【RFID】基于MATLAB的RFID 系统的空中接口过程以及防碰撞算法仿真

1.软件版本

matlab2013b

2.本算法理论知识

RFID的接口过程满足如下的结构框图：

3.核心代码

clc;                  %清屏
close all;            %关闭所有窗口
clear all;            %清除所有变量
warning off;
addpath 'func\'


%%
%参数定义
%信息码长度
SNR           = [10:1:17];
TDL           = [500,400,300,200,100,50,20,10];
ERR           = zeros(1,length(SNR));

for jj = 1:length(SNR)
    jj
    Num = 0;
    Ber = 0;
    while Ber <= TDL(jj); 
    Num = Num + 1;
    Ber

    Frame_length  = 10*64;    
    %信息码速率为10KHz
    Rates         = 10e3; 
    %发送带宽20KHz
    Bwidth        = 2*Rates;     
    %发送信号功率2W
    Tpower        = 2;                        
    %载波频率70MHz
    fc            = 70e6;      
    %采样频率280MHz,满足四倍采样
    fs            = fc*4;        
    %20KHz方波
    Swave1        = 20e3;            
    %40KHz方波
    Swave2        = 40e3;             
    %采样点数
    M             = fs/(2*Swave2);   
    %信息码采样点
    L             = fs/Rates; 
    %2ASK调制的调制度
    ma            = 0.5;     
    %alpha值
    alpha         = 2*ma/(1-ma);                         


    %%
    %随机信息码产生
    data_code0 = zeros(1,Frame_length);
    %随机产生信息码
    data_code0 =(randn(1,Frame_length)>=0.5);

    %%
    %CRC校验
    data_code  = func_CRC(data_code0);

    %%
    %数据采样化
    data_code_sample = func_samples(data_code,Frame_length,L);

    %%
    %编码
    data_code_sample = func_encode(data_code_sample,data_code,Frame_length,L,M);

    %%
    %调制发送
    %FIR低通滤波器设计
    data_sample_fir  = func_filter(data_code_sample,fs,fc);
    T                = Frame_length*L*(1/fs);
    t                = [0:1/fs:T-(1/fs)];
    Carriers         = cos(2*pi*fc*t);
    %ASK调制
    RFID_ASK         =((2*Tpower).^0.5)*(1+alpha*data_sample_fir).*Carriers;
    %ASK调制信号加正弦波干扰
    RFID_ASK_sin     = RFID_ASK + 10*cos(2*pi*fc*t+pi/6); 
 

    %高斯信道
    snr                = SNR(jj);                                  
    RFID_ASK_sin_N     = awgn(RFID_ASK_sin,snr,'measured');


    figure(1);
    subplot(221)
    plot(RFID_ASK(100:1000));
    title('2ASK调制信号');
    axis([0,1000,-10,10]);

    subplot(222)
    plot(RFID_ASK_sin(100:1000));
    grid on;
    title('ASK调制信号加正弦波干扰');
    axis([0,1000,-30,30]);

    subplot(223)
    plot(RFID_ASK_sin_N(100:1000));
    grid on;
    title('过信道之后信号');
    axis([0,1000,-30,30]);


    %限幅
    AMP                = 10;
    RFID_ASK_sin_N_amp = func_amp_limit(RFID_ASK_sin_N,AMP);


    %ASK解调
    [RFID_deASK_filter,amp]=func_AKS_Demod(RFID_ASK_sin_N_amp,Carriers,fc,fs);


    subplot(224)
    plot(RFID_deASK_filter(100:end));
    grid on;
    title('2ASK解调信号');
    axis([0 L*Frame_length -5 20]);


    %判决门限
    RFID_deASK10  = func_unsamples(amp,Frame_length,M);

    %解码
    data_code_rec = func_decode(RFID_deASK10,Frame_length);

    %统计误码率
    Err_rate      = func_err(data_code_rec,data_code,Frame_length);
    Ber           = Ber + Err_rate*Frame_length;
    end
    ERR(jj) = Ber/(Num*Frame_length);
end

figure;
semilogy(SNR,ERR,'b-o');
xlabel('SNR');
ylabel('BER');
grid on;

4.操作步骤与仿真结论

 5.参考文献

A01-94