7.1.6 Resource allocation
36.2133GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical layer proceduresRelease 17TS
The UE shall interpret the resource allocation field depending on the PDCCH/EPDCCH DCI format detected. A resource allocation field in each PDCCH/EPDCCH includes two parts, a resource allocation header field and information consisting of the actual resource block assignment.
PDCCH DCI formats 1, 2, 2A, 2B, 2C and 2D with type 0 and PDCCH DCI formats 1, 2, 2A, 2B, 2C and 2D with type 1 resource allocation have the same format and are distinguished from each other via the single bit resource allocation header field which exists depending on the downlink system bandwidth (Clause 5.3.3.1 of [4]), where type 0 is indicated by 0 value and type 1 is indicated otherwise. PDCCH with DCI format 1A, 1B, 1C and 1D have a type 2 resource allocation while PDCCH with DCI format 1, 2, 2A, 2B, 2C and 2D have type 0 or type 1 resource allocation. PDCCH DCI formats with a type 2 resource allocation do not have a resource allocation header field.
EPDCCH DCI formats 1, 2, 2A, 2B, 2C and 2D with type 0 and EPDCCH DCI formats 1, 2, 2A, 2B, 2C and 2D with type 1 resource allocation have the same format and are distinguished from each other via the single bit resource allocation header field which exists depending on the downlink system bandwidth (Clause 5.3.3.1 of [4]), where type 0 is indicated by 0 value and type 1 is indicated otherwise. EPDCCH with DCI format 1A, 1B, and 1D have a type 2 resource allocation while EPDCCH with DCI format 1, 2, 2A, 2B, 2C and 2D have type 0 or type 1 resource allocation. EPDCCH DCI formats with a type 2 resource allocation do not have a resource allocation header field.
If the UE is configured with higher layer parameter shortTTI, PDCCH/SPDCCH with DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G utilizes a higher layer configured resource allocation type 0 or resource allocation type 2.
If the UE is configured with higher layer parameter ce-pdsch-maxBandwidth-config with value 20MHz and the resource block assignment flag is set to 0
– MPDCCH with DCI format 6-1A utilizes a type 0 resource allocation.
else if the UE is configured with higher layer parameter ce-pdsch-maxBandwidth-config with value 20MHz and the resource block assignment flag is set to 1, or the UE is configured with higher layer parameter ce-pdsch-maxBandwidth-config with value 5 MHz, or mpdcch-PDSCH-MaxBandwidth-SC-MTCH is set to 24 PRBs,
For system bandwidth larger than 1.4 MHz,
MPDCCH with DCI format 6-1A utilizes same type 2 resource allocation within each allocated narrowband.
otherwise,
MPDCCH with DCI format 6-1A utilizes a type 2 resource allocation.
otherwise
– MPDCCH with DCI format 6-1A utilizes a type 2 resource allocation.
Resource allocation for MPDCCH with DCI format 6-1B is given by the Resource block assignment field as described in [4]. For a UE configured with higher layer parameter ce-pdsch-maxBandwidth-config with value 20MHz and CEModeB, the allocated widebands (WBs) are based on the wideband combination index according to Table 7.1.6-2.
MPDCCH with DCI format 6-2 assigns a set of six contiguously allocated localized virtual resource blocks within a narrowband. Localized virtual resource blocks are always used in case of MPDCCH with DCI format 6-1A, 6-1B, or 6-2.
A UE may assume, for any PDSCH transmission scheduled by a cell with physical cell identity given in NAICS-AssistanceInfo-r12 and the PDSCH transmission mode belonging to transmissionModeList-r12 associated with the cell except spatial multiplexing using up to 8 transmission layers in transmission mode 10, that the resource allocation granularity and precoding granularity in terms of PRB pairs in the frequency domain are both given by N, where N is given by the higher layer parameter resAllocGranularity-r12 associated with the cell. The first set of N consecutive PRB pairs of the resource allocation starts from the lowest frequency of the system bandwidth and the UE may assume the same precoding applies to all PRB pairs within a set.
