8.5.7 Open loop power control
25.3313GPPProtocol specificationRadio Resource Control (RRC)Release 17TS
For FDD, and prior to PRACH transmission or prior to a transmission in Enhanced Uplink in CELL_FACH state and Idle mode, the UE shall:
1> acquire valid versions of the necessary System Information IEs as follows:
2> if the UE has stored valid versions of the IEs "Primary CPICH Tx power" and "Constant value":
3> use the stored content of the IEs.
2> otherwise:
3> read and store the IE "Primary CPICH Tx power" and "Constant value" in System Information Block type 6 (or System Information Block type 5 or System Information Block type 5bis, if System Information Block type 6 is not being broadcast).
2> if variable READY_FOR_COMMON_EDCH is set to TRUE; and
2> if IE "UL interference for common E-DCH" is included in system information block type 5 or 5bis:
3> use the stored value of IE "UL interference for common E-DCH".
2> otherwise:
3> if the UE has a valid version of the IE "UL interference" stored:
4> use the stored content of the IE "UL interference".
3> otherwise:
4> read and store the IE "UL interference" in System Information Block type 7;
4> if the UE fails to read the IE "UL interference" in System Information Block type 7 due to bad radio conditions, the UE shall use the last stored IE "UL interference".
1> measure the value for the CPICH_RSCP;
1> calculate the power for the first preamble as:
Preamble_Initial_Power = Primary CPICH TX power – CPICH_RSCP + UL interference + Constant Value
Where,
Primary CPICH TX power shall have the value of IE "Primary CPICH Tx power",
UL interference shall have the value of IE "UL interference for common E-DCH" if variable READY_FOR_COMMON_EDCH is set to TRUE and IE "UL interference for common E-DCH" is included in SIB 5/5bis; otherwise UL interference shal have the value of IE "UL interference"; and
Constant Value shall have the value of IE "Constant value".
1> as long as the physical layer is configured for PRACH transmission or the PRACH preamble part (as part of the Enhanced Uplink in CELL_FACH state and Idle mode):
2> continuously recalculate the Preamble_Initial_Power when any of the broadcast parameters used in the above formula changes; and
2> resubmit to the physical layer the new calculated Preamble_Initial_Power.
For 3.84 Mcps TDD or 7.68 Mcps TDD the UE shall:
1> if in the IE "Uplink DPCH Power Control info" the "CHOICE UL OL PC info" has the value "Broadcast UL OL PC info":
2> prior to DPCH transmission the UE shall:
3> acquire valid versions of the necessary System Information IEs as follows:
4> if the UE has stored valid versions of the IEs "Primary CCPCH Tx power" and "DPCH Constant value":
5> use the stored content of the IEs.
4> otherwise:
5> read and store the IE "Primary CCPCH Tx power" and "DPCH Constant value" in System Information Block type 6 (or System Information Block type 5, if System Information Block type 6 is not being broadcast).
3> if the UE has a valid version of the IE "UL interference" for each active UL timeslot stored:
4> use the stored content of the IE "UL interference" for each active UL timeslot.
3> otherwise:
4> read and store the IE "UL Timeslot Interference" for each active UL timeslot in System Information Block type 14;
4> if the UE fails to read the IE "UL Timeslot Interference" for each active UL time slot in System Information Block type 14 due to bad radio conditions, the UE shall use the last stored IE "UL Timeslot interference" for each active UL timeslot.
1> otherwise:
2> acquire Reference Power, Constant Values and IBTS for all active UL timeslots from the IE "Uplink DPCH Power Control info".
1> for PUSCH, PRACH and HS-SICH power control:
2> prior to PUSCH or PRACH transmission the UE shall:
3> acquire valid versions of the necessary System Information IEs as follows:
4> if the UE has stored valid versions of the IEs "Primary CCPCH Tx power" and "PUSCH Constant value" for PUSCH transmissions or "PRACH Constant value" for PRACH transmissions:
5> use the stored content of the IEs.
4> otherwise:
5> read and store the IE "Primary CCPCH Tx power" and "PUSCH Constant value" for PUSCH transmissions or "PRACH Constant value" for PRACH transmissions in System Information Block type 6 (or System Information Block type 5, if System Information Block type 6 is not being broadcast).
