6.10.3 UE-specific reference signals associated with PDSCH

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UE-specific reference signals associated with PDSCH

– are transmitted on antenna port(s) , , , ,, , , or on the antenna ports indicated in Table 6.3.4.4-1, where is the number of layers used for transmission of the PDSCH;

– are present and are a valid reference for PDSCH demodulation only if the PDSCH transmission is associated with the corresponding antenna port according to clause 7.1 of TS 36.213 [4];

– are transmitted only on the physical resource blocks upon which the corresponding PDSCH is mapped.

A UE-specific reference signal associated with PDSCH is not transmitted in resource elements in which one of the physical channels or physical signals other than the UE-specific reference signals defined in 6.1 are transmitted using resource elements with the same index pair regardless of their antenna port .

A UE-specific reference signal associated with subslot-PDSCH or slot-PDSCH is only transmitted in physical resource blocks in frequency domain assigned for PDSCH transmission where

– the assignment maps to both physical resource blocks of a given PRG (see clause 6.4.2);

– in case of subslot-PDSCH, the associated SPDCCH is not mapped to resource elements of a given PRG assigned for PDSCH transmission (see clause 6.4.2)..

For frame structure type 3, for PDSCH in a subframe with the same duration as the DwPTS duration of a special subframe configuration, the UE-specific reference signals are defined the same as that for the corresponding special subframe configuration.

6.10.3.1 Sequence generation

For antenna port 5, the UE-specific reference-signal sequence is defined by

where denotes the assigned bandwidth in resource blocks of the corresponding PDSCH transmission. 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 is as described in clause 7.1 TS 36.213 [4].

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

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.

For BL/CE UEs, the same scrambling sequence is applied per subframe to the UE-specific reference-signal sequence 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 PDSCH. The PDSCH transmissions span consecutive subframes, including subframes that are not BL/CE DL subframes where the PDSCH transmission is postponed. For a BL/CE UE configured in CEModeA, . For a BL/CE UE configured with CEModeB, for frame structure type 1 and for frame structure type 2.

The quantities , , are given by

– if no value for is provided by higher layers or if DCI format 1A, 2B or 2C is used for the DCI associated with the PDSCH transmission

– otherwise

The value of is zero unless specified otherwise. For a PDSCH transmission on ports 7 or 8, is given by the DCI format 2B, 2C, 2D, 6-1A, 7-1E, 7-1F and 7-1G in TS 36.212 [3] associated with the PDSCH transmission.
In the case of DCI format 2B or 7-1E, is indicated by the scrambling identity field according to Table 6.10.3.1-1. In the case of DCI format 2C or 2D, is given by Table 5.3.3.1.5C-1, Table 5.3.3.1.5C-2 or Table 5.3.3.1.5C-6 in TS 36.212 [3]. In the case of DCI format 7-1F or 7-1G, is given by Table 5.3.3.1.22-1, Table 5.3.3.1.22-2, Table 5.3.3.1.22-3 or Table 5.3.3.1.5C-6 in TS 36.212 [3]. For a PDSCH transmission on ports 11 or 13, is given by the DCI format 2C or 2D in TS 36.212 [3] associated with the PDSCH transmission where is given by Table 5.3.3.1.5C-2 in TS 36.212 [3].

Table 6.10.3.1-1: Mapping of scrambling identity field in DCI format 2B to values for antenna ports 7 and 8

Scrambling identity field in

DCI format 2B

(TS 36.212 [3])

6.10.3.2 Mapping to resource elements

For antenna port 5, in a physical resource block with frequency-domain index assigned for the corresponding PDSCH transmission, the reference signal sequence shall be mapped to complex-valued modulation symbols with in a subframe according to:

Normal cyclic prefix:

Extended cyclic prefix:

where is the counter of UE-specific reference signal resource elements within a respective OFDM symbol of the PDSCH transmission.

The cell-specific frequency shift is given by .

The mapping shall be in increasing order of the frequency-domain index of the physical resource blocks assigned for the corresponding PDSCH transmission. The quantity denotes the assigned bandwidth in resource blocks of the corresponding PDSCH transmission.

Figure 6.10.3.2-1 illustrates the resource elements used for UE-specific reference signals for normal cyclic prefix for antenna port 5.

Figure 6.10.3.2-2 illustrates the resource elements used for UE-specific reference signals for extended cyclic prefix for antenna port 5.

The notation is used to denote a resource element used for reference signal transmission on antenna port.

Figure 6.10.3.2-1: Mapping of UE-specific reference signals, antenna port 5 (normal cyclic prefix)

Figure 6.10.3.2-2: Mapping of UE-specific reference signals, antenna port 5 (extended cyclic prefix)

For antenna ports , , , , , , or the antenna ports indicated in Table 6.3.4.4-1 in a physical resource block with frequency-domain index assigned for the corresponding PDSCH transmission, 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 6.10.3.2-1.

