how to find the BER and PAPR for mimo ofdm systems using matlab code

how to find out the ber,papr and power spectral density of a 2x2 ldpc mimo ofdm ?

[Darshan Ramakant Bhat]

Found a related File Exchange Submission. Contact the File Exchange Author for more information regarding the algorithm :

https://www.mathworks.com/matlabcentral/fileexchange/28437-simulating-2-2-mimo-ldpc-base-band-systems

[Kasyap Suresh]

I am just referring to ABDUL's post here. This is about simulating a QPSK system and evaluating its BER for MIMO OFDM based systems. Given below is the code. Hope you find this useful. All the best.

M=4;

k=log2(M); % number of bits/symbol

number_of_data_points=64; % FFT Size or total number of subcarriers=N=64= IFFT size

block_size=16; % Block Size, no of rows,data subcarriers

BW=8*10^6; % Bandwidth of the OFDM system

Nsp=52;

%Derived Parameters

deltaf=BW/number_of_data_points;%bandwidth of each subcarriers including used and unused subacarriers

TFFT=1/deltaf; % ofdm_symbol_duration

TGI=TFFT/4; % duration of the cyclic prefix= guard interval duration 25% of the subcarriers to be used as a GI

% possible guard band values 1/4, 1/8, 1/16 and 1/32

Tsignal= TGI+TFFT ; % total ofdm symbol duration

Ncp=number_of_data_points*(TGI/TFFT); % length of the cyclic prefix

cp_len=ceil(0.25*block_size);

fft_points=number_of_data_points;

ifft_points=number_of_data_points;

Nt=2;

Nr=2;

cp_start=block_size-cp_len;

cp_end=block_size;

actual_cp=zeros(cp_len, block_size);

data_subcarriers=cp_start+Nsp;

nsf=8/7;

Fs=ceil(nsf*BW);

% initialization of SNR

SNRstart=0;

SNRincrement=1;

SNRend=25;

index=0;

%-------------------------------------------------------------------------%

%1. 1st Block -Implementation of binary data %

%1st Block -Implementation of bianry data- generation %

%-------------------------------------------------------------------------%

x1=randi([0 1],1,64);

br=BW; %Let us transmission bit rate 1000000

fc=br; % minimum carrier frequency

Tc=1/br; % bit duration

tmod=Tc/99:Tc/99:Tc; % Time vector for one bit information

H=[1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1;0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,1,1,0,0,0,1,1,0,0,0;1,0,1,0,0,1,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0;0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,1,0,0,0,1,0,1,1,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,1;0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0;0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0,1,0,0,1,0,0,0,0;0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,1,0,0,0,0,0,0,0,0,0,0;0,0,1,0,1,0,0,1,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0;0,0,0,1,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0;0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,1,1,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,1,0,0,0,0,0,1,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,1,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0;1,1,0,0,0,0,0,0,1,1,0,1,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,1,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0;0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0;0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1;0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,1,0,1,1,0,0,0,0,1,0,1,0,0,0,0,0,0,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,1,0;0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,1,0,0,0;0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,1;0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,1,1,0;0,0,0,1,0,0,1,0,0,0,0,1,0,1,0,1,1,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0;1,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,1,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,1,0,0,0,0,1,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,1,0,1,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,1,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,0,0;1,0,0,0,1,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,0;0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,1;0,0,1,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,0;0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0;0,0,1,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1;1,0,0,0,1,1,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,1,0,0,0,1,1,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0;0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0;0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,1,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0;0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0;0,1,0,0,1,0,0,0,0,1,1,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0;0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0,0,0,0,0;1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0;0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,1,0,0,0,0,0,0,0,0;0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,1,0,0,0,0,1,1,0,0,0,1,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0;0,0,1,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,1,0,0,0,1,0,1,0,0,0,0,1,1,0,1,1];

%-------------------------------------------------------------------------%

%------- encoded data by using LDPC Encoder and Parity Check Matrix-------%

%-------------------------------------------------------------------------%

data_encoded=x1*H;

mod_data=mod(data_encoded,2);

%-------------------------------------------------------------------------%

%---------3. modulation of the data by using psk------------------------- %

%-------------------------------------------------------------------------%

data_NRZ=2*mod_data-1; % Data Represented at NZR form for QPSK modulation

s_p_data=reshape(data_NRZ,2,length(x1)/2); % S/P convertion of data

ymod=[];

ycomplex=[];

y_in=[];

y_qd=[];

for imod = 1:length(x1)/2

y1 = s_p_data(1,imod)*cos(2*pi*fc*tmod); % inphase component

y2 = s_p_data(2,imod)*sin(2*pi*fc*tmod) ;% Quadrature component

y_in = [y_in y1]; % inphase signal vector

y_qd = [y_qd y2]; %quadrature signal vector

ymod=[ymod y1+y2]; % modulated signal vector

ycomplex = [ycomplex (sign(y1))+(1i*sign(y2))];

end

psk_mod=ycomplex;

Tx_sig1=ymod; % transmitting signal after modulation

Tx_sig=ycomplex; % transmitting signal after modulation

Tx_sig_complex=ycomplex;

ttmod=Tc/99:Tc/99:(Tc*length(x1))/2;