3> if the UE has a valid version of the IE "UL interference" for each active UL timeslot stored:
4> use the stored content of the IE "UL interference" for each active UL timeslot.
3> otherwise:
4> read and store the IE "UL Timeslot Interference" for each active UL timeslot in System Information Block type 14;
4> if the UE fails to read the IE "UL Timeslot Interference" for each active UL time slot in System Information Block type 14 due to bad radio conditions, the UE shall use the last stored IE "UL Timeslot interference" for each active UL timeslot.
calculate the UL transmit power according to the following formula for the PRACH continuously while the physical channel is active:
PPRACH = LPCCPCH + IBTS + PRACH Constant value,
2> 3dB shall be added to RACH Constant Value in the above equation for the case where RACH Spreading Factor = 8;
2> for 7.68 Mcps TDD, 3dB shall be added to RACH Constant Value in the above equation for the case where RACH Spreading Factor = 16.
1> calculate the UL transmit power according to the following formula for the DPCH continuously while the physical channel is active:
PDPCH = LPCCPCH+(1-)L0 + IBTS + SIRTARGET+ DPCH Constant value
1> calculate the UL transmit power according to the following formula for the PUSCH continuously while the physical channel is active:
PPUSCH = LPCCPCH+(1-)L0 + IBTS + SIRTARGET+ PUSCH Constant value
1> calculate the initial UL transmit power for HS-SICH according to the following formula:
PHS-SICH = LPCCPCH+(1-)L0 + IBTS + SIRTARGET+ HS-SICH Constant value
Where, for all the above equations for 3.84 Mcps TDD or 7.68 Mcps TDD the following apply:
– PPRACH, PDPCH, PPUSCH and PHS-SICH: Transmitter power level in dBm;
– Pathloss values:
– LPCCPCH: Measurement representing path loss in dB based on beacon channels (the reference transmit power is signalled as the value of the IE "Primary CCPCH Tx Power" on BCH in System Information Block type 6 (or System Information Block type 5, according to subclause 8.1.1.6.5), or individually signalled in the IE" Uplink DPCH Power Control info").
– L0: Long term average of path loss in dB;
– If the midamble is used in the evaluation of LPCCPCH and L0, and the Tx diversity scheme used for the P-CCPCH involves the transmission of different midambles from the diversity antennas, the received power of the different midambles from the different antennas shall be combined prior to evaluation of the variables.
– IBTS: Interference signal power level at cell’s receiver in dBm. IBTS shall have the value of the IE "UL Timeslot Interference" (IE "UL Timeslot Interference" is broadcast on BCH in System Information Block type 14 or individually signalled to each UE in the IE "Uplink DPCH Power Control info" for each active uplink timeslot).
– : is a weighting parameter, which represents the quality of path loss measurements. may be a function of the time delay between the uplink time slot and the most recent down link PCCPCH time slot. is calculated at the UE. shall be smaller or equal to the value of the IE "Alpha". If the IE "Alpha" is not explicitly signalled to the UE shall be set to 1. If UE is capable of estimating its position by using the OTDOA IPDL method, the UE shall use the IPDL- parameter.
– SIRTARGET: Target SNR in dB. This value is individually signalled to UEs in IE "UL target SIR" in IE "Uplink DPCH Power Control Info" or in IE "PUSCH Power Control Info" or in IE "HS-SICH Power Control Info".
– PRACH Constant value: PRACH Constant value shall have the value of the IE "PRACH Constant value".
– DPCH Constant value: DPCH Constant value shall have the value of the IE "DPCH Constant value".
– PUSCH Constant value: PUSCH Constant value shall have the value of the IE "PUSCH Constant value".
– HS-SICH Constant value: HS-SICH Constant value shall have the value of the IE "HS-SICH Constant value".
– Values received by dedicated signalling shall take precedence over broadcast values.
– If IPDLs are applied, the UE may increase UL Tx power by the value given in the IE "Max power increase". This power increase is only allowed in the slots between an idle slot and the next beacon slot.
For 1.28 Mcps TDD the UE shall:
1> acquire valid versions of the necessary System Information IEs as follows:
2> if the UE has stored a valid version of the IE "Primary CCPCH Tx Power":
3> use the stored content of the IE.
