lteSLSCH

Sidelink shared channel

Syntax

cw = lteSLSCH(ue,outlen,trblkin)

Description

cw = lteSLSCH(ue,outlen,trblkin) returns the codeword column vector for the specified UE settings structure and output length. lteSLSCH applies the complete sidelink shared channel (SL-SCH) transport channel processing to the input data, trblkin.

For more information, see Sidelink Shared Transport Channel Processing.

Examples

Create and Decode SL-SCH Codeword

Use the physical channel bit capacity information to configure the output codeword size for SL-SCH coding. Decode the resulting codeword and check for CRC errors.

ue = struct('NSLRB',50,'CyclicPrefixSL','Normal');
ue.PRBSet = (10:12)';
ue.Modulation = '16QAM';
ue.RV = 0;

[~,psschinfo] = ltePSSCHIndices(ue);
cwlength = psschinfo.G;

trblk = randi([0 1],100,1);
cw = lteSLSCH(ue,cwlength,trblk);
[rxtrblk,err] = lteSLSCHDecode(ue,length(trblk),cw);
err

err = logical
   0

The transport block is recovered with no error.

Create SL-SCH Codeword Sequence

Create a cell array containing the redundancy version (RV) sequence of four codewords that is ready for transmission on the PSSCH.

Initialize a UE settings structure.

ue = struct('NSLRB',50,'CyclicPrefixSL','Normal');
ue.PRBSet = (10:12)';
ue.Modulation = '16QAM';

Use the physical channel bit capacity information to configure the output codeword size for SL-SCH coding. Create a transport block of information bits.

[~,psschinfo] = ltePSSCHIndices(ue);
cwlength = psschinfo.G;

trblk = randi([0 1],100,1);

Use a for loop to create a cell array containing the sequence of four SL-SCH codewords. RV = 0,2,3,1 for transmission on the PSSCH.

rvseq = [0 2 3 1];
for ii = 1:length(rvseq)
    ue.RV = rvseq(ii);
    cwseq = lteSLSCH(ue,cwlength,trblk);
    cwseqCell{ii} = cwseq;
end

Alternatively, the same cell array of SL-SCH codeword sequences can be created using an anonymous function handle.

rvseq = [0 2 3 1];

cwgenfn = @(rv)lteSLSCH(setfield(ue,'RV',rv),cwlength,trblk); %#ok<SFLD>

cwseqCell2 = arrayfun(cwgenfn,rvseq,'UniformOutput',false);

Input Arguments

ue — User equipment settings

structure

User equipment settings, specified as a parameter structure containing these fields:

SidelinkMode — Sidelink mode

'D2D' (default) | 'V2X' | optional

Sidelink mode, specified as 'D2D' or 'V2X'.

Data Types: char | string

CyclicPrefixSL — Cyclic prefix length

'Normal' (default) | 'Extended' | optional

Cyclic prefix length, specified as 'Normal' or 'Extended'.

Data Types: char | string

Modulation — Modulation type

'QPSK' | '16QAM'

Modulation type, specified as 'QPSK' or '16QAM'.

Data Types: char | string

RV — Redundancy version indicator

0 | 1 | 2 | 3 | vector with element values from 0 to 3

Redundancy version indicator, specified as an integer scalar or vector with element values from 0 to 3.

Example: [0 2 3 1], indicates the RV sequence order for transmission on the PSSCH.

Data Types: double

Data Types: struct

outlen — Codeword length

integer scalar

Codeword length, specified as an integer scalar. For more information, see Sidelink Shared Transport Channel Processing.

Data Types: double

trblkin — Transport block data bits

bit vector

Transport block data bits, specified as a bit vector.

Data Types: double

Output Arguments

cw — PSSCH codeword

integer vector

PSSCH codeword, returned as an M_bit-by-1 integer vector. M_bit is equal to outlen and is the number of bits transmitted on the physical sidelink shared channel in one subframe. outlen must be a multiple of the number of bits per symbol. For more information, see Sidelink Shared Transport Channel Processing.

More About

Sidelink Shared Transport Channel Processing

The sidelink shared channel (SL-SCH) transport channel processing includes type-24A CRC calculation, code block segmentation (including type-24B CRC attachment, if present), turbo encoding, rate matching with redundancy version (RV), code block concatenation, and PUSCH interleaving. lteSLSCH generates this transport channel codeword as specified by TS 36.212, Section 5.4.2.

The SL-SCH transport channel codeword carrying the information bits of a single transport block is transmitted on the physical sidelink shared channel. Use the ltePSSCH and ltePSSCHIndices functions to generate the modulated symbols and populate the resource grid for transmission.

The length of the codeword output by lteSLSCH represents the bit capacity of the physical channel. For PSSCH, the input codeword length is M_bits = N_RE × N_bps, where N_bps is the number of bits per symbol. The PSSCH modulation is either QPSK (2 bits per symbol) or 16QAM (4 bits per symbol). The number of PSSCH resource elements (N_RE) in a subframe is N_RE = N_PRB × N_REperPRB × N_SYM and includes symbols associated with the sidelink SC-FDMA guard symbol.

• N_PRB is the number of physical resource blocks (PRB) used for transmission.

• N_REperPRB is the number of resource elements in a PRB. Each PRB has 12 resource elements.

• N_SYM is the number of SC-FDMA symbols in a PSSCH subframe, including symbols associated with the sidelink SC-FDMA guard symbol. N_SYM is 12 for D2D normal cyclic prefix or 10 for D2D extended cyclic prefix and V2X.

For D2D sidelink, the SL-SCH codeword carrying the information bits of a single transport block is always transmitted four times on four consecutive PSSCH subframes using the fixed RV sequence, RV = 0,2,3,1. The transmission subframes are selected from a subset of the PSSCH subframe pool. There is no HARQ feedback involved in the process. For V2X, there can be either one or two transmissions of a transport block using the RV sequence, RV = 0,2. For more information on the SL-SCH transmission and the sidelink HARQ process, see TS 36.321, Section 5.14.2.2.

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.

[2] 3GPP TS 36.321. “Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol Specification.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.

Version History

Introduced in R2016b