What is the difference between PEI and WUS?

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#1

Hello, I’m doing a research about WUS(Wake Up signal)(Rel-16).

I found that there is similar one in Rel-17 called PEI or EPI (Paging Eary Indication).

I could only find that WUS is for ‘connected’ state and PEI is for ‘idle’ state.

What is the main differenece between WUS and PEI? and how these two work differently?

Thank you