2> otherwise:
3> read and store the IE "Primary CCPCH Tx Power" from System Information Block type 6 (or System Information Block type 5, if System Information Block type 6 is not being broadcast).
1> calculate the UL transmit power according to the following formula for each UpPCH code transmission:
PUpPCH = LPCCPCH + PRXUpPCHdes + (i-1)* Pwrramp
NOTE: When i equals 1, the initial signature power "Signature_Initial_Power" defined in [33] corresponds to PUpPCH with i set to 1.
1> calculate the UL transmit power according to the following formula for each PRACH transmission:
PPRACH = LPCCPCH + PRXPRACHdes + (iUpPCH-1) * Pwrramp
1> calculate the initial UL transmit power according to the following formula for the PUSCH. Once the UE receives TPC bits relating to the PUSCH then it transitions to closed loop power control. If successive PUSCH resource allocations are contiguous then no return is made to open loop power control at the beginning of the succeeding resource allocation.
PUSCH = PRXPUSCHdes + LPCCPCH
1> calculate the initial UL transmit power for HS-SICH according to the following formula:
PHS-SICH = PRXHS-SICH + LPCCPCH
1> calculate the initial UL transmit power according to the following formula for the DPCH. Once the UE receives TPC bits relating to the uplink DPCH then it transitions to closed loop power control.
PDPCH = PRXDPCHdes + LPCCPCH
1> calculate the initial UL transmit power for E-PUCH according to the following formula:
PE-PUCH = PRXdes_base + LPCCPCH +
Where:
– PUpPCH, PPRACH, PDPCH, PHS-SICH, PUSCH, & PE-PUCH: Transmitter power level in dBm.
– LPCCPCH: Measurement representing path loss in dB (reference transmit power "Primary CCPCH Tx Power" is broadcast on BCH in System Information Block type 5 and System Information Block type 6, or individually signalled to each UE in the IE" Uplink DPCH Power Control info").
– i is the number of transmission attempts on UpPCH, i=1…Max SYNC_UL Transmissions.
– iUpPCH is the final value of i.
– PRXPRACHdes: Desired PRACH RX power at the cell’s receiver in dBm signalled to the UE by the network in the FPACH response to the UE’s successful SYNC_UL transmission.
– PRXUpPCHdes: Desired UpPCH RX power at the cell’s receiver in dBm. The value is broadcast in "PRXUpPCHdes" in IE "SYNC_UL info" on BCH and shall be read on System Information Block type 5 and System Information Block type 6. It can also be signalled directly to the UE in IE "Uplink Timing Advance Control" contained in a protocol message triggering a hard handover or a transition from cell FACH to cell DCH state.
– PRXPUSCHdes: Desired PUSCH RX power at the cell’s receiver in dBm signalled to the UE in IE "PUSCH Power Control Info".
– PRXDPCHdes: Desired DPCH RX power at the cell’s receiver in dBm signalled to the UE in IE "Uplink DPCH Info" and IE "Uplink DPCH Power Control Info".
– Pwrramp: The UE shall increase its transmission power by the value of the IE "Power Ramp step" by every UpPCH transmission. Its value is signalled in the IE "SYNC UL info" in System Information Block type 5 and System Information Block type 6 or is signalled to the UE in the IE "Uplink Timing Advance Control" contained in a protocol message triggering a hard handover or a transition from cell FACH state to cell DCH state.
– PRXHS-SICH: Desired HS-SICH RX power at the cell’s receiver in dBm signalled to the UE in IE "Downlink HS-PDSCH Information".
– Ack-Nack Power Offset: Difference in the desired RX power between HS-SICH transmissions conveying an acknowledgement and transmissions conveying a negative acknowledgement signalled to the UE in IE "HS-SCCH Info".
– PRXdes_base: Reference Desired E-PUCH RX power at the cell’s receiver in dBm signalled to the UE in CELL_DCH in IE "E-PUCH Info" via dedicated signalling; or via System Information Block 5 for UE in enhanced CELL_FACH and Idle mode.
– : Gain factor for the selected E-TFC transport block size, the allocated E-PUCH physical resources, and the Modulation type and the HARQ power offset (see [33]).