For a BL/CE UE, the resource allocation for PDSCH carrying SystemInformationBlockType1-BR and SI messages is a set of six contiguously allocated localized virtual resource blocks within a narrowband. The number of repetitions for the PDSCH carrying SystemInformationBlockType1-BR is determined based on the parameter schedulingInfoSIB1-BR configured by higher-layers and according to Table 7.1.6-1. If the value of the parameter schedulingInfoSIB1-BR configured by higher-layers is set to 0, UE assumes that SystemInformationBlockType1-BR is not transmitted.
Table 7.1.6-1: Number of repetitions for PDSCH carrying SystemInformationBlockType1-BR for BL/CE UE.
|
Value of schedulingInfoSIB1-BR |
Number of PDSCH repetitions |
|
0 |
N/A |
|
1 |
4 |
|
2 |
8 |
|
3 |
16 |
|
4 |
4 |
|
5 |
8 |
|
6 |
16 |
|
7 |
4 |
|
8 |
8 |
|
9 |
16 |
|
10 |
4 |
|
11 |
8 |
|
12 |
16 |
|
13 |
4 |
|
14 |
8 |
|
15 |
16 |
|
16 |
4 |
|
17 |
8 |
|
18 |
16 |
|
19-31 |
Reserved |
Table 7.1.6-2: Wideband combination index for a UE configured with higher layer parameter ce-pdsch-maxBandwidth-config with value 20MHz and CEModeB
|
Wideband combination index |
Indices of allocated WBs |
||
 |
 |
 |
|
|
0 |
0 |
0 |
0 |
|
1 |
1 |
1 |
1 |
|
2 |
0,1 |
2 |
2 |
|
3 |
Reserved |
0,1 |
3 |
|
4 |
NA |
1,2 |
0,1 |
|
5 |
NA |
0,2 |
2,3 |
|
6 |
NA |
0,1,2 |
0,1,2 |
|
7 |
NA |
Reserved |
0,1,2,3 |
7.1.6.1 Resource allocation type 0
In resource allocations of type 0, resource block assignment information includes a bitmap indicating the Resource Block Groups (RBGs) that are allocated to the scheduled UE where a RBG is a set of consecutive virtual resource blocks (VRBs) of localized type as defined in Clause 6.2.3.1 of [3].
For a UE configured with higher layer parameter ce-pdsch-maxBandwidth-config with value 20MHz and the resource block assignment flag is set to 0
– Resource block group size (P) is given by the value S described in sub clause 5.3.3.1.12 of [4].
– and is used in place of for the rest of this clause, unless explicitly mentioned.
otherwise
– Resource block group size (P) is a function of the system bandwidth as shown in Table 7.1.6.1-1A if a UE is configured with higher layer parameter shortTTI and for DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G, Table 7.1.6.1-1 otherwise.
For DCI formats other than DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G, the total number of RBGs () for downlink system bandwidth of is given by where of the RBGs are of size P and if then one of the RBGs is of size. If a UE is configured with higher layer parameter shortTTI and for DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G, the total number of RBGs () for downlink system bandwidth of is given by where of the RBGs are of size P and if then the last RBGs is of size . The bitmap is of size bits with one bitmap bit per RBG such that each RBG is addressable.
For a UE configured with higher layer parameter ce-pdsch-maxBandwidth-config with value 20MHz and the resource block assignment flag is set to 0
– The RBGs shall be indexed according to RBG indexing described in Clause 8.1.5.1 by replacing with , ‘uplink’ with ‘downlink’ , and with (but not 
).
otherwise
– For DCI formats other than DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G, the RBGs shall be indexed in the order of increasing frequency and non-increasing RBG sizes starting at the lowest frequency.
– For DCI formats 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G, the RBGs shall be indexed in the order of increasing frequency and non-decreasing RBG sizes starting at the lowest frequency.
The order of RBG to bitmap bit mapping is such that RBG 0 to RBG are mapped to MSB to LSB of the bitmap. The RBG is allocated to the UE if the corresponding bit value in the bitmap is 1, the RBG is not allocated to the UE otherwise.
