What is Trellis Coding?
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- เผยแพร่เมื่อ 1 ต.ค. 2024
- Explains Trellis Coding using a basic example.
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![L35 : Trellis Diagram (Graphical Representation of Convolutional Coding) [In Hindi]](http://i.ytimg.com/vi/z9Ngc3mZ9LA/mqdefault.jpg)
How are evaluate the spectrum and energy efficiency of TCM?
Am I the only one who finds it weird and unhelpful that nowhere in the Trellis modulation Wikipedia page does it ever mention anything about error correcting? It just describes it as a method for "higher efficiency over band-limited channels ". Doesn't even tell you to see other error correcting codes, as if Trellis coding is just an unrelated concept entirely unto itself.🤨
Yes, I agree. These sort of things are a major motivator for me to make my videos. There are so many "connections" that are overlooked or not well understood, across many topics in applied maths.
Hi Sir. Hope ur doing well. Question: do u have a video that shows how to compute the BER vs EBNO for different modulation schemes with Low Parity Density Codes? How does the spectral efficiency change with LDPC? Thanks and looking forward to ur response.
Right now I don't have any videos on this sorry. I'll add it to my "to do" list. The characterisation of BER of specific coding schemes is complicated. It depends on many parameters.
Thanks for the video! Found it extremely helpful :)
Glad it helped!
Hi Iain. One question: Is this the optimal constellation for Trellis coding? I understood that idea is increase the Hamming distance between 2 close points on constellation diagram which is opposite to Gray diagram. When I tried to reproduce it, the first 2 steps were identical in my case (positions for 000, 100, 010 and 110), but I ended up with different position for remaining 4 positions because I first put "11" and you did with "01". So to summarize my positions are (starting from 000): 000, 011, 010, 001, 100, 111, 110, 101. For some positions this leads to better/worse Hamming distance comparing with your result. Is my approach valid, or I missed point for step 3 (adding "11" and "01")? Thanks in advance...
It depends on the convolutional code you're using. The important factor is to maximise the metric between different codewords that are being compared in the Viterbi decoder. Perhaps this video might help: "Decoding Convolutional Codes: The Viterbi Algorithm Explained" th-cam.com/video/IJE94FhyygM/w-d-xo.html
I am sorry but is this what people call ungerboecl partitioning rule ?
Yes, that's right. Ungerboeck was one of the pioneers of trellis coding.
Hi Iain, thank you very much. On less than one week, with almost zero notions on the subject, I feel that I grasped a lot thanks to your videos ! Is there any video on turbo coding ? I'd really enjoy (and I seem not to be alone on this) to see your video on the subject.
Thanks, I'm glad you have found the videos helpful. And thanks for the topic suggestion. It's a good one. I've put it on my "to do" list.
sir could you please do a video on concatenated codes, LDPC codes, turbo codes and coded modulation. Thank you sir.
Thanks for the suggestions. They were already on my "to do" list, but I've just moved them up the priority order.
What is disadvantages of TCM?
When using TCM, will I use the channel code?
Trellis coded modulation (TCM) combines the channel coding and the modulation, so there is generally no need to use another channel coder in addition. However there is often still other coding at higher layers, such as ARQ and TCP.
@@iain_explains Yes, thanks u.
God bless you