basic vht data recovery -凯发k8网页登录

basic data recovery

wlan toolbox™ provides functions to generate and recover ieee® 802.11ac™ standards-compliant waveforms. the data recovery process comprises these steps.

the block diagram shows these steps, along with their corresponding commands.

create vht configuration object.

cfg = wlanvhtconfig;

create a vht transmit waveform by using the vht configuration object. set the data sequence to [1;0;1;1]. the waveform generator function repeats the data sequence to generate the specified number of packets.

txsig = wlanwaveformgenerator([1;0;1;1],cfg);

pass the received signal through an awgn channel.

rxsig = awgn(txsig,10);

determine the field indices of the waveform.

ind = wlanfieldindices(cfg);

extract the vht-ltf from the received signal.

rxvhtltf = rxsig(ind.vhtltf(1):ind.vhtltf(2),:);

demodulate the vht-ltf. estimate the channel response by using the demodulated signal.

demodvhtltf = wlanvhtltfdemodulate(rxvhtltf,cfg);
chest = wlanvhtltfchannelestimate(demodvhtltf,cfg);

extract the vht data field.

rxdata = rxsig(ind.vhtdata(1):ind.vhtdata(2),:);

recover the information bits by using the channel and noise variance estimates. confirm that the first 8 bits match two repetitions of the input data sequence of [1;0;1;1].

rxbits = wlanvhtdatarecover(rxdata,chest,0.1,cfg);
rxbits(1:8)

ans = 8x1 int8 column vector
   1
   0
   1
   1
   1
   0
   1
   1

data recovery with frequency correction

data recovery when a carrier frequency offset is present is accomplished by these steps.

the block diagram shows these steps, along with their corresponding commands.

set the channel bandwidth and sample rate.

cbw = 'cbw160';
fs = 160e6;

create a vht configuration object that supports a 2x2 mimo transmission.

cfg = wlanvhtconfig('channelbandwidth',cbw, ...
    'numtransmitantennas',2,'numspacetimestreams',2);

generate a vht waveform containing a random psdu.

txpsdu = randi([0 1],cfg.psdulength*8,1);
txsig = wlanwaveformgenerator(txpsdu,cfg);

create a 2x2 tgac channel.

tgacchan = wlantgacchannel('samplerate',fs,'channelbandwidth',cbw, ...
    'numtransmitantennas',2,'numreceiveantennas',2);

create a phase and frequency offset object.

pfoffset = comm.phasefrequencyoffset('samplerate',fs,'frequencyoffsetsource','input port');

pass the transmitted waveform through the noisy tgac channel.

rxsignonoise = tgacchan(txsig);
rxsig = awgn(rxsignonoise,15);

introduce a frequency offset of 500 hz to the received signal.

rxsigfreqoffset = pfoffset(rxsig,500);

find the start and stop indices for all component fields of the ppdu.

ind = wlanfieldindices(cfg);

extract the l-stf. estimate and correct for the carrier frequency offset.

rxlstf = rxsigfreqoffset(ind.lstf(1):ind.lstf(2),:);
foffset1 = wlancoarsecfoestimate(rxlstf,cbw);
rxsig1 = pfoffset(rxsigfreqoffset,-foffset1);

extract the l-ltf from the corrected signal. estimate and correct for the residual frequency offset.

rxlltf = rxsig1(ind.lltf(1):ind.lltf(2),:);
foffset2 = wlanfinecfoestimate(rxlltf,cbw);
rxsig2 = pfoffset(rxsig1,-foffset2);

extract and demodulate the vht-ltf. estimate the channel coefficients.

rxvhtltf = rxsig2(ind.vhtltf(1):ind.vhtltf(2),:);
demodvhtltf = wlanvhtltfdemodulate(rxvhtltf,cfg);
chest = wlanvhtltfchannelestimate(demodvhtltf,cfg);

extract the vht data field from the received and frequency-corrected ppdu. recover the data field.

rxdata = rxsig2(ind.vhtdata(1):ind.vhtdata(2),:);
rxpsdu = wlanvhtdatarecover(rxdata,chest,0.03,cfg);

calculate the number of bit errors in the received packet.

numerr = biterr(txpsdu,rxpsdu)

numerr = 2