Table 7.1.6.1-1: Type 0 resource allocation RBG size vs. Downlink System Bandwidth
|
System Bandwidth |
RBG Size |
 |
(P) |
|
≤10 |
1 |
|
11 – 26 |
2 |
|
27 – 63 |
3 |
|
64 – 110 |
4 |
Table 7.1.6.1-1A: Type 0 resource allocation RBG size vs. Downlink System Bandwidth for DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G
|
System Bandwidth |
RBG Size |
 |
(P) |
|
≤10 |
1 |
|
11 – 24 |
2 |
|
25 – 63 |
6 |
|
64 – 110 |
12 |
7.1.6.2 Resource allocation type 1
In resource allocations of type 1, a resource block assignment information of size indicates to a scheduled UE the VRBs from the set of VRBs from one of P RBG subsets. The virtual resource blocks used are of localized type as defined in Clause 6.2.3.1 of [3]. Also P is the RBG size associated with the system bandwidth as shown in Table 7.1.6.1-1. A RBG subset , where , consists of every th RBG starting from RBG . The resource block assignment information consists of three fields [4].
The first field with bits is used to indicate the selected RBG subset among RBG subsets.
The second field with one bit is used to indicate a shift of the resource allocation span within a subset. A bit value of 1 indicates shift is triggered. Shift is not triggered otherwise.
The third field includes a bitmap, where each bit of the bitmap addresses a single VRB in the selected RBG subset in such a way that MSB to LSB of the bitmap are mapped to the VRBs in the increasing frequency order. The VRB is allocated to the UE if the corresponding bit value in the bit field is 1, the VRB is not allocated to the UE otherwise. The portion of the bitmap used to address VRBs in a selected RBG subset has size and is defined as
The addressable VRB numbers of a selected RBG subset start from an offset, to the smallest VRB number within the selected RBG subset, which is mapped to the MSB of the bitmap. The offset is in terms of the number of VRBs and is done within the selected RBG subset. If the value of the bit in the second field for shift of the resource allocation span is set to 0, the offset for RBG subset is given by . Otherwise, the offset for RBG subset is given by , where the LSB of the bitmap is justified with the highest VRB number within the selected RBG subset. is the number of VRBs in RBG subset and can be calculated by the following equation,
Consequently, when RBG subset is indicated, bit for in the bitmap field indicates VRB number,
.
7.1.6.3 Resource allocation type 2
For BL/CE UEs with resource allocation type 2 resource assignment, and is used in the rest of this Clause.
In resource allocations of type 2, the resource block assignment information indicates to a scheduled UE a set of contiguously allocated localized virtual resource blocks or distributed virtual resource blocks. In case of resource allocation signalled with PDCCH DCI format 1A, 1B or 1D, or for resource allocation signalled with EPDCCH DCI format 1A, 1B, or 1D, one bit flag indicates whether localized virtual resource blocks or distributed virtual resource blocks are assigned (value 0 indicates Localized and value 1 indicates Distributed VRB assignment) while distributed virtual resource blocks are always assigned in case of resource allocation signalled with PDCCH DCI format 1C and localized virtual resource blocks are always assigned in case of resource allocation signalled with PDCCH/SPDCCH DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G. Localized VRB allocations for a UE vary from a single VRB up to a maximum number of VRBs spanning the system bandwidth. For DCI format 1A the distributed VRB allocations for a UE vary from a single VRB up to VRBs, where is defined in [3], if the DCI CRC is scrambled by P-RNTI, RA-RNTI, or SI-RNTI. With PDCCH DCI format 1B, 1D with a CRC scrambled by C-RNTI, or with DCI format 1A with a CRC scrambled with C-RNTI, SPS C-RNTI or Temporary C-RNTI distributed VRB allocations for a UE vary from a single VRB up to VRBs if is 6-49 and vary from a single VRB up to 16 if is 50-110. With EPDCCH DCI format 1B, 1D with a CRC scrambled by C-RNTI, or with DCI format 1A with a CRC scrambled with C-RNTI, SPS C-RNTI distributed VRB allocations for a UE vary from a single VRB up to VRBs if is 6-49 and vary from a single VRB up to 16 if is 50-110. With PDCCH DCI format 1C and 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G, VRB allocations for a UE vary from VRB(s) up to VRBs with an increment step of , where value is determined depending on the downlink system bandwidth as shown in Table 7.1.6.3-1 for DCI format 1C and Table 7.1.6.3-1A for DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G.
