while watching. You can also switch on the subtitles. happy learning

+J.D. Kouam - Thanks a lot. Happy Learning.

66% is used for example. It can vary.

+Mohammadhussain Hussaini - Yes! You don't need any guard band between subcarriers. If you see carefully the guard bands are located somewhere else. Hope we could clarify your doubt. Happy Learning.

We thought that it would be easier as we are not native speakers, I guess that was stupid of us. But we have now moved on to human voice in our latest videos. Do share your review about it.

I understand. I just want to emphasize the good job you guys do with the videos. The robotic voice was really holding you back. Good you decided to change!

I'm sorry what do you mean?

The process is to choose sub carrier frequencies that are harmonics of the base frequency.In LTE the base frequency starts with 15khz.To this base frequency, values of 2,3,4 and so on are multiplied to get subsequent subcarrier frequency. The modulating signal which is going to modulate these sub carriers must have a 1/15khz symbol duration. The above two steps ensure orthogonality.

FFT. You need a transform function that is orthogonal. For LTE, FFT is used. For fibre, DCT is used.

Because it isn't. But we will be uploading the same with human voice shortly. Happy Learning.