基于MATLAB的MIMO - OFDM通信系统的仿真代码

好的，以下是一个基于MATLAB的MIMO-OFDM通信系统仿真的示例代码：

%% 仿真参数设置
clc;
clear all;
close all;

% 调制方式
modulation = '16qam';

% 子载波数目
numSubcarriers = 64;

% 循环前缀长度
cpLength = 16;

% 天线数
numTxAntennas = 2;
numRxAntennas = 2;

% 信噪比范围
snrRange = 0:2:20;

% 仿真帧数
numFrames = 100;

% 编码方式
trellis = poly2trellis(7, [133 171]);

%% 构建通信系统模型
% OFDM调制解调器
ofdmMod = comm.OFDMModulator('FFTLength', numSubcarriers, ...
    'CyclicPrefixLength', cpLength, 'NumGuardBandCarriers', [6;5], ...
    'InsertDCNull', true, 'PilotInputPort', true, ...
    'NumPilotCarriers', numSubcarriers/4, 'PilotCarrierIndices', ...
    [12;26;40;54], 'Windowing', true, 'WindowLength', 24, ...
    'WindowName', 'Hanning', 'NormalizationMethod', 'power', ...
    'AveragePower', 1);

ofdmDemod = comm.OFDMDemodulator('FFTLength', numSubcarriers, ...
    'CyclicPrefixLength', cpLength, 'NumGuardBandCarriers', [6;5], ...
    'RemoveDCCarrier', true, 'PilotOutputPort', true, ...
    'NumPilotCarriers', numSubcarriers/4, 'PilotCarrierIndices', ...
    [12;26;40;54], 'Windowing', true, 'WindowLength', 24, ...
    'WindowName', 'Hanning', 'NormalizationMethod', 'power');

% 调制解调器
switch modulation
    case 'bpsk'
        mod = comm.BPSKModulator();
        demod = comm.BPSKDemodulator();
    case 'qpsk'
        mod = comm.QPSKModulator();
        demod = comm.QPSKDemodulator();
    case '16qam'
        mod = comm.RectangularQAMModulator('ModulationOrder', 16, ...
            'BitInput', true);
        demod = comm.RectangularQAMDemodulator('ModulationOrder', 16, ...
            'BitOutput', true);
    case '64qam'
        mod = comm.RectangularQAMModulator('ModulationOrder', 64, ...
            'BitInput', true);
        demod = comm.RectangularQAMDemodulator('ModulationOrder', 64, ...
            'BitOutput', true);
    otherwise
        error('不支持该调制方式');
end

% 编码解码器
encoder = comm.TrellisEncoder(trellis);
decoder = comm.TrellisDecoder(trellis, 'OutputDataType', 'double');

% MIMO信道
mimoChan = comm.MIMOChannel('SampleRate', 2e6, 'PathDelays', [0 1.5e-6], ...
    'AveragePathGains', [0 -3], 'MaximumDopplerShift', 30, ...
    'SpatialCorrelationSpecification', 'None', 'ReceiveCorrelationMatrix', ...
    eye(numRxAntennas), 'TransmitCorrelationMatrix', eye(numTxAntennas), ...
    'NumTransmitAntennas', numTxAntennas, 'NumReceiveAntennas', numRxAntennas);

% AWGN信道
awgnChan = comm.AWGNChannel('NoiseMethod', 'Signal to noise ratio (SNR)', ...
    'SNR', 0);

%% 开始仿真
% 误码率存储
ber = zeros(length(snrRange), 1);

for snrIdx = 1:length(snrRange)
    awgnChan.SNR = snrRange(snrIdx);
    errorRate = comm.ErrorRate();

    for frameIdx = 1:numFrames
        % 生成随机数据
        data = randi([0 1], numSubcarriers*mod.InputBitPerSymbol*numTxAntennas, 1);

        % 编码
        encodedData = encoder(data);

        % 调制
        modData = mod(encodedData);

        % OFDM调制
        ofdmData = ofdmMod(reshape(modData, numSubcarriers, []));

        % MIMO发送
        txSig = mimoChan(ofdmData.');

        % AWGN信道
        rxSig = awgnChan(txSig);

        % MIMO接收
        rxOfdmData = mimoChan(rxSig);

        % OFDM解调
        demodData = ofdmDemod(rxOfdmData).';

        % 解调
        demodulatedData = demod(demodData(:));

        % 解码
        decodedData = decoder(demodulatedData);

        % 计算误码率
        errorStats = errorRate(data, decodedData);
    end

    % 存储误码率
    ber(snrIdx) = errorStats(1);
end

%% 结果展示
% 绘制误码率曲线
figure;
semilogy(snrRange, ber);
title('MIMO-OFDM系统误码率曲线');
xlabel('信噪比（dB）');
ylabel('误码率');
grid on;

此代码实现了一个基于16QAM调制的MIMO-OFDM通信系统的仿真，包括了调制解调、编码解码、OFDM调制解调、MIMO发送接收、AWGN信道等模块，并且可以绘制误码率曲线进行性能评估。您可以根据实际需求进行修改和扩展。