Table 7.1.6.3-1: values vs. Downlink System Bandwidth
|
System BW ()
|
 |
|
DCI format 1C |
|
|
6-49 |
2 |
|
50-110 |
4 |
Table 7.1.6.3-1A: values vs. Downlink System Bandwidth
|
System BW ()
|
 |
|
DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G |
|
|
20 – 26 |
4 |
|
27 – 63 |
6 |
|
64 – 110 |
4 |
For PDCCH DCI format 1A, 1B, or 1D or for PDCCH DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G and <20, or for EPDCCH DCI format 1A, 1B, or 1D, or for MPDCCH DCI format 6-1A, or for SPDCCH DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G and <20, a type 2 resource allocation field consists of a resource indication value (RIV) corresponding to a starting resource block () and a length in terms of virtually contiguously allocated resource blocks .
The resource indication value is defined by
if then
else
where≥ 1 and shall not exceed .
For a BL/CE UE configured with CEModeA, and configured with higher layer parameter ce-PDSCH-FlexibleStartPRB-AllocConfig-r15, and 
, the 
and 
is determined according to Table 7.1.6.3-2 where,
– 
is the smallest and the largest physical resource-block number, respectively, of the allocated narrowband as defined in Clause 6.2.7 of [3]
– 
is the value of the downlink system bandwidth
– P is the RBG size associated with the downlink system bandwidth,, according to Table 7.1.6.1-1
– 
– Physical resource-blocks with indices 
or 
, 
correspond to physical resource-blocks outside the allocated narrowband relative to physical resource-block 
– shall not exceed (
)
Table 7.1.6.3-2: 
and 
for 
and CEModeA
|
|
|
|
|
0 |
|
2 |
|
1 |
3 |
|
|
2 |
4 |
|
|
3 |
5 |
|
|
4 |
6 |
|
|
5 |
|
6 |
|
6 |
|
5 |
|
7 |
|
4 |
|
8 |
|
3 |
|
9 |
|
2 |
For PDCCH DCI format 1C or for PDCCH/SPDCCH DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G and , a type 2 resource block assignment field consists of a resource indication value (RIV) corresponding to a virtual starting resource block (=, , ,…, ) and a length in terms of virtually contiguously allocated resource blocks (=, ,…, ).
The resource indication value is defined by:
if then
else
where , and , and where
≥ 1 and shall not exceed .
For PDCCH DCI format 1C or for PDCCH/SPDCCH DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G and , the starting resource block index is the same as the virtual starting resource block index (). For PDCCH/SPDCCH DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G and , the LSB of RIV indicates whether the starting resource block index is or (value 0 indicates and value 1 indicates ). In case of resource allocation signalled with
– PDCCH/SPDCCH DCI format 7-1A/7-1B/7-1C/7-1D, and , if the resource allocation indicates the corresponding PDSCH is mapped to RB index 23, the UE shall assume the PDSCH is also mapped to RB index 24.
– PDCCH/SPDCCH DCI format 7-1A/7-1B/7-1C/7-1D/7-1E/7-1F/7-1G, and 
, if the resource allocation indicates the corresponding PDSCH is mapped to RB index 47, the UE shall assume the PDSCH is also mapped to RB index 48 and 49.
– PDCCH/SPDCCH DCI format 7-1A/7-1B/7-1C/7-1D, and 
, if the resource allocation indicates the corresponding PDSCH is mapped to RB index 71, the UE shall assume the PDSCH is also mapped to RB index 72, 73 and 74.
– PDCCH/SPDCCH DCI format 7-1E/7-1F/7-1G, and 
, if the resource allocation indicates the corresponding PDSCH is mapped to RB index 71, the UE shall assume the PDSCH is also mapped to RB index 72, and 73.
7.1.6.4 PDSCH starting position
This Clause describes PDSCH starting position for UEs that are not BL/CE UEs.
