ofdm.rar_OFDM信道估计_matlab ofdm程序_ofdm_ofdm 信道估计

echo off; % 关闭回显 clear all; % 从内存中清除变量和函数 close all; % 关闭所有图形 fprintf( '\n OFDM仿真\n \n') ; % 设置显示格式 % --------------------------------------------- % % 参数定义 % % --------------------------------------------- % IFFT_bin_length = 1024; % 发送端的IFFT变换长度, 接收端的FFT变换长度，R代表接受，T代表发送 carrier_count = 200; % 子载波数 bits_per_symbol = 2; % 位数/符号 symbols_per_carrier = 50; % 符号数/载波 cp_length = input('cp length = '); % 输入循环前缀长度 d4 = input('d4 = '); % 输入最大多径时延扩展 a4 = input('a4 = '); % 输入最大多径时延扩展的系数 SNR = input('SNR = '); % 输入信道信噪比(dB) % --------------------------------------------- % % 初始参数设置完毕 % % --------------------------------------------- % baseband_out_length = carrier_count * symbols_per_carrier * bits_per_symbol; % 计算发送的二进制序列长度：基带传送长度=载波数× 符号数/载波×位数/符号 carriers = (1:carrier_count) + (floor(IFFT_bin_length/4) - floor(carrier_count/2)); % 载波（坐标）：(1:200) + 256 - 100 = 157:356 conjugate_carriers = IFFT_bin_length - carriers + 2; % 载波变换（坐标）：1024 - (157:356) + 2 = 1026 - (157:356) = (869:670) %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % 构造共轭时间－载波矩阵，以便应用所谓的RCC，Reduced Computational Complexity算法，即ifft之后结果为实数 % 也可以用flipdim函数构造对称共轭矩阵 %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % --------------------------------------------- % % 发送信号 % % --------------------------------------------- % %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % Generate a random binary output signal: % - a row of uniform random numbers (between 0 and 1), rounded to 0 or 1 % - this will be the baseband signal which is to be transmitted. %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ baseband_out = round(rand(1,baseband_out_length)); %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % round：朝最近的整数取整，rand:产生均匀分布的随机数矩阵（1×baseband_out_length阶） % Convert to 'modulo N' integers where N = 2^bits_per_symbol % - this defines how many states each symbol can represent % - first, make a matrix with each column representing consecutive bits % from the input stream and the number of bits in a column equal to the % number of bits per symbol % - then, for each column, multiply each row value by the power of 2 that % it represents and add all the rows % - for example: input 0 1 1 0 0 0 1 1 1 0 % bits_per_symbol = 2 % convert_matrix = 0 1 0 1 1 % 1 0 0 1 0 % modulo_baseband = 1 2 0 3 2 %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ convert_matrix = reshape(baseband_out,bits_per_symbol,length(baseband_out)/bits_per_symbol) ; %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % RESHAPE Change size. 把baseband_out变为M×N阶的矩阵 % RESHAPE(X,M,N) returns the M-by-N matrix whose elements % are taken columnwise from X. An error results if X does % not have M*N elements. %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ for k = 1:(length(baseband_out)/bits_per_symbol) modulo_baseband(k) = 0 ; for i = 1:bits_per_symbol modulo_baseband(k) = modulo_baseband(k) + convert_matrix(i,k)*2^(bits_per_symbol - i) ; end end %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % Serial to Parallel Conversion 串并转换 % - convert the serial modulo N stream into a matrix where each column % represents a carrier and each row represents a symbol % - for example: % serial input stream = a b c d e f g h i j k l m n o p % parallel carrier distribution = % C1/s1=a C2/s1=b C3/s1=c C4/s1=d % C1/s2=e C2/s2=f C3/s2=g C4/s2=h % C1/s3=i C2/s3=j C3/s3=k C4/s3=l % . . . . % . . . . %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ carrier_matrix = reshape(modulo_baseband, carrier_count, symbols_per_carrier)'; % 生成时间－载波矩阵（carrier_count×symbols_per_carrier） %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % Apply differential coding to each carrier string % - append an arbitrary start symbol (let it be 0, that works for all % values of bits_per_symbol) (note that this is done using a vertical % concatenation [x;y] of a row of zeros with the carrier matrix, sweet!) % - perform modulo N addition between symbol(n) and symbol(n-1) to get the % coded value of symbol(n) % - for example: % bits_per_symbol = 2 (modulo 4) % symbol stream = 3 2 1 0 2 3 % start symbol = 0 % % coded symbols = 0 + 3 = 3 % 3 + 2 = 11 = 1 % 1 + 1 = 2 % 2 + 0 = 2 % 2 + 2 = 10 = 0 % 0 + 3 = 3 % % coded stream = 0 3 1 2 2 0 3 %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % --------------------------------------------- % % QDPSK调制 % % --------------------------------------------- % carrier_matrix = [zeros(1,carrier_count);carrier_matrix]; % 添加一个差分调制的初始相位，为0 for i = 2:(symbols_per_carrier + 1) carrier_matrix(i,:) = rem(carrier_matrix(i,:)+carrier_matrix(i-1,:),2^bits_per_symbol); % 差分调制（rem除后取余） end %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % Convert the differential coding into a phase % - each phase represents a different state of the symbol % - for example: % bits_per_symbol = 2 (modulo 4) % symbols = 0 3 2 1 % phases = % 0 * 2pi/4 = 0 (0 degrees) % 3 * 2pi/4 = 3pi/2 (270 degrees) % 2 * 2pi/4 = pi (180 degrees) % 1 * 2pi/4 = pi/2 (90 degrees) %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ carrier_matrix = carrier_matrix * ((2*pi)/(2^bits_per_symbol)); % 产生差分相位 %－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－－ % Convert the phase to a complex number % - each symbol is given a magnitude of 1 to go along with its phase % (via the ones(r,c) function) % - it is then converted from polar to cartesian (complex) form % - the result is 2 matrices, X with the real values and Y with the imaginary % - each X column has all the real values for a carrier,