6.8A Enhanced physical downlink control channel
36.2113GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical channels and modulationRelease 17TS
For frame structure type 3, for a subframe with the same duration as the DwPTS duration of a special subframe configuration, the enhanced physical downlink control channel is defined the same as that for the corresponding special subframe configuration.
6.8A.1 EPDCCH formats
The enhanced physical downlink control channel (EPDCCH) carries scheduling assignments. An enhanced physical downlink control channel 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. The number of ECCEs used for one EPDCCH depends on the EPDCCH format as given by Table 6.8A.1-2 and the number of EREGs per ECCE is given by Table 6.8A.1-1. Both localized and distributed transmission is supported.
An EPDCCH can use either localized or distributed transmission, differing in the mapping of ECCEs to EREGs and PRB pairs.
A UE shall monitor multiple EPDCCHs as defined in TS 36.213 [4]. One or two sets of physical resource-block pairs which a UE shall monitor for EPDCCH transmissions can be configured. All EPDCCH candidates in EPDCCH set 
use either only localized or only distributed transmission as configured by higher layers. Within EPDCCH set 
in subframe 
, the ECCEs available for transmission of EPDCCHs are numbered from 0 to 
and ECCE number 
corresponds to
– EREGs numbered 
in PRB index 
for localized mapping, and
– EREGs numbered 
in PRB indices 
for distributed mapping,
where 
, 
is the number of EREGs per ECCE, and 
is the number of ECCEs per resource-block pair. The physical resource-block pairs constituting EPDCCH set 
are in this paragraph assumed to be numbered in ascending order from 0 to 
.
Table 6.8A.1-1: Number of EREGs per ECCE, 
|
Normal cyclic prefix |
Extended cyclic prefix |
|||
|
Normal subframe |
Special subframe, configuration 3, 4, 8 |
Special subframe, configuration 1, 2, 6, 7, 9, 10 |
Normal subframe |
Special subframe, configuration 1, 2, 3, 5, 6 |
|
4 |
8 |
|||
Table 6.8A.1-2: Supported EPDCCH formats
|
EPDCCH format |
Number of ECCEs for one EPDCCH, |
|||
|
Case A |
Case B |
|||
|
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 |
– |
32 |
– |
16 |
Case A in Table 6.8A.1-2 is used when the conditions corresponding to case 1 in clause 9.1.4 of TS 36.213 [4] are satisfied, otherwise case B is used. The quantity 
for a particular UE and referenced in TS 36.213 [4] is defined as the number of downlink resource elements 
available for EPDCCH transmission in a physical resource-block pair configured for possible EPDCCH transmission of EPDCCH set 
and fulfilling all of the following criteria:
– they are part of any one of the 16 EREGs in the physical resource-block pair, and
– they are assumed by the UE not to be used for cell-specific reference signals, where the positions of the cell-specific reference signals are given by clause 6.10.1.2 with the number of antenna ports for and the frequency shift of cell-specific reference signals derived as described in clause 6.10.1.2 unless other values for these parameters are provided by clause 9.1.4.3 in TS 36.213 [4], and-
– they are assumed by the UE not to be used for transmission of CSI reference signals, where the positions of the CSI reference signals are given by clause 6.10.5.2 with the configuration for zero power CSI reference signals obtained as described in clause 6.10.5.2 unless other values are provided by clause 9.1.4.3 in TS 36.213 [4], and with the configuration for non-zero power CSI reference signals obtained as described in clause 6.10.5.2, and
– for frame structure type 1 and 2, the index 
in the first slot in a subframe fulfils 
where 
is given by clause 9.1.4.1 of TS 36.213 [4], and
– for frame structure type 3,
– if the higher layer parameter subframeStartPosition indicates ‘s07’ and if the downlink transmission starts in the second slot of a subframe
– the index 
in the second slot in the subframe fulfils 
where 
is given by clause 9.1.4.1 of TS 36.213 [4],
– otherwise
– the index 
in the first slot in the subframe fulfils 
where 
is given by clause 9.1.4.1 of TS 36.213 [4].
