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Primary Synchronization Signal (PSS) in 5G-NR

PSS Role and Synchronization:

  • Primary Synchronization Signal (PSS) aids User Equipment (UE) in:
  • Determining physical-layer identity NID(2).
  • Achieving synchronization up to PSS periodicity.

PSS Generation:

  • PSS created using BPSK-modulated m-sequence of length 127.
  • LTE uses Zadoff-Chu sequence to generate PSS.
  • NID(2) identification requires three distinct m-sequences due to PSS variations.

PSS Sequence Variation:

  • PSS m-sequence of length 127 cyclically shifted by 0, 43, or 86 steps.
  • Shifting depends on the Physical Cell Identity (PCI) used in the cell.
  • Mapping on 127 subcarriers sequentially from subcarrier 56 to 182.

Transmission and Timing:

  • PSS transmitted periodically at the same rate as Synchronization Signal Blocks (SSBs).
  • Occurs at Specific Subcarrier Spacing (SSB periodicity).

Decoding and PCI Derivation:

  • Decoding PSS reveals one of three identities for NID(2).
  • To derive PCI, decoding Secondary Synchronization Signal (SSS) is necessary.
  • PCI group number NID(1) obtained from decoded SSS.

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