nrPUCCHDecode

Decode PUCCH modulation symbols

Since R2021b

Syntax

[uciBits,symbols,detMet] = nrPUCCHDecode(carrier,pucch,ouci,sym)

[uciBits,symbols,detMet] = nrPUCCHDecode(carrier,pucch,ouci,sym,nVar)

[uciBits,symbols,detMet] = nrPUCCHDecode(___,'DetectionThreshold',detectionThreshold)

Description

[uciBits,symbols,detMet] = nrPUCCHDecode(carrier,pucch,ouci,sym) decodes physical uplink control channel (PUCCH) format-specific decoding and returns the uplink control information (UCI) bits, uciBits, as defined in TS 38.211 Sections 6.3.2.3 to 6.3.2.6 for all PUCCH formats. The function also returns received constellation symbols, symbols, and the detection metric, detMet. Input carrier specifies the carrier configuration. Input pucch specifies the format-specific PUCCH configuration. Input ouci specifies the uncoded UCI bits. When the number of UCI bits is less than 12, the function performs discontinuous transmission (DTX) detection by finding the normalized correlation coefficient of all of the possible reference sequences and then compares the maximum value against a threshold.

[uciBits,symbols,detMet] = nrPUCCHDecode(carrier,pucch,ouci,sym,nVar) specifies the variance of additive white Gaussian noise (AWGN) on the received symbols.

[uciBits,symbols,detMet] = nrPUCCHDecode(___,'DetectionThreshold',detectionThreshold) specifies the detection threshold to perform DTX in addition to any of the input argument combinations in the previous syntaxes.

Examples

Decode PUCCH Format 0 Symbols for Positive SR Transmission

Create a default carrier configuration object.

carrier = nrCarrierConfig;

Specify a 15 kHz carrier with a normal cyclic prefix. Set the slot number to 63.

carrier.SubcarrierSpacing = 15;
carrier.CyclicPrefix = 'normal';
carrier.NSlot = 63;

Create a default PUCCH format 0 configuration object.

pucch = nrPUCCH0Config;

Specify the first symbol index in the PUCCH transmission slot as 11 and the number of allocated PUCCH symbols as 2. Enable intraslot frequency hopping and group hopping. Set the hopping identity to 512 and the initial cyclic shift to 5.

pucch.SymbolAllocation = [11 2];
pucch.FrequencyHopping = 'intraSlot';
pucch.GroupHopping = 'enable';
pucch.HoppingID = 512;
pucch.InitialCyclicShift = 5;

Specify a transmission without hybrid automatic repeat request acknowledgment (HARQ-ACK) and with a positive scheduling request (SR).

ack = zeros(0,1);
sr = 1;           % Positive SR transmission

Generate PUCCH format 0 modulation symbols.

sym = nrPUCCH(carrier,pucch,{ack sr});

Decode the PUCCH format 0 modulation symbols.

uci = nrPUCCHDecode(carrier,pucch,[numel(ack) numel(sr)],sym); 

Verify that the received UCI bits match the transmitted UCI bits.

isequal(uci{1},ack)

ans = logical
   1

isequal(uci{2},sr)

ans = logical
   1

Decode PUCCH Format 1 Symbols with Detection Threshold

Create a default carrier configuration object.

carrier = nrCarrierConfig;

Specify a 60 kHz carrier with an extended cyclic prefix. Set the slot number to 7.

carrier.SubcarrierSpacing = 60;
carrier.CyclicPrefix = 'extended';
carrier.NSlot = 7;

Create a default PUCCH format 1 configuration object.

pucch = nrPUCCH1Config;

Specify the first symbol index in the PUCCH transmission slot as 3 and the number of allocated PUCCH symbols as 9. Enable intraslot frequency hopping and group hopping. Set the hopping identity to 512, the initial cyclic shift to 9, and the orthogonal cover code index to 1.

pucch.SymbolAllocation = [3 9];
pucch.FrequencyHopping = 'intraSlot';
pucch.GroupHopping = 'enable';
pucch.HoppingID = 512;
pucch.InitialCyclicShift = 9;
pucch.OCCI = 1;

Generate PUCCH format 1 modulation symbols for 1-bit UCI.

uci = 1;
sym = nrPUCCH(carrier,pucch,uci);

Decode the PUCCH format 1 modulation symbols with a detection threshold of 0.7.

rxUCI = nrPUCCHDecode(carrier,pucch,numel(uci),sym,'DetectionThreshold',0.7);

Verify that the received UCI bits match the transmitted UCI bits.

isequal(rxUCI{1},uci)

ans = logical
   1

Decode PUCCH Format 2 Symbols

Create a default carrier configuration object.

