Posts Tagged cell_dch

What is the distinct difference between Cell_DCH and other states' measurements?

In Cell_DCH, the UE makes measurements and reports them to the UTRAN for action by the UTRAN.

However, in other states, the measurements are not reported to the UTRAN and the UE takes action based on the measurements. (though Cell_FACH measurement has some common things with Cell_DCH)


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UE ID dedicated channels

In Cell_DCH (using DPCHs), UE is addressed explicitly using the physical layer parameters such as the frequency channelization code, scrambling code etc.

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UE location in Cell_DCH

In the Cell_DCH, the UE location is known to

1. cell level by the UTRAN

2. serving RNC by the CN

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What is Cell_DCH?



One of states in connected mode.

The UE is assigned a dedicated physical channel (DPCH) either in response to the RRC connection request or via some UTRAN controlled bearer reconfiguration procedure.

If UE releases (or asked to release by the network) dedicated channel, the UE can move to any other states in RRC connected mode (Cell_FACH, Cell_PCH, URA_PCH).

If UE releases the RRC connection, it moves to idle.

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In Cell_DCH, UE does not send or receive data, but why large power is still consumed ?

In Cell_DCH state, regardless of data transmission or reception, DPCCH channel needs to be up.

This is why.

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How to switch between Cell_DCH and Cell_FACH?

Note that it is not efficient to have a code sequence allocated to an inactive user since this may block the assignment of new connections due to the code availability in downlink.

Thus, in such case, DCH channel needs to beĀ  de-allocated and the UE should use RACH/FACH channel.

On the other hand, when the buffer of UE excceeds a certain amount of data the DCH channel needs to be allocated.

These changes between Cell_DCH and Cell_FACH can be done via Transport Channel Type Switching messages.

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