lteRateRecoverTurbo

R2026b

Turbo rate recovery

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Syntax

[out,rminfo] = lteRateRecoverTurbo(in,trblklen,rv)
[out,rminfo] = lteRateRecoverTurbo(in,trblklen,rv,chs,cbsbuffers)

Description

[out,rminfo] = lteRateRecoverTurbo(in,trblklen,rv) performs rate recovery of the input vector, in, creating a cell array of vectors, out. out represents the turbo encoded code blocks before concatenation. rminfo is a structure that contains intermediate rate matching calculations such as soft buffer sizes, code block dimensions, and buffer output offsets. This function is the inverse of the rate matching operation for turbo encoded data. For more information, see lteRateMatchTurbo and TS 36.212, Section 5.1.4.1 [1]. This function includes the inverses of the subblock interleaving, bit collection, and bit selection and pruning stages. The dimensions of out are deduced from trblklen, which represents the length of the original encoded transport block. This parameterization is required to recover the original number of code blocks, their encoded lengths, and the locations of any filler bits. The parameter rv controls the redundancy version of the output. The bit selection recovery assumes a quadrature phase shift-keying (QPSK) transmission mapped onto a single layer. It also assumes no restriction on the number of soft bits, as in an uplink UL-SCH transport channel.

example

[out,rminfo] = lteRateRecoverTurbo(in,trblklen,rv,chs,cbsbuffers) specifies two additional inputs. The chs input structure allows additional control of the bit selection recovery stage through parameters for the soft buffer size and physical channel configuration. The cbsbuffers input allows combining with pre-existing soft information for the HARQ process.

Examples

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Open Live Script

Create a codeword from a transport block then rate recover the codeword back into a set of coded code blocks. The transport block is originally segmented into a single code block so the rateRecovered output variable is a cell array containing a single turbo coded code block.

Define the transport block length prior to CRC and turbo coding, code word length, redundancy version, and CRC polynomial. Use these parameters to perform coding operations.

trBlkLen = 135; 
codewordLen = 450; 
rv = 0;
crcPoly = '24A';
trblockwithcrc = lteCRCEncode(zeros(trBlkLen,1),crcPoly);
codeblocks = lteCodeBlockSegment(trblockwithcrc);
turbocodedblocks = lteTurboEncode(codeblocks);
codeword = lteRateMatchTurbo(turbocodedblocks,codewordLen,rv);
rateRecovered = lteRateRecoverTurbo(codeword,trBlkLen,rv)
rateRecovered = 1×1 cell array
    {492×1 int8}

rateRecovered is a cell array with a single coded code block of size indicated above.

Further turbo decoding, desegmentation and CRC decoding of rateRecovered would result in a decoded transport block of length equal to the original transport block. Note that the trBlkLen parameter of the lteRateRecoverTurbo function is the transport block length before CRC and turbo coding, not the length after turbo coding or rate matching.

Input Arguments

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Input data, specified as a numeric vector.

Data Types: double

Length of the original encoded transport block before encoding, specified as a numeric value.

Data Types: double

Redundancy version used to recover data, specified as a nonnegative integer. If PMCHTimeInterleavingN is not present in the chs structure, rv must be in the range [0, 3]. If PMCHTimeInterleavingN is present, rv must be in the range [0, PMCHTimeInterleavingN–1].

Data Types: double

Channel transmission configuration, specified as a structure. It allows additional control of the bit selection stage through parameters for the soft buffer size and physical channel configuration.

For DL-SCH and PCH turbo coded transport channels that place a limit on the soft buffer size for a transport block, you can control the soft buffer dimensions by including either NIR or the combined set of NSoftbits, TxScheme, and DuplexMode. If DuplexMode is 'TDD', also specify TDDConfig. If included, NIR takes precedence for controlling the soft buffer dimensions. The above soft bit rules apply if PMCHTimeInterleavingN is not present.

For the multicast channel (MCH) transport channel, if PMCHTimeInterleavingN is present and set to 1 or [] then there is no limit on the number of soft bits. If PMCHTimeInterleavingN is present and greater than 1, you can control the soft buffer dimensions by including either NIR or the combined set of NSoftbits, ScalingFactorBeta, and PMCHTimeInterleavingM. If included, NIR takes precedence.

