8
votes
Accepted
SC-FDMA in LTE system
First of all, in refering to standard specification, please mention the version because the numeration between versions can be different.
My answer should be only a comment but I think with images it ...
- 6,725
7
votes
Why is LTE either FDD or TDD?
You are mixing two things modulation and multiple access. SC-FDMA has been chosen because it is battery-friendly modulation. SC-FDMA is used in both FDD and TDD modes.
There are several reasons why ...
- 6,725
3
votes
Accepted
SC-FDMA disadvantages
Some more disadvantages:
Channel estimation using pilots is harder, because you do not have orthogonal data on each frequency bin, compared to OFDM. That's why e.g. LTE uplink resorts to a midamble ...
- 6,238
2
votes
Accepted
For a 20 MHz channel, with 1200 usable subcarriers(18 MHz occupied), what should be the size of the FFT on the transmitter before IFFT is applied?
We perform M point FFT on each Q block, then map the FFT results to intended positions of 1200 available subcarriers (subcarrier mapping), which are finally the input of a 2048-iFFT operation. See the ...
- 6,725
1
vote
SC-FDMA vs single carrier signal PAPR
Consider some actual use cases for further insight:
Unmodulated Carrier: The peak to average ratio is 3 dB given the relationship between the rms and peak level of a sine wave.
Unfiltered Single-...
- 55k
1
vote
Why is LTE either FDD or TDD?
Agree with the other answer that the question is mixing up concepts. TDD/FDD has nothing to do with the multiple access provided by OFDMA. TDD/FDD is about duplexing, which is, how the traffic in the ...
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