6.8B MTC physical downlink control channel
36.2113GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical channels and modulationRelease 17TS
6.8B.1 MPDCCH formats
The MPDCCH formats are defined as in Clause 6.8A.1 with the following exceptions:
– The term EPDCCH is replaced by MPDCCH.
– The MTC physical downlink control channel carries downlink control information and is transmitted across 
consecutive BL/CE DL subframes. Within each of the 
BL/CE DL subframes an MPDCCH is transmitted using an aggregation of one or several consecutive enhanced control channel elements (ECCEs) where each ECCE consists of multiple enhanced resource element groups (EREGs), defined in clause 6.2.4A.
– For frame structure type 2,
– If repetition is not configured for the MPDCCH, the number of EREGs per ECCE is given by Table 6.8A.1-1. If repetition is configured for the MPDCCH, the number of EREGs per ECCE is given by Table 6.8B.1-1.
– For those special subframes where the MPDCCH is not supported, these special subframes are considered BL/CE DL subframes for both MPDCCH and PDSCH transmission, only if they are indicated as BL/CE DL subframe by higher layer signalling.
– For an MPDCCH associated with 2 or 4 PRBs, if repetition is not configured for the MPDCCH, the supported MPDCCH formats are given by Table 6.8A.1-2. Otherwise, the supported MPDCCH formats are given by Table 6.8B.1-2. However, for MPDCCH format 5, the equation defining the relation between ECCE index and EREG index does not apply and the number of ECCEs refers to the MPDCCH mapping to the REs of the 2+4 PRB set as defined in Clause 6.8B.5.
Table 6.8B.1-1: Number of EREGs per ECCE, 
, for frame structure type 2.
|
Normal cyclic prefix |
Extended cyclic prefix |
||
|
Normal subframe |
Special subframe, configuration 3, 4, 8 |
Normal subframe |
Special subframe, configuration 1, 2, 3, 5, 6 |
|
4 |
8 |
||
Table 6.8B.1-2: Supported MPDCCH formats
|
MPDCCH format |
Number of ECCEs in a subframe for one MPDCCH, |
|||
|
|
|
|||
|
Localized transmission |
Distributed transmission |
Localized transmission |
Distributed transmission |
|
|
0 |
2 |
2 |
1 |
1 |
|
1 |
4 |
4 |
2 |
2 |
|
2 |
8 |
8 |
4 |
4 |
|
3 |
16 |
16 |
8 |
8 |
|
4 |
– |
– |
– |
– |
|
5 |
24 |
24 |
12 |
12 |
=4
=86.8B.2 Scrambling
Scrambling shall be perfomed according to Clause 6.8A.2 with EPDCCH replaced by MPDCCH except that the same scrambling sequence is applied per subframe to MPDCCH for a given block of 
subframes and 
is the MPDCCH set number. For an MPDCCH associated with a 2+4 PRB set as defined in [4], 
is used to generate the scrambling sequence for mapping to REs in 6 PRBs as well as 2 PRBs and 4 PRBs.
The subframe number of the first subframe in each block of 
consecutive subframes, denoted as 
, satisfies 
. For the 
block of 
subframes, the scrambling sequence generator shall be initialised with
where
and 
is the absolute subframe number of the first downlink subframe intended for the MPDCCH. The MPDCCH transmission spans 
consecutive subframes, including subframes that are not BL/CE DL subframes where the MPDCCH transmission is postponed.
For BL/CE UEs,
– if the MPDCCH transmission is associated with P-RNTI or SC-RNTI:
– 
for frame structure type 1 and 
for frame structure type 2
– otherwise
– 
for UEs assuming CEModeA (according to the definition in Clause 12 of [4]) or configured with CEModeA:
– 
for frame structure type 1 and 
for frame structure type 2 for UEs assuming CEModeB (according to the definition in Clause 12 of [4]) or configured with CEModeB.
6.8B.3 Modulation
Modulation shall be performed according to 6.8A.3 with EPDCCH replaced by MPDCCH.
6.8B.4 Layer mapping and precoding
Layer mapping and precoding shall be done according to Clause 6.8A.4 with EPDCCH replaced by MPDCCH.
6.8B.5 Mapping to resource elements
Mapping to resource elements shall be done according to Clause 6.8A.5 with the following exceptions:
– The term EPDCCH shall be replaced by MPDCCH.
– The mapping shall be repeated across each of the 
BL/CE DL subframes.
– 
is the number of ECCEs used for this MPDCCH in the first of the 
subframes.
– For an MPDCCH associated with a 2+4 PRB set as defined in [4], the mapping to resource elements 
on antenna port 
shall be in increasing order of first the index 
and then the index
over the 6 PRBs for MPDCCH format 5 and over the 2 or 4 PRBs for the other MPDCCH formats.
– For localized transmission and MPDCCH format 5, the single antenna port 
to use is given by Table 6.8A.5-1 with
where 
equals the C-RNTI.
– Resource elements occupied by CSI reference signals shall be counted in the MPDCCH mapping but not used for transmission of the MPDCCH.
– PRB pairs occupied by RSS shall be counted in the MPDCCH mapping but not used for transmission of the MPDCCH.
