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Performance Evaluation of WiMAX/IEEE 802.16 OFDM Physical Layer - page 95 / 107

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%CP length C P _ l e n = I E E E 8 0 2 1 6 p a r a m s . O f d m . G * s i z e ( t i m e d o m a i n _ d a t a , 1 ) ;

% append the CP at the beginning of time data t i m e d o m a i n _ d a t a _ c p = [ t i m e d o m a i n _ d a t a ( e n d + 1 ­ C P _ l e n : e n d , : ) ; t i m e d o m a i n _ d a t a ] ;

% time domain data vector timedomain_data_vec=timedomain_data_cp(:).'; %IEEE 802.16 Receiver

% ofdm demodulator function [data_sub,pilot_sub]=ofdm_demodulator(rx_signal) %% ofdm_demodulator(rx_signal):generate frequency domain OFDM symbol global IEEE80216params;

symbol_length=IEEE80216params.Ofdm.Nfft*(1+IEEE80216params.Ofdm.G);%symbol length no_of_symbols=floor(size(rx_signal,2)/symbol_length);%number of symbol

for i=1:IEEE80216params.simOpts.RxDiv

rx_data=rx_signal(i,:);

clear rx_signal; ofdm_symbol=rx_data(1:no_of_symbols*symbol_length); ofdm_symbol=reshape(ofdm_symbol,symbol_length,no_of_symbols);

clear rx_data; % separating guard ofdm_symbol=ofdm_symbol(symbol_length­IEEE80216params.Ofdm.Nfft+1:symbol_length,:); %f t operation

freq_domain_data=fft(ofdm_symbol)/(IEEE80216params.Ofdm.Nfft/sqrt(IEEE80216params.Ofdm.Nused) /IEEE80216params.simOpts.RxDiv);

%separation of pilot and data symbol data_sub(i,:,:)=freq_domain_data(IEEE80216params.Map.DataSubCars,:); pilot_sub(i,:,:)=freq_domain_data(IEEE80216params.Map.PilotSubCars,:); end

% de­mapper function demod_bit_stream=demodulator(ofdm_demod_symbol) % demodulator(ofdm_demod_symbol): demodulate according to the selected scheme. % rescaling has been done since symbols were scaled before in mapping global IEEE80216params;

switch (IEEE80216params.Modulation.Type) case 'BPSK' %There is no need for scaling in BPSK demodulated_symbol=pskdemod(ofdm_demod_symbol,2); symbol_size=1; case 'QPSK' %scaling scalin_fact=sqrt(1/2); o f d m _ d e m o d _ s y m b o l = o f d m _ d e m o d _ s y m b o l / s c a l i n _ f a c t %4QAM demodulation ;

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