8.5.72 Selection of common E-DCH TTI (FDD only)

25.3313GPPProtocol specificationRadio Resource Control (RRC)Release 17TS

A common E-DCH resource may employ either 2 or 10 ms TTI. The UE shall make the selection on an appropriate TTI length according to the procedure below and indicate the selection to the lower layers.

The UE shall:

1> if the CHOICE "TTI selection" in the IE "Concurrent Deployment of 2ms and 10ms TTI" has the value "Fixed":

2> if "Fixed common E-DCH TTI selection" is set to "10ms":

3> indicate a selection of common E-DCH TTI of 10 ms to the physical layer for all preamble transmissions.

2> if "Fixed common E-DCH TTI selection" is set to "2ms":

3> indicate a selection of common E-DCH TTI of 2 ms to the physical layer for all preamble transmissions.

1> if the CHOICE "TTI selection" in the IE "Concurrent Deployment of 2ms and 10ms TTI" has the value "Threshold based":

2> perform TTI selection as follows:

3> for the first preamble transmission:

4> when the UE calculates the initial preamble transmit power ("Preamble_Initial_Power") as specified in subclause 8.5.7:

5> calculate a transmit power headroom,

Headroom = {min(Maximum allowed UL tx power, P_MAX) – (Preamble_Initial_Power + DPp-e )}

where "Maximum allowed UL tx power" is the maximum allowed uplink transmit power indicated in system information (in dBm), P_MAX is the maximum RF output power of the UE (dBm) and DPp-e is the Power offset between the last transmitted preamble and the initial DPCCH transmission as defined in [26].

NOTE 1: the expression Preamble_Initial_Power + DPp-e represents the DPCCH power if the common E-DCH transmission would be sent after the initial preamble.

3> for preamble transmissions other than the first:

4> when the UE calculates the preamble transmit power ("Commanded Preamble Power") as specified [29] subclause 6.1A:

5> calculate a transmit power headroom,

Headroom = {min(Maximum allowed UL tx power, P_MAX) – (Commanded Preamble Power + DPp-e )}

where "Maximum allowed UL tx power" is the maximum allowed uplink transmit power indicated in system information (in dBm), P_MAX is the maximum RF output power of the UE (dBm) and DPp-e is the Power offset between the last transmitted preamble and the initial DPCCH transmission as defined in [26].

3> if the resulting "Headroom" value is less than "Common E-DCH TTI selection threshold":

4> indicate a selection of common E-DCH TTI of 10 ms to the physical layer for the preamble transmission.

3> else:

4> indicate a selection of common E-DCH TTI of 2 ms to the physical layer for the preamble transmission.

2> for emergency call, the UE is allowed to select a common E-DCH TTI of 10ms.