out = lteTurboDecode(in)
out = lteTurboDecode(in,nturbodecits)
the result of turbo decoding the input data
out = lteTurboDecode(
The function can decode single data vectors or cell arrays of data
vectors. In the case of cell array input, the output is a cell array
containing the separately decoded input array vectors. The input data
is assumed to be soft bit data that has been encoded with the parallel
concatenated convolutional code (PCCC), as defined in TS 36.212 , Section 22.214.171.124. Each input
data vector is assumed to be structured as three encoded parity streams
concatenated in a block-wise fashion,
[S P1 P2],
S is the vector of systematic bits,
the vector of encoder 1 bits, and
P2 is the vector
of encoder 2 bits. The decoder uses a default value of 5 iteration
cycles. It returns the decoded bits in output vector
performing turbo decoding using a sub-log-MAP (Max-Log-MAP) algorithm.
Perform turbo decoding of soft bits obtained from a noisy constellation.
Create a bit stream, turbo encode the bit stream, and modulate it. Create noise, add it to the modulated symbols. Display the transmitted and received symbols on a scatter plot.
txBits = randi([0 1],6144,1); codedData = lteTurboEncode(txBits); txSymbols = lteSymbolModulate(codedData,'QPSK'); noise = 0.5*complex(randn(size(txSymbols)),randn(size(txSymbols))); rxSymbols = txSymbols + noise; scatter(real(rxSymbols),imag(rxSymbols),'co'); hold on; scatter(real(txSymbols),imag(txSymbols),'rx') legend('Rx constellation','Tx constellation')
Demodulate the symbols and turbo decode soft bits. Compare the transmitted and recovered bits.
softBits = lteSymbolDemodulate(rxSymbols,'QPSK','Soft'); rxBits = lteTurboDecode(softBits); numberErrors = sum(rxBits ~= int8(txBits))
numberErrors = 0
in— Soft bit input data
Soft bit input data, specified as a numeric vector or a cell array of vectors. The decoder expects the input bits to be encoded with the parallel concatenated convolutional code (PCCC), as defined in TS 36.212 , Section 5.1.3.
nturbodecits— Number of turbo decoding iteration cycles
Number of turbo decoder iteration cycles, specified as a positive scalar integer between 1 and 30. Optional.
out— Turbo decoded bits
Turbo decoded bits, returned as an integer column vector or a cell array of integer column vectors.
 3GPP TS 36.212. “Multiplexing and channel coding.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA). URL: http://www.3gpp.org.