| (1c) |
System information
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Once found and synchronised to a strongest cell, PHY tries to read PBCH and PDSCH for MIB and SIBs respectively. These are passed on to RRC over BCCH transport. Through system information, RRC comes to know about PLMN identities of found cell. RRC passes cell/PLMN information to NAS (along with measured RSRP - Reference Signal Received Power) for found cells. Ref: [36.304:5.1.2.2], [36.331:5.2]
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| (1d) |
Cell selection
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Though separated out, steps 1b & 1c are part of cell selection procedure. Cell selection is controlled by RRC, based on PLMN selection process being done by NAS on one side and actual scanning & camping being done by PHY on the other. The cell as found to be strongest by PHY can be Acceptable, Suitable, Barred, or Reserved. Barred and Reserved (IEs in SIB1) are not for public use or are for operator specific use only. Acceptable and Suitable are both good to camp on - cell selection criterion [36.304:5.2.3.2] satisfied and not barred - but Suitable cell is one with most correct PLMN (as determined by NAS). More details about cell selection (and reselection) can be found at [36.304:5.2], [43.022:4.5].
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