Timeline for Determining sampling rate in OFDM demodulation
Current License: CC BY-SA 3.0
11 events
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| Apr 20, 2013 at 2:41 | comment | added | Karan Talasila | @JasonR reference: en.wikipedia.org/wiki/Sampling_%28signal_processing%29 | |
| Apr 20, 2013 at 2:40 | comment | added | Karan Talasila | @JasonR The signal sent is complex baseband. Maybe as you say,it's complex sampling rate,if it is the case, then sampling it at fs=B satisfies nyquist criterion. | |
| Apr 19, 2013 at 20:25 | history | edited | Jim Clay | CC BY-SA 3.0 |
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| Apr 19, 2013 at 14:42 | history | edited | Jim Clay | CC BY-SA 3.0 |
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| Apr 19, 2013 at 14:18 | comment | added | Jason R | @JimClay: In one way of looking at it, each of the subcarriers is oversampled by a large factor (the FFT size $N$). OFDM is really just the transmission of many low-rate modulated signals at carefully-chosen carrier frequencies, such that the modulation can be recovered easily using a DFT. So, the sample rate is usually many times larger than the "symbol rate" for OFDM. | |
| Apr 19, 2013 at 14:11 | comment | added | Jim Clay | @talasila Your own example says that the sample frequency is higher than the bandwidth. I said that traditional demodulators (e.g. PSK) often do twice the symbol rate. I said that OFDM demodulators do NOT do twice the symbol rate because they don't need to. Yes, there is an equivalence relationship between bandwidth and symbol rate. | |
| Apr 19, 2013 at 14:09 | comment | added | Jim Clay | @talasila Jason is correct, twice the symbol rate far exceeds what is needed in terms of the Nyquist criterion if the samples are complex. | |
| Apr 19, 2013 at 13:39 | comment | added | Jason R | @talasila: Is the sample rate that you're referring to complex or real? If it is complex and you're analyzing a complex baseband signal, then you haven't violated the Nyquist criterion. | |
| Apr 19, 2013 at 13:21 | comment | added | Karan Talasila | The paper i have attached says bandwidth is 1.25MHz and sampling frequency is 1.48MHZ.That's not slightly lesser than twice the bandwidth. Is the data wrong? secondly, you say that it should sample at twice the symbol rate. Isn't it twice the bandwidth of signal.Is there a equivalence relation between bandwidth and symbol rate here. | |
| Apr 19, 2013 at 13:15 | history | edited | Jim Clay | CC BY-SA 3.0 |
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| Apr 19, 2013 at 13:09 | history | answered | Jim Clay | CC BY-SA 3.0 |