ofdmdemod
Demodulate using OFDM method
Syntax
Description
demodulates the input time domain signal specified in Y
= ofdmdemod(X
,nfft
,cplen
)X
using
the orthogonal frequency division multiplexing (OFDM) method with an FFT size
specified by nfft
and cyclic prefix length specified by
cplen
. For information, see OFDM Demodulation.
removes null subcarriers from the locations specified in
Y
= ofdmdemod(X
,nfft
,cplen
,symOffset
,nullidx
)nullidx
. For this syntax, the symbol sampling offset is
applied to each OFDM symbol and the number of rows in the output is
nfft
–
length(
, which accounts for the
removal of null subcarriers. Use null subcarriers to account for guard bands and DC
subcarriers. For information, see Subcarrier Allocation and Guard Bands.nullidx
)
[
returns pilot subcarriers for the pilot indices specified in
Y
,pilots
] = ofdmdemod(X
,nfft
,cplen
,symOffset
,nullidx
,pilotidx
)pilotidx
. For this syntax, the symbol sampling offset is
applied to each OFDM symbol and number of rows in the output Y
is nfft
–
length(
–
nullidx
)length(
, which accounts for
the removal of null and pilot subcarriers. The function assumes that pilot
subcarrier locations are the same across each OFDM symbol and transmit
antenna.pilotidx
)
specifies the optional oversampling factor name-value argument in addition to input
arguments in previous syntaxes. The oversampling factor for an upsampled input
signal must be specified as a positive scalar, and the products
(Y
= ofdmdemod(X
,nfft
,cplen
,___,OversamplingFactor=Value)OversamplingFactor
×nfft
) and
(OversamplingFactor
×cplen
) must both
result in integers. The default value for OversamplingFactor
is
1
.
For example, ofdmdemod(inSym,nfft,cplen,OversamplingFactor=2)
demodulates assuming the input signal was upsampled by a factor of two.
Tip
If you set the oversampling factor to an irrational number, specify the fractional value. For
example, with an FFT length of 12
and an oversampling factor of
4/3
, their product is the integer 16
. However,
rounding 4/3
to 1.333
when setting the oversampling
factor results in a noninteger product of 15.9960
, which results in a
code error.