carrier = nrCarrierConfig;

Create a default PUCCH format 2 configuration object.

pucch = nrPUCCH2Config;

Specify the data scrambling identity as 1000 and the radio network temporary identifier as 160.

pucch.NID = 1000;
pucch.RNTI = 160;

Get random UCI bits.

ouci = 20;
uci = randi([0 1],ouci,1);

Encode the UCI bits.

uciCW = nrUCIEncode(uci,100);

Generate PUCCH modulation format 2 symbols.

sym = nrPUCCH(carrier,pucch,uciCW);

Decode the PUCCH modulation format 2 symbols.

rxUCI = nrPUCCHDecode(carrier,pucch,ouci,sym);

Verify that the received UCI bits match the transmitted UCI bits.

isequal(uciCW,double(rxUCI{1}<0))

ans = logical
   1

Decode PUCCH Format 3 Symbols

Create a default carrier configuration object.

carrier = nrCarrierConfig;

Specify a 30 kHz carrier with an extended cyclic prefix. Set the number of resource blocks in the carrier resource grid to 80.

carrier.SubcarrierSpacing = 30;
carrier.NSizeGrid = 80;

Create a default PUCCH format 3 configuration object.

pucch = nrPUCCH3Config;

Specify the modulation scheme as pi/2-BPSK, the physical resource blocks (PRB) allocation of the PUCCH to range from 70 to 74 (occupying 5 resource blocks), and the radio network temporary identifier as 2560.

pucch.Modulation = 'pi/2-BPSK';
pucch.PRBSet = 70:74;
pucch.RNTI = 2560;

Generate PUCCH format 3 resource element indices.

[pucchIndices,pucchInfo] = nrPUCCHIndices(carrier,pucch);
G = pucchInfo.G;                                          % Rate-matched length

Get random UCI bits.

ouci = 30;
uciBits = randi([0 1],ouci,1);

Encode the UCI bits.

codedUCI = nrUCIEncode(uciBits,G);

Generate PUCCH format 3 modulated symbols.

sym = nrPUCCH(carrier,pucch,codedUCI);

Generate demodulation reference signal (DM-RS) symbols and indices.

dmrsSym = nrPUCCHDMRS(carrier,pucch);
dmrsInd = nrPUCCHDMRSIndices(carrier,pucch);

Create a resource grid. Map the PUCCH symbols and the DM-RS symbols to the grid.

resGrid = nrResourceGrid(carrier);
resGrid(pucchIndices) = sym;
resGrid(dmrsInd) = dmrsSym;

Perform orthogonal frequency division multiplexing (OFDM) modulation.

txWaveform = nrOFDMModulate(carrier,resGrid);

Perform back-to-back decoding.

rxWaveform = txWaveform;
rxGrid = nrOFDMDemodulate(carrier,rxWaveform);

Extract PUCCH format 3 symbols from the received grid.

rxSym = nrExtractResources(pucchIndices,rxGrid);

Decode the PUCCH format 3 modulation symbols, and then decode the UCI bits.

rxUCI = nrPUCCHDecode(carrier,pucch,ouci,rxSym);
rxUCIBits = nrUCIDecode(rxUCI{1},ouci);

Verify that the received UCI bits match the transmitted UCI bits.

isequal(uciBits,rxUCIBits)

ans = logical
   1

Decode PUCCH Format 4 Symbols

Create a default carrier configuration object, and then set the cell identity as 140.

carrier = nrCarrierConfig;
carrier.NCellID = 140;

Create a default PUCCH format 4 configuration object.

pucch = nrPUCCH4Config;

Specify the spreading factor as 4, the OCCI as 3, and the radio network temporary identifier as 750.

pucch.SpreadingFactor = 4;
pucch.OCCI = 3;
pucch.RNTI = 750;

Get random UCI bits.

ouci = 20;
uci = randi([0 1],ouci,1);

Encode the UCI bits.

uciCW = nrUCIEncode(uci,60);

Generate PUCCH modulation format 4 symbols.

sym = nrPUCCH(carrier,pucch,uciCW);

Decode the PUCCH modulation format 4 symbols.

rxUCI = nrPUCCHDecode(carrier,pucch,ouci,sym);

Verify that the received UCI bits match the transmitted UCI bits.

isequal(uciCW,double(rxUCI{1}<0))

ans = logical
   1

Generate and Decode Symbols for Mixed PUCCH Transmission

Compare the transmission and reception of PUCCH formats 0 and 2 for two different user equipments.

