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IQ imbalance impairment in MATLAB

This section of MATLAB source code covers IQ imbalance impairment and IQ amplitude and phase imbalance effect on constellation diagram using matlab code.

Part A and PART C of the matlab code is same as mentioned on AWGN page.

Source code-PART B

IQ_amp_imb = input('Enter IQ amplitude imbalance(default:0.03):'); % amplitude imbalance
IQ_phase_imb = input('Enter IQ phase imbalance(default:0.03):'); % phase imbalance
N = size(mapper_out_ori);
IQ_amp_imb = IQ_amp_imb.*randn(1,N); % linear value (not in %)
IQ_phase_imb = IQ_phase_imb*2.*(rand(1,N)-0.5); % in radians
mapper_out=mapper_out';
for i=1:N
alph = cos(IQ_phase_imb(i))-j*sin(IQ_phase_imb(i))*IQ_amp_imb(i);
beta = IQ_amp_imb(i)*cos(IQ_phase_imb(i))+j*sin(IQ_phase_imb(i));
out(:,i) = alph*mapper_out(:,i)+beta*conj(mapper_out(:,i));
end
figure;plot(real(out),imag(out),'b+');title('constellation with IQ imbalance');

Input and output constellation diagram

constellation input
IQ imbalance effect on constellation

Useful Links to MATLAB codes

Refer following as well as links mentioned on left side panel for useful MATLAB codes.
OFDM Preamble generation  Time off estimation corr  Freq off estimation corr  channel estimation  11a WLAN channel  PN sequence generation  OFDMA Tx Rx  AES DES  carrier aggregation  CCDF  FIR Filter  IIR Filter  Low Pass FIR  Viterbi decoder  CRC8 CRC32 

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