4 Frame structure and physical resources
38.2113GPPNRPhysical channels and modulationRelease 17TS
4.1 General
Throughout this specification, unless otherwise noted, the size of various fields in the time domain is expressed in time units 
where Hz and 
. The constant 
where 
, 
and 
.
Throughout this specification, unless otherwise noted, statements using the term "UE" in clauses 4, 5, 6, or 7 are equally applicable to the IAB-MT part of an IAB-node.
4.2 Numerologies
Multiple OFDM numerologies are supported as given by Table 4.2-1 where and the cyclic prefix for a downlink or uplink bandwidth part are obtained from the higher-layer parameters subcarrierSpacing and cyclicPrefix, respectively.
Table 4.2-1: Supported transmission numerologies.
|
|
|
Cyclic prefix |
|
0 |
15 |
Normal |
|
1 |
30 |
Normal |
|
2 |
60 |
Normal, Extended |
|
3 |
120 |
Normal |
|
4 |
240 |
Normal |
|
5 |
480 |
Normal |
|
6 |
960 |
Normal |
4.3 Frame structure
4.3.1 Frames and subframes
Downlink, uplink, and sidelink transmissions are organized into frames with 
duration, each consisting of ten subframes of 
duration. The number of consecutive OFDM symbols per subframe is . Each frame is divided into two equally-sized half-frames of five subframes each with half-frame 0 consisting of subframes 0 – 4 and half-frame 1 consisting of subframes 5 – 9.
There is one set of frames in the uplink and one set of frames in the downlink on a carrier.
Uplink frame number 
for transmission from the UE shall start before the start of the corresponding downlink frame at the UE where
– and are given by clause 4.2 of [5, TS 38.213], except for msgA transmission on PUSCH where shall be used;
– given by clause 4.2 of [5, TS 38.213] is derived from the higher-layer parameters TACommon, TACommonDrift, and TACommonDriftVariation if configured, otherwise ;
– given by clause 4.2 of [5, TS 38.213] is computed by the UE based on UE position and serving-satellite-ephemeris-related higher-layers parameters if configured, otherwise .
Figure 4.3.1-1: Uplink-downlink timing relation.
4.3.2 Slots
For subcarrier spacing configuration 
, slots are numbered in increasing order within a subframe and in increasing order within a frame. There are 
consecutive OFDM symbols in a slot where 
depends on the cyclic prefix as given by Tables 4.3.2-1 and 4.3.2-2. The start of slot in a subframe is aligned in time with the start of OFDM symbol 
in the same subframe.
OFDM symbols in a slot in a downlink or uplink frame can be classified as ‘downlink’, ‘flexible’, or ‘uplink’. Signaling of slot formats is described in clause 11.1 of [5, TS 38.213].
In a slot in a downlink frame, the UE shall assume that downlink transmissions only occur in ‘downlink’ or ‘flexible’ symbols.
In a slot in an uplink frame, the UE shall only transmit in ‘uplink’ or ‘flexible’ symbols.
A UE not capable of full-duplex communication and not supporting simultaneous transmission and reception as defined by parameter simultaneousRxTxInterBandENDC, simultaneousRxTxInterBandCA or simultaneousRxTxSUL [10, TS 38.306] among all cells within a group of cells is not expected to transmit in the uplink in one cell within the group of cells earlier than after the end of the last received downlink symbol in the same or different cell within the group of cells where is given by Table 4.3.2-3.
A UE not capable of full-duplex communication and not supporting simultaneous transmission and reception as defined by parameter simultaneousRxTxInterBandENDC, simultaneousRxTxInterBandCA or simultaneousRxTxSUL [10, TS 38.306] among all cells within a group of cells is not expected to receive in the downlink in one cell within the group of cells earlier than after the end of the last transmitted uplink symbol in the same or different cell within the group of cells where is given by Table 4.3.2-3.
For DAPS handover operation, a UE not capable of full-duplex communication is not expected to transmit in the uplink to a cell earlier than after the end of the last received downlink symbol in the different cell where is given by Table 4.3.2-3.
For DAPS handover operation, a UE not capable of full-duplex communication is not expected to receive in the downlink from a cell earlier than after the end of the last transmitted uplink symbol in the different cell where is given by Table 4.3.2-3.
A UE not capable of full-duplex communication is not expected to transmit in the uplink earlier than after the end of the last received downlink symbol in the same cell where is given by Table 4.3.2-3.
A UE not capable of full-duplex communication is not expected to receive in the downlink earlier than after the end of the last transmitted uplink symbol in the same cell where is given by Table 4.3.2-3.
