课设中mimo的demo

First I'd better find a mimo demo in matlab.
Introductioin to MIMO system

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Step Analysis

• Generate data vector per frame
  data = randi([0 P-1], frmLen, 1);
• Modulate data
  modData = bpskMod(data);
• Alamouti Space-Time Block Encoder
  encData = ostbcEnc(modData);
• Create the Rayleigh distributed channel response matrix for 2*2 antennas

H = zeros(frmLen, N, M);
H(1:N:end, :, :) = (randn(frmLen/2, N, M) + ...
                         1i*randn(frmLen/2, N, M))/sqrt(2);
% assume held constant for 2 symbol periods
H(2:N:end, :, :) = H(1:N:end, :, :); % I don't know why:(

其中，randn(a,b,c)
normally distributed number and a,b,c indicates the size of the matrix

• Extract part of H to represent the 1x1, 2x1 and 1x2 channels

 H11 = H(:,1,1);
 H21 = H(:,:,1)/sqrt(2);  % 2*1 channel  why /sqrt(2)
 H12 = squeeze(H(:,1,:));  % 1*2 channel squeeze: same elements but with dimensions of length 1 removed

• Pass through the channels

chanOut11 = H11 .* modData; % for 1*1 channel  no need to be encoded
chanOut21 = sum(H21.* encData, 2);
chanOut12 = H12 .* repmat(modData, 1, 2);

Question: how to set the channel and calculate the output?

• 4 channel , sum up

why sqrt2? what if I use rayleigh channel module?

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Additional Gain

for 1:numPackets
            every frame

Using loops to decrease the computation load