PDSCH starting position for BL/CE UEs is described in Clause 7.1.6.4A.
The starting OFDM symbol for the PDSCH of each activated serving cell is given by index .
For a UE configured in transmission mode 1-9, for a given activated serving cell
– if the PDSCH is assigned by EPDCCH received in the same serving cell, or if the UE is configured to monitor EPDCCH in the subframe and the PDSCH is not assigned by a PDCCH/EPDCCH, and if the UE is configured with the higher layer parameter epdcch-StartSymbol-r11
– is given by the higher-layer parameter epdcch-StartSymbol-r11.
– else if PDSCH and the corresponding PDCCH/EPDCCH are received on different serving cells
– is given by the higher-layer parameter pdsch-Start-r10 for the serving cell on which PDSCH is received,
– Otherwise
– is given by the CFI value in the subframe of the given serving cell when , and is given by the CFI value + 1 in the subframe of the given serving cell when .
For a UE configured in transmission mode 10, for a given activated serving cell
– if the PDSCH is assigned by a PDCCH with DCI format 1C or by a PDCCH with DCI format 1A and with CRC scrambled with P-RNTI/RA-RNTI/SI-RNTI/Temporary C-RNTI
– is given by the span of the DCI given by the CFI value in the subframe of the given serving cell according to Clause 5.3.4 of [4].
– if the PDSCH is assigned by a PDCCH/EPDCCH with DCI format 1A and with CRC scrambled with C-RNTI and if the PDSCH transmission is on antenna ports 0 – 3
– if the PDSCH is assigned by EPDCCH received in the same serving cell
– is given by for the EPDCCH-PRB-set where EPDCCH with the DCI format 1A was received ( as defined in Clause 9.1.4.1),
– else if PDSCH and the corresponding PDCCH/EPDCCH are received on different serving cells
– is given by the higher-layer parameter pdsch-Start-r10 for the serving cell on which PDSCH is received.
– otherwise
– is given by the CFI value in the subframe of the given serving cell when , and is given by the CFI value+1 in the subframe of the given serving cell when .
– if the PDSCH is assigned by or semi-statically scheduled by a PDCCH/EPDCCH with DCI format 1A and if the PDSCH transmission is on antenna port 7
– if the value of the higher layer parameter pdsch-Start-r11 determined from parameter set 1 in table 7.1.9-1 for the serving cell on which PDSCH is received belongs to {1,2,3,4},
– is given by the higher layer parameter pdsch-Start-r11 determined from parameter set 1 in table 7.1.9-1 for the serving cell on which PDSCH is received.
– else,
– if PDSCH and the corresponding PDCCH/EPDCCH are received on different serving cells,
– is given by the higher-layer parameter pdsch-Start-r10 for the serving cell on which PDSCH is received
– otherwise
– is given by the CFI value in the subframe of the given serving cell when , and is given by the CFI value + 1 in the subframe of the given serving cell when .
– if the subframe on which PDSCH is received is indicated by the higher layer parameter mbsfn-SubframeConfigList-r11 determined from parameter set 1 in table 7.1.9-1 for the serving cell on which PDSCH is received, or if the PDSCH is received on subframe 1 or 6 for the frame structure type 2,
– ,
– otherwise
– .
– if the PDSCH is assigned by or semi-persistently scheduled by a PDCCH/EPDCCH with DCI format 2D,
– if the value of the higher layer parameter pdsch-Start-r11 determined from the DCI (according to Clause 7.1.9) for the serving cell on which PDSCH is received belongs to {1,2,3,4},
– is given by parameter pdsch-Start-r11 determined from the DCI (according to Clause 7.1.9) for the serving cell on which PDSCH is received except if UE is configured with Type C quasi co-location and when two codewords are transmitted then is given by the maximum of the pdsch-Start-r11and pdsch-Start2-r15 parameters,
– else,
– if PDSCH and the corresponding PDCCH/EPDCCH are received on different serving cells,
– is given by the higher-layer parameter pdsch-Start-r10 for the serving cell on which PDSCH is received
– Otherwise
– is given by the CFI value in the subframe of the given serving cell when , and is given by the CFI value+1 in the subframe of the given serving cell when .
