Role of GSCN in PSS detection


I want to detect PSS from incoming stream to UE. Cross correlation of incoming stream with locally generated 3 PSS sequences then finding out the maximum peak result is the method i understood. My doubts are as follow :

  1. With the result of cross correlation , how we can find out SSref ?
  2. Does UE know GSCN numbers , it supports without any communication from gNB