The definition of nr's pci is: each 5G (NR) cell has a physical cell ID (PCI) used to identify the cell on the wireless side, and the specific reference signal of each cell is mainly determined by PCI .
And to avoid PCI collisions as a network planning principle, adjacent cells cannot use the same PCI; if adjacent cells use the same PCI and cross-coverage areas, only one cell can be synchronized in the initial (cell) search ; This situation is called a collision.
Physically spaced PCI usage can prevent the UE from receiving multiple (same PCI) cell signals; the PCI reuse distance needs to be increased as much as possible.
The PCI in 5G NR is:
1. The biggest difference is that there are 1008 PCIs in 5G, and the set of all PCIs is divided into 168 groups (corresponding to protocol 38.211, Value range: 0 ~ 335), each group contains 3 cell IDs.
2. Mode 3 interference: affects the synchronization signal demodulation of PSS; Mode 4 interference: DMRS for PBCH on the subcarrier is calculated through mod 4, which may cause DMRS interference. Mode 30 interference: Same as LTE.
The allocation of PCI in LTE is:
1. The starting position of the reference symbol within an RB is also related to the cell-specific frequency offset. LTE defines 6 frequency offsets, which are related to the cell PCI, and their value is PCI mod 6. This frequency offset can avoid time-frequency resource conflicts between cell-specific reference signals of up to 6 neighboring cells.
2. Through the cell search process, the UE can obtain the PCI of the cell. Moreover, the cell-specific reference signal and its time-frequency position are in one-to-one correspondence with the PCI. Therefore, after the cell search process, the UE also knows the cell-specific reference signal sequence and its time-frequency position of the cell.
3. LTE-1*** defines 504 different PCIs (corresponding to protocol 36.211, value range 0 ~ 503), and each PCI corresponds to a specific downlink reference signal sequence.
The set of all PCIs is divided into 168 groups (corresponding to protocol 36.211, value range 0 ~ 167), each group contains 3 cell IDs (corresponding to protocol 36.211, value range 0 ~ 2).