16.6 Narrowband physical downlink control channel related procedures

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

Throughout this clause, if a NB-IoT UE is configured with higher layer parameter k-Mac, Kmac = k-Mac otherwise, Kmac = 0.

A UE shall monitor a set of NPDCCH candidates (described in Clause 10.2.5.1 of [3]) as configured by higher layer signalling for control information, where monitoring implies attempting to decode each of the NPDCCHs in the set according to all the monitored DCI formats.

The set of NPDCCH candidates to monitor are defined in terms of NPDCCH search spaces.

The UE shall monitor one or more of the following search spaces

– a Type1-NPDCCH common search space,

– a Type1A-NPDCCH common search space,

– a Type2-NPDCCH common search space,

– a Type2A-NPDCCH common search space, and

– a NPDCCH UE-specific search space.

A UE is not required to simultaneously monitor a NPDCCH UE-specific search space and a Type-1-NPDCCH common search space.

A UE is not required to simultaneously monitor a NPDCCH UE-specific search space and a Type2-NPDCCH common search space.

A UE is not required to simultaneously monitor a Type-1-NPDCCH common search space and a Type2-NPDCCH common search space.

A UE is not required to monitor Type1A-NPDCCH common search space or Type2A-NPDCCH common search space in subframes in which the UE monitors a Type1-NPDCCH common search space or in subframes in which the UE receives NPDSCH assigned by NPDCCH with DCI CRC scrambled by P-RNTI

A UE is not required to monitor Type1A-NPDCCH common search space or Type2A-NPDCCH common search space in subframes in which the UE monitors a Type2-NPDCCH common search space or in subframes in which the UE receives NPDSCH assigned by NPDCCH with DCI CRC scrambled by C-RNTI or Temporary C-RNTI.

A UE is not required to monitor Type2A-NPDCCH common search space in the same subframe in which it monitors Type1A-NPDCCH common search space.

UE is not required to monitor Type1A-NPDCCH common search space in subframes in which the UE receives NPDSCH assigned by NPDCCH with DCI CRC scrambled by SC-RNTI.

UE is not required to monitor Type2A-NPDCCH common search space in subframes in which the UE receives NPDSCH assigned by NPDCCH with DCI CRC scrambled by G-RNTI or SC-RNTI.

Until UE receives higher layer configuration of NPDCCH UE-specific search space, the UE monitors NPDCCH according to the same configuration of NPDCCH search space as that for NPDCCH scheduling Msg4.

A UE is not required to monitor Type1-NPDCCH common search space or NWUS if the set of subframes comprising the NPDCCH candidates or the set of subframes where NWUS may be received include any subframes in which the UE has initiated an NPUSCH transmission using preconfigured uplink resource on a given serving cell.

A UE is not required to monitor Type-1 NPDCCH common search space or NWUS in subframes in which the UE monitors a UE-specific NPDCCH search space given by PUR-RNTI.

An NPDCCH search space at aggregation level ( for TDD special subframe, otherwise), and repetition level is defined by a set of NPDCCH candidates where each candidate is repeated in a set of consecutive NB-IoT downlink subframes excluding subframes used for transmission of SI messages starting with subframe .

For NPDCCH UE-specific search space, the aggregation and repetition levels defining the search spaces and the corresponding NPDCCH candidates are listed in Table 16.6-1 by substituting the value of with the higher layer configured parameter npdcch-NumRepetitions, except for NPDCCH candidates associated with PUR-RNTI in which case it is given by higher layer parameter npdcch-NumRepetition­s in PUR-Config-NB.

For Type1-NPDCCH common search space and Type1A-NPDCCH common search space, the aggregation and repetition levels defining the search spaces are listed in Table 16.6-2 by substituting the value of

– with the higher layer configured parameter npdcch-NumRepetitionPaging for Type1-NPDCCH common search space;

– with the higher layer configured parameter npdcch-NumRepetitions-SC-MCCH for Type1A-NPDCCH common search space.