– if the subframe on which PDSCH is received is indicated by the higher layer parameter mbsfn-SubframeConfigList-r11 determined from the DCI (according to Clause 7.1.9) for the serving cell on which PDSCH is received, or if the PDSCH is received on subframe 1 or 6 for frame structure type 2,
– ,
– otherwise
– .
7.1.6.4A PDSCH starting position for BL/CE UEs
The starting OFDM symbol for PDSCH is given by index in the first slot in a subframe and is determined as follows
– for reception of SIB1-BR
– if for the cell on which PDSCH is received
– if for the cell on which PDSCH is received
– else
– is given by the higher layer parameter startSymbolBR
– if subframe is a special subframe or configured as an MBSFN subframe, and if the BL/CE UE is configured in CEModeA
–
– else
– .
7.1.6.5 Physical Resource Block (PRB) bundling
A UE configured for transmission mode 9 for a given serving cell c may assume that precoding granularity is multiple resource blocks in the frequency domain when PMI/RI reporting is configured.
For a given serving cell c, if a UE is configured for transmission mode 10
– if PMI/RI reporting is configured for all configured CSI processes for the serving cell c, the UE may assume that precoding granularity is multiple resource blocks in the frequency domain,
– otherwise, the UE shall assume the precoding granularity is one resource block in the frequency domain.
If the UE is non-BL/CE UE,
– if the UE is configured for transmission mode 9, 10 with PMI/RI reporting and with higher layer parameter widebandPRG-Subframe and the scheduled PRBs are consecutive PRBs, the UE may assume that the same precoder applies on all the scheduled PRBs,
– otherwise, fixed system bandwidth dependent Precoding Resource block Groups (PRGs) of size partition the system bandwidth and each PRG consists of consecutive PRBs. The PRG size a UE may assume for a given system bandwidth is given by Table 7.1.6.5-1. If then one of the PRGs is of size . The PRG size is non-increasing starting at the lowest frequency. The UE may assume that the same precoder applies on all scheduled PRBs within a PRG.
If the UE is a BL/CE UE not configured with higher layer parameter ce-PDSCH-FlexibleStartPRB-AllocConfig-r15, PRGs of size 
=3 partition a narrowband with RB indices 0-2 in the narrowband in one PRG and RB indices 3-5 in the narrowband in another PRG.
If the UE is a BL/CE UE configured with CEModeA and configured with higher layer parameter ce-PDSCH-FlexibleStartPRB-AllocConfig-r15,
– if in Table 7.1.6.3-2, then the set of two PRGs is starting from ;
– if , then the set of two PRGs is ending ending at .
If the UE is a BL/CE UE configured with CEModeB and configured with higher layer parameter ce-PDSCH-FlexibleStartPRB-AllocConfig-r15, the set of PRGs is starting from the lowest RB of the narrowband shifted by , according to Table 6.2.7-1 [3].
Table 7.1.6.5-1
|
System Bandwidth ()
|
PRG Size ()
(PRBs) |
|
≤10 |
1 |
|
11 – 26 |
2 |
|
27 – 63 |
3 |
|
64 – 110 |
2 |
For a given serving cell c and for slot/subslot-PDSCH transmissions,
– if the UE is configured for transmission mode 9, 10 with PMI/RI reporting and with higher layer parameter widebandPRG- SlotSubslot and the scheduled PRBs are consecutive PRBs, the UE may assume that the same precoder applies on all the scheduled PRBs,
– otherwise, for a UE configured for transmission mode 9, 10 using frame structure type 1 or transmission modes 8, 9, 10 using frame structure type 2, precoding granularity is 2 resource blocks in frequency domain. Precoding Resource block Groups (PRGs) of size 2 partition the system bandwidth and each PRG consists of consecutive PRBs. The UE is expected to receive UE-specific reference signal corresponding to a PDSCH over both resource blocks of a PRG. If then, PDSCH is not mapped to the last resource block. The UE may assume that the same precoder applies on the two PRBs within a PRG.