– Resource elements belonging to PRBs in which PRS is transmitted (including PRS muted subframes) shall be counted in the MPDCCH mapping but not used for transmission of the MPDCCH.
– A BL/CE UE not configured with higher layer parameter ce-pdsch-maxBandwidth-config and not configured with higher layer parameter ce-PDSCH-FlexibleStartPRB-AllocConfig may assume there is no MPDCCH transmission which uses overlapping sets of subframes as PDSCH transmissions to that UE, where the MPDCCH is located at a different narrowband than the PDSCH.
– A BL/CE UE configured with higher layer parameter ce-pdsch-maxBandwidth-config may assume that there is no MPDCCH transmission which uses overlapping sets of subframes as PDSCH transmissions to that UE, where the MPDCCH transmission and PDSCH transmission in any of the overlapping subframes span a PRB region larger than X contiguous PRBs where X=25 if ce-pdsch-maxBandwidth-config is set to 5 MHz and X=100 if ce-pdsch-maxBandwidth-config is set to 20 MHz.
– A BL/CE UE configured with higher layer parameter ce-PDSCH-FlexibleStartPRB-AllocConfig may assume there is no MPDCCH transmission in MPDCCH candidates not fully contained within the tuning narrowband defined for PDSCH in Clause 6.2.8.
– For BL/CE UEs in CEModeB, in MBSFN subframe(s), resource elements that correspond to the positions of cell-specific reference signals as in subframe #0 shall not be counted in the MPDCCH mapping and not used for transmission of the MPDCCH.
– Resource elements belonging to synchronization signals, the core part of PBCH, PBCH repetitions, or resource elements reserved for reference signals in the mapping operation of PBCH but not used for transmission of reference signals, shall be counted in the MPDCCH mapping but not used for transmission of the MPDCCH.
– If MPDCCH transmission in the LTE control region is configured by the higher layer parameter transmissionInControlChRegion,
– For frame structure type 1 and frame structure type 2 except special subframe configuration 9 or 10,
– Symbols used for transmission of MPDCCH or demodulation signals associated with MPDCCH and mapped to resource element in the second slot, where , shall additionally be mapped to resource element in the first slot.
– For frame structure type 2 and special subframe configuration 9 or 10,
– Symbols used for transmission of MPDCCH or demodulation signals associated with MPDCCH and mapped to resource element in the first slot, where , shall additionally be mapped to resource element in the first slot, if resource element in the first slot is not used for cell-specific reference signals.
– In the subframes where an MPDCCH or its associated PDSCH is transmitted in response to a physical random access transmission initiated by a PDCCH order, the UE shall receive the MPDCCH or its associated PDSCH, and assume no other UE-specific reception is needed.
– For MPDCCH transmission associated with C-RNTI or TPC-PUCCH-RNTI or TPC-PUSCH-RNTI or SPS C-RNTI that are not configured to use the Type2-MPDCCH common search space, frequency hopping of the MPDCCH is enabled when higher layer parameter mpdcch-pdsch-HoppingConfig is set.
– For MPDCCH transmission associated with PUR-RNTI using UE-specific MPDCCH search space, frequency hopping of the MPDCCH is enabled when mpdcch-FreqHopping in higher layer parameter PUR-MPDCCH-Config is set.
– For MPDCCH transmission associated with Type2-MPDCCH common search space, frequency hopping of the MPDCCH is enabled when higher layer parameter rar-HoppingConfig is set. Further
– if PRACH CE level 0 or 1 is used for the last PRACH attempt, 
is set to the higher layer parameter interval-DlHoppingConfigCommonModeA;
– if PRACH CE level 2 or 3 is used for the last PRACH attempt, 
is set to the higher layer parameter interval-DlHoppingConfigCommonModeB.
– For MPDCCH transmission associated with SC-RNTI, frequency hopping of the MPDCCH is enabled when higher layer parameter mpdcch-pdsch-HoppingConfig-SC-MCCH is set. Further
– if mpdcch-pdsch-HoppingConfig-SC-MCCH is set to CEModeA, 
is set to the higher layer parameter interval-DlHoppingConfigCommonModeA;
– if mpdcch-pdsch-HoppingConfig-SC-MCCH is set to CEModeB, 
is set to the higher layer parameter interval-DlHoppingConfigCommonModeB.
– For MPDCCH transmission associated with G-RNTI, frequency hopping of the MPDCCH is enabled when higher layer parameter mpdcch-pdsch-HoppingConfig-SC-MTCH is set. Further
– if mpdcch-pdsch-CEmodeConfig-SC-MTCH is set to CEModeA, is set to the higher layer parameter interval-DlHoppingConfigCommonModeA;
– if mpdcch-pdsch-CEmodeConfig-SC-MTCH is set to CEModeB, 
is set to the higher layer parameter interval-DlHoppingConfigCommonModeB.
– The narrowband 
for MPDCCH transmission in the first subframe of MPDCCH search space is provided by higher layers. Starting subframe configuration of a search space where UE monitors an MPDCCH is also provided by higher layers. The MPDCCH search space uses 
subframes, spanning 
consecutive subframes, including subframes that are not BL/CE DL subframes where the MPDCCH transmission is postponed.
