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60 Threads found on Carrier Ofdm
in 802.11a, 48 sub-carriers are used to transmit data, and they are not carrying conjugate data on index like sub-carrier(x) and sub-carrier(N-x). also in some thsis I come across designs that transmit conjugate data on sub-carriers that are symmetric around the FFT size N, which results in waste of half the bandwidth. (...)
Hi, What is the performance difference of MMSE equalizer and ZF equalizer in a ofdm system. I have simulation 3 tap Rayleigh channel for QPSK ODFM system and found out that both the equalizers give the same performance. But in Single carrier Frequency Domain Equalization, MMSE performs significantly better than ZF. I modeled the equal
........ from the introduction in this link i understand that ofdm carrier is generated by modulating a complex waveform with original data and this resulting waveform is the ofdm subcarriers and these sub carriers r bundled by ifft to obtain the ofdm signal... (correct me if i'm wrong)....
Hello all, Why when we use space-time block coding (STBC) with single-carrier frequency-domain equalization (SC-FDE) we use a permutation matrix, while we don't use it in case of orthogonal frequency division multiplexing (ofdm)? Thanks
please explian me synchronisation and frequency offset problem in ofdm
Hi, I am working on the ofdm transmitter system. I have observed that the carrier signal peak power level is -3dBm whereas the peak power level of the ofdm (256 sub carriers) signal observed is -42dBm. Also the channel power measured is -42dBm . Frequency of operation is 2.45GHz. Power amplifier used is MMZ25332BT1. I (...)
One reference says that: "we know that the CFO (carrier frequency offset) causes the phase distortion in the ofdm symbol which can be denoted as 2πβn/N where B describes the CFO effect.."" so, any one can explain how this phase distortion (2πβn/N) is obtained?? Plz explain...
This picture is from book MIMO-ofdm Wireless Communications with Matlab by Cho Y.S. The MATLAB code is located in book directly below the figure. function y_CFO=add_CFO(y,CFO,Nfft) % add CFO (carrier frequency offset) % y : Received signal % CFO = IFO (integral CFO) + FFO (fractional CFO) % Nfft = FFT size nn=0:length(y)-1; y_CFO = y.*exp(j*2*pi*C
I am trying to understand the relations between ofdm symbol duration and subcarriers far as i went ,i understood that regarding W and R as total bandwidth & transmission rate of transmission respectively the duration of a distinct subcarrier is just T ,where T=N*Ts with Ts the symbol duration in the single carrier case (...)
My input signal is a multi-channel/carrier ofdm. Each channel have 5MHz bandwitdh. Now, I would like to simulate a 2-tone test for its IMD. I plan to measure the 3rd order at say +/-0.2 MHz offsets from the edge (4.8MHz and 5.2MHz). My computation is a spacing of Fcarrier +/-1.8GHz, in order to create the 3rd order tones. Is this correct?
My system uses 0to2khz freqs. Hence I do not want to use any RF it possible to generate ofdm signal in this BW range and transmit it without using any carrier. If so what factors determine the carrier freqs and no of carriers. My BW and Symbol time is known and fixed. Thanks
Hai What is difference between carrier interferometry uwb signal format and uwb-ofdm signal format......Please give answer.....
The following code is used to estimate and correct the frequency offset errors for a single carrier system %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% freqOffset = 0; phaseOffset = 0; hPFO = comm.PhaseFrequencyOffset('FrequencyOffset', freqOffset, ... 'PhaseOffset', phaseOffset, ... 'SampleRate', samplesPerSymbol/Ts); rx_signal1l = step(
ofdm Receiver: non-synchronous sampling scheme Hi all, we want to implemented an ofdm receiver in SDR (software defined radio),so for this reason we have the below problems 1-symbol timing synchronization(correct symbol start position before FFT) 2- the carrier frequency synchronization 3-the sampling clock (...) com discrete carriers(present in ifft) modulate input sequence? 2.which parameter of carrier is changing?(after this base band or band pass modulation? 4.why ofdm spectrum is continues? i,e sinc each having null at center of adjacent carrier..
Here is a better explanation of the PAR (crest factor): As you see, almost every signal have some kind of peak to average. For a multi-carrier signal (as ofdm) generally the peak-to-average can be calculated with: PAR = 10*LOG(Number-of-carriers) For example the PAR of a 12 carriers signal would
In MIMO-ofdm system a delay (cyclic delay diversity) is added to the sub-carrier in each antenna in order to have different spacial dimensions for the signals but this done before adding the cyclic prefix for a reason what is it???
Hi All, I'm really in trouble because of this awgn. I am trying to add noise awgn to oversampled ofdm signal. my signal is oversampled 20 times and modulated on a high frequency carrier. After applying band pass filter I have tried to do this SNR = EbNo + 10*log10(k) - 10*log10(upsamp) corrupted = awgn(usig, SNR,'measured','dB'); where u
I think you gave yourself a difficult task. I would still go for the synchronous data stream- you can asynchronously transform the "wild" data onto sync data. I do not think the 432 MHz band offers enough bandwidth for your ten OOK data channels. I think there are 432,434, etc, SAW resonators available for small keychain oscillators. I would s
Perheaps the reason of the failure is the Peak-to-Average of the modulated signal. Most of the single carrier digital modulations have a Peak to Average in a range of about 4dB to 8dB. Multi-carrier modulation types (as ofdm) have even higher peaks. If your PA works fine at P1dB using a CW signal, when the input reach higher peaks (due to (...)