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5G NR PCI Calculator & Planner

Split a 5G NR Physical Cell ID into NID(1) (SSS) and NID(2) (PSS), or build it back — with mod-3 and mod-30 groups for collision, confusion and PRACH/DMRS planning.

📡 PCI = 3·N_ID1 + N_ID2 · 0–1007 (TS 38.211)

mod-3 = PSS group (avoid between neighbours); mod-30 affects PRACH root & DMRS planning.

How it worksThe PCI formula

A 5G NR Physical Cell ID is built from two layers, per 3GPP TS 38.211 §7.4.2:

PCI = 3 × N_ID1 + N_ID2

N_ID1 = floor(PCI / 3)   (SSS group, 0–335)
N_ID2 = PCI mod 3       (PSS, 0–2)

1008 unique PCIs (0–1007)

For planning, three rules matter: collision (two neighbours share the same PCI), confusion (a cell has two neighbours with the same PCI), and mod-3 / mod-30 separation. mod-3 sets the PSS sequence — reusing it on overlapping cells degrades the SSS detection; mod-30 governs the PRACH root-sequence and PUSCH/PDSCH DMRS allocation, so a good plan keeps neighbours in different mod-3 and mod-30 classes.

FAQFrequently asked questions

How is a 5G PCI calculated?
PCI = 3 × N_ID1 + N_ID2, where N_ID1 (the SSS group) is 0–335 and N_ID2 (the PSS) is 0–2. That yields 1008 unique values, 0–1007.
How many PCIs are there in 5G NR?
1008 — the same count as LTE. They run from 0 to 1007.
What is PCI mod 3 used for?
PCI mod 3 equals N_ID2, the PSS index. Neighbouring overlapping cells should use different mod-3 values so their primary sync signals don't interfere.
What is PCI mod 30?
mod-30 affects PRACH root-sequence assignment and DMRS sequence planning. Keeping neighbours in different mod-30 classes reduces uplink and reference-signal interference.

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