%% 物理層參數設置
cfg = wlanNonHTConfig;  % 使用802.11a標準配置
cfg.ChannelBandwidth = 'CBW20';  % 20MHz帶寬
cfg.NumTransmitAntennas = 1;     % 單天線
cfg.NumSpaceTimeStreams = 1;     % 單空間流
cfg.Modulation = '16QAM';        % 調製方式
cfg.CodeRate = '3/4';            % 編碼速率

% OFDM參數
N_fft = 64;        % FFT點數
N_cp = 16;         % 循環前綴長度
N_gi = 8;          % 保護間隔長度
N_subcarriers = 48; % 有效子載波數

% 生成MAC幀頭和服務字段
mac_header = randi([0 1], 24 * 8, 1);  % 24字節MAC頭
service_field = zeros(16,1,'uint8'); % 16字節服務字段

% 生成有效載荷數據
payload_bits = randi([0 1], 1000 * 8, 1);  % 1000字節數據

% 組合PSDU數據
psdu = [mac_header service_field payload_bits];

% 卷積編碼
trellis = poly2trellis(7, [133 171]);  % 約束長度7，生成多項式
encoded_bits = convenc(psdu, trellis);

% 擾碼生成
scrambler = comm.Scrambler([1 1 1 1 1 1 1], 0);
scrambled_bits = scrambler(encoded_bits);

% 塊交織
interleaver = comm.BlockInterleaver([48 48 48 48]);
interleaved_bits = interleaver(scrambled_bits);

% 16QAM映射
modulator = comm.RectangularQAMModulator('NormalizationMethod', 'Average power', ...
                                       'AveragePower', 1);
modulated_symbols = modulator(interleaved_bits);

% IFFT變換
tx_waveform = ifft(modulated_symbols, N_fft);

% 添加循環前綴
tx_waveform_cp = [tx_waveform(end-N_cp+1:end,:) tx_waveform];

% 創建萊斯信道模型
rician_chan = comm.RicianChannel('SampleRate', 20e6, ...
                               'PathDelays', [0 1.7e-6 2.8e-6], ...
                               'AveragePathGains', [0 -5 -8], ...
                               'KFactor', 10);

% 通過信道
received_signal = rician_chan(tx_waveform_cp);

% 添加高斯噪聲
SNR = 20;  % 信噪比(dB)
noise_power = var(received_signal)/10^(SNR/10);
noise = sqrt(noise_power/2)*(randn(size(received_signal)) + 1j*randn(size(received_signal)));
received_signal_noisy = received_signal + noise;

% STF同步（短訓練序列）
stf = [1 1 -1 -1 1 1 -1 -1 -1 -1 1 1 1 1 1 1 1 1 -1 -1 1 1 -1 -1 1 1 1 1];
correlation = xcorr(received_signal_noisy, stf);
[~, peak_idx] = max(abs(correlation));
sync_pos = peak_idx - length(stf) + 1;

% 剩餘時延估計
delay_estimate = sync_pos - 16;  % 假設STF長度為16
received_aligned = received_signal_noisy(delay_estimate:end);

% 去除循環前綴
rx_without_cp = received_aligned(1:end-N_cp);

% FFT變換
rx_spectrum = fft(rx_without_cp, N_fft);

% 提取有效子載波
rx_data = rx_spectrum(2:N_subcarriers+1);  % 跳過DC子載波

% 導頻提取與信道估計
pilot_indices = [6 20 33 47];  % 導頻子載波位置
pilot_values = rx_data(pilot_indices);

% 最小二乘信道估計
H_est = zeros(N_subcarriers,1);
H_est(pilot_indices) = pilot_values;

% 均衡處理
equalized_data = rx_data ./ H_est;

% 解交織
deinterleaver = comm.BlockDeinterleaver([48 48 48 48]);
deinterleaved_data = deinterleaver(equalized_data);

% Viterbi解碼
trellis_dec = poly2trellis(7, [133 171]);
decoded_bits = vitdec(deinterleaved_data, trellis_dec, 5, 'trunc', 'hard');

% 原始數據與接收數據對比
ber = sum(psdu ~= decoded_bits)/length(psdu);
fprintf('誤碼率(BER): %.4f\n', ber);

% 根據SNR動態調整調製方式
if SNR > 25
    cfg.Modulation = '64QAM';
elseif SNR > 15
    cfg.Modulation = '16QAM';
else
    cfg.Modulation = 'QPSK';
end

% 基於導頻的頻偏估計
freq_offset = angle(sum(pilot_values .* conj(pilot_est))) / (2*pi);
rx_compensated = rx_data .* exp(-1j*2*pi*freq_offset*(0:N_subcarriers-1));

% 主函數框架
function main()
    % 參數配置
    [tx_waveform, cfg] = generate_phy_signal();
    
    % 信道傳輸
    received_signal = channel_model(tx_waveform);
    
    % 接收處理
    rx_data = receive_processing(received_signal);
    
    % 解碼與評估
    [ber, decoded_data] = decode_and_evaluate(rx_data, cfg);
    
    % 可視化
    plot_constellation(rx_data);
    plot_ber_curve(ber);
end

% 多天線配置
cfg.NumTransmitAntennas = 2;
cfg.NumSpaceTimeStreams = 2;
tx_waveform = wlanWaveformGenerator(psdu, cfg);

% 基於信道質量的速率自適應
if rssi > -65
    cfg.CodeRate = '3/4';
    cfg.Modulation = '64QAM';
else
    cfg.CodeRate = '1/2';
    cfg.Modulation = 'QPSK';
end