Wireless Oom » cell_pch

Cell_PCH data call flow

wirelessoom — Mon, 15 Mar 2010 20:00:27 +0000

Pre release 7

Release 7

UTRAN originated page vs. CN originated page

wirelessoom — Sun, 26 Jul 2009 22:34:57 +0000

Page can be originated

1. UTRAN

2. CN

If the UE is in idle mode, then CN will originate the page.

If the UE is in Cell_PCH or URA_PCH, then UTRAN will originate the page.

UE location in Cell_PCH

wirelessoom — Sun, 26 Jul 2009 15:11:09 +0000

The UE location is known to the level of the cell in Cell_PCH.

The purpose of this state is to save power (performing DRX like idle mode)

but allow rapid network access to the UE by knowing that only one cell needs to be paged (and no RRC connection setup reqired.)

What is Cell_PCH?

wirelessoom — Sun, 26 Jul 2009 15:06:58 +0000

Cell_PCH

one of states in RRC connected mode.

In Cell_PCH, the UE has no uplink resources. The UE monitors the paging channel using the assigned discontinous reception (DRX) parameters.

The UE will entern into Cell_FACH

1. when it detects the cell change, it performs cell update in Cell_FACH

2. when it is paged by the UTRAN

Idle vs. Cell_PCH vs. URA_PCH upon receiving paging

wirelessoom — Wed, 24 Jun 2009 05:35:35 +0000

When a paging arrives at a UE,

in idle mode, UE sends RRC connection establishment

in Cell_PCH and URA_PCH, the UE moves to Cell_FACH and sends Cell Update message with cause “paging response”

Idle vs Cell_PCH vs URA_PCH

wirelessoom — Fri, 19 Jun 2009 18:02:14 +0000

I heard that there is no much difference between idle and Cell_PCH from UE perspective.

In idle, UE is located within registration area.

In Cell_PCH, UE’s location is known in cell level.

Then, what about URA_PCH?

In URA_PCH, UE’s location is known in registration area level.

Then, is it true that there is no difference between idle and URA_PCH ?

It is said that the idle mode is characterized by the absense of an RRC connection.

That means in Cell_PCH and URA_PCH modes, UE still has RRC connection.

Recall that in idle, Cell_PCH, and URA_PCH, UE does not have any radio resources allocated and therefore it cannot start any type of user data transfer in the dedicated and common channels.

The difference among idle and other connected modes (Cell_PCH, URA_PCH) is happening when UE tries to talk to the network.

In idle, UE simply sends RRC connection Request via RACH.

In Cell_PCH and URA_PCH, UE moves to Cell_FACH sends some messages such as Cell Update message (probably not the RRC connection Request since it already has RRC connection).

So, UE doesn’t have to establish RRC connection and Signaling connection again.

Thus, UE can save some time to get service from the network in Cell_PCH and URA_PCH. (needs verification)

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Also, consider this from FACH perspective.

In idle mode, CCCH is mapped to FACH since there is no RRC connection.

However, in connected mode, DCCH can be mapped to FACH since there is RRC connection.

This complies the definition of CCCH and DCCH.