ofdm预编码技术的MATLAB代码

A：

由于OFDM预编码有多种实现方式，因此提供一个通用的MATLAB代码可能会比较困难。以下代码为一种实现方式的示例，仅供参考：

% OFDM预编码

clc; clear all; close all;

%% 参数设置

N_subcarriers = 64; % 64个子载波

N_data = 48; % 数据子载波数

N_pilot = 4; % 导频子载波数

N_null = N_subcarriers - N_data - N_pilot; % 空载波数

N_bits = 1000; % 待发送的二进制比特数

EbN0 = 10; % 信噪比

antenna_num_tx = 2; % 发送天线数

antenna_num_rx = 2; % 接收天线数

%% 发送端

% 生成虚拟二进制数据

tx_data = randi([0 1],N_bits,1);

% 将虚拟二进制数据转换为符号

data_sym_I = 2 * tx_data - 1;

data_sym_Q = zeros(size(data_sym_I));

data_sym = complex(data_sym_I,data_sym_Q);

% 预编码

precode_mat = hadamard(N_subcarriers);

precode_data_sym = precode_mat(1:N_data,:) * data_sym;

% 插入导频

pilot_sym = (-1).^(0:N_pilot-1);

precode_sym = [pilot_sym,precode_data_sym,zeros(N_null,size(precode_data_sym,2))];

% IFFT

pre_ifft_sym = ifft(precode_sym);

% 添加循环前缀

prefix_len = N_subcarriers;

pre_prefix_sym = [pre_ifft_sym(N_subcarriers-prefix_len+1:end,:);pre_ifft_sym];

% 调整天线数并完成并行信号传输

tx_signal = zeros(size(pre_prefix_sym,1),antenna_num_tx);

for i = 1:antenna_num_tx

tx_signal(:,i) = pre_prefix_sym(:,1); % 实际上在这里需要添加对多天线情形的支持

end

%% 信道

% 转化为链路块矩阵并加性高斯白噪声

H = randn(antenna_num_rx,antenna_num_tx) + 1i*randn(antenna_num_rx,antenna_num_tx);

noise_power = 10^(-EbN0/10);

noise = sqrt(noise_power/2) * randn(size(tx_signal)) + 1i*sqrt(noise_power/2) * randn(size(tx_signal));

rx_signal = H*tx_signal + noise;

%% 接收端

% 提取前缀

pre_prefix_rx_sym = rx_signal(N_subcarriers+1:end,:);

% 去除前缀

pre_rx_sym = pre_prefix_rx_sym(prefix_len+1:end,:);

% FFT

rx_sym = fft(pre_rx_sym);

% 提取导频估计H矩阵

pilot_rx_sym = rx_sym(1:N_pilot,:);

pilot_est_sym = [1./mean(abs(pilot_rx_sym),2)].*pilot_rx_sym;

H_est = diag((pilot_est_sym*conj(pilot_sym).')/N_pilot);

% 数据解码

precode_rx_sym = H_est' * rx_sym;

data_rx_sym = precode_rx_sym(N_pilot+1:N_pilot+N_data,:);

rx_data_I = real(data_rx_sym(:)) > 0;

rx_data_Q = imag(data_rx_sym(:)) > 0;

rx_data = [rx_data_I;rx_data_Q];

%% 结果分析

% 根据误码率进行结果分析

bit_errors = sum(xor(tx_data(:),rx_data(:)));

BER = bit_errors/N_bits;

fprintf('误码率为%e\n',BER);