When neither NIR nor NSoftbits are present, or they are set to zero, the function assumes an uplink or sidelink turbo coded transport channel and places no limit on the number of soft bits.

chs can contain the following fields.

Modulation scheme, specified as 'QPSK', '16QAM', '64QAM', '256QAM', or '1024QAM'.

Data Types: char | string

Number of transmission layers for transport block, specified as a positive integer in the interval [1, 8]. DL-SCH rate matching only. Not necessary if TxScheme is set to 'Port0', 'TxDiversity', 'Port5', or 'Port8'.

Data Types: double

PDSCH transmission scheme, specified as one of the following options.

Transmission schemeDescription
'Port0'Single antenna port, port 0
'TxDiversity'Transmit diversity
'CDD'Large delay cyclic delay diversity scheme
'SpatialMux'Closed loop spatial multiplexing
'MultiUser'Multi-user MIMO
'Port5'Single-antenna port, port 5
'Port7-8'Single-antenna port, port 7, when NLayers = 1. Dual layer transmission, ports 7 and 8, when NLayers = 2.
'Port8'Single-antenna port, port 8
'Port7-14'Up to eight layer transmission, ports 7–14

Data Types: char | string

Soft buffer size for the entire input transport block, specified as a nonnegative integer.

Data Types: double

Total number of soft channel bits, specified as a nonnegative integer.

Data Types: double

Duplex mode, specified as 'FDD' or 'TDD'.

Data Types: char | string

Uplink or downlink configuration, specified as a nonnegative scalar integer in the interval [0, 6]. Optional. Only required if DuplexMode is set to 'TDD'.

Data Types: double

Since R2026b

Number of retransmissions of a single transport block in a time-interleaved physical multicast channel (PMCH) set, specified as [] or an integer in the range [1, 16]. Optional. Use this field for MCH transport channel rate matching.

If PMCHTimeInterleavingN is greater than 1, the function performs rate recovery for an MCH configured with time interleaving. If PMCHTimeInterleavingN is 1 or empty, the function performs rate recovery for an MCH without time interleaving.

In both cases, rv must be in the range [0, PMCHTimeInterleavingN–1].

Data Types: double

Since R2026b

Fractional coefficient for MCH soft buffer size calculation, specified as a scalar in the range [0, 1]. Optional. The function uses this input only when PMCHTimeInterleavingN is greater than 1.

Data Types: double

Since R2026b

Number of different transport blocks in a time-interleaved PMCH set, specified as an integer in the range [4, 32]. Optional. The function uses this input only when PMCHTimeInterleavingN is greater than 1.

Data Types: double

Data Types: struct

Code block soft information buffers, specified as a cell array. This input argument represents any pre-existing code block-oriented soft information to be additively combined with the recovered turbo encoded code blocks. It allows the direct soft combining of consecutive HARQ retransmissions and is typically returned by a previous call to the function to recover an earlier transmission of the same transport block. The cbsbuffers cell array either:

  • dimensionally matches the output code blocks, out

  • can be empty to represent the processing of an initial HARQ transmission

  • or can be scalar to add a constant offset to all the deinterleaved soft data in a code block.

Data Types: cell

Output Arguments

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Turbo encoded code blocks before concatenation, returned as a cell array of numeric column vectors. The dimensions of out are deduced from trblklen, which represents the length of the original encoded transport block.

Data Types: cell

Since R2026b

Rate matching information, returned as a structure containing the following fields.

Soft buffer size for the transport block, returned as a nonnegative integer. A value of 0 means no limit.

Data Types: double

Total number of code blocks, returned as a nonnegative integer.

Data Types: double

Soft buffer size divided by the number of code blocks, returned as a nonnegative integer. A value of 0 means no limit.

Data Types: double

Circular buffer lengths (encoded code block lengths) of the code blocks, returned as a vector.

Data Types: double

Soft buffer sizes for the code blocks, returned as a vector.

Data Types: double

Rate matched sizes of the code blocks, returned as a vector.

Data Types: double

Buffer output offsets for the code blocks, returned as a vector.

Data Types: double

Data Types: struct

References

[1] 3GPP TS 36.212. “Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.

Version History

Introduced in R2013b

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See Also

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