Talk:Single-carrier FDMA

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Telecommunications

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Yellow marking pf P-to-S and S-to-P in the figure

The picture is wrong in my opinion, since P-to-S and S-to-P are also needed for regular OFDM-systems. —Preceding unsigned comment added by 129.69.173.180 (talk) 09:27, 20 March 2008 (UTC)[reply]

In practice, the FFT and IFFT algorithms can take a parallel form as input (a vector of elements saved in a buffer, which will be read out of order), and output serial form (an ordered sequence of elements). Alternatively the algorithm may input serial form, and output parallell form. But still, there is no difference between SC-FDMA and OFDMA in this sence. Mange01 (talk) 20:54, 31 March 2008 (UTC)[reply]

I agree, the figure is incorrect in labeling the P/S and S/P blocks in yellow. —Preceding unsigned comment added by Mel aad (talk • contribs) 16:10, 24 June 2010 (UTC)[reply]

I think the figure is incorrect as mentioned above. Needs to be corrected. — Preceding unsigned comment added by 76.184.250.205 (talk) 18:48, 24 January 2012 (UTC)[reply]

Single-carrier frequency domain equalization (SC-FDE)

What is the difference from single-carrier frequency domain equalization (SC-FDE)? In what sence is this a multiple access/channel access method such as OFDMA, i.e. for several users? SC-FDE is only a digital modulation method based on inverse multiplexing and multiplexing, correspodning to OFDM? Mange01 (talk) 20:54, 31 March 2008 (UTC)[reply]

Explain why Single Carrier

DFT precoded OFDM is easy to understand. It is not easy why the name Single Carrier is given. I will try to give the reasoning, and we need to edit the article one day. The explanation is suitable when we consider multiuser access as in OFDMA and SCFDMA. In OFDMA, each data symbol is carried by a single sub-carrier and single user is given multiple sub-carriers. In SC-FDMA, due to DFT the each data symbol is spread to multiple sub-carriers. These multiple sub-carriers, if they are localized, and allotted to a single user, can be viewed as one frequency band carrying data sequentially as in a standard FDMA. Here the single carrier is with reference to this and not with reference to the sub-carrier. — Preceding unsigned comment added by 76.184.250.205 (talk) 19:00, 24 January 2012 (UTC)[reply]

The first sentence calls it a multiple-access scheme, but I think it is better understood as a spread-OFDM scheme (like Yee & Linnartz MC-CDMA, but with DFT coefficients as the spreading code). Early papers (1999-2001) referred to it as pulse shaping. A concise explanation of "single carrier" is that the spreading matrix maps each data symbol to a pulse waveform produced by the sum of OFDM subcarriers, and within each OFDM symbol is a sequence of these pulses, each modulated with a different data symbol, so the OFDM signal resembles a single-carrier signal. Bojabi (talk) 17:42, 28 December 2015 (UTC)Boj[reply]

It doesnt look like multiple access to a newbie like me!

If you look at the figure in section "Transmitter and Receiver Structure of LP-OFDMA/SC-FDMA". There is one bit stream coming in! Where are the other users' bit streams in this diagram? How does this diagram show how multiple bit bit streams share the medium?

31.142.132.93 (talk) 10:45, 30 April 2012 (UTC)[reply]

It doesnt look like multiple access to a newbie like me!

If you look at the figure in section "Transmitter and Receiver Structure of LP-OFDMA/SC-FDMA". There is one bit stream coming in! Where are the other users' bit streams in this diagram? How does this diagram show how multiple bit bit streams share the medium? 31.142.132.93 (talk) 11:02, 30 April 2012 (UTC)[reply]

Different users are assigned to different Fourier coefficients. Similar to OFDMA. This assignment is taken care of in the mapping and demapping blocks.

You are right that the illustration does not show this. Perhaps the illustration should show two transmitters, and a receiver that detects two signals. The receiver should than include two demapping blocks, and two of everything after that block.

It would also be nice with a separate illustration of SC-FDE, i.e. the single-user version of the same technology. Mange01 (talk) 11:40, 30 April 2012 (UTC)[reply]

Unlike other wiki pages, this page is in justified print

This seems like some formatting issue that should be addressed. Douira100 (talk) 18:03, 8 November 2017 (UTC)[reply]