Paging process in UMTS or HSDPA system is called UMTS Paging.
The Paging Channel (PCH) is a downlink transport channel. The PCH is always transmitted over the entire cell. The transmission of the PCH is associated with the transmission of physical-layer generated Paging Indicators, to support efficient sleep-mode procedures.
Paging Channel selection
System information block type 5 (SIB 5) defines common channels to be employed in Idle mode.The UE may use Discontinuous Reception (DRX) in idle mode in order to reduce power consumption. When DRX is used the UE needs only to monitor one Page Indicator, PI, in one Paging Occasion per DRX cycle.
The Paging Indicator Channel (PICH) is a fixed rate (SF=256) physical channel used to carry the paging indicators.
Basically two types of Paging Procedures in UMTS Paging.
1) Idle Mode Paging
2) Dedicated Mode Paging
In Idle mode paging is used when UE is in idle mode so we can say UE is in Cell PCH or URA PCH.PAGING TYPE 1 message on an appropriate paging occasion on the PCCH.
UE dedicated paging procedure is used to transmit dedicated paging information to one UE in connected mode in CELL_DCH or CELL_FACH state.PAGING TYPE 2 message on the DCCH using AM RLC.
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