16.2 Power control

36.2133GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical layer proceduresRelease 17TS

16.2.1 Uplink power control

Uplink power control controls the transmit power of the different uplink physical channels.

16.2.1.1 Narrowband physical uplink shared channel

16.2.1.1.1 UE behaviour

The setting of the UE Transmit power for a Narrowband Physical Uplink Shared Channel (NPUSCH) transmission is defined as follows. For FDD, if the UE is capable of enhanced random access power control [12], and it is configured by higher layers, and for TDD, enhanced random access power control shall be applied for a UE which started the random access procedure in the first or second configured NPRACH repetition level.

The UE transmit power for NPUSCH transmission in NB-IoT UL slot i for the serving cell is given by:

For NPUSCH (re)transmissions corresponding to the random access response grant if enhanced random access power control is not applied, and for all other NPUSCH transmissions except for NPUSCH (re)transmission corresponding to preconfigured uplink resource, when the number of repetitions of the allocated NPUSCH RUs is greater than 2:

[dBm]

otherwise

[dBm]

where,

– is the configured UE transmit power defined in [6] in NB-IoT UL slot i for serving cell .

– is the NPUSCH transmission resource bandwidth normalized by 15 kHz, where {1/4} is used for 3.75 kHz subcarrier spacing and {1, 3, 6, 12} are used for 15kHz subcarrier spacing

– is a parameter composed of the sum of a component provided from higher layers and a component provided by higher layers for j=1, 3 and for serving cell where . For NPUSCH (re)transmissions corresponding to a dynamic scheduled grant or a semi-persistent grant then j=1, for NPUSCH (re)transmissions corresponding to the random access response grant then j=2 and for NPUSCH transmission using preconfigured uplink resource then j=3. . If enhanced random access power control is not applied, , where the parameter preambleInitialReceivedTargetPower [8] () and are signalled from higher layers for serving cell . If enhanced random access power control is applied,

– For j=1, for NPUSCH format 2, =1; for NPUSCH format 1, is provided by higher layers for serving cell . For j=2, For j=3, is the parameter alpha in PUR-Config-NB provided by higher layers for serving cell .

– is the downlink path loss estimate calculated in the UE for serving cell in dB and = nrs-Power + nrs-PowerOffsetNonAnchor – NRSRP, where nrs-Power is provided by higher layers and Clause 16.2.2, and nrs-PowerOffsetNonAnchor is set to zero if it is not provided by higher layers and NRSRP is defined in [5] for serving cell .

– If a NB-IoT UE is configured with npusch-16QAM-Config or pur-UL-16QAM-Config, then for NPUSCH (re)transmissions with QPSK and 16QAM,

– for and for where is given by the parameter deltaMCS-Enabled provided by higher layers for serving cell , and

– where is the code block size and is the number of resource elements determined as where , , are defined in [3], and is defined in section 16.5.1.1

– otherwise .

16.2.1.1.2 Power headroom

If the UE transmits NPUSCH in NB-IoT UL slot for serving cell , power headroom is computed using

[dB]

where, , , , and, are defined in Clause 16.2.1.1.1.

The power headroom shall be rounded down to the closest value in the set [PH1, PH2, PH3, PH4] dB if enhanced PHR is not configured and [PH1, PH2, …, PH15, PH16] dB if enhanced PHR is configured as defined in [10]. The power headroom is delivered by the physical layer to higher layers.

16.2.1.2 SR

16.2.1.2.1 UE behaviour

If the UE is configured with higher layer parameter sr-WithoutHARQ-ACK-Config, the setting of the UE transmit power for SR transmission without HARQ-ACK is defined as follows.

The UE transmit power for SR transmission in NB-IoT UL slot i for the serving cell is given by:

[dBm]

where,

– is the configured UE transmit power defined in [6] in NB-IoT UL slot i for serving cell .

– is {1/3} for NPRACH format 2 and {1}for NPRACH format 0/1.

– is signaled from higher layers for serving cell .

– is signaled from higher layers for serving cell .

– is defined in Clause 16.2.1.1.1.

16.2.2 Downlink power allocation

The eNodeB determines the downlink transmit energy per resource element.

For an NB-IoT cell, the UE may assume NRS EPRE is constant across the downlink NB-IoT system bandwidth and constant across all subframes that contain NRS, until different NRS power information is received.

The downlink NRS EPRE can be derived from the downlink narrowband reference-signal transmit power given by nrs-Power + nrs-PowerOffsetNonAnchor, where the parameter nrs-Power is provided by higher layers and nrs-PowerOffsetNonAnchor is zero if it is not provided by higher layers. The downlink narrowband reference-signal transmit power is defined as the linear average over the power contributions (in [W]) of all resource elements that carry narrowband reference signals within the operating NB-IoT system bandwidth.

A UE may assume that the ratio of NWUS EPRE to NRS EPRE is 0 dB.

A UE may assume the ratio of NPDSCH EPRE to NRS EPRE among NPDSCH REs (not applicable to NPDSCH REs with zero EPRE) is 0 dB for an NB-IoT cell with one NRS antenna port and -3 dB for an NB-IoT cell with two NRS antenna ports if higher layer parameter nrs-PowerRatio is not configured.

If a UE is configured with the higher layer parameter nrs-PowerRatio in npdsch-16QAM-Config or pur-DL-16QAM-Config,

– the ratio of NPDSCH EPRE to NRS EPRE among NPDSCH REs in symbols with NRS is given by for a cell with one NRS antenna port and for a cell with two NRS antenna ports, where is given by the parameter nrs-PowerRatio.

– if higher layer parameter operationModeInfo indicates ’10’ or ’11’,

– the ratio of NPDSCH EPRE to NRS EPRE among NPDSCH REs (not applicable to NPDSCH REs with zero EPRE) is given by the parameter nrs-PowerRatio in symbols without NRS

– otherwise,

– the ratio of NPDSCH EPRE to NRS EPRE among NPDSCH REs (not applicable to NPDSCH REs with zero EPRE) is given by the parameter nrs-PowerRatio in symbols without NRS and CRS, and

– the ratio of NPDSCH EPRE to NRS EPRE among NPDSCH REs (not applicable to NPDSCH REs with zero EPRE) is given by the parameter nrs-PowerRatioWithCRS in symbols with CRS.

A UE may assume the ratio of NPBCH EPRE to NRS EPRE among NPBCH REs (not applicable to NPBCH REs with zero EPRE) is 0 dB for an NB-IoT cell with one NRS antenna port and -3 dB for an NB-IoT cell with two NRS antenna ports.

A UE may assume the ratio of NPDCCH EPRE to NRS EPRE among NPDCCH REs (not applicable to NPDCCH REs with zero EPRE) is 0 dB for an NB-IoT cell with one NRS antenna port and -3 dB for an NB-IoT cell with two NRS antenna ports.

If higher layer parameter operationModeInfo indicates ’00’ or samePCI-Indicator indicates ‘samePCI‘ for a cell, the ratio of NRS EPRE to CRS EPRE is given by the parameter nrs-CRS-PowerOffset if the parameter nrs-CRS-PowerOffset is provided by higher layers, and the ratio of NRS EPRE to CRS EPRE may be assumed to be 0 dB if the parameter nrs-CRS-PowerOffset is not provided by higher layers. If nrs-CRS-PowerOffset is provided by higher layers and is a non-integer value, the value of nrs-Power is 0.23 dBm higher than indicated.