5.5.3 Sounding reference signal

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

Two types of sounding reference signals can be configured:

– basic sounding reference signal, supporting periodic or aperiodic transmission

– additional sounding reference signal, supporting aperiodic transmission only

Basic SRS corresponds to either SRS trigger type 0 or type 1 in clause 8.2 of [4]. Additional SRS corresponds to SRS trigger type 2 in clause 8.2 of [4].

5.5.3.1 Sequence generation

5.5.3.1.1 Sequence generation for basic SRS

The sounding reference signal sequence is defined by clause 5.5.1, where is the sequence-group number defined in clause 5.5.1.3, is the base sequence number defined in clause 5.5.1.4, and . The cyclic shift of the sounding reference signal is given as

,

where is configured separately for periodic and each configuration of aperiodic sounding by the higher-layer parameters cyclicShift and cyclicShift-ap, respectively, for each UE and is the number of antenna ports used for sounding reference signal transmission. The parameter if , otherwise . The parameter is given by the higher layer parameter transmissionCombNum if configured, otherwise .

5.5.3.1.2 Sequence generation for additional SRS

The sounding reference signal is defined by clause 5.5.3.1.1 with the following exceptions

– is given by the higher-layer parameter srs-CyclicShiftAdd

– is given by the higher-layer parameter srs-AntennaPortAdd

– is given by the higher-layer parameter srs-TransmissionCombNumAdd

– the function in clause 5.5.1.3 is given by

where is the SC-FDMA symbol index within the slot and is the number of SC-FDMA symbols per slot

– the function in clause 5.5.1.4 is given by

5.5.3.2 Mapping to physical resources

5.5.3.2.1 Mapping to physical resources for basic SRS

The sequence shall be multiplied with the amplitude scaling factor in order to conform to the transmit power specified in clause 5.1.3.1 in TS 36.213 [4], and mapped in sequence starting with to resource elements on antenna port according to

where is the number of antenna ports used for sounding reference signal transmission and the relation between the index and the antenna port is given by Table 5.2.1-1. The set of antenna ports used for sounding reference signal transmission is configured independently for periodic and each configuration of aperiodic sounding. The quantity is the frequency-domain starting position of the sounding reference signal and for and is the length of the sounding reference signal sequence defined as

where is given by Table 5.5.3.2-1 through Table 5.5.3.2-4 for each uplink bandwidth . The cell-specific parameter srs-BandwidthConfig, and the UE-specific parameter srs-Bandwidth, are given by higher layers. For UpPTS, shall be reconfigured to if this reconfiguration is enabled by the cell-specific parameter srsMaxUpPts given by higher layers, otherwise if the reconfiguration is disabled ,where is a SRS BW configuration and is the set of SRS BW configurations from the Tables 5.5.3.2-1 to 5.5.3.2-4 for each uplink bandwidth , is the number of format 4 PRACH in the addressed UpPTS and derived from Table 5.7.1-4.

The frequency-domain starting position is defined by

where for normal uplink subframes is defined by

and for UpPTS by

The quantity is given by

where the relation between the index and the antenna port is given by Table 5.2.1-1, is given by the UE-specific parameter transmissionComb or transmissionComb-ap for periodic and each configuration of aperiodic transmission, respectively, provided by higher layers for the UE, and is frequency position index. The variable is equal to 0 for UpPTS in the first half frame and equal to 1 for UpPTS in the second half frame of a radio frame.

The frequency hopping of the sounding reference signal is configured by the parameter , provided by higher-layer parameter srs-HoppingBandwidth. Frequency hopping is not supported for aperiodic transmission, except for additional SRS. If frequency hopping of the sounding reference signal is not enabled (i.e., ), the frequency position index remains constant (unless re-configured) and is defined by where the parameter is given by higher-layer parameters freqDomainPosition and freqDomainPosition-ap for periodic and each configuration of aperiodic transmission, respectively. If frequency hopping of the sounding reference signal is enabled (i.e., ), the frequency position indexes are defined by

where is given by Table 5.5.3.2-1 through Table 5.5.3.2-4 for each uplink bandwidth ,

where regardless of the value on Table 5.5.3.2-1 through Table 5.5.3.2-4, and

counts the number of UE-specific SRS transmissions, where is UE-specific periodicity of SRS transmission defined in clause 8.2 of TS 36.213 [4], is SRS subframe offset defined in Table 8.2-2 of TS 36.213 [4] and is the maximum value of for a certain configuration of SRS subframe offset.

The sounding reference signal shall be transmitted in the last symbol of the uplink subframe.