% to find out the number of columns after reshaping

num_colums=(size(Tx_sig_complex,1)*size(Tx_sig_complex,2))/block_size;

%-------------------------------------------------------------------------%

% 5.to perform serial to parallel conversion %

%-------------------------------------------------------------------------%

reshaped_mod_data = reshape(Tx_sig1,[block_size, num_colums]);

%-------------------------------------------------------------------------%

% 6. To Perform IFFT and Cyclic Prefix %

% to create empty matrix to put ifft data %

% 7.operate column wise and do cyclic prefix, column wise cyclic prefix is done

%-------------------------------------------------------------------------%

for ireshape=1:num_colums

ifft_data_matrix(:,ireshape)=ifft(reshaped_mod_data(:,ireshape));

for jcplen= 1:cp_len % compute cyclic prefix data

actual_cp(jcplen,ireshape) = ifft_data_matrix(jcplen+cp_start,ireshape).';

end

ifft_data_after_cp(:,ireshape) = vertcat(actual_cp(:,ireshape),ifft_data_matrix(:,ireshape));% perform cyclic prefix

end

%-------------------------------------------------------------------------%

% 8. to perform parallel to serial conversion %

%-------------------------------------------------------------------------%

parallel_serial_tx = reshape(ifft_data_after_cp(:,:),size(ifft_data_after_cp(:,:),2),size(ifft_data_after_cp(:,:),1));

%-------------------------------------------------------------------------%

% 12. To find the number of rows and colums after ifft %

%-------------------------------------------------------------------------%

[ifft_rows,ifft_colums]=size(parallel_serial_tx);

ofdm_length=ifft_rows*ifft_colums;

%-------------------------------------------------------------------------%

% to convert to serial stream for to obtain OFDM Signal %

% to generate ofdm signal - begin %

%-------------------------------------------------------------------------%

ofdm_signal= reshape(parallel_serial_tx,1,ofdm_length) ;% serial_parallel_form = reshape( b,block_size,num_colums) ;1x130

received_bits=zeros(size(SNRstart:SNRincrement:SNRend));

index=0;

for snr=SNRstart:SNRincrement:SNRend

index=index+1;

%creation of multipath channel

channel = randn(size(parallel_serial_tx))+sqrt(-1)*randn(size(parallel_serial_tx));

% Pass the signal thru the channel

after_channel = filter(reshape(channel,1,[]),1,ofdm_signal);

%generate AWGN noise

awgn_noise=awgn(after_channel,snr,'measured');

% received signal

received_signal = after_channel+awgn_noise;

% To perform Serial to Parallel Conversion

serial_parallel_form_rx = reshape(received_signal,[ifft_rows,ifft_colums]).';%64x2

%To Remove Cyclic Prefix

serial_parallel_form_rx(1:cp_len,:,:)=[];

% To Perform FFT operation

receivd_signal_fft_rx=fft(serial_parallel_form_rx);

% To Perform Parallel to Serial Conversion

parallel_serial_form_rx= reshape(receivd_signal_fft_rx,1,[]);

% To pass through Demodulator

Rx_data=[];

Rx_sig=parallel_serial_form_rx; % Received signal

Rx_sig_real=sign(real(Rx_sig));

Rx_sig_imag=sign(imag(Rx_sig));

for (idemod=1:1:length(x1)/2)

%%XXXXXX inphase coherent dector XXXXXXX

Z_in=Rx_sig_real((idemod-1)*length(tmod)+1:idemod*length(tmod)).*cos(2*pi*fc*tmod);

% Z_in=Rx_sig_real(((idemod-1)*length(tmod)+1:idemod*length(tmod)).*cos(2*pi*fc*tmod));

% Z_in=Rx_sig_real((idemod-1)*length(tmod)+1:}.2demod*length(tmod)).*cos(2*pi*fc*tmod);

% above line indicat multiplication of received & inphase carred signal

Z_in_intg=(trapz(tmod,Z_in))*(2/Tc);% integration using trapizodial rull

if(Z_in_intg>0) % Decession Maker

Rx_in_data=1;

else

Rx_in_data=0;

end

%%XXXXXX Quadrature coherent dector XXXXXX

Z_qd=Rx_sig_imag(((idemod-1)*length(tmod))+1:idemod*length(tmod)).*sin(2*pi*fc*tmod);

%above line indicat multiplication ofreceived & Quadphase carred signal

Z_qd_intg=(trapz(tmod,Z_qd))*(2/Tc);%integration using trapizodial rull

if (Z_qd_intg>0)% Decession Maker

Rx_qd_data=1;

else

Rx_qd_data=0;

end

Rx_data=[Rx_data Rx_in_data Rx_qd_data]; % Received Data vector

end

psk_demod_mod=Rx_data;

Hinv=H.';

rece_decoder=psk_demod_mod*Hinv;

rece_decoder_mod=mod(rece_decoder,2);

% [n, received_bits(index)]=biterr(x1,psk_demod_mod);

[n, received_bits(index)]=biterr(x1,rece_decoder_mod);

end

snr=SNRstart:SNRincrement:SNRend;

%% Plotting BER vs SNR

figure (6)

semilogy(snr,(received_bits),'-ok');

grid;

title('OFDM Bit Error Rate .VS. Signal To Noise Ratio');

ylabel('BER');

xlabel('SNR [dB]');