Table 4.3.2-1: Number of OFDM symbols per slot, slots per frame, and slots per subframe for normal cyclic prefix.
|
0 |
14 |
10 |
1 |
|
1 |
14 |
20 |
2 |
|
2 |
14 |
40 |
4 |
|
3 |
14 |
80 |
8 |
|
4 |
14 |
160 |
16 |
|
5 |
14 |
320 |
32 |
|
6 |
14 |
640 |
64 |
Table 4.3.2-2: Number of OFDM symbols per slot, slots per frame, and slots per subframe for extended cyclic prefix.
|
2 |
12 |
40 |
4 |
Table 4.3.2-3: Transition time and
|
Transition time |
FR1 |
FR2 |
|
25600 |
13792 |
|
|
25600 |
13792 |
4.4 Physical resources
4.4.1 Antenna ports
An antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed.
Two antenna ports are said to be quasi co-located if the large-scale properties of the channel over which a symbol on one antenna port is conveyed can be inferred from the channel over which a symbol on the other antenna port is conveyed. The large-scale properties include one or more of delay spread, Doppler spread, Doppler shift, average gain, average delay, and spatial Rx parameters.
4.4.2 Resource grid
For each numerology and carrier, a resource grid of 
subcarriers and OFDM symbols is defined, starting at common resource block 
indicated by higher-layer signalling. There is one set of resource grids per transmission direction (uplink, downlink, or sidelink) with the subscript set to DL, UL, and SL for downlink, uplink, and sidelink, respectively. When there is no risk for confusion, the subscript may be dropped. There is one resource grid for a given antenna port , subcarrier spacing configuration , and transmission direction (downlink, uplink, or sidelink).
For uplink and downlink, the carrier bandwidth for subcarrier spacing configuration is given by the higher-layer parameter carrierBandwidth in the SCS-SpecificCarrier IE. The starting position for subcarrier spacing configuration is given by the higher-layer parameter offsetToCarrier in the SCS-SpecificCarrier IE.
The frequency location of a subcarrier refers to the center frequency of that subcarrier.
For the downlink, the higher-layer parameter txDirectCurrentLocation in the SCS-SpecificCarrier IE indicates the location of the transmitter DC subcarrier in the downlink for each of the numerologies configured in the downlink. Values in the range 0 – 3299 represent the number of the DC subcarrier and the value 3300 indicates that the DC subcarrier is located outside the resource grid.
For the uplink, the higher-layer parameter txDirectCurrentLocation in the UplinkTxDirectCurrentBWP IE indicates the location of the transmitter DC subcarrier in the uplink for each of the configured bandwidth parts, including whether the DC subcarrier location is offset by 7.5 kHz relative to the center of the indicated subcarrier or not. Values in the range 0 – 3299 represent the number of the DC subcarrier, the value 3300 indicates that the DC subcarrier is located outside the resource grid, and the value 3301 indicates that the position of the DC subcarrier in the uplink is undetermined.
4.4.3 Resource elements
Each element in the resource grid for antenna port and subcarrier spacing configuration is called a resource element and is uniquely identified by where 
is the index in the frequency domain and 
refers to the symbol position in the time domain relative to some reference point. Resource element corresponds to a physical resource and the complex value . When there is no risk for confusion, or no particular antenna port or subcarrier spacing is specified, the indices and may be dropped, resulting in or .
4.4.4 Resource blocks
4.4.4.1 General
A resource block is defined as consecutive subcarriers in the frequency domain.
4.4.4.2 Point A
Point A serves as a common reference point for resource block grids and is obtained from:
– offsetToPointA for a PCell downlink where offsetToPointA represents the frequency offset between point A and the lowest subcarrier of the lowest resource block, which overlaps with the SS/PBCH block used by the UE for initial cell selection, expressed in units of resource blocks assuming 15 kHz subcarrier spacing for FR1 and 60 kHz subcarrier spacing for FR2;
– for operation without shared spectrum channel access in FR1 and FR2-1, the lowest resource block has the subcarrier spacing provided by the higher layer parameter subCarrierSpacingCommon;
– for operation with shared spectrum channel access in FR1 or FR2, and for operation without shared spectrum channel access in FR2-2, the lowest resource block has the subcarrier spacing same as the SS/PBCH block used by the UE for initial cell selection;
– absoluteFrequencyPointA for all other cases where absoluteFrequencyPointA represents the frequency-location of point A expressed as in ARFCN.
4.4.4.3 Common resource blocks
Common resource blocks are numbered from 0 and upwards in the frequency domain for subcarrier spacing configuration . The center of subcarrier 0 of common resource block 0 for subcarrier spacing configuration coincides with ‘point A’.
