Documentation

ltePMISelect

PDSCH precoder matrix indicator calculation

Syntax

  • [pmiset,info,sinrs,subbandsinrs] = ltePMISelect(enb,chs,hest,noiseest)
    example

Description

example

[pmiset,info,sinrs,subbandsinrs] = ltePMISelect(enb,chs,hest,noiseest) performs PDSCH precoder matrix indication (PMI) set calculation for the given cell-wide settings, enb, channel configuration structure, chs, channel estimate resource array, hest, and receiver noise variance, noiseest.

The PMI selection is performed using the codebooks specified in TS 36.213, Section 7.2.4 [2]. For the 'Port7-14' transmission scheme, the CSI reporting codebook is used when CSI-RS ports are equal to 8. For other numbers of CSI-RS ports in the 'Port7-14' transmission scheme and for other transmission schemes, the PMI selection is performed using the codebook for closed-loop spatial multiplexing. This term is defined in TS 36.211, Tables 6.3.4.2.3-1 and 6.3.4.2.3-2 [1].

PMIMode= 'Wideband' corresponds to PUSCH reporting Mode 1-2 or PUCCH reporting Mode 1-1 (PUCCH Report Type 2). PMIMode= 'Subband' corresponds to PUSCH reporting Mode 3-1. PMI selection is based on the rank indicated by chs.NLayers, except for the 'TxDiversity' transmission scheme, where the rank is 1. In PUCCH reporting Mode 1-1, you can achieve codebook subsampling for submode 2 (TS 36.213, Table 7.2.2-1D [2]) with an appropriate chs.CodebookSubset.

Examples

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PMI Selection

This example shows PMI selection and configuration of a downlink transmission with the selected PMI set.

Populate an empty resource grid for RMC R.13 with cell specific reference signal symbols. OFDM modulate the grid to create txWaveform. Initialize channel configuration structure. Pass txWaveform through channel and demodulate rxWaveform to recover rxSubframe

enb = lteRMCDL('R.13');
enb.PDSCH.PMIMode = 'Subband';
reGrid = lteResourceGrid(enb);
reGrid(lteCellRSIndices(enb)) = lteCellRS(enb);

[txWaveform,info] = lteOFDMModulate(enb,reGrid);

chcfg.SamplingRate = info.SamplingRate;
chcfg.DelayProfile = 'EPA';
chcfg.NRxAnts = 4;
chcfg.DopplerFreq = 5;
chcfg.MIMOCorrelation = 'Low';
chcfg.InitTime = 0;
chcfg.Seed = 1;

rxWaveform = lteFadingChannel(chcfg,txWaveform);
rxSubframe = lteOFDMDemodulate(enb,rxWaveform);
Warning: Using default value for parameter field InitPhase (Random) 
Warning: Using default value for parameter field ModelType (GMEDS) 
Warning: Using default value for parameter field NTerms (16) 
Warning: Using default value for parameter field NormalizeTxAnts (On) 
Warning: Using default value for parameter field NormalizePathGains (On) 

Note: The warning messages generated simply advise you that default values are available and being used for uninitialized parameters. To suppress warnings for defaulted lte parameter settings precede code with the following command lteWarning('off','DefaultValue').

Initialize channel estimation structure. Perform channel estimation. Use estimates of the channel and noise power spectral density for PMI selction. This PMI set is then used to configure a downlink transmission.

cec.FreqWindow = 1;
cec.TimeWindow = 31;
cec.InterpType = 'cubic';
cec.PilotAverage = 'UserDefined';
cec.InterpWinSize = 1;
cec.InterpWindow = 'Centered';

[hest, noiseEst] = lteDLChannelEstimate(enb,cec,rxSubframe);

pmi = ltePMISelect(enb,enb.PDSCH,hest,noiseEst)
enb.PDSCH.PMISet = pmi;
txWaveform = lteRMCDLTool(enb,[1;0;0;1]);
Warning: Using default value for parameter field CodebookSubset
(1111111111111111) 

pmi =

     1
     1
     6
     2
    12
    12
    12
    12
    12

Input Arguments

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enb — Cell-wide settingsstructure

Cell-wide settings, specified as a structure containing the following fields:

Parameter FieldRequired or OptionalValuesDescription
NDLRBRequired

Scalar integer (6, ..., 110). Standard bandwidth values are 6, 15, 25, 50, 75, and 100. NDLRB will also accept the standardized bandwidths in string format from the set {'1.4MHz', '3MHz', ‘5MHz', '10MHz', ‘15MHz', ‘20MHz'}.

