ofdm 仿真的程序，包括参数定义，fft，ifft，调制解调等源码，很好用啊.zip

echo off;clear all;close all;clc; fprintf( 'OFDM仿真\n') ; tic % --------------------------------------------- % % 参数定义 % % --------------------------------------------- % % Initialize the parameters NumLoop = 1000; NumSubc = 128; NumCP = 8; SyncDelay = 0; %----------------------------------------------- % 子载波数 128 % 位数/ 符号 2 % 符号数/ 载波 1000 % 训练符号数 0 % 循环前缀长度 8 (1/16)*T % 调制方式 4-QAM % 多径信道数 3 % IFFT Size 128 % 信道最大时延 2 %----------------------------------------------- % --------------------------------------------- % % QAM MODULATION % % --------------------------------------------- % % Generate the random binary stream for transmit test BitsTx = floor(rand(1,NumLoop*NumSubc)*2); % Modulate (Generates QAM symbols) % input: BitsTx(1,NumLoop*NumSubc); output: SymQAM(NumLoop,NumSubc/2) SymQAMtmp = reshape(BitsTx,2,NumLoop*NumSubc/2).'; SymQAMtmptmp = bi2de(SymQAMtmp,2,'left-msb'); %-------------------------------------------------------------------------- % 函数说明： % bin2dec(binarystr) interprets the binary string binarystr and returns the % equivalent decimal number. % bi2de是把列向量的每一个元素都由2进制变为10进制 % D = BI2DE(...,MSBFLAG) uses MSBFLAG to determine the input orientation. % MSBFLAG has two possible values, 'right-msb' and 'left-msb'. Giving a % 'right-msb' MSBFLAG does not change the function's default behavior. % Giving a 'left-msb' MSBFLAG flips the input orientation such that the % MSB is on the left. % % % D = BI2DE(...,P) converts a base P vector to a decimal value. % % Examples: % % >> B = [0 0 1 1; 1 0 1 0]; % % >> T = [0 1 1; 2 1 0]; % % % % >> D = bi2de(B) >> D = bi2de(B,'left-msb') >> D = bi2de(T,3) % % D = D = D = % % 12 3 12 % % 5 10 5 %-------------------------------------------------------------------------- % QAM modulation % 00->-1-i,01->-1+i,10->1-i,11->1+i % 利用查表法进行QAM星座映射 QAMTable = [-1-i -1+i 1-i 1+i]; SymQAM = QAMTable(SymQAMtmptmp+1); % plot(SymQAM,'o'); % axis([-2,2,-2,2]); % --------------------------------------------- % % IFFT % % --------------------------------------------- % % input: SymQAM(NumLoop,NumSubc/2); output: SymIFFT(NumSubc,NumLoop) SymIFFT = zeros(NumSubc,NumLoop); SymIFFTtmp = reshape(SymQAM,NumSubc/2,NumLoop); SymIFFTtmptmp = zeros(NumSubc,NumLoop); SymIFFTtmptmp(1,:) = real(SymIFFTtmp(1,:)); % 实数 SymIFFTtmptmp(NumSubc/2+1,:) = imag(SymIFFTtmp(1,:)); % 实数 % 这么安排矩阵的目的是为了构造共轭对称矩阵 % 共轭对称矩阵的特点是 在ifft/fft的矢量上 N点的矢量 % 在0，N/2点必须是实数 一般选为0 % 1至N/2点 与 （N/2）+1至N-1点关于N/2共轭对称 SymIFFTtmptmp(2:NumSubc/2,:) = SymIFFTtmp(2:NumSubc/2,:); SymIFFTtmptmp((NumSubc/2+2):NumSubc,:) = flipdim(conj(SymIFFTtmp(2:NumSubc/2,:)),1); %-------------------------------------------------------------------------- % 函数说明： % B = flipdim(A,dim) returns A with dimension dim flipped. % When the value of dim is 1, the array is flipped row-wise down. When dim is 2, % the array is flipped columnwise left to right. flipdim(A,1) is the same as % flipud(A), and flipdim(A,2) is the same as fliplr(A). %-------------------------------------------------------------------------- % % >> a = [1 2 3; 4 5 6; 7 8 9; 10 11 12] % % a = % % 1 2 3 % % 4 5 6 % % 7 8 9 % % 10 11 12 % % >> b = flipdim(a,1) % % b = % % 10 11 12 % % 7 8 9 % % 4 5 6 % % 1 2 3 SymIFFT = ifft(SymIFFTtmptmp,NumSubc,1);%按列做ifft % --------------------------------------------- % % Add cyclic prefix % % --------------------------------------------- % % input: SymIFFT(NumSubc,NumLoop); output: SymCP(NumSubc + NumCP,NumLoop) NumAddPrefix = NumSubc + NumCP; SymCP = zeros(NumAddPrefix,NumLoop); RowPrefix = (NumSubc - NumCP + 1):NumSubc; SymCP = [SymIFFT(RowPrefix,:);SymIFFT]; % --------------------------------------------- % % Go through the channel % % --------------------------------------------- % % input: SymCP(NumSubc + NumCP,NumLoop); output: SymCh(1,(NumSubc + NumCP)*NumLoop) SymCh = zeros(1,(NumSubc + NumCP)*NumLoop); SymChtmp = SymCP(:).'; % 进行这个转置操作之后就成了一个矢量 % 相当于把矩阵的列向量依次排列 改变为一个行向量 Ch = [1 1/2 1/4]; SymChtmptmp = filter(Ch,1,SymChtmp); %-------------------------------------------------------------------------- % 函数说明： % Firlter data with an infinite impulse response (IIR) or finite impulse response % (FIR) filter % y = filter(b,a,X) filters the data in vector X with the filter described by % numerator coefficient vector b and denominator coefficient vector a. If a(1) is % not equal to 1, filter normalizes the filter coefficients by a(1). If a(1) equals % 0, filter returns an error. %-------------------------------------------------------------------------- % If X is a matrix, filter operates on the columns of X. If X is a multidimensional % array, filter operates on the first nonsingleton dimension. %------------------------------------------------------------------------- % Add the AWGN BerSnrTable = zeros(20,3); for snr=0:19; % = SNR + 10*log10(log2(2)); BerSnrTable(snr+1,1) = snr; SymCh = awgn(SymChtmptmp,snr,'measured'); %-------------------------------------------------------------------------- % 函数说明： % AWGN Add white Gaussian noise to a signal. % Y = AWGN(X,SNR) adds white Gaussian noise to X. The SNR is in dB. % The power of X is assumed to be 0 dBW. If X is complex, then % AWGN adds complex noise. % ------------------------------------------------------------------------ % Y = AWGN(X,SNR,SIGPOWER) when SIGPOWER is numeric, it represents % the signal power in dBW. When SIGPOWER is 'measured', AWGN measures % the signal power before adding noise. % ------------------------------------------------------------------------- % Y = AWGN(X,SNR,SIGPOWER,STATE) resets the state of RANDN to STATE. % % Y = AWGN(..., POWERTYPE) specifies the units of SNR and SIGPOWER. % POWERTYPE can be 'db' or 'linear'. If POWERTYPE is 'db', then SNR % is measured in dB and SIGPOWER is measured in dBW. If POWERTYPE is % 'linear', then SNR is measured as a ratio and SIGPOWER is measured % in Watts. % % Example: To specify the power of X to be 0 dBW and add noise to produce % an SNR of 10dB, use: % X = sqrt(2)*sin(0:pi/8:6*pi); % Y = AWGN(X,10,0); % % Example: To specify the power of X to be 0 dBW, set RANDN to the 1234th % state and add noise to produce an SNR of 10dB, use: % X = sqrt(2)*sin(0:pi/8:6*pi); % Y = AWGN(X,10,0,1234); % % Example: To specify the power of X to be 3 Watts and add noise to % produce a linear SNR of 4, use: % X = sqrt(2)*sin(0:pi/8:6*pi); % Y = AWGN(X,4,3,'linear'); % % Example: To cause AWGN to measure the power of X, set RANDN to the % 1234th state and add noise to produce a linear SNR of 4, use: % X = sqrt(2)*sin(0:pi/8:6*pi); % Y = AWGN(X,4,'measured',1234,'linear'); % --------------------------------------------- % % Remove Guard Intervals % % --------------------------------------------- % % input: SymCh(1,(NumSubc + NumCP)*NumLoop); output: SymDeCP(NumSubc,NumLoop) SymDeCP = zeros(NumS