generate vht multi-凯发k8网页登录

this example shows how to generate a vht multi-user waveform from individual components. it also shows how to generate the same waveform by using the wlanwaveformgenerator function.

create a vht configuration object, specifying three users and three transmit antennas.

vht = wlanvhtconfig('numusers',3,'numtransmitantennas',3);

set the number of space-time streams to the vector [1 1 1], which indicates that each user is assigned one space-time stream. set the user positions to [0 1 2]. set the group id to 5. group id values from 1 to 62 apply for multiuser operation.

vht.numspacetimestreams = [1 1 1];
vht.userpositions = [0 1 2];
vht.groupid = 5;

set a different mcs value for each user.

vht.mcs = [0 2 4];

set the apep length to 2000, 1400, and 1800 bytes. each element corresponds to the number of bytes assigned to each user.

vht.apeplength = [2000 1400 1800]

vht = 
  wlanvhtconfig with properties:
       channelbandwidth: 'cbw80'
               numusers: 3
          userpositions: [0 1 2]
    numtransmitantennas: 3
    numspacetimestreams: [1 1 1]
         spatialmapping: 'direct'
                    mcs: [0 2 4]
          channelcoding: 'bcc'
             apeplength: [2000 1400 1800]
          guardinterval: 'long'
                groupid: 5
   read-only properties:
             psdulength: [2000 6008 12019]

display the psdu lengths for the three users. the psdu length is a function of both the apep length and the mcs value.

vht.psdulength

ans = 1×3
        2000        6008       12019

display the field indices for the vht waveform.

ind = wlanfieldindices(vht)

ind = struct with fields:
       lstf: [1 640]
       lltf: [641 1280]
       lsig: [1281 1600]
    vhtsiga: [1601 2240]
     vhtstf: [2241 2560]
     vhtltf: [2561 3840]
    vhtsigb: [3841 4160]
    vhtdata: [4161 48000]

create the individual fields that comprise the vht waveform.

lstf = wlanlstf(vht);
lltf = wlanlltf(vht);
lsig = wlanlsig(vht);
[vhtsiga,sigabits] = wlanvhtsiga(vht);
vhtstf = wlanvhtstf(vht);
vhtltf = wlanvhtltf(vht);
[vhtsigb,sigbbits] = wlanvhtsigb(vht);

extract the first two vht-sig-a information bits and convert them to their decimal equivalent.

bw = bit2int(double(sigabits(1:2)),2,false)

bw = 2

the value, 2, corresponds to an 80 mhz bandwidth (see ).

extract vht-sig-a information bits 5 through 10, and convert them to their decimal equivalent.

groupid = bit2int(double(sigabits(5:10)),6,false)

groupid = 5

the extracted group id, 5, matches the corresponding property in the vht configuration object.

extract the packet length from the vht-sig-b information bits. for multiuser operation with an 80 mhz bandwidth, the first 19 bits contain the apep length information. convert the field lengths to their decimal equivalents. multiply them by 4 because the length of the vht-sig-b field is expressed in units of 4 bytes.

pktlen = bit2int(double(sigbbits(1:19,:)),19,false)'*4

pktlen = 3×1
        2000
        1400
        1800

confirm that the extracted apep length matches the value set in the configuration object.

isequal(pktlen',vht.apeplength)

ans = logical
   1

extract the mcs values from the vht-sig-b information bits. the mcs component is specified by bits 20 to 23.

mcs = bit2int(double(sigbbits(20:23,:)),4,false)'

mcs = 3×1
     0
     2
     4

the values correspond to those set in the vht configuration object.

create three data sequences, one for each user.

d1 = randi([0 1],vht.psdulength(1)*8,1);
d2 = randi([0 1],vht.psdulength(2)*8,1);
d3 = randi([0 1],vht.psdulength(3)*8,1);

generate a vht data field using these data sequences.

vhtdata = wlanvhtdata({d1 d2 d3},vht);

generate a multiuser vht waveform with windowing is disabled. extract the data field from the waveform.

wv = wlanwaveformgenerator({d1 d2 d3},vht,'windowtransitiontime',0);
wvdata = wv(ind.vhtdata(1):ind.vhtdata(2),:);

confirm that the two generation approaches produce identical results.

isequal(vhtdata,wvdata)

ans = logical
   1

visualize the waveform by plotting its magnitude.

t = ((1:length(wv))'-1)/80e6;
plot(t,abs(wv))
xlabel('time (s)')
ylabel('magnitude')