For Type2-NPDCCH common search space and Type2A-NPDCCH common search space, the aggregation and repetition levels defining the search spaces and the corresponding monitored NPDCCH candidates are listed in Table 16.6-3 by substituting the value of

– with the higher layer configured parameter npdcch-NumRepetitions-RA for Type2-NPDCCH common search space;

– with the higher layer configured parameter npdcch-NumRepetitions-SC-MTCH for Type2A-NPDCCH common search space.

The locations of starting subframe are given by where is the th consecutive NB-IoT DL subframe from subframe , excluding subframes used for transmission of SI messages, and , and , and where

– subframe is a subframe satisfying the condition , where , T≥4.

– for NPDCCH UE-specific search space,

– is given by the higher layer parameter npdcch-StartSF-USS, except for NPDCCH candidates associated with PUR-RNTI in which case it is given by higher layer parameter npdcch-StartSF-USS in PUR-Config-NB,

– is given by the higher layer parameter npdcch-Offset-USS, except for NPDCCH candidates associated with PUR-RNTI in which case it is given by higher layer parameter npdcch-Offset-USS in PUR-Config-NB,

– for NPDCCH Type2-NPDCCH common search space,

– is given by the higher layer parameter npdcch-StartSF-CSS-RA,

– is given by the higher layer parameter npdcch-Offset-RA,

– for NPDCCH Type2A-NPDCCH common search space,

– is given by the higher layer parameter npdcch-startSF-SC-MTCH,

– is given by the higher layer parameter npdcch-Offset-SC-MTCH,

For Type1-NPDCCH common search space,and is determined from locations of NB-IoT paging opportunity subframes.

For Type1A-NPDCCH common search space, and subframe is a subframe satisfying the condition , where , T≥4 and

– is given by the higher layer parameter npdcch-StartSF-SC-MCCH,

– is given by the higher layer parameter npdcch-Offset-SC-MCCH.

For UE-specific search space by C-RNTI,

if the UE is configured by higher layers with a NB-IoT carrier for monitoring of NPDCCH UE-specific search space,

– the UE shall monitor the NPDCCH UE-specific search space on the higher layer configured NB-IoT carrier,

– the UE is not expected to receive NPSS, NSSS, NPBCH on the higher layer configured NB-IoT carrier.

otherwise,

– the UE shall monitor the NPDCCH UE-specific search space on the same NB-IoT carrier on which NPSS/NSSS/NPBCH are detected.

For UE-specific search space by PUR-RNTI, the UE is configured by the higher layer parameter carrierConfig in PUR-Config-NB with a NB-IoT carrier for monitoring of NPDCCH UE-specific search space,

– the UE shall monitor the NPDCCH UE-specific search space on the higher layer configured NB-IoT carrier,

– the UE is not expected to receive NPSS, NSSS, NPBCH on the higher layer configured NB-IoT carrier if the NB-IoT carrier is not the same as the NB-IoT carrier on which NPSS/NSSS/NPBCH are detected.

If the UE has initiated a NPUSCH transmission using preconfigured uplink resource ending in subframe n, the UE shall monitor the NPDCCH UE-specific search space in a search space window starting in subframe n+4+Kmac with duration given by higher layer parameter pur-SS-window-duration, where is provided by higher layer parameter K-mac, otherwise . Upon detection of a NPDCCH with DCI format N0 with CRC scrambled by PUR-RNTI intended for the UE within the search space window and the value of "modulation and coding scheme" field () in the corresponding DCI is set to ’14’, the UE is not required to monitor the NPDCCH UE-specific search space for the remaining search space window duration.

Table 16.6-1: NPDCCH UE- specific search space candidates

DCI subframe repetition number

NCCE indices of monitored NPDCCH candidates

L’=1

L’=2

1

1

00

{0},{1}

{0,1}

2

1

00

{0},{1}

{0,1}

2

01

–

{0,1}

4

1

00

–

{0,1}

2

01

–

{0,1}

4

10

–

{0,1}

>=8

00

–

{0,1}

01

–

{0,1}

10

–

{0,1}

11

–

{0,1}

Note 1: {x}, {y} denotes NPDCCH Format 0 candidate with NCCE index ‘x’, and NPDCCH Format 0 candidate with NCCE index ‘y’ are monitored

Note 2: {x,y} denotes NPDCCH Format1 candidate corresponding to NCCEs ‘x’ and ‘y’ is monitored.

