ltePDCCHDecode

Physical downlink control channel decoding

Syntax

[bits,symbols] = ltePDCCHDecode(enb,sym)

[bits,symbols] = ltePDCCHDecode(enb,sym,hest,noiseest)

[bits,symbols] = ltePDCCHDecode(enb,sym,hest,noiseest,alg)

Description

[bits,symbols] = ltePDCCHDecode(enb,sym) performs the inverse of Physical Downlink Control Channel (PDCCH) processing on the matrix of complex modulated PDCCH symbols, sym, and cell-wide settings structure, enb. The channel inverse processing includes resource element group deinterleaving and cyclic shifting, deprecoding, symbol demodulation, and descrambling.

The function returns a column vector of soft bits, bits, and received constellation of complex symbol vector, symbols, resulting from performing the inverse of PDCCH processing. See TS 36.211 [1], Section 6.8 and ltePDCCH for details.

[bits,symbols] = ltePDCCHDecode(enb,sym,hest,noiseest) decodes the complex PDCCH symbols, sym, using cell-wide settings, enb, the channel estimate, hest, and the noise estimate, noiseest. For the TxDiversity transmission scheme, when CellRefP is 2 or 4, the reception is performed using an orthogonal space frequency block code (OSFBC) decoder. For the Port0 transmission scheme, when CellRefP is 1, the reception is performed using minimum mean square error (MMSE) equalization.

[bits,symbols] = ltePDCCHDecode(enb,sym,hest,noiseest,alg) provides control over weighting the output soft bits, bits, with channel state information (CSI) calculated during the equalization stage using algorithmic configuration structure, alg. When alg.CSI is 'On', bits is scaled by channel state information calculated during the equalization process.

Examples

Decode PDCCH Symbols

Generate and decode the complex PDCCH modulated symbols for RMC R.0 from cell-wide settings structure, enb.

enb = lteRMCDL('R.0');
pdcchInfo = ltePDCCHInfo(enb);
codewordBits = randi([0,1],pdcchInfo.MTot,1);
pdcchSym = ltePDCCH(enb,codewordBits);
[softBits,symbols] = ltePDCCHDecode(enb,pdcchSym);

Input Arguments

enb — Cell-wide settings

scalar structure

Cell-wide settings, specified as a scalar structure. enb contains the following fields.

Parameter Field	Required or Optional	Values	Description
CellRefP	Required	1, 2, 4	Number of cell-specific reference signal (CRS) antenna ports
NCellID	Required	Integer from 0 to 503	Physical layer cell identity
NSubframe	Required	0 (default), nonnegative scalar integer	Subframe number

Data Types: struct

sym — PDCCH modulation symbols

complex numeric matrix

PDCCH modulation symbols, specified as a complex numeric matrix of size NRE-by-NRxAnts. NRE is the number of QPSK symbols per antenna assigned to the PDCCH (that is, the number of control region resource elements) and NRxAnts is the number of receive antennas.

Data Types: double
Complex Number Support: Yes

hest — Channel estimate

3-D numeric array

Channel estimate, specified as a 3-D numeric array of size NRE-by-NRxAnts-by-CellRefP. NRE are the frequency and time locations corresponding to the PDCCH RE positions (a total of NRE positions). NRxAnts is the number of receive antennas, and CellRefP is the number of cell-specific reference signal antennas, given by enb.CellRefP.

Data Types: double
Complex Number Support: Yes

noiseest — Noise estimate

numeric scalar

Noise estimate, specified as a numeric scalar. This input argument is an estimate of the noise power spectral density per RE on received subframe. Produce this estimate using the lteDLChannelEstimate function.

Data Types: double

alg — Algorithmic configuration to calculate CSI for weighting soft bits

structure

Algorithmic configuration to calculate CSI for weighting soft bits, specified as a structure having the following fields.

Parameter Field	Required or Optional	Values	Description
CSI	Optional	'On' (default), 'Off'	Flag provides control over weighting the soft values that are used to determine the output values with the channel state information (CSI) calculated during the equalization process. If 'On', soft values are weighted by CSI.

Data Types: struct

Output Arguments

bits — Soft bits

numeric column vector

Soft bits, returned as a numeric column vector. bits is the received PDCCH payload containing coded downlink control information (DCI) messages. It is optionally scaled by channel state information (CSI) calculated during the equalization process.

Data Types: double

symbols — Received constellation symbols

complex numeric column vector

Received constellation symbols, returned as a complex numeric column vector.

Data Types: double
Complex Number Support: Yes

References

[1] 3GPP TS 36.211. “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.

Version History

Introduced in R2014a