contains information relevant to the DRAC procedure.

For FDD mode only.

Sent via FACH and the SCCPCH.

Spreading factor range: from 4 to 256

Thus, minimum data rate is 15kbps (SF=256, N_data = 10 bits)

maximum data rate is 1908kbps (SF=4 with N_data = 1272 bits in a single slot)

It is not about what information which logical channels take care.

Thus, two main categoires: (1) dedicated and (2) common

1. Dedicated

DCH (Dedicated Channel):  DCH includes either user or control information.

In the case of single service, a usual situation is that two DCHs are allocated;

one for the traffic logical channel (DTCH) and another for the signaling (DCCH).

Four DCCHs (SRBs) can be multiplexed into a single transport channel (DCH).

Also note that there will be uplink DCH and downlink DCH.

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2. Common

a. BCH (Broadcast Channel):

only in the downlink

transport BCCH logical channel which includes system information.

a fixed low bit rate and relatively high power level in order for all UEs in the cell to decode its information

b. PCH (Paging Channel):

only in the downlink.

transport the PCCH logical channel, which contains pagings and notifications from the network to specific UEs.

c. RACH (Random Access Channel):

only in the uplink.

very low quality requirements (transmission of short packets without delay constraints) or for signal info during the initial access to the system.

different transmission bit rates may be used.

d. FACH (Forward Access Channel):

only in the downlink.

differnt bit rates.

e. HS-DSCH (High Speed Downlink Shared Channel):

to support HSDPA

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Different transport channels may be multiplexed together over the same physical resources forming a Coded Composite Transport Channel (CCTrCH).

CPCH (Common Packet Channel) and DSCH (Downlink Shared Channel) are obsolete.

The network configures

1. what objects to measure (e.g., the cells, transport channels, physical channels)

2. criteria to be used (e.g., periodic reporting or event-trigger)

3. RLC mode to be used (e.g., AM or UM)

This configuration is done by means of Measurement Control Message.

Measurements are required only by UEs in Cell_DCH and Cell_FACH states.

In some cases such as traffic volume monitoring, UEs in Cell_PCH may also send measurement reports. –> I think this is why power consumption during Cell_PCH is higher (around 5mA)  than idle mode (around 1mA).

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I found out later that even in idle, URA_PCH, measurements may be done.

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.

CELL_PCH, URA_PCH, idle: Paging Type 1 message is used.

When the System Information gets changed MIB value tag is updated and Paging message is transmitted indicating that System Information has changed. Then, the UE’s in IDLE, CELL_PCH and URA_PCH will be able to read the updated System Information.

In CELL_FACH state, the change of system information is notified through FACH channel by means of System Information Change Indication message.

This is why BCCH is mapped into FACH channel.

In Cell_PCH and URA_PCH, a paging type I message in a PCH channel will notify UEs.

Then, what about CELL_DCH? No system information change indication ?

If dedicated channels are used, then no need for RNTI.

Two types:

1. C-RNTI (cell)

2. U-RNTI(URA)

C-RNTI identifies a UE within a cell, so it can only be used when the UE’s location is known.

Otherwise, U-RNTI is used.

C-RNTI will be allocated to a UE every time it moves to a new cell and conducts a cell-update procedure.

FACH channel also use C-RNTI to whether the data is for me or not.