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基于MATLAB的多输入多输出空时分组码通信系统仿真

news 2025/10/1 17:05:34

基于MATLAB的多输入多输出（MIMO）空时分组码（STBC）通信系统仿真实现方案

一、系统模型设计

1. 系统架构

% 参数设置
numTx = 2;    % 发射天线数
numRx = 2;    % 接收天线数
numSymbols = 1000; % 传输符号数
SNR_dB = 0:2:20; % 信噪比范围
modOrder = 4;   % QPSK调制阶数

2. 关键模块

STBC编码：采用Alamouti方案（2x2天线配置）
调制方式：QPSK
信道模型：瑞利衰落信道+AWGN
信道估计：基于导频符号的LS估计
解码算法：最大似然检测

二、完整MATLAB代码实现

function ber = MIMO_STBC_Simulation()% 参数初始化numTx = 2; numRx = 2; numSymbols = 1000;SNR_dB = 0:2:20; modOrder = 4;EbNo = 10.^(SNR_dB/10); % 转换为线性值% 生成随机数据data = randi([0 modOrder-1], numTx*numSymbols, 1);txBits = bi2de(reshape(data, numTx, numSymbols)); % 转换为符号% STBC编码（Alamouti方案）encodedData = STBC_Encode(txBits);% 调制modData = qammod(encodedData, modOrder, 'UnitAveragePower', true);% 信道传输rxSignal = zeros(size(modData));for snr = 1:length(SNR_dB)% 添加瑞利衰落H = (1/sqrt(2))*(randn(numRx,numTx) + 1j*randn(numRx,numTx));% 添加高斯噪声noise = (1/sqrt(2))*(randn(size(modData)) + 1j*randn(size(modData)));rxSignal(:,:,snr) = H*modData + 10^(-SNR_dB(snr)/20)*noise;end% 信道估计与解码rxBits = zeros(size(txBits));for snr = 1:length(SNR_dB)% 导频提取（假设每2个符号插入1个导频）pilotIdx = 1:2:numSymbols;pilotSymbol = encodedData(pilotIdx);% LS信道估计H_est = zeros(numRx,numTx);for tx = 1:numTxH_est(:,tx) = rxSignal(pilotIdx,tx,snr) / pilotSymbol;end% STBC解码decodedData = STBC_Decode(rxSignal(:,:,snr), H_est);% 解调rxBits(:,snr) = de2bi(de2bi(qamdemod(decodedData, modOrder)), 1);end% 误码率计算[~, ber] = biterr(txBits, rxBits);
end% STBC编码函数
function encoded = STBC_Encode(data)[numTx, numSym] = size(data);encoded = zeros(2*numSym, numTx);for sym = 1:numSymencoded(2*sym-1,:) = data(:,sym);encoded(2*sym,:) = -conj(data(:,sym+1));end
end% STBC解码函数
function decoded = STBC_Decode(rx, H)[numRx, numTx] = size(H);numSym = size(rx,1)/2;decoded = zeros(numTx, numSym);for sym = 1:numSym% 构建接收矩阵Rx = rx(2*sym-1:2*sym,:)';% 最大似然检测H_sub = H(:,1:numTx-1);R_sub = Rx(1:end-1);% 计算候选符号candidates = exp(1j*angle(R_sub * pinv(H_sub)));[~, idx] = max(abs(candidates));decoded(:,sym) = [real(candidates(idx)); imag(candidates(idx))];end
end

三、仿真结果分析

1. BER曲线绘制

ber = MIMO_STBC_Simulation();
semilogy(SNR_dB, ber, 'b-o', 'LineWidth', 1.5);
grid on;
xlabel('SNR (dB)');
ylabel('BER');
title('MIMO-STBC系统BER性能曲线');
legend('仿真结果', '理论值');