Table 16.6-2: Type 1/Type 1A – NPDCCH common search space candidates

NCCE indices of monitored NPDCCH candidates

L’=1

L’=2

1

1

–

–

–

–

–

–

–

–

{0,1}

2

1

2

–

–

–

–

–

–

–

{0,1}

4

1

2

4

–

–

–

–

–

–

{0,1}

8

1

2

4

8

–

–

–

–

–

{0,1}

16

1

2

4

8

16

–

–

–

—

{0,1}

32

1

2

4

8

16

32

–

–

–

{0,1}

64

1

2

4

8

16

32

64

–

–

{0,1}

128

1

2

4

8

16

32

64

128

–

{0,1}

256

1

4

8

16

32

64

128

256

–

{0,1}

512

1

4

16

32

64

128

256

512

–

{0,1}

1024

1

8

32

64

128

256

512

1024

–

{0,1}

2048

1

8

64

128

256

512

1024

2048

–

{0,1}

DCI subframe repetition number

000

001

010

011

100

101

110

111

Note 1: {x,y} denotes NPDCCH Format1 candidate corresponding to NCCEs ‘x’ and ‘y’ is monitored.

Table 16.6-3: Type 2/Type 2A – NPDCCH common search space candidates

DCI subframe repetition number

NCCE indices of monitored NPDCCH candidates

L’=1

L’=2

1

1

00

–

{0,1}

2

1

00

–

{0,1}

2

01

–

{0,1}

4

1

00

–

{0,1}

2

01

–

{0,1}

4

10

–

{0,1}

>=8

00

–

{0,1}

01

–

{0,1}

10

–

{0,1}

11

–

{0,1}

Note 1: {x,y} denotes NPDCCH Format1 candidate corresponding to NCCEs ‘x’ and ‘y’ is monitored.

For a NPDCCH UE-specific search space, if a NB-IoT UE is configured with higher layer parameter twoHARQ-ProcessesConfig or npusch-MultiTB-Config and if the NB-IoT UE detects NPDCCH with DCI Format N0 ending in subframe n, and if the corresponding NPUSCH format 1 transmission starts from n+k or in a NTN serving cell, from an uplink subframe which, after accounting for uplink transmission timing, overlaps with downlink subframe n+k,

– if the corresponding NPDCCH with DCI format N0 with CRC scrambled by C-RNTI schedules two transport blocks as determined by the Number of scheduled TB for Unicast field if present, the UE is not required to monitor an NPDCCH candidate in any subframe starting from subframe n+1 to subframe n+k-1, otherwise the UE is not required to monitor an NPDCCH candidate in any subframe starting from subframe n+k-2 to subframe n+k-1; and

  • the UE does not expect to receive a DCI Format N0 before subframe n+k-2 for which the corresponding NPUSCH format 1 transmission ends later than subframe n+k+255 if the corresponding NPDCCH with DCI format N0 schedules one transport block.

– for TDD, and if the corresponding NPUSCH format1 transmission ends in subframe n+m, the UE is not required to monitor NPDCCH in any subframe starting from subframe n+ k to subframe n+m-1.

otherwise

– if the NB-IoT UE detects NPDCCH with DCI Format N0 ending in subframe n or receives a NPDSCH carrying a random access response grant ending in subframe n, and if the corresponding NPUSCH format 1 transmission starts from n+k or in a NTN serving cell, from an uplink subframe which, after accounting for uplink transmission timing, overlaps with downlink subframe n+k, the UE is not required to monitor NPDCCH in any subframe starting from subframe n+1 to subframe n+k-1.

– for TDD, if the NB-IoT UE detects NPDCCH with DCI Format N0 ending in subframe n or receives a NPDSCH carrying a random access response grant ending in subframe n, and if the corresponding NPUSCH format 1 transmission ends in n+k, the UE is not required to monitor NPDCCH in any subframe starting from subframe n+1 to subframe n+k.

