Why is SC-FDMA called "Single Carrier"?

Рет қаралды 5,203

Iain Explains Signals, Systems, and Digital Comms

Жыл бұрын

Explains the relationship between SC-FDMA, OFDMA and FDMA in digital mobile communication systems.
* Note that I should have drawn the sub-carrier/sub-channel side lobes having zeros under the peaks of the neighbouring sub-carriers/sub-channels. I was a bit too representational/simplistic in my drawings. The reason I don't pay too much attention to the zero-crossings in the frequency domain, is because they are not actually "the reason" the sub-channels are orthogonal (although many people believe it is). More details on why the sub-carriers are orthogonal can be found here: "Orthogonal Basis Functions in the Fourier Transform" • Orthogonal Basis Funct...
Check out my search for signals in everyday life, by following my social media feeds:
Facebook: profile.php?...
Instagram: / iainexplains
Related videos: (see: iaincollings.com)
• What is SC-FDMA? And why is it used for the Uplink of 4G/5G Mobile? • What is SC-FDMA? And w...
• What is PAPR? and its relationship to OFDM • What is PAPR? and its ...
• Why is the OFDM Symbol Prefix Shorter in 5G Mobile and 802.11ac WiFi? • Why is the OFDM Symbol...
• Why is Subcarrier Spacing Bigger in 5G Mobile Communications? • Why is Subcarrier Spac...
• How are OFDM Sub Carrier Spacing and Time Samples Related? • How are OFDM Sub Carri...
• What is Multi-User MIMO Communications (MU MIMO)? • What is Multi-User MIM...
• What is MIMO OFDM? • What is MIMO OFDM?
• 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...
• Modelling mmWave MIMO Channels • Modelling mmWave MIMO ...
• What are Doppler Shift, Doppler Spread, and Doppler Spectrum? • What are Doppler Shift...
• What are Flat Fading and Frequency Selective Fading? • What are Flat Fading a...
Full categorised list of videos with pdf Summary Sheets: iaincollings.com

Пікірлер: 18

@geneschroedertech7501 11 ай бұрын

Thank you for your excellent video where you address this confusing topic head-on. I worked for many years in LTE and never understood it. But I must say, my professor of abstract algebra once told me not too worry too much about some of the terms that were used to represent concepts, just think of them as labels for what they are. Over the years I have found that to apply many times in mathematics and engineering - the terminology is sometimes not very intuitive, often for historical reasons. But everyone is used to it (except new people). I think the term "SC-FDMA" falls into that category, and I treat it as just a well-known label for a technique. Personally, I like the term DFT-Spread OFDM. It is more jargon but as least it is descriptive. By the way, your video on how SC-FDMA reduces PAPR is also excellent, and another topic I never understood.

@iain_explains 11 ай бұрын

Yes, I agree, there are times when it is best to forget/overlook the jargon, for exactly the reason you say. I try not to make videos about jargon - I try to stick to explaining the fundamental underlying process - which is what I tried to do here. I'm glad you like the videos - and thanks for your nice comments.

@nelsonmariasotoarraiz424 11 күн бұрын

Good

@AM-tu1rc Жыл бұрын

Yet another legendary video. Always confused on this aspect of what SC-FDMA vs OFDMA really was, wish I had something like this earlier on in my career!

@iain_explains Жыл бұрын

Thanks. I'm so glad you're finding the videos on the channel helpful.

@uncleroq Жыл бұрын

I was actually asking this question a couple months ago. Thanks for the clarification!

@iain_explains Жыл бұрын

Glad it helped.

@pitmaler4439 Жыл бұрын

Thanks for all of the videos. With regard to the lower diagram in the middle: I thought the zeros of the other subcarriers meet at the top of the other subcarriers. But, here tops meet tops.

@iain_explains Жыл бұрын

Yes, great point. Sorry about that. I was a bit casual about the sketch. You're right, I should have shown the side lobes having zeros under the peaks of the neighbouring subchannels. The reason I don't pay too much attention to that, is because that is not "the reason" the subchannels are orthogonal (although many people believe it is). More details on why they are orthogonal can be found here: "Orthogonal Basis Functions in the Fourier Transform" kzfaq.info/get/bejne/pJibmNZ9yLa9Z6M.html

@3abaass Жыл бұрын

Thank you, the amout of knowlege I learned from this channel is just incredible.

@iain_explains Жыл бұрын

I'm so glad to hear you're finding the channel helpful.

@georgepalafox5967 Жыл бұрын

Excellent explanation!!! Thanks Sir!

@iain_explains Жыл бұрын

I'm so glad you like the video.

@yelloowXL 2 ай бұрын

Can you make a video that explains "Index Modulation" and "IM-NOMA Technique"? Thanks much.

@iain_explains 2 ай бұрын

Thanks for the topic suggestion. I'll add it to my "to do" list.

@uncleroq Жыл бұрын

But what's the difference in subchannel allocation between SC-FDMA and OFDMA. Since OFDMA is dynamic in the way it assigns resources, aren't there instances when SC-FDMA allocation scheme is the same as OFDMA?

@iain_explains Жыл бұрын

Perhaps this video will give some more insights into your question: "What is SC-FDMA? And why is it used for the Uplink of 4G/5G Mobile?" kzfaq.info/get/bejne/haqoatB1qNCop4U.html

@uncleroq Жыл бұрын

@@iain_explains Thank you Professor!