5.2 Slot structure and physical resources

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

5.2.1 Resource grid

The transmitted signal in each slot is described by one or several resource grids of subcarriers and SC-FDMA symbols. The resource grid is illustrated in Figure 5.2.1-1. The quantity depends on the uplink transmission bandwidth configured in the cell and shall fulfil

where and are the smallest and largest uplink bandwidths, respectively, supported by the current version of this specification. The set of allowed values for is given by TS 36.101 [7].

The number of SC-FDMA symbols in a slot depends on the cyclic prefix length configured by the higher layer parameter UL-CyclicPrefixLength and is given in Table 5.2.3-1.

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. There is one resource grid per antenna port. The antenna ports used for transmission of a physical channel or signal depends on the number of antenna ports configured for the physical channel or signal as shown in Table 5.2.1-1. The index is used throughout clause 5 when a sequential numbering of the antenna ports is necessary.

Figure 5.2.1-1: Uplink resource grid

Table 5.2.1-1: Antenna ports used for different physical channels and signals

Physical channel or signal	Index	Antenna port number as a function of the number of antenna ports configured for the respective physical channel/signal
		1	2	4
PUSCH	0	10	20	40
	1	–	21	41
	2	–	–	42
	3	–	–	43
SRS	0	10	20	40
	1	–	21	41
	2	–	–	42
	3	–	–	43
PUCCH, SPUCCH	0	100	200	–
	1	–	201	–

5.2.2 Resource elements

Each element in the resource grid is called a resource element and is uniquely defined by the index pair in a slot where and are the indices in the frequency and time domains, respectively. Resource element on antenna port corresponds to the complex value .
When there is no risk for confusion, or no particular antenna port is specified, the index may be dropped.
Quantities corresponding to resource elements not used for transmission of a physical channel or a physical signal in a slot shall be set to zero.

5.2.3 Resource blocks

A physical resource block is defined as consecutive SC-FDMA symbols in the time domain and consecutive subcarriers in the frequency domain, where and are given by Table 5.2.3-1.
A physical resource block in the uplink thus consists of resource elements, corresponding to one slot in the time domain and 180 kHz in the frequency domain.

Table 5.2.3-1: Resource block parameters

Configuration
Normal cyclic prefix	12	7
Extended cyclic prefix	12	6

The relation between the physical resource block number in the frequency domain and resource elements in a slot is given by

5.2.3A Resource unit

Resource units are used to describe the mapping of PUSCH using sub-PRB allocations to resource elements for BL/CE UEs. A resource unit is defined as SC-FDMA symbols in the time domain and consecutive subcarriers in the frequency domain, where and are given by Table 5.2.3A-1.

Table 5.2.3A-1: Supported combinations of , , and for PUSCH using sub-PRB allocations for Frame Structure type 1 and Frame Structure type 2.

Physical channel		Modulation scheme					Comment
PUSCH	15 kHz	π/2-BPSK	12	3	16	7	2 out of 3 subcarriers used
		QPSK		3	8
				6	4

5.2.4 Narrowbands and widebands

A narrowband is defined as six non-overlapping consecutive physical resource blocks in the frequency domain. The total number of uplink narrowbands in the uplink transmission bandwidth configured in the cell is given by

The narrowbands are numbered in order of increasing physical resource-block number where narrowband is composed of physical resource-block indices

where

If , a wideband is defined as four non-overlapping narrowbands in the frequency domain. The total number of uplink widebands in the uplink transmission bandwidth configured in the cell is given by

and the widebands are numbered in order of increasing narrowband number where wideband is composed of narrowband indices where .

If , then and the single wideband is composed of the non-overlapping narrowband(s).

5.2.5 Guard period for narrowband and wideband retuning

For BL/CE UEs, a guard period of at most SC-FDMA symbols is created for Tx-to-Tx frequency retuning between two consecutive subframes.

– If the higher layer parameter ce-RetuningSymbols is set, then equals ce-RetuningSymbols, otherwise .