For a NPDCCH UE-specific search space, if a NB-IoT UE is configured with higher layer parameter twoHARQ-ProcessesConfig or npdsch-MultiTB-Config

– and if the NB-IoT UE detects NPDCCH with DCI Format N1 ending in subframe n, and if a NPDSCH transmission starts from n+k,

– if the corresponding NPDCCH with DCI format N1 with CRC scrambled by C-RNTI schedules two transport blocks as determined by the Number of scheduled TB for Unicast field if present, the UE is not required to monitor an NPDCCH candidate in any subframe starting from subframe n+1 to subframe n+k-1;

– otherwise, the UE is not required to monitor an NPDCCH candidate in any subframe starting from subframe n+k-2 to subframe n+k-1;

otherwise

– if the NB-IoT UE detects NPDCCH with DCI Format N1 or N2 ending in subframe n, and if the corresponding NPDSCH transmission starts from n+k, the UE is not required to monitor NPDCCH in any subframe starting from subframe n+1 to subframe n+k-1.

If a NB-IoT UE detects NPDCCH with DCI Format N1 ending in subframe n, and if the corresponding NPDSCH transmission starts from n+k, and

– for FDD, if the corresponding NPUSCH format 2 transmission starts from subframe n+m or in a NTN serving cell, from an uplink subframe which, after accounting for uplink transmission timing, overlaps with downlink subframe n+m, the UE is not required to monitor NPDCCH in any subframe starting from subframe n+ k to subframe n+m-1.

– for TDD, if the corresponding NPUSCH format 2 transmission ends in subframe n+m the UE is not required to monitor NPDCCH in any subframe starting from subframe n+ k to subframe n+m-1.

If a NB-IoT UE detects NPDCCH with DCI Format N1 for "PDCCH order" ending in subframe n, and

– for FDD, if the corresponding NPRACH transmission starts from subframe n+k or in a NTN serving cell, from an uplink subframe which, after accounting for uplink transmission timing, overlaps with downlink subframe n+k, the UE is not required to monitor NPDCCH in any subframe starting from subframe n+1 to subframe n+k-1.

– for TDD, if the corresponding NPRACH transmission ends in subframe n+k, the UE is not required to monitor NPDCCH in any subframe starting from subframe n+1 to subframe n+k-1.

If a NB-IoT UE is configured with higher layer parameter twoHARQ-ProcessesConfig

– and if the UE has a NPUSCH transmission ending in subframe n,

– the UE is not required to receive transmissions in the Type B half-duplex guard periods as specified in [3]for FDD ; and

– the UE is not expected to receive an NPDCCH with DCI format N0/N1 for the same HARQ process ID as the NPUSCH transmission in any subframe starting from subframe n+1 to subframe n+3 or in a NTN serving cell, in any downlink subframe that overlaps with uplink subframe n+1 to subframe n+Kmac+3;

else if the UE is not using higher layer parameter edt-Parameters or if the UE is using higher layer parameter edt-Parameters and

– if the NB-IoT UE has a NPUSCH transmission ending in subframe n , the UE is not required to monitor NPDCCH in any subframe starting from subframe n+1 to subframe n+3 or in a NTN serving cell, in any downlink subframe that overlaps with uplink subframe n+1 to subframe n+Kmac+3.

otherwise,

– If the NB-IoT UE has a NPUSCH transmission for Msg3 ending in subframe with transport block size , whereas if would have been selected the NPUSCH transmission would have ended in subframe n, the UE is not required to monitor NPDCCH in any subframe starting from subframe n’+1 to subframe n+3 or in a NTN serving cell, in any downlink subframe that overlaps with uplink subframe n’+1 to subframe n+Kmac+3.

If a NB-IoT UE receives a NPDSCH transmission ending in subframe n, and if the UE is not required to transmit a corresponding NPUSCH format 2, the UE is not required to monitor NPDCCH in any subframe starting from subframe n+1 to subframe n+12.

