6.10.3A Demodulation reference signals associated with EPDCCH, MPDCCH, or SPDCCH

36.2113GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical channels and modulationRelease 17TS

The demodulation reference signal associated with EPDCCH/MPDCCH/SPDCCH

– is transmitted on the same antenna port as the associated EPDCCH/MPDCCH/SPDCCH physical resource;

– is present and is a valid reference for EPDCCH/MPDCCH/SPDCCH demodulation only if the EPDCCH/MPDCCH/SPDCCH transmission is associated with the corresponding antenna port;

– is transmitted only on the physical resource blocks upon which the corresponding EPDCCH/MPDCCH/SPDCCH is mapped.

A demodulation reference signal associated with EPDCCH/MPDCCH/SPDCCH is not transmitted in resource elements in which one of the physical channels or physical signals other than the demodulation reference signals defined in 6.1 are transmitted using resource elements with the same index pair regardless of their antenna port .

6.10.3A.1 Sequence generation

For any of the antenna ports , the reference-signal sequence is defined by

.

For non-BL/CE UEs, the pseudo-random sequence is defined in clause 7.2. The pseudo-random sequence generator shall be initialised with

at the start of each subframe where

– and shall be replaced by and , respectively, for the EPDCCH

– and shall be replaced by and , respectively, for the SPDCCH

– , , and

– is configured by higher layers.

The EPDCCH/SPDCCH set to which the EPDCCH/SPDCCH associated with the demodulation reference signal belong is denoted .

For BL/CE UEs, the same scrambling sequence is applied per subframe to the demodulation reference signal associated with MPDCCH for a given block of subframes. 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 MPDCCH. The MPDCCH transmissions span 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.

The quantities and are configured by higher layers. The MPDCCH set to which the MPDCCH associated with the demodulation reference signal belong is denoted . For an MPDCCH associated with a 2+4 PRB set as defined in [4], is used to generate the scrambling sequence for the 6 PRBs as well as for the 2 PRBs and 4 PRBs.

6.10.3A.2 Mapping to resource elements

For the antenna port in a physical resource block assigned for the associated EPDCCH/MPDCCH, a part of the reference signal sequence shall be mapped to complex-valued modulation symbols in a subframe according to

Normal cyclic prefix:

where

The sequence is given by Table 6.10.3A.2-1.

Table 6.10.3A.2-1: The sequence for normal cyclic prefix

Antenna port
107
108
109
110

Extended cyclic prefix:

where

The sequence is given by Table 6.10.3A.2-2.

Table 6.10.3A.2-2: The sequence for extended cyclic prefix

Antenna port
107
108

For extended cyclic prefix, demodulation reference signals are not supported on antenna ports 109 to 110.

For the antenna port in a physical resource block assigned for the SPDCCH, a part of the reference signal sequence shall be mapped to complex-valued modulation symbols in a subframe according to the procedure used for UE-specific reference signals associated with subslot-PDSCH on antenna port described in clause 6.10.3.2 with the following amendments:

– for slot-SPDCCH, ,

– for slot-SPDCCH in MBSFN subframes, the procedure used for the baseline pattern of UE-specific reference signals associated with subslot-PDSCH is applied

– for slot-SPDCCH in normal subframes, the procedure used for the shifted pattern of UE-specific reference signals associated with subslot-PDSCH depending on the cell-specific frequency shift is applied.

Resource elements used for transmission of demodulation reference signals to one UE on any of the antenna ports in the set , where or shall

– not be used for transmission of EPDCCH/MPDCCH on any antenna port in the same slot, and

– not be used for demodulation reference signals to the same UE on any antenna port other than those in in the same slot.

Replacing antenna port numbers 7 – 10 by 107 – 110 in Figure 6.10.3.2-3 provides an illustration of the resource elements used for demodulation reference signals associated with EPDCCH/MPDCCH for normal cyclic prefix. Replacing antenna port numbers 7 – 8 by 107 – 108 in Figure 6.10.3.2-4 provides an illustration of the resource elements used for demodulation reference signals associated with EPDCCH/MPDCCH for extended cyclic prefix.

For frame structure type 3, for EPDCCH in a subframe with the same duration as the DwPTS duration of a special subframe configuration, the mapping of the demodulation reference signals to the resource elements is the same as that for the corresponding special subframe configuration.

For BL/CE UEs, 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,

– If all OFDM symbols in a PRB are reserved, the demodulation reference signal transmission in that PRB is dropped.