nrSSBMeasurements

SSB-based physical layer measurements

Since R2022b

Syntax

meas = nrSSBMeasurements(ssbGrid,ncellid)

meas = nrSSBMeasurements(___,ibarSSB)

Description

meas = nrSSBMeasurements(ssbGrid,ncellid) returns physical layer measurements meas for synchronization signal block (SSB) ssbGrid, as defined in TS 38.215 Sections 5.1.1 and 5.1.3 [1]. The returned structure meas contains the reference signal received power (RSRP), received signal strength indicator (RSSI), and reference signal received quality (RSRQ). The input ssbGrid specifies a single SS block. The input ncellid specifies the physical layer cell identity number.

meas = nrSSBMeasurements(___,ibarSSB) also specifies the time-dependent part of the DM-RS scrambling initialization, ibarSSB, in addition to the input arguments in the previous syntax. Use this syntax to include the physical broadcast channel demodulation reference signal (PBCH DM-RS) symbols in the RSRP measurement.

Examples

Perform SSB Measurements

Create an SSB for one receive antenna.

ssblock = zeros(240,4);

Set the cell identity and the corresponding PSS symbols.

ncellid = 17;
pssSymbols = nrPSS(ncellid);
ssblock(nrPSSIndices) = pssSymbols;

Set the SSS symbols.

sssSymbols = nrSSS(ncellid);
ssblock(nrSSSIndices) = sssSymbols;

Perform OFDM modulation on the SS block.

scs = 15;
initialNSlot = 0;
txWaveform = nrOFDMModulate(ssblock,scs,initialNSlot);

Pass the time-domain waveform through an AWGN channel with a signal-to-noise ratio of 10 dB.

snr = 10;
rxWaveform = awgn(txWaveform,snr,"measured");

Demodulate the received waveform and perform SSB-based measurements.

nrb = 20;
ssbGrid = nrOFDMDemodulate(rxWaveform,nrb,scs,initialNSlot);
meas = nrSSBMeasurements(ssbGrid,ncellid)

meas = struct with fields:
    RSRPPerAntenna: 30.0225
    RSSIPerAntenna: 48.2352
    RSRQPerAntenna: -5.2024

Perform SSB Measurements with PBCH DM-RS Symbols

Create an SSB for one receive antenna.

ssblock = zeros(240,4);

Set the cell identity and the corresponding PSS symbols.

ncellid = 17;
pssSymbols = nrPSS(ncellid);
ssblock(nrPSSIndices) = pssSymbols;

Set the SSS symbols.

 sssSymbols = nrSSS(ncellid);
 ssblock(nrSSSIndices) = sssSymbols;

Create and set the PBCH symbols, using a random codeword, the cell identity, and a scrambling sequence phase of 0.

cw = randi([0 1],864,1);
v = 0;
pbchSymbols = nrPBCH(cw,ncellid,v);
pbchIndices = nrPBCHIndices(ncellid);
ssblock(pbchIndices) = pbchSymbols;

Create and set the PBCH DM-RS symbols using the cell identity and the time-dependent part of the DM-RS scrambling initialization.

ibarSSB = 0;
dmrsSymbols = nrPBCHDMRS(ncellid,ibarSSB);
dmrsIndices = nrPBCHDMRSIndices(ncellid);
ssblock(dmrsIndices) = dmrsSymbols;

Perform OFDM modulation on the SS block.

scs = 15;
initialNSlot = 0;
txWaveform = nrOFDMModulate(ssblock,scs,initialNSlot);

Apply power scaling to the transmitted waveform.

EsdBm = -50;
rxWaveform = txWaveform * sqrt(10^((EsdBm-30)/10));

Demodulate the received waveform and perform the SSB-based measurements, including the PBCH DM-RS symbols.

nrb = 20;
ssbGrid = nrOFDMDemodulate(rxWaveform,nrb,scs,initialNSlot);
meas = nrSSBMeasurements(ssbGrid,ncellid,ibarSSB)

meas = struct with fields:
    RSRPPerAntenna: -50
    RSSIPerAntenna: -26.8298
    RSRQPerAntenna: -10.1599

Input Arguments

ssbGrid — SSB grid

complex-valued array

SSB grid, specified as a complex-valued array of size 240-by-4-by-R, where R is the number of receive antennas.

Data Types: single | double
Complex Number Support: Yes

ncellid — Physical layer cell identity number

integer

Physical layer cell identity number, specified as an integer from 0 to 1007.

Data Types: double

ibarSSB — Time-dependent part of DM-RS scrambling initialization

integer from 0 to 7 (default)

Time-dependent part of the DM-RS scrambling initialization, specified as an integer from 0 to 7. Specify this input based on the least significant bits (LSBs) of the SS/PBCH block index and the half-frame number from the SS burst configuration.

• If the number of SS/PBCH blocks per half-frame is 4, ibarSSB = i_SSB + 4 × n_hf, where i_SSB is the two LSBs of the SS/PBCH block index (0 to 3). n_hf is the half-frame number within the frame (0,1).

• If the number of SS/PBCH blocks per half-frame is 8 or 64, ibarSSB is the three LSBs of the SS/PBCH block index (0 to 7).

Data Types: double

Output Arguments

meas — SSB-based physical layer measurements

structure

SSB-based physical layer measurements, returned as a structure containing these fields.

Field	Value	Description
RSRPPerAntenna	Real-valued column vector	Vector of RSRP values in dBm relative to 1 milliwatt in 1 ohm
RSSIPerAntenna	Real-valued column vector	Vector of RSSI values in dBm relative to 1 milliwatt in 1 ohm
RSRQPerAntenna	Real-valued column vector	Vector of RSRQ values in dB

The rows of these column vectors correspond to receive antennas.

Data Types: struct

References

[1] 3GPP TS 38.215. “NR; Physical layer measurements.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2022b