If a NB-IoT UE is configured with higher layer parameter twoHARQ-ProcessesConfig

– the UE is not required to monitor an NPDCCH candidate of an NPDCCH search space if the candidate ends in subframe n, and if the UE is configured to monitor NPDCCH candidates of another NPDCCH search space having starting subframe k0 before subframe n+5

otherwise

– the UE is not required to monitor NPDCCH candidates of an NPDCCH search space if an NPDCCH candidate of the NPDCCH search space ends in subframe n, and if the UE is configured to monitor NPDCCH candidates of another NPDCCH search space having starting subframe k0 before subframe n+5.

An NB-IoT UE is not required to monitor NPDCCH candidates of an NPDCCH search space during an NPUSCH UL gap.

An NB-IoT UE is not required to monitor NPDCCH candidates of a Type2A-NPDCCH common search space during the scheduling gap or the processing gap.

For an NB-IoT UE configured with higher layer parameter sr-WithoutHARQ-ACK-Config, if the transmission of a narrowband random access preamble for SR ends on subframe n,

– in case of frame structure type 1 with NPRACH format 0 and 1 when the number of NPRACH repetitions is greater than or equal to 64, or NPRACH format 2 when the number of NPRACH repetitions is greater than or equal to 16, the UE is not required to monitor NPDCCH UE-specific search space from subframe n to subframe n+40 or in a NTN serving cell, in any downlink subframes that overlap with uplink subframe n to subframe n+Kmac+40,

– otherwise, the UE is not required to monitor NPDCCH UE-specific search space from subframe n to subframe n+3 or in a NTN serving cell, in any downlink subframes that overlap with uplink subframe n to subframe n+Kmac+3.

16.6.1 NPDCCH starting position

The starting OFDM symbol for NPDCCH given by index in the first slot in a subframe and is determined as follows

– if higher layer parameter eutraControlRegionSize is present

– if subframe is a special subframe for NPDCCH without repetition

– where is given by the higher layer parameter eutraControlRegionSize

– else is given by the higher layer parameter eutraControlRegionSize

  • otherwise

–

16.6.2 NPDCCH control information procedure

A UE shall discard the NPDCCH if consistent control information is not detected.

16.6.3 NPDCCH validation for semi-persistent scheduling

A UE shall validate a Semi-Persistent Scheduling assignment NPDCCH only if all the following conditions are met:

– the CRC parity bits obtained for the NPDCCH payload are scrambled with the Semi-Persistent Scheduling C-RNTI

– the new data indicator field is set to ‘0’.

Validation is achieved if all the fields for the used DCI format N0 are set according to Table 16.6.3-1 or Table 16.6.3-2.

If validation is achieved, the UE shall consider the received DCI information accordingly as a valid semi-persistent activation or release.

If validation is not achieved, the received DCI format shall be considered by the UE as having been received with a non-matching CRC.

Table 16.6.3-1: Special fields for Semi-Persistent Scheduling Activation NPDCCH Validation

DCI format N0

HARQ process number (present if UE is configured with 2 uplink HARQ processes)

set to ‘0’

Redundancy version

set to ‘0’

Modulation and coding scheme

set to ‘0000’

Resource assignment

set to ‘000’

Table 16.6.3-2: Special fields for Semi-Persistent Scheduling Release NPDCCH Validation

DCI format N0

HARQ process number (present if UE is configured with 2 uplink HARQ processes)

set to ‘0’

Redundancy version

set to ‘0’

Repetition number

set to ‘000’

Modulation and coding scheme

set to ‘1111’

Subcarrier indication

Set to all ‘1’s

16.6.4 Preconfigured uplink resource ACK/fallback procedure

If a UE has initiated a NPUSCH transmission using preconfigured uplink resource on a given serving cell, and upon detection of a NPDCCH with DCI format N0 with CRC scrambled by PUR-RNTI intended for the UE within the PUR search space window as defined in Clause 16.6, and the value of "modulation and coding scheme" field () in the corresponding DCI set to ’14’, the UE shall deliver the PUR ACK/fallback indication and the NPUSCH repetition adjustment, as signaled on the NPDCCH, to the higher layers.