Carrier Configuration

Create a default carrier configuration object, and then set the cell identity to 10.

carrier = nrCarrierConfig;
carrier.NCellID = 10;

PUCCH Configuration

Create a PUCCH format 0 configuration object with the specified properties for user equipment (UE) 1.

pucch0 = nrPUCCH0Config;
pucch0.PRBSet = 0;
pucch0.HoppingID = 0;

Create a PUCCH format 2 configuration object with the specified properties for UE 2.

pucch2 = nrPUCCH2Config;
pucch2.PRBSet = 0;
pucch2.RNTI = 10;

Channel Propagation Model Configuration

Define the channel configuration structure using an nrTDLChannel System object.

channel = nrTDLChannel;
channel.NumReceiveAntennas = 4;
info1 = nrOFDMInfo(carrier);
channel.SampleRate = info1.SampleRate;                         % Set waveform sample rate
chInfo = info(channel);
maxChDelay = chInfo.MaximumChannelDelay;

Noise Configuration

Normalize the noise power of the carrier, and the configure the random number generator.

SNRdB = 21.0;
SNR = 10^(SNRdB/20);
N = 1/(SNR*sqrt(double(info1.Nfft)))/sqrt(2.0);
rng('default');

PUCCH Symbols and Indices Generation for Format 0 and Format 2

Specify the HARQ-ACK bits for PUCCH format 0.

hi1 = [0;1];
disp('hi1:');

hi1:

disp(hi1.');

     0     1

Generate PUCCH format 0 modulation symbols.

pucch0Sym = nrPUCCH(carrier,pucch0,hi1);

Generate DM-RS symbols for PUCCH formats 0 and 2.

pucch0DMRSSym = nrPUCCHDMRS(carrier,pucch0);
pucch2DRSSym = nrPUCCHDMRS(carrier,pucch2);

Generate PUCCH format 2 resource element indices.

[pucch2Ind,pucch2Info] = nrPUCCHIndices(carrier,pucch2);

Create channel quality information (CQI) bits.

cqi = [0; 1; 1; 0; 0; 1];
disp('cqi:');

cqi:

disp(cqi.');

     0     1     1     0     0     1

Encode the CQI bits.

codedcqi = nrUCIEncode(cqi,pucch2Info.G);

Generate PUCCH format 2 modulation symbols.

pucch2Sym = nrPUCCH(carrier,pucch2,codedcqi);

PUCCH Index Generation for Format 0 and Format 2

Generate PUCCH indices for formats 0 and 2.

pucch0Indices = nrPUCCHIndices(carrier,pucch0);    
pucch2Indices = nrPUCCHIndices(carrier,pucch2);        

Generate DM-RS indices for PUCCH formats 0 and 2.

pucch0DMRSIndices = nrPUCCHDMRSIndices(carrier,pucch0);  
pucch2DMRSIndices = nrPUCCHDMRSIndices(carrier,pucch2);

Transmission with PUCCH Format 0

Create a resource grid. Map the PUCCH symbols and DM-RS symbols of format 0 to the grid.

grid1 = nrResourceGrid(carrier);
grid1(pucch0Indices) = pucch0Sym;
grid1(pucch0DMRSIndices) = pucch0DMRSSym;

Perform OFDM modulation and pass the waveform through the tapped delay line (TDL) channel.

txwave1 = nrOFDMModulate(carrier,grid1);
txwave1 = [txwave1; zeros(maxChDelay,size(txwave1,2))];
[rxwave1,pathGains1,sampleTimes1] = channel(txwave1);

Transmission with PUCCH Format 2

Create a resource grid. Map the PUCCH symbols and DM-RS symbols of format 2 to the grid.

grid2 = nrResourceGrid(carrier);
grid2(pucch2Indices) = pucch2Sym;            
grid2(pucch2DMRSIndices) = pucch2DRSSym; 

Perform OFDM modulation, and then pass the waveform through the TDL channel.

txwave2 = nrOFDMModulate(carrier,grid2);
release(channel);
channel.Seed = 15;
txwave2 = [txwave2; zeros(maxChDelay,size(txwave2,2))];
[rxwave2,pathGains,sampleTimes] = channel(txwave2);

Reception at Base Station

Add AWGN to the received signal.

rxwave = rxwave1 + rxwave2;                                  % Add both the faded signals      
noise = N*complex(randn(size(rxwave)),randn(size(rxwave)));
rxwave = rxwave + noise;

Demodulate the received signal and extract PUCCH format 0 RE indices.

rxgrid1 = nrOFDMDemodulate(carrier,rxwave(1:end,:));
rxpucch0 = nrExtractResources(pucch0Indices,rxgrid1);

Decode PUCCH Format 0 Symbols

Decode the PUCCH format 0 symbols.

rxhi1 = nrPUCCHDecode(carrier,pucch0,length(hi1),rxpucch0);
disp('rxhi1:');

rxhi1:

disp(rxhi1{1}.');

   0   1

Verify that the received HARQ-ACK bits match the transmitted HARQ-ACK bits.

if isequal(hi1,rxhi1{1})
    disp('PUCCH format 0 data decoded')
else
    disp('PUCCH format 0 data not decoded')
end

PUCCH format 0 data decoded

Decode PUCCH Format 2 Symbols

Estimate the timing offset for the transmission, and then perform the OFDM demodulation on the received waveform.

