OFDM Demodulation

OFDM demodulation.

ofdm demodulation

Description

The OFDM Demodulation block estimates the synchronisation offset to the strongest SS block using the PSS reference sequence (NID2). After frequency offset correction, the centre frequencies of the reference PSS and the received signal are considered to be aligned, after which the OFDM Demodulation block demodulates the synchronised signal and extracts the SS block.

The block performs the following actions:

Creates a reference grid for time estimation usage of the detected PSS. The PSS is placed in the second OFDM symbol of the reference grid because the first OFDM symbol contains a special cyclic prefix length.
Estimates the synchronisation offset relative to the OFDM symbol to the detected SSB based on the contents of the reference grid.
Performs OFDM synchronisation, demodulation and extraction of the strongest SS block.

Configuring the block includes 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

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

The detected PSS (NID2) sequence in the received signal.

Data types: Float64.

CorWfm - frequency shifted signal as a complex matrix
matrix

Frequency shifted signal returned as a complex matrix.

Data types: ComplexF64.

Output

ResGrid - demodulated output signal as a complex matrix
matrix

Demodulated output 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 programme code
Block parameter	`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 in MHz
5 (By default) | 10 | 40

Set the minimum channel bandwidth for the NR band in MHz.

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

References

Glossary: Standard 5G