5G • RAN
Cyclic Shift (Ncs)
Zero Correlation Zone Configuration (Ncs)
Time-domain shift parameter defining the guard window between adjacent PRACH preambles to absorb round-trip delay.
Technical Explanation
The cyclic shift Ncs defines the minimum spacing between preambles derived from the same Zadoff-Chu root. Ncs must be larger than the maximum round-trip propagation delay plus channel delay spread to ensure that signals from distant UEs do not alias into adjacent preamble detection bins.
Key Functions
- Sets zero correlation zone preventing preamble false detection
- Proportional to maximum cell radius and propagation delay
- Determines number of preambles obtainable from a single root sequence
Specifications
3GPP TS 38.211
Interfaces
Uu
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