Number of downlink (DL) resource blocks (RBs)

NCellIDRequired

Nonnegative scalar integer (0,…,503)

Physical layer cell identity

CellRefPRequired

1 (default), 2, 4, 8

Number of cell-specific reference signal (CRS) antenna ports

CyclicPrefixOptional

'Normal' (default), 'Extended'

Cyclic prefix length

DuplexModeOptional

'FDD' (default), 'TDD'

Duplexing mode, specified as:

  • 'FDD' for Frequency Division Duplex or

  • 'TDD' for Time Division Duplex

The following parameters apply when DuplexMode is set to 'TDD'.

  TDDConfigOptional

0 (default), 1, 2, 3, 4, 5, 6

Uplink or downlink configuration

  SSCOptional

0 (default), 1, 2, 3, 4, 5, 6, 7, 8, 9

Special subframe configuration (SSC)

  NSubframeRequired

Nonnegative scalar integer

Subframe number

The following parameters apply when chs.TxScheme is set to 'Port7–14' transmission scheme.

  CSIRefPRequired

1, 2, 4

Array of number of CSI-RS antenna ports

  CSIRSConfigRequired

scalar integer

Array CSI-RS configuration indices. See TS 36.211, Table 6.10.5.2-1.

[1]
  CSIRSPeriodOptional

'On' (default), 'Off', Icsi-rs (0,...,154), [Tcsi-rs Dcsi-rs]. You can also specify values in a cell array of configurations for each resource.

CSI-RS subframe configurations for one or more CSI-RS resources. Multiple CSI-RS resources can be configured from a single common subframe configuration or from a cell array of configurations for each resource.

  NframeOptional

0 (default), Nonnegative scalar integer

Frame number

Data Types: struct

chs — Channel transmission configurationstructure

Channel transmission configuration, specified as a structure containing the following fields:

Parameter FieldRequired or OptionalValuesDescription
NLayersRequired1, 2, 3, 4, 5, 6, 7, 8

Number of transmission layers

PMIModeOptional

'Wideband' (default), 'Subband'

PMI reporting mode

TxSchemeOptional

Default TxScheme is RMC-dependent. Valid values include: 'SpatialMux', 'Port0', 'TxDiversity', 'CDD', 'MultiUser', 'Port5', 'Port7-8', 'Port8', 'Port7-14'

Transmission scheme, specified as one of the following options.

  • 'SpatialMux' — Closed-loop spatial multiplexing.

  • 'Port0' — Single-antenna port, port 0.

  • 'TxDiversity' — Transmit diversity scheme.

  • 'CDD' — Large delay CDD scheme.

  • 'MultiUser' — Multiuser MIMO scheme.

  • 'Port5' — Single-antenna port, port 5.

  • 'Port7-8' — Single-antenna port, port 7 (NLayers = 1). Dual layer transmission, ports 7 and 8 (NLayers = 2).

  • 'Port8' — Single-antenna port, port 8.

  • 'Port7-14' — Up to 8-layer transmission, ports 7–14.

CodebookSubsetOptional

String or vector, all ones (default)

Codebook subset restriction, specified as a string bitmap. The default values are all ones, permitting all PMI values. This parameter is configured by higher layers and indicates the values of PMI that can be reported. The bitmap, defined in TS 36.213, Section 7.2, is arranged a_A-1,a_A-2,...a_0. For example, the element CodebookSubset(1) corresponds to a_A-1 and the element CodebookSubset(end) corresponds to a_0. The length of the bitmap is given by the info.CodebookSubsetSize field returned by ltePMIInfo. You can also specify the bitmap in a hexadecimal form by prefixing the string with '0x'. Alternatively, you can specify a numeric array identical to the PMISET output, indicating to restrict the selection to only those PMISET values. Specifying the parameter in this way enables you to obtain SINR estimates against an existing reported PMI for RI and CQI selection. If this parameter field is defined but is empty, no codebook subset restriction is applied. (codebookSubsetRestriction)

Data Types: struct

hest — Channel estimatemultidimensional array

Channel estimate, specified as a multidimensional array of size K-by-L-by-NRxAnts-by-P where:

  • K is the number of subcarriers.

