PSS Search and Frequency Offset Correction

PSS retrieval and frequency correction.

Description

The PSS Search and Frequency Correction block receives the 5G downlink signal of the NR main frequency band as input and performs PSS search and coarse frequency offset estimation by performing the following steps:

Shift the frequency of the received signal by the estimated shift frequency. The estimated shifts are spaced half the subcarrier frequency apart.
Comparing the frequency shifted received signal with each of the three possible PSS sequences (NID2) and extracting the strongest correlation peak. The PSS reference sequences are frequency centred. Consequently, the strongest correlation peak provides a measure of the coarse frequency offset relative to the centre frequency of the carrier. The peak also indicates which of the three PSS sequences (NID2) was detected in the received signal and the moment of best channel state time.
Estimation of the frequency offset below half of the subcarrier by correlating the cyclic prefix of each OFDM symbol in the SSB with the corresponding useful parts of the OFDM symbols. The phase of this correlation is proportional to the frequency offset in the signal.

Configuring the block involves setting the following parameters:

Block Pattern frequency range setting: FR1: Case A, Case B, Case C, FR2: Case D, Case E.
Specifying the number of information blocks Bitmap of SS blocks transmitted: 4, 8, 64.
Specifying the subcarrier spacing Subcarrier spacing (kHz): 15 kHz or 30 kHz for FR1, 60 kHz or 120 kHz for FR2.
Setting the minimum channel bandwidth for the NR band Minimum channel bandwidth for the NRb band (MHz) 5 MHz, 10 MHz, 40 MHz.

Ports

Input

Wfm - 5G-NR signal in time domain as a complex matrix
matrix

5G NR signal in time domain returned as a complex matrix. The number of columns of the matrix corresponds to the number of transmit antennas.

Data types: ComplexF64.

Output

Nid - detected PSS sequence (NID2) in the received signal
scalar

Detected PSS (NID2) sequence in the received signal.

Data types: Float64.

SSBoff - frequency shift value
scalar

Frequency shift value.

Data types: Float64.

CorWfm - frequency shifted signal as a complex matrix
matrix

Frequency shifted signal returned as a complex matrix.

Data types: ComplexF64.

Parameters

Main

Block Pattern - frequency range identifier
Case A | Case B (by default) | Case C | Case D | Case E

For the 5G standard, the frequency range used is specified in the documentation.

Frequency range designation Frequency range

Frequency range designation	Frequency range
FR1: `Case A`,`Case B`,`Case C`	410 MHz - 7125 MHz
FR2: `Case D`,`Case E`	24250 MHz - 52600 MHz

FR1: Case A,Case B,Case C

410 MHz - 7125 MHz

FR2: Case D,Case E

24250 MHz - 52600 MHz

Usage in program code
Block Parameter	`BlockPattern` `BlockPattern`
Values	`Case A` \| `Case B` \| `Case C` \| `Case D` \| `Case E`
By default	`Case B`

Bitmap of SS blocks transmitted - number of information blocks transmitted
4 | 8 (by default) | 64

Number of information blocks transmitted.

Usage in program code
Block parameter	`TransmittedBlocks`
Values	`4` \| `8` \| `64`
By default	`8`

Subcarrier spacing (kHz) - subcarrier spacing in kHz
15(by default) | 30 | 60 | 120

Subcarrier spacing in kHz for all channels and carrier reference signals.

Selectable values: 15 or 30 for FR1, 60 or 120 for FR2.

Usage in program code
Block parameter	`SubcarrierSpacingCommon`
Values	`15` \| `30` \| `60` \| `120`
By default	`15`

Minimum channel bandwidth for the NRb (MHz) - setting the minimum channel bandwidth for the NR band
5 MHz (By default) | 10 MHz | 40 MHz

Set the minimum channel bandwidth for the NR band.

Usage in program code
Block Parameter	`MainChannelBW`
Values	`5 MHz` \| `10 MHz` \| `40 MHz`
By default	`5 MHz`

References

Dictionary of Parameters and Variables: 5G Standard