– If the higher layer parameter ce-pusch-maxBandwidth-config is set to 5 MHz, then the rules for guard period creation defined in the remainder of this clause do not apply for retuning between narrowbands but for retuning between widebands and for transmissions involving multiple widebands.

– If a UE is configured with higher layer parameter ce-PUSCH-FlexibleStartPRB-AllocConfig and the allocation resources are not fully within one narrowband, the rules for guard period creation defined in the remainder of this clause apply for retuning between tuning narrowbands, where

– In case of CEModeA, the tuning narrowband is defined as the 6 consecutive PRBs starting from defined in 8.1.1 of [4] with the center frequency set in the middle.

– In case of CEModeB, the tuning narrowband is defined as the 6 consecutive PRBs with the center frequency set in the middle of allocated two PRBs.

– If the UE retunes from a first narrowband carrying PUSCH to a second narrowband carrying PUSCH, or if the UE retunes from a first narrowband carrying PUCCH to a second narrowband carrying PUCCH,

– if , a guard period is created by the UE not transmitting the last SC-FDMA symbol in the first subframe;

– if , a guard period is created by the UE not transmitting the last SC-FDMA symbol in the first subframe and the first SC-FDMA symbol in the second subframe.

– If the UE retunes from a first narrowband carrying PUCCH to a second narrowband carrying PUSCH,

– if the PUCCH uses a shortened PUCCH format and , a guard period is created by the UE not transmitting the last SC-FDMA symbol in the first subframe;

– if the PUCCH uses a shortened PUCCH format and , a guard period is created by the UE not transmitting the last SC-FDMA symbol in the first subframe and the first SC-FDMA symbol in the second subframe;

– if the PUCCH uses a normal PUCCH format, a guard period is created by the UE not transmitting the first SC-FDMA symbols in the second subframe.

– If the UE retunes from a first narrowband carrying PUSCH to a second narrowband carrying PUCCH,

– a guard period is created by the UE not transmitting the last SC-FDMA symbols in the first subframe.

– For CEModeA, if the PUSCH is associated with C-RNTI or SPS C-RNTI and the higher layer parameter ce-pusch-maxBandwidth-config is set to 5 MHz,

– If the PUSCH resource allocation is within a 5 MHz wideband, the center frequency of the transmission bandwidth is the center frequency of the wideband;

– If the PUSCH resource allocation spans two 5 MHz widebands, the center frequency of transmission bandwidth is in the center of PUSCH resource allocation.

Furthermore, for BL/CE UEs configured with the higher layer parameter srs-UpPtsAdd, a guard period of at most SC-FDMA symbols is created for Tx-to-Tx frequency retuning between a first special subframe and a second uplink subframe for frame structure type 2 according to:

– If the UE retunes from a first narrowband carrying SRS in the last UpPTS symbol to a second narrowband carrying PUSCH,

– a guard period is created by the UE not transmitting the first SC-FDMA symbols in the second subframe.

– If the UE retunes from a first narrowband carrying SRS in the last but one UpPTS symbol, but not in the last UpPTS symbol, to a second narrowband carrying PUSCH,

– if , a guard period is created by the UE not transmitting the last UpPTS symbol in the first subframe;

– if , a guard period is created by the UE not transmitting the last UpPTS symbol in the first subframe and the first SC-FDMA symbol in the second subframe.

– If the UE retunes from a first narrowband carrying SRS to a second narrowband carrying PUCCH,

– if , a guard period is created by the UE not transmitting the last UpPTS symbol in the first subframe;

– if , a guard period is created by the UE not transmitting the last UpPTS symbol in the first subframe and the first SC-FDMA symbol in the second subframe.

For , and for SRS transmission in a special subframe, a BL/CE UE is not expected to be configured with a first SRS transmission in symbol l and a second SRS transmission in any of symbols if the first SRS transmission and the second SRS transmission use different narrowbands.