get_channel_ir.m

ofdm系统仿真

%General channel impulse response
function cir = get_channel_ir(sys_parm)
    if sys_parm.ChannelMode == 2   %RAILEITH CHANNEL       
        delay = [0 : ceil(10 * (sys_parm.MaxDelay * (1e-9)) * sys_parm.SampFreq)];
        cir = rayleighchan(1 / sys_parm.SampFreq, 0, - delay  / sys_parm.SampFreq);
    elseif sys_parm.ChannelMode == 1
        if sys_parm.MaxDelay == 0
            Kmax = 0;
            env = 1;
        else
            %Calculate the exponential decay envelope
            Kmax = ceil(10 * (sys_parm.MaxDelay * (1e-9)) * sys_parm.SampFreq) - 1;
            var0 = (1 - exp(- 1 / (sys_parm.SampFreq * (sys_parm.MaxDelay * (1e-9))))) / ...
                (1 - exp(- 1 * ((Kmax + 1) * sys_parm.SampFreq / (sys_parm.MaxDelay * (1e-9)))));
            k = [0: Kmax];
            env = var0 * exp(- k / (sys_parm.SampFreq * (sys_parm.MaxDelay * (1e-9))));
        end

        stdDevReOrIm = sqrt(env / 2);
        cir = stdDevReOrIm .* (randn(1, Kmax + 1) + j * randn(1, Kmax + 1));
        cir = cir / sqrt(cir * cir');
    else    %AWGN CHANNEL
        cir = ones(1,1);
    end
end