802.11ah PER performance

I want to compute PER at different SNR when the tgahChannel.LargeScaleFadingEffect = 'Pathloss and shadowing' & tgahChannel.TransmitReceiveDistance = 50;

also PER at different DISTANCE when SNR is 30, can't get reasonable PER result. LOOKING FORWARD TO YOUR ADVICE!!! REALLY APPRECIATE!!!

% Create S1G configuration object for single user S1G short preamble
% transmission with 2 transmit antennas and 2 space-time streams
cfgS1G = wlanS1GConfig;
cfgS1G.ChannelBandwidth = 'CBW2'; % 2 MHz channel bandwidth
cfgS1G.Preamble = 'Short';        % Short preamble
cfgS1G.NumTransmitAntennas = 2;   % 2 transmit antennas
cfgS1G.NumSpaceTimeStreams = 2;   % 2 space-time streams
cfgS1G.APEPLength = 256;          % APEP length in bytes
cfgS1G.MCS = 3;                 

% Create and configure the TGah channel
tgahChannel = wlanTGahChannel;
tgahChannel.DelayProfile = 'Model-F';
tgahChannel.NumTransmitAntennas = cfgS1G.NumTransmitAntennas;
tgahChannel.NumReceiveAntennas = 2;
tgahChannel.TransmitReceiveDistance = 50; 
tgahChannel.ChannelBandwidth = cfgS1G.ChannelBandwidth;
tgahChannel.LargeScaleFadingEffect = 'Pathloss and shadowing';

snr = 20:5:40;
maxNumPackets = 5e2; % Maximum number of packets at an SNR point
% Indices for accessing each field within the time-domain packet
fieldInd = wlanFieldIndices(cfgS1G);
% OFDM information
ofdmInfo = wlanS1GOFDMInfo('S1G-Data',cfgS1G);
% Set the sampling rate of the channel
tgahChannel.SampleRate = wlanSampleRate(cfgS1G);
if ~strcmp(packetFormat(cfgS1G),'S1G-Short')
    error('This example only supports the S1G-Short packet format');
end
packetErrorRate = zeros(numel(snr),1);
for i = 1:numel(snr) % Use 'for' to debug the simulation
    % Set random substream index per iteration to ensure that each
    % iteration uses a repeatable set of random numbers
    stream = RandStream('combRecursive','Seed',0);
    stream.Substream = i;
    RandStream.setGlobalStream(stream);

    % Create an instance of the AWGN channel per SNR point simulated
    awgnChannel = comm.AWGNChannel;
    awgnChannel.NoiseMethod = 'Signal to noise ratio (SNR)';
    % Account for energy in nulls
    awgnChannel.SNR = snr(i)-10*log10(ofdmInfo.FFTLength/ofdmInfo.NumTones);

    % Loop to simulate multiple packets
    numPacketErrors = 0;
    numPkt = 1; % Index of packet transmitted
    while numPkt<=maxNumPackets 
        % Generate a packet for 802.11ah short preamble
        txPSDU = randi([0 1],cfgS1G.PSDULength*8,1);
        txWaveform = wlanWaveformGenerator(txPSDU,cfgS1G);
        % Add trailing zeros to allow for channel delay
        tx = [txWaveform; zeros(50,cfgS1G.NumTransmitAntennas)];
        preChSigPwr_dB = 10*log10(mean(abs(tx)));
        sigPwr1 = 10^((preChSigPwr_dB(1)-tgahChannel.info.Pathloss)/10);
        sigPwr2 = 10^((preChSigPwr_dB(2)-tgahChannel.info.Pathloss)/10);
        sigPwr=[sigPwr1,sigPwr2];
        awgnChannel.SignalPower = sigPwr;
        % Pass through fading indoor TGah channel
        reset(tgahChannel); % Reset channel for different realization
        rx = tgahChannel(tx);
        % Add noise
        rx = awgnChannel(rx);
        % Synchronize
        % The received signal is synchronized to the start of the packet by
        % compensating for a known delay and the default OFDM demodulation
        % symbol sampling offset.
        delay = 4;
        rxSync = rx(delay+1:end,:);
        % LTF demodulation and channel estimation
        % Demodulate S1G-LTF1
        rxLTF1 = rxSync(fieldInd.S1GLTF1(1):fieldInd.S1GLTF1(2),:);
        demodLTF1 = wlanS1GDemodulate(rxLTF1,'S1G-LTF1',cfgS1G);
        % If required, demodulate S1G-LTF2N, and perform channel estimation
        if cfgS1G.NumSpaceTimeStreams>1
            % Use S1G-LTF1 and S1G-LTF2N for channel estimation
            rxLTF2N = rxSync(fieldInd.S1GLTF2N(1):fieldInd.S1GLTF2N(2),:);
            demodLTF2N = wlanS1GDemodulate(rxLTF2N,'S1G-LTF2N',cfgS1G);
            chanEst = s1gLTFChannelEstimate([demodLTF1 demodLTF2N],cfgS1G);
        else
            % Use only S1G-LTF1 for channel estimation
            chanEst = s1gLTFChannelEstimate(demodLTF1,cfgS1G);
        end
        % Noise variance estimate from S1G-LTF1 demodulated symbols
        noiseVarEst = helperNoiseEstimate(demodLTF1);
        % Extract S1G-Data field
        rxData = rxSync(fieldInd.S1GData(1):fieldInd.S1GData(2),:);
        % OFDM demodulation
        demodSym = wlanS1GDemodulate(rxData,'S1G-Data',cfgS1G);
        % Extract data subcarriers from demodulated symbols and channel
        % estimate
        demodDataSym = demodSym(ofdmInfo.DataIndices,:,:);
        chanEstData = chanEst(ofdmInfo.DataIndices,:,:);
        % MMSE frequency domain equalization
        [eqDataSym,csi] = helperSymbolEqualize(demodDataSym,chanEstData,noiseVarEst);
        % Recover PSDU bits
        rxPSDU = s1gDataBitRecover(eqDataSym,noiseVarEst,csi,cfgS1G);
        % Determine if any bits are in error, i.e. a packet error
        packetError = any(biterr(txPSDU,rxPSDU));
        numPacketErrors = numPacketErrors+packetError;
        numPkt = numPkt+1;
    end
    % Compute PER for this SNR point
    packetErrorRate(i) = numPacketErrors/(numPkt-1);
    disp(['SNR ' num2str(snr(i))...
          ' completed after ' num2str(numPkt-1) ' packets,'...
          ' PER: ' num2str(packetErrorRate(i))]);
      disp( num2str(tgahChannel.TransmitReceiveDistance))
          disp(num2str(tgahChannel.DelayProfile))
end