– If downlink resource reservation is enabled for the UE as specified in [9], then in case of MPDCCH transmission associated with C-RNTI or SPS C-RNTI using UE-specific MPDCCH search space,
– In a subframe that is fully reserved as defined in clause 7.1 in [4], the MPDCCH transmission is postponed until the next BL/CE downlink subframe that is not fully reserved.
– In a subframe that is partially reserved, the reserved resource elements shall be counted in the MPDCCH mapping but not used for transmission of the MPDCCH.
– If frequency hopping is not enabled for MPDCCH, the repetitions of an MPDCCH candidate are located at the same PRB resources in the same narrowband 
, and
– if frequency hopping is enabled for MPDCCH, an MPDCCH candidate shall be transmitted in absolute subframe 
using the same PRB resources within each narrowband 
where 
is the absolute subframe number of the first downlink subframe of MPDCCH search space, and 
, 
and 
are cell-specific higher-layer parameters. The UE shall not expect MPDCCH transmission in absolute subframe 
if it is not a BL/CE DL subframe.
– The UE may assume the same precoding matrix being used for a PRB across a block of 
consecutive subframes for MPDCCH, where the subframe number of the first subframe in each block of 
consecutive subframes, denoted as 
, satisfies 
.
– If crs-ChEstMPDCCH-ConfigCommon or crs-ChEstMPDCCH-ConfigDedicated is configured by higher layers, the relation between the MPDCCH and CRS antenna ports is defined as follows:
– When one CRS port is configured by the eNB, the antenna port(s) used for MPDCCH transmission are equivalent to CRS port 0.
– For distributed transmission and when two CRS ports are configured by the eNB, the relation between the symbols transmitted on the antenna ports used for MPDCCH transmission and CRS ports 0 – 1 is defined by the precoder matrix for single-layer transmission in Table 6.3.4.2.3-1 using codebook index for antenna port 107 and codebook index for antenna port 109.
– For distributed transmission and when four CRS ports are configured by the eNB, in absolute subframe and resource block index within one or two MPDCCH PRB sets where UE monitors an MPDCCH, the relation between the symbols transmitted on the antenna ports used for MPDCCH transmission and CRS ports 0 – 3 is defined by the precoder matrix for single-layer transmission in Table 6.3.4.2.3-2 using codebook index for antenna port 107 and codebook index for antenna port 109, where
– For localized transmission, when two CRS ports are configured by the eNB and predefined mapping type is used, in absolute subframe and resource block index within one or two MPDCCH PRB sets where UE monitors an MPDCCH, the relation between the symbols transmitted on the antenna port used for MPDCCH transmission and CRS ports 0 – 1 is defined by the precoder matrix for single-layer transmission in Table 6.3.4.2.3-1, with codebook index , where
– For localized transmission, when four CRS ports are configured by the eNB and predefined mapping type is used, in absolute subframe and resource block index within one or two MPDCCH PRB sets where UE monitors an MPDCCH, the relation between the symbols transmitted on the antenna port used for MPDCCH transmission and CRS ports 0 – 3 is given by the precoder matrix for single-layer transmission in Table 6.3.4.2.3-2 using codebook index where
– For localized transmission and when CSI-based or reciprocity-based mapping type is used, the relation between the symbols transmitted on the antenna port used for MPDCCH transmission and the CRS ports is given in [4]. When it is indicated in [4] that the antenna port is changed for an MPDCCH candidate with aggregation level 2, the antenna port shall be replaced by the antenna port determined for an MPDCCH candidate with aggregation level 4 in the same search space.
– NOTE: , with for and otherwise, where the ordering of PRBs within the PRB set(s) is in increasing order of PRB index.
The UE may assume that an MPDCCH associated with the P-RNTI is transmitted on the set 
of narrowbands where 
is defined in Clause 6.4.1. For a UE monitoring an MPDCCH associated with the P-RNTI, the first MPDCCH narrowband is given by 
where 
, 
is the Paging Narrowband (PN) obtained according to [10], and 
is the higher-layer parameter paging-narrowBands.
– If the higher-layer parameter si-HoppingConfigCommon disables frequency hopping for an MPDCCH associated with P-RNTI, each MPDCCH candidate shall be located in the same PRB in narrowband 
where 
.
– If the higher-layer parameter si-HoppingConfigCommon enables frequency hopping for an MPDCCH with P-RNTI, an MPDCCH candidate shall be located in narrowband 
in absolute subframe 
using the same PRB resources within each narrowband 
where
where 
is the absolute subframe number of the first downlink subframe of MPDCCH search space according to locations of paging opportunity subframes, and 
, 
and 
are cell-specific higher-layer parameters. For MPDCCH associated with P-RNTI, if interval-DlHoppingConfigCommonModeB is signalled in SIB1-BR, then the frequency hopping granularity 
is set to interval-DlHoppingConfigCommonModeB; otherwise, 
is set to interval-DlHoppingConfigCommonModeA signalled in SIB1-BR.
The UE shall not expect MPDCCH transmission in absolute subframe 
if it is not a BL/CE DL subframe.