  • L is the number of OFDM symbols.

  • NRxAnts is the number of received antennas.

  • P is the number of planes.

Data Types: double
Complex Number Support: Yes

noiseest — Receiver noise variancenumeric scalar

Receiver noise variance, specified as a numeric scalar. This input argument specifies an estimate of the received noise power spectral density.

Data Types: double

Output Arguments

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pmiset — PMI set selectedcolumn vector | integer

Precoder matrix indications (PMI) set selected, returned as a column vector or an integer. For the 'Port7-14' transmission scheme with eight CSI-RS ports, pmiset has info.NSubbands + 1 rows. The first row indicates wideband codebook index i1. The subsequent info.NSubbands rows indicate the subband codebook indices i2 or if info.NSubbands=1, the wideband codebook index i2. For other numbers of CSI-RS ports in the 'Port7-14' transmission scheme, and for other transmission schemes, pmiset has 'info.NSubbands' rows. Each row gives the subband codebook index for that subband. For wideband reporting (info.NSubbands = 1), pmiset is a scalar specifying the selected wideband codebook index.

    Note:   pmiset is empty if the noise estimate, noiseest, is zero or NaN, or if the channel estimate, hest, contains any NaNs in the locations of the reference signal REs used for PMI estimation.

info — Information related to PMI reportingstructure

Information related to PMI reporting, returned as a scalar structure. info contains the following fields:

Parameter FieldDescriptionValues
k

Subband size, in resource blocks (equal to NRB for wideband PMI reporting or transmission schemes without PMI reporting).

numeric scalar
NSubbands

Number of subbands for PMI reporting (equal to 1 for wideband PMI reporting) or transmission schemes without PMI reporting.

numeric scalar
MaxPMI

Maximum permitted PMI value for the given configuration. Valid PMI values range from 0 to MaxPMI. For CSI reporting, when CSIRefP = 8, MaxPMI is a 2–element vector, indicating the maximum permissible values of i1 and i2, the first and second codebook indices. For transmission schemes without PMI reporting, MaxPMI = 0.

nonnegative numeric scalar
CodeBookSubsetSize

Size of the codebook subset restriction bitmap. For transmission schemes without PMI reporting, CodebookSubsetSize=0.

scalar

sinrs — Signal-to-interference plus noise ratiosmultidimensional array

Signal to interference plus noise ratios, returned as a multidimensional array of size K-by-L-by-N1-by-N2, where:

  • K is the number of subcarriers

  • L is the number of OFDM symbols

  • Definition of N1 and N2 depends on the CSI-RS ports:

    • For the 'Port7-14' transmission scheme with eight CSI-RS ports, N1 and N2 are the number of possible first and second codebook indices:

      • N1 is info.MaxPMI (1)+1

      • N2 is info.MaxPMI (2)+1

    • For other numbers of CSI-RS ports in the 'Port7-14' transmission scheme, and for other transmission schemes:

      • N1 is 1

      • N2 is info.MaxPMI +1

The array contains non-NaN values in the time and frequency locations (first two dimensions) of the reference signal REs. This array is used for PMI estimation for all possible codebook indices (last two dimensions). These values are the calculated sinrs in the reference signal RE locations for each codebook index combination. You can obtain the values using a linear MMSE SINR metric. All locations not corresponding to a reference signal RE are set to NaN.

subbandsinrs — Subband signal-to-interference plus noise ratiosmultidimensional array

Subband signal-to-interference plus noise ratios (sinrs), returned as a multidimensional array. The size of the array is ‘INFO.NSubbands'-by-N1-by-N2-by-chs.NLayers. This array indicates the average linear SINR in the subband specified for each possible PMI value (N1 and N2 dimensions) and each layer. The sinrs output is formed by summing a 5–dimensional K-by-L-by-N1-by-N2-by-chs.NLayers estimate of the sinrs across all of the layers. subbandsinrs is formed by averaging that same five-dimensional estimate across each subband that is in the appropriate region of the K dimension and across the L dimension.

References

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

[2] 3GPP TS 36.213. "Physical layer procedures." 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA). URL: http://www.3gpp.org.

Introduced in R2014a

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