[t,mag] = nrTimingEstimate(carrier,rxwave,pucch2DMRSIndices,pucch2DRSSym);
if t > maxChDelay
    t = 0;
end
rxgrid2 = nrOFDMDemodulate(carrier,rxwave(1+t:end,:));

Get the practical channel estimate, and then extract PUCCH format 2 RE indices.

[H2, n0] = nrChannelEstimate(carrier,rxgrid2,pucch2DMRSIndices,pucch2DRSSym);
[pucchrx2, pucchH2] = nrExtractResources(pucch2Indices,rxgrid2,H2);

Perform minimum mean square error (MMSE) equalization on the extracted PUCCH format 2 resource elements.

pucch2eq = nrEqualizeMMSE(pucchrx2,pucchH2,n0);

Decode the PUCCH format 2 modulation symbols, and then decode the CQI bits.

rxcodedcqi = nrPUCCHDecode(carrier,pucch2,length(cqi),pucch2eq);
rxcqi = nrUCIDecode(rxcodedcqi{1},length(cqi));
disp('rxcqi:');

rxcqi:

disp(rxcqi.');

   0   1   1   0   0   1

Verify that the received CQI bits match the transmitted CQI bits.

if isequal(cqi,rxcqi)
    disp('PUCCH format 2 data decoded')
else
    disp('PUCCH format 2 data not decoded')
end

PUCCH format 2 data decoded

Input Arguments

carrier — Carrier configuration parameters

nrCarrierConfig object

Carrier configuration parameters for a specific OFDM numerology, specified as an nrCarrierConfig object. This function uses only these properties of the nrCarrierConfig object.

• NCellID

• SubcarrierSpacing

• CyclicPrefix

• NSizeGrid

• NStartGrid

• NSlot

• IntraCellGuardBands

pucch — PUCCH configuration parameters

nrPUCCH0Config object | nrPUCCH1Config object | nrPUCCH2Config object | nrPUCCH3Config object | nrPUCCH4Config object

PUCCH configuration parameters, specified as one of these options.

• For format 0, specify an nrPUCCH0Config object. The function uses only these object properties.

  • SymbolAllocation

  • PRBSet

  • FrequencyHopping

  • Interlacing

  • RBSetIndex

  • InterlaceIndex

  • GroupHopping

  • HoppingID

  • InitialCyclicShift

• For format 1, specify an nrPUCCH1Config object. The function uses only these object properties.

  • SymbolAllocation

  • PRBSet

  • FrequencyHopping

  • Interlacing

  • RBSetIndex

  • InterlaceIndex

  • GroupHopping

  • HoppingID

  • InitialCyclicShift

  • OCCI

• For format 2, specify an nrPUCCH2Config object. The function uses only these object properties.

  • Interlacing

  • RBSetIndex

  • InterlaceIndex

  • SpreadingFactor

  • OCCI

  • NID

  • RNTI

• For format 3, specify an nrPUCCH3Config object. The function uses only these object properties.

  • PRBSet

  • Modulation

  • Interlacing

  • RBSetIndex

  • InterlaceIndex

  • SpreadingFactor

  • OCCI

  • NID

  • RNTI

• For format 4, specify an nrPUCCH4Config object. The function uses only these object properties.

  • Modulation

  • PRBSet

  • SpreadingFactor

  • OCCI

  • NID

  • RNTI

For PUCCH formats 0 to 3 and operation with shared spectrum channel access for frequency range 1 (FR1), set the corresponding Interlacing property to true, and use the RBSetIndex and InterlaceIndex object properties to specify the allocated frequency resources. In addition, for PUCCH formats 2 and 3, you can use the SpreadingFactor and OCCI properties with single-interlace configurations. (since R2023b)

ouci — Number of uncoded UCI bits

nonnegative integer | two-element vector of nonnegative integers

Number of uncoded UCI bits, specified as a nonnegative integer or depending on the format type.

• For format 0, you must specify a nonnegative integer or a two-element vector of nonnegative integers.

