How can i use the Offset 16QAM or Offset 64 QAM in communication toolbox - Matlab 2015b.

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Hase
Hase 2015-10-21
回答： preet kaur 2017-4-19
I am using toolbox communication of Matlab 2015b version. How can i use Offset 16QAM or Offset 64 QAM in this toolbox? There is only OQPSK (comm.OQPSKModulator). Thank you in advanced.

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采纳的回答

Mike McLernon
Mike McLernon 2015-11-9
You can build up the offset QAM transmitter by doing the following:
  1. Create the 16QAM or 64QAM signal with the Rectangular QAM Modulator Baseband block (in Simulink) or the comm.RectangularQAMModulator System object (in MATLAB).
  2. Filter the signal with an appropriate pulse shaping filter -- a raised cosine filter would be a common choice. Interpolate by 4, 8, or some other even number.
  3. Manually delay the quadrature channel of the QAM signal by half of the interpolation factor.
  1 个评论
Hase
Hase 2015-11-9
编辑：Hase 2015-11-9
Hi Mr. Mike McLernon,
Thank you very much for your great support. I do step by step instructions but the constellation is incorrect. Maybe i compose the Matlab code is not properly. Could you help me to check it?
Thank you very much.
Van.
%%% Here is Matlab code for 16 OQAM %%
M = 16; % Modulation order
k = log2(M); % Bits/symbol
n = 2000; % Transmitted bits nSamp = 8; % Samples per symbol, Interpolate factor
EbNo = 10; % Eb/No (dB)
hMod = comm.RectangularQAMModulator(M,'BitInput',true);
span = 10; % Filter span in symbols
rolloff = 0.25; % Rolloff factor
hTxFilter = comm.RaisedCosineTransmitFilter('RolloffFactor',rolloff, ... 'FilterSpanInSymbols',span,'OutputSamplesPerSymbol',nSamp);
fvtool(hTxFilter,'impulse');
x = randi([0 1],n,1); % data binary
modSig = step(hMod,x); % 16 QAM symbol
txSig = step(hTxFilter,modSig); % apply the RC filter with nSamp = 4
hdelay = dsp.Delay(nSamp/2); % delay object
q_channel = step(hdelay,imag(txSig)); % delay Q channel by nSamp/2 oqam_sig = real(txSig) + 1i*q_channel; % 16 OQAM signal
scatterplot(txSig); scatterplot(oqam_sig);

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更多回答（2 个）

chandra sekhar uppu
How can we get intrinsic interfernce OQAM transmiison at particular time index? thanks in advance
preet kaur
preet kaur 2017-4-19
how can i use window function in ofdm?

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