Table 5.5.3.2-1: and , , values for the uplink bandwidth of

SRS bandwidth configuration

SRS-Bandwidth

SRS-Bandwidth

SRS-Bandwidth

SRS-Bandwidth

0

36

1

12

3

4

3

4

1

1

32

1

16

2

8

2

4

2

2

24

1

4

6

4

1

4

1

3

20

1

4

5

4

1

4

1

4

16

1

4

4

4

1

4

1

5

12

1

4

3

4

1

4

1

6

8

1

4

2

4

1

4

1

7

4

1

4

1

4

1

4

1

Table 5.5.3.2-2: and , , values for the uplink bandwidth of

SRS bandwidth configuration

SRS-Bandwidth

SRS-Bandwidth

SRS-Bandwidth

SRS-Bandwidth

0

48

1

24

2

12

2

4

3

1

48

1

16

3

8

2

4

2

2

40

1

20

2

4

5

4

1

3

36

1

12

3

4

3

4

1

4

32

1

16

2

8

2

4

2

5

24

1

4

6

4

1

4

1

6

20

1

4

5

4

1

4

1

7

16

1

4

4

4

1

4

1

Table 5.5.3.2-3: and , , values for the uplink bandwidth of

SRS bandwidth configuration

SRS-Bandwidth

SRS-Bandwidth

SRS-Bandwidth

SRS-Bandwidth

0

72

1

24

3

12

2

4

3

1

64

1

32

2

16

2

4

4

2

60

1

20

3

4

5

4

1

3

48

1

24

2

12

2

4

3

4

48

1

16

3

8

2

4

2

5

40

1

20

2

4

5

4

1

6

36

1

12

3

4

3

4

1

7

32

1

16

2

8

2

4

2

Table 5.5.3.2-4: and, , values for the uplink bandwidth of

SRS bandwidth configuration

SRS-Bandwidth

SRS-Bandwidth

SRS-Bandwidth

SRS-Bandwidth

0

96

1

48

2

24

2

4

6

1

96

1

32

3

16

2

4

4

2

80

1

40

2

20

2

4

5

3

72

1

24

3

12

2

4

3

4

64

1

32

2

16

2

4

4

5

60

1

20

3

4

5

4

1

6

48

1

24

2

12

2

4

3

7

48

1

16

3

8

2

4

2
5.5.3.2.2 Mapping to physical resources for additional SRS

An additional SRS spans one or more SC-FDMA symbols in the time domain, where

– the starting SC-FDMA symbol within the subframe is given by the higher-layer parameter srs-StartPosAdd;

– the duration in number of SC-FDMA symbols, including potential guard symbols, is given by the higher-layer parameter srs-DurationAdd.

Mapping to physical resources shall be done according to clause 5.5.3.2.1 with the following exceptions:

– frequency hopping between SC-FDMA symbols is supported and if a UE is configured by higher layer parameter srs-GuardSymbolFH-Add, a guard symbol is added between every frequency hop;

– antenna switching within a subframe is supported and if a UE is configured by higher layer parameter srs-GuardSymbolAS-Add, a guard symbol is added between every antenna switching;

– where is the additional SRS transmission number not counting guard symbol(s) within the subframe with corresponding to the starting SC-FDMA symbol , and is the repetition factor given by the higher-layer parameter srs-RepNumAdd;

– is given by the higher-layer parameter srs-BandwidthAdd;

– is given by the higher-layer parameter srs-HoppingBandwidthAdd;

– is the number of frequency hops with the same antenna/antenna pair for additional SRS, derived from if antenna switching is not configured for additional SRS, and from if antenna switching is configured for additional SRS, where is the repetition factor given by the higher-layer parameter srs-RepNumAdd, is the number of antenna switches for additional SRS defined in 8.2 of [4], is the guard-symbol configuration for antenna switching given by the higher-layer parameter srs-GuardSymbolAS, is the guard symbol configuration for frequency hopping given by the higher-layer parameter srs-GuardSymbolFH, and is given by the higher-layer parameter srs-DurationAdd;

– is given by the higher-layer parameter srs-FreqDomainPosAdd;

– is given by the higher-layer parameter srs-AntennaPortAdd;

– is given by the higher-layer parameter srs-CyclicShiftAdd;

– is given by the higher-layer parameter srs-TransmissionCombNumAdd;

– is given by the higher-layer parameter srs-TransmissionCombAdd.

5.5.3.3 Sounding reference signal subframe configuration

The cell-specific subframe configuration period and the cell-specific subframe offset for the transmission of sounding reference signals are listed in Tables 5.5.3.3-1 and 5.5.3.3-2, for frame structures type 1 and 2 respectively, where the parameter srs-SubframeConfig is provided by higher layers. Sounding reference signal subframes are the subframes satisfying. For frame structure type 2, a sounding reference signal is transmitted only in uplink subframes or UpPTS.

Table 5.5.3.3-1: Frame structure type 1 sounding reference signal subframe configuration

srs-SubframeConfig

Binary

Configuration Period

(subframes)

Transmission offset

(subframes)

0

0000

1

{0}

1

0001

2

{0}

2

0010

2

{1}

3

0011

5

{0}

4

0100

5

{1}

5

0101

5

{2}

6

0110

5

{3}

7

0111

5

{0,1}

8

1000

5

{2,3}

9

1001

10

{0}

10

1010

10

{1}

11

1011

10

{2}

12

1100

10

{3}

13

1101

10

{0,1,2,3,4,6,8}

14

1110

10

{0,1,2,3,4,5,6,8}

15

1111

reserved

reserved

Table 5.5.3.3-2: Frame structure type 2 sounding reference signal subframe configuration

srs-SubframeConfig

Binary

Configuration Period

(subframes)

Transmission offset

(subframes)

0

0000

5

{1}

1

0001

5

{1, 2}

2

0010

5

{1, 3}

3

0011

5

{1, 4}

4

0100

5

{1, 2, 3}

5

0101

5

{1, 2, 4}

6

0110

5

{1, 3, 4}

7

0111

5

{1, 2, 3, 4}

8

1000

10

{1, 2, 6}

9

1001

10

{1, 3, 6}

10

1010

10

{1, 6, 7}

11

1011

10

{1, 2, 6, 8}

12

1100

10

{1, 3, 6, 9}

13

1101

10

{1, 4, 6, 7}

14

1110

reserved

reserved

15

1111

reserved

reserved