Table 6.10.3.2-1: The sequence for normal cyclic prefix

Antenna port
7
8
9
10
11
12
13
14

Extended cyclic prefix:

where

The sequence is given by Table 6.10.3.2-2.

Table 6.10.3.2-2: The sequence for extended cyclic prefix and for slot/subslot-PDSCH

Antenna port
7
8
9
10

For extended cyclic prefix, UE-specific reference signals are not supported on antenna ports 9 to 14.

For slot-PDSCH transmission, the baseline pattern (see ‘Baseline’ in Figure 6.10.3.2-2A) of UE-specific reference signals is defined as follows. It is applied in MBSFN subframes.

where

–

and

– if the slot where the PDSCH is transmitted in () fulfils

The sequence is given by Table 6.10.3.2-2.

For slot-PDSCH transmission in normal subframes,is generated as for the baseline slot-PDSCH UE-specific reference signal pattern for the same values of , while is given by and depends on the cell-specific frequency shift as follows (see ‘v0’, ‘v1’ and ‘v2’ in Figure 6.10.3.2-2A for , , and , respectively):

– For , ,

– For , .

Figure 6.10.3.2-2A: Mapping of UE-specific reference signals for slot-PDSCH, antenna ports 7, 8, 9 and 10 (normal cyclic prefix)

For subslot-PDSCH transmission, the baseline pattern (see ‘Baseline’ in Figure 6.10.3.2-2B) of UE-specific reference signals is defined as follows. It is applied if the presence of UE-specific reference signals is indicated in the DCI associated with the subslot-PDSCH (see DMRS position indicator field in TS 36.212 [3]), and in downlink subslots where the baseline pattern, including all the REs associated with if the parameter maxLayersMIMO-STTI is configured with 2 layers, or if the parameter maxLayersMIMO-STTI is configured with 4 layers, has no overlapping resource element with CRS and no overlapping resource element with configured zero-power and non-zero-power CSI reference signals:

where

The sequence is given by Table 6.10.3.2-2.For subslot-PDSCH transmission in normal subframes, in downlink subslots where the baseline pattern, including all the REs associated with if the parameter maxLayersMIMO-STTI is configured with 2 layers, or if the parameter maxLayersMIMO-STTI is configured with 4 layers, has overlapping resource elements with configured zero-power or non-zero-power CSI reference signals or has overlapping resource elements with CRS, if the presence of UE-specific reference signals is indicated in the DCI associated (see DMRS position indicator field in TS 36.212 [3]) with the subslot-PDSCH, a shifted pattern of UE-specific reference signals is applied. In the shifted pattern,is generated as for the baseline subslot-PDSCH UE-specific reference signal pattern for the same value of , while is given by and depends on the cell-specific frequency shift as follows (see also ‘v0′,’v1’ and ‘v2’ in Figure 6.10.3.2-2B for , , and , respectively):

– For , ,

For subslot-PDSCH transmission in MBSFN subframes, in downlink subslots where the baseline pattern, including all the REs associated with if the parameter maxLayersMIMO-STTI is configured with 2 layers, or if the parameter maxLayersMIMO-STTI is configured with 4 layers, has overlapping resource elements with configured zero-power or non-zero-power CSI reference signals, if the presence of UE-specific reference signals is indicated in the DCI associated (see DMRS position indicator field in TS 36.212 [3]) with the subslot-PDSCH, the shifted pattern of UE-specific reference signals for , as defined above, is applied (see ‘v0’ in Figure 6.10.3.2-2B for ).

Figure 6.10.3.2-2B: Mapping of UE-specific reference signals for subslot-PDSCH, antenna ports 7, 8, 9 and 10 (normal cyclic prefix)

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

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

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

Figure 6.10.3.2-3 illustrates the resource elements used for UE-specific reference signals for normal cyclic prefix for antenna ports 7, 8, 9 and 10. Figure 6.10.3.2-4 illustrates the resource elements used for UE-specific reference signals for extended cyclic prefix for antenna ports 7, 8.

For BL/CE UEs, if downlink resource reservation is enabled for the UE as specified in [9], and the Resource reservation field in the DCI is set to 1, then in case of PDSCH transmission associated with C-RNTI or SPS C-RNTI using UE-specific MPDCCH search space including PDSCH transmission without a corresponding MPDCCH,

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

Figure 6.10.3.2-3: Mapping of UE-specific reference signals, antenna ports 7, 8, 9 and 10 (normal cyclic prefix)

Figure 6.10.3.2-4: Mapping of UE-specific reference signals, antenna ports 7 and 8 (extended cyclic prefix)