  • When you specify this value as a scalar, the uncoded UCI bits represents the hybrid automatic repeat request acknowledgment (HARQ-ACK) bits.

  • When you specify this value as a vector, the first element represents the HARQ-ACK bits, and the second element represents the scheduling request (SR) bit.

• For format 1, you must specify a nonnegative integer. When you specify this value, the uncoded UCI bits represents the HARQ-ACK bits or SR bits.

• For formats 2, 3, and 4, the uncoded UCI bits represents the number of UCI bits in both parts.

Data Types: double

sym — PUCCH modulation symbols

complex-valued column vector | complex-valued matrix

PUCCH modulation symbols for the specified format, returned as a complex-valued column vector or complex-valued matrix.

For formats 0 and 1, the sym argument must be a matrix with the number of columns equal to the number of receive antennas. For formats 2, 3, and 4, the sym argument must be a column vector.

Data Types: single | double
Complex Number Support: Yes

nVar — Noise variance

1e-10 (default) | nonnegative scalar

Noise variance, specified as a nonnegative scalar. The function scales the symbols with the variance of additive white Gaussian noise (AWGN). The default value corresponds to an signal to noise ratio (SNR) of 100 dB, assuming unit signal power.

When the noise variance value is less than 1e-10, the function uses the value of 1e-10.

Data Types: double

detectionThreshold — Detection threshold

[] | scalar in range from 0 to 1

Detection threshold, specified as [] or a scalar in range from 0 to 1. When you do not specify the input or you set it to [], the function selects one of these default values based on the format type.

• For format 0, the default value is 0.49 for one OFDM symbol and 0.42 for two OFDM symbols.

• For format 1, the default value is 0.22.

• For formats 2, 3, and 4, the default value is 0.45.

Data Types: double

Output Arguments

uciBits — UCI bits

one-element cell array | two-element cell array

UCI bits, returned as a one- or two-element cell array depending on the format type. For format 0 and 1, the data type of uciBits is int8. For format 2, 3, and 4, uciBits inherits the data type of the sym input.

• For format 0, uciBits is a one- or two-element cell array with UCI hard bits.

  • For a one-element cell array, the function returns the HARQ-ACK hard bits.

  • For a two-element cell array, the function returns the first element as HARQ-ACK hard bits and the second element as SR bit.

  PUCCH format 0 decoding involves DTX detection followed by finding the sequence that has the maximum normalized correlation metric.

• For format 1, uciBits is a one-element cell array with UCI hard bits. PUCCH format 1 decoding involves DTX detection followed by matched filtering.

• For formats 2, 3, and 4, uciBits is a one-element cell array with UCI soft bits. For PUCCH formats 2, 3, and 4, UCI soft bits are returned post DTX detection (applicable up to 12 uncoded uci bits) and inverse processing of PUCCH encoding.

Data Types: cell

symbols — Received constellation symbols

column-valued column vector

Received constellation symbols, returned as a column-valued column vector. symbols inherits the data type of the sym input.

Data Types: double | single
Complex Number Support: Yes

detMet — Detection metric

integer

Detection metric, returned as an integer. For PUCCH formats 2, 3, and 4, when the ouci input is not in the range from 3 to 11, this output is 0.

Data Types: double | single

References

[1] 3GPP TS 38.211. “NR; Physical channels and modulation.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

Names and values in name-value pair arguments must be compile-time constants. For example, when specifying 'single' as the output data type, include {coder.Constant('OutputDataType'),coder.Constant('single')} in the -args value of the codegen function. For more information, see the coder.Constant (MATLAB Coder) class.

Version History

Introduced in R2021b

R2023b: Configure intracell guard bands

Use the IntraCellGuardBands object property of the carrier input to specify intracell guard bands.

R2023b: Support for release 16 interlacing for operation in unlicensed spectrum (NR-U)

For PUCCH formats 0 to 3, use the Interlacing, RBSetIndex, and InterlaceIndex object properties of the pucch input argument to configure interlaced PUCCH transmissions. In addition, for PUCCH formats 2 and 3, you can use the SpreadingFactor and OCCI properties with single-interlace configurations.

R2022a: SR bit output value in PUCCH format 0 decoding has changed

For PUCCH format 0, the function now returns 0 instead of [] for the SR bit value when the detection metric is below the DTX detection threshold. For PUCCH format 0, the SR bit is returned in the second cell of the uciBits output of the function.

R2022a: Detection threshold in PUCCH format 1 decoding has changed

For PUCCH format 1, the function now uses 0.22 instead of 0.36 as the default DTX detection threshold.