The relation between the common resource block number in the frequency domain and resource elements 
for subcarrier spacing configuration is given by
where 
is defined relative to point A such that corresponds to the subcarrier centered around point A.
4.4.4.4 Physical resource blocks
Physical resource blocks for subcarrier spacing configuration are defined within a bandwidth part and numbered from 0 to where is the number of the bandwidth part. The relation between the physical resource block in bandwidth part and the common resource block is given by
where is the common resource block where bandwidth part starts relative to common resource block 0. When there is no risk for confusion the index may be dropped.
4.4.4.5 Virtual resource blocks
Virtual resource blocks are defined within a bandwidth part and numbered from 0 to where is the number of the bandwidth part.
4.4.4.6 Interlaced resource blocks
Multiple interlaces of resource blocks are defined where interlace consists of common resource blocks , with being the number of interlaces given by Table 4.4.4.6-1. The relation between the interlaced resource block in bandwidth part and interlace and the common resource block is given by
where is the common resource block where bandwidth part starts relative to common resource block 0. When there is no risk for confusion the index may be dropped.
The UE expects that the number of common resource blocks in an interlace contained within bandwidth part is no less than 10.
Table 4.4.4.6-1: The number of resource block interlaces.
|
0 |
10 |
|
1 |
5 |
4.4.5 Bandwidth part
A bandwidth part is a subset of contiguous common resource blocks defined in clause 4.4.4.3 for a given numerology 
in bandwidth part 
on a given carrier. The starting position and the number of resource blocks in a bandwidth part shall fulfil and , respectively. Configuration of a bandwidth part is described in clause 12 of [5, TS 38.213].
A UE can be configured with up to four bandwidth parts in the downlink with a single downlink bandwidth part being active at a given time. The UE is not expected to receive PDSCH, PDCCH, or CSI-RS (except for RRM) outside an active bandwidth part.
A UE can be configured with up to four bandwidth parts in the uplink with a single uplink bandwidth part being active at a given time. If a UE is configured with a supplementary uplink, the UE can in addition be configured with up to four bandwidth parts in the supplementary uplink with a single supplementary uplink bandwidth part being active at a given time. The UE shall not transmit PUSCH or PUCCH outside an active bandwidth part. For an active cell, the UE shall not transmit SRS outside an active bandwidth part.
Unless otherwise noted, the description in this specification applies to each of the bandwidth parts. When there is no risk of confusion, the index may be dropped from , , , and .
4.4.6 Common MBS frequency resource
A common MBS frequency resource is a contiguous subset of common resource blocks within a bandwidth part. The starting position of the common MBS frequency resource is defined relative to point A and the size of the common MBS frequency resource is given by . Resource blocks in a common MBS frequency resource are numbered in the same way as resource blocks in clause 4.4.4.4 with and replaced by and , respectively.
A UE is not expected to receive PDSCH or PDCCH associated with MBS transmissions scheduled with G-RNTI, G-CS-RNTI or MCCH-RNTI outside the common MBS frequency resource.
4.5 Carrier aggregation
Transmissions in multiple cells can be aggregated. Unless otherwise noted, the description in this specification applies to each of the serving cells.
For carrier aggregation of cells with unaligned frame boundaries, the slot offset between a PCell/PScell and an SCell is determined by higher-layer parameter ca-SlotOffset for the SCell. The quantity is defined as the maximum of the lowest subcarrier spacing configuration among the subcarrier spacings given by the higher-layer parameters scs-SpecificCarrierList configured for PCell/PSCell and the SCell, respectively. The slot offset fulfills
– when the lowest subcarrier spacing configuration among the subcarrier spacings configured for the cell is for both cells or for both cells, the start of slot 0 for the cell whose point A has a lower frequency coincides with the start of slot for the other cell where if point A of the PCell/PSCell has a frequency lower than the frequency of point A for the SCell, otherwise ;
– otherwise, the start of slot 0 for the cell with the lower subcarrier spacing of the lowest subcarrier spacing given by the higher-layer parameters scs-SpecificCarrierList configured for the two cells, or the Pcell/PSCell if both cells have the same lowest subcarrier spacing given by the higher-layer parameters scs-SpecificCarrierList configured for the two cells, coincides with the start of slot for the other cell where if the lowest subcarreier spacing configuration given by scs-SpecificCarrierList of the PCell/PSCell is smaller than or equal to the lowest subcarrier spacing given by scs-SpecificCarrierList for the SCell, otherwise .