Physical Cell ID - LTE 4G vs 5GNR
Why is PCI required ?
PCI is used for Downlink Synchronization includes
- Frequency Synchronization
- Timing Synchronization
- Cell ID Detection
PCI includes two signals i.e., Primary Synchronization Signal and Secondary Synchronization Signal
After successful decode of SSS you will able to get PCI
PCI is calculated using the formula
PCI = (3 × SSS) + PSS
LTE 4G:
PSS has 3 values i.e., 0 to 2 and generated using Zad-off Chu sequence
SSS has 168 values i.e., 0 to 167 and generated using concatenation of 2 m-sequences
PCI = (3 * 167) + 2 = 503
So PCI values will vary from 0 to 503. LTE supports 504 unique PCIs
5GNR:
PSS has 3 values i.e., 0 to 2 and generated using m-sequence
SSS has 336 values i.e., 0 to 335 and generated using PN Gold sequence
In 5G-NR, the basic structure of PSS is the same but the number of SSS are increased
PCI = (3 * 335) + 2 = 1007
So PCI values will vary from 0 to 1007. 5GNR supports 1008 unique PCIs
Conclusion:
5G NR has double of the PCI’s compared to LTE 4G.
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