6.8A.2 Scrambling
The block of bits 
to be transmitted on an EPDCCH in a subframe shall be scrambled, resulting in a block of scrambled bits 
according to
where the UE-specific scrambling sequence 
is given by clause 7.2. The scrambling sequence generator shall be initialized with 
where 
is the EPDCCH set number.
6.8A.3 Modulation
The block of scrambled bits 
shall be modulated as described in clause 7.1, resulting in a block of complex-valued modulation symbols 
. Table 6.8A.3-1 specifies the modulation mappings applicable for the enhanced physical downlink control channel.
Table 6.8A.3-1: EPDCCH modulation schemes
|
Physical channel |
Modulation schemes |
|
EPDCCH |
QPSK |
6.8A.4 Layer mapping and precoding
The block of complex-valued modulation symbols shall be mapped to a single layer and precoded according to 6.3.4.1 as for 
, 
.
6.8A.5 Mapping to resource elements
The block of complex-valued symbols 
shall be mapped in sequence starting with 
to resource elements 
on the associated antenna port which meet all of the following criteria:
– they are part of the EREGs assigned for the EPDCCH transmission, and
– they are assumed by the UE not to be used for cell-specific reference signals, where the positions of the cell-specific reference signals are given by clause 6.10.1.2 with the number of antenna ports for and the frequency shift of cell-specific reference signals derived as described in clause 6.10.1.2 unless other values for these parameters are provided by clause 9.1.4.3 in TS 36.213 [4], and
– they are assumed by the UE not to be used for transmission of:
– zero-power CSI reference signals, where the positions of the CSI reference signals are given by clause 6.10.5.2. The configuration for zero power CSI reference signals is
– obtained as described in clause 6.10.5.2 unless other values are provided by clause 9.1.4.3 in TS 36.213 [4], and
– obtained by higher-layer configuration of up to five reserved CSI-RS resources as part of the discovery signal configuration following the procedure for zero-power CSI-RS in clause 6.10.5.2.
– non-zero-power CSI reference signals for CSI reporting, except for non-zero power CSI reference signals configured by csi-RS-ConfigNZP-ApList, with the configuration for non-zero power CSI reference signals for CSI reporting obtained as described in clause 6.10.5.2, and
– for frame structure type 1 and 2, the index 
in the first slot in a subframe fulfils 
where 
is given by clause 9.1.4.1 of TS 36.213 [4], and
– for frame structure type 3,
– if the higher layer parameter subframeStartPosition indicates ‘s07’ and if the downlink transmission starts in the second slot of a subframe
– the index 
in the second slot in the subframe fulfils 
where 
is given by clause 9.1.4.1 of TS 36.213 [4],
– otherwise
– the index 
in the first slot in the subframe fulfils 
where 
is given by clause 9.1.4.1 of TS 36.213 [4].
The mapping to resource elements 
on antenna port 
meeting the criteria above shall be in increasing order of first the index 
and then the index
, starting with the first slot and ending with the second slot in a subframe.
For localized transmission, the single antenna port 
to use is given by Table 6.8A.5-1 with
where 
is the lowest ECCE index used by this EPDCCH transmission in the EPDCCH set, 
equals the C-RNTI, and 
is the number of ECCEs used for this EPDCCH.
Table 6.8A.5-1: Antenna port to use for localized EPDCCH transmission
|
|
Normal cyclic prefix |
Extended cyclic prefix |
|
|
Normal subframes, Special subframes, |
Special subframes, |
Any subframe |
|
|
0 |
107 |
107 |
107 |
|
1 |
108 |
109 |
108 |
|
2 |
109 |
– |
– |
|
3 |
110 |
– |
– |
For distributed transmission, each resource element in an EREG is associated with one out of two antenna ports in an alternating manner, starting with antenna port 107, where 
for normal cyclic prefix and 
for extended cyclic prefix.