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# ltePUCCH2DRS

PUCCH format 2 demodulation reference signal

## Syntax

• ``seq = ltePUCCH2DRS(ue,chs,ack)``
example
• ``````[seq,info] = ltePUCCH2DRS(ue,chs,ack)``````
example

## Description

example

````seq = ltePUCCH2DRS(ue,chs,ack)` returns a matrix containing demodulation reference signal (DRS) associated with PUCCH format 2 transmission, given a structure of UE-specific settings, a structure with channel transmission configuration settings, and hybrid ARQ (HARQ) indicator values, `ack`. ```

example

``````[seq,info] = ltePUCCH2DRS(ue,chs,ack)``` also returns a PUCCH information structure array, `info`.```

## Examples

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Generate PUCCH Format 2 DM-RS symbols for UE specific settings.

Initialize input configuration structures (`ue` and `chs`). Here no HARQ bits will be sent by inputting an empty `ack` vector. Generate the PUCCH Format 2 DM-RS symbols.

```ue.NCellID = 1; ue.NSubframe = 0; ue.CyclicPrefixUL = 'Normal'; ue.Hopping = 'Off'; chs.ResourceIdx = 0; chs.ResourceSize = 0; chs.CyclicShifts = 0; sym = ltePUCCH2DRS(ue,chs,[]); ```

Demonstrate Uplink Release 11 cooordinated multipoint (CoMP) operation. Intercell interference can be avoided by using a virtual cell identity for a potentially interfering UE in a neighboring cell.

Configuration for UE of interest, UE 1 in cell 1.

```ue1.NCellID = 1; ue1.NSubframe = 0; ue1.CyclicPrefixUL = 'Normal'; ue1.Hopping = 'Off'; chs1.ResourceIdx = 0; chs1.ResourceSize = 0; chs1.CyclicShifts = 0; ack1 = 0; ```

Configuration for interferer, UE 2 in cell 2.

```ue2.NCellID = 2; ue2.NSubframe = 0; ue2.CyclicPrefixUL = 'Normal'; ue2.Hopping = 'Off'; chs2.ResourceIdx = 1; chs2.ResourceSize = 0; chs2.CyclicShifts = 0; ack2 = 0; ```

Measure the interference between the DM-RS signals.

```interferenceNoCoMP = abs(sum(ltePUCCH2DRS(ue1,chs1,ack1).*conj(ltePUCCH2DRS(ue2,chs2,ack2)))) ```
```interferenceNoCoMP = 5.4903 ```

Reconfigure interferer for CoMP operation: use virtual cell identity equal to the cell identity for the UE of interest.

```ue2.NPUCCHID = ue1.NCellID; ```

Measure the interference between the DM-RS signals when using CoMP.

```interferenceUsingCoMP = abs(sum(ltePUCCH2DRS(ue1,chs1,ack1).*conj(ltePUCCH2DRS(ue2,chs2,ack2)))) ```
```interferenceUsingCoMP = 3.9627e-15 ```

Comparing the correlations between the DM-RS signals for two UEs with and without CoMP, `interferenceUsingCoMP` and `interferenceNoCoMP` respectively. Using CoMP, the interference is reduced to effectively zero.

Generate the PUCCH format 2 DM-RS sequences for two transmit antenna paths.

Initialize UE-specific and channel configuration structures. Provide an empty vector for the `ack`, indicating there are no HARQ bits for this PUCCH transmission. Generate PUCCH 2 DM-RS and information outputs.

```ue.NCellID = 1; ue.NSubframe = 0; ue.CyclicPrefixUL = 'Normal'; ue.Hopping = 'Off'; chs.ResourceIdx = [0 3]; chs.ResourceSize = 0; chs.CyclicShifts = 0; ack = []; [drsSeq,info] = ltePUCCH2DRS(ue,chs,ack); ```

Because there are two antennas, the DM-RS sequences are output as a two- column vector, and the `info` output structure contains two elements.

```drsSeq(1:10,:) size(info) ```
```ans = 0.5000 + 0.5000i 0.5000 + 0.5000i -0.1830 + 0.6830i -0.6830 - 0.1830i -0.1830 - 0.6830i 0.1830 + 0.6830i 0.5000 - 0.5000i -0.5000 - 0.5000i 0.6830 + 0.1830i 0.6830 + 0.1830i -0.1830 - 0.6830i 0.6830 - 0.1830i 0.5000 + 0.5000i -0.5000 - 0.5000i 0.1830 - 0.6830i -0.6830 - 0.1830i 0.6830 - 0.1830i 0.6830 - 0.1830i -0.5000 - 0.5000i 0.5000 - 0.5000i ans = 1 2 ```

View the contents of the two `info` structure elements.

```info(1) info(2) ```
```ans = struct with fields: Alpha: [1.0472 3.1416 1.5708 2.0944] SeqGroup: [1 1] SeqIdx: [0 0] NResourceIdx: [1 10] NCellCyclicShift: [193 89 101 234] Symbols: [1×4 double] OrthSeq: [2×2 double] ans = struct with fields: Alpha: [2.6180 4.7124 0 0.5236] SeqGroup: [1 1] SeqIdx: [0 0] NResourceIdx: [4 7] NCellCyclicShift: [193 89 101 234] Symbols: [1×4 double] OrthSeq: [2×2 double] ```

## Input Arguments

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UE-specific configuration settings, specified as a structure that can contain the following fields.

Parameter FieldRequired or OptionalValuesDescription
`NCellID`Required

Integer from 0 to 503

Physical layer cell identity

`NSubframe`Required

0 (default), nonnegative scalar integer

Subframe number

`CyclicPrefixUL`Optional

`'Normal'` (default), `'Extended'`

Cyclic prefix length

`Hopping`Optional

`'Off'` (default), `'Group'`

Frequency hopping method.

`NPUCCHID`Optional`NCellID` (default),

Integer from 0 to 503

PUCCH virtual cell identity. If this field is not present, `NCellID` is used as the identity.

Data Types: `struct`

PUCCH channel settings, specified as a structure that can contain the following fields.

Parameter FieldRequired or OptionalValuesDescription
`ResourceIdx`Optional

0 (default), integer from 0 to 1185 or vector of integers.

PUCCH resource indices which determine the physical resource blocks, cyclic shift, and orthogonal cover used for transmission. (${n}_{PUCCH}^{\left(2\right)}$). Define one index for each transmission antenna.

`ResourceSize`Optional

0 (default), integer from 0 to 98.

Size of resource allocated to PUCCH Format 2 (${N}_{RB}^{\left(2\right)}$)

`CyclicShifts`Optional

0 (default), integer from 0 to 7

Number of cyclic shifts used for format 1 in resource blocks (RBs) with a mixture of format 1 and format 2 PUCCH, specified as an integer from 0 to 7. (${N}_{cs}^{\left(1\right)}$)

Hybrid ARQ indicator values, specified as nonnegative integer vector. This vector is expected to be the block of bits b(0),...,b(Mbit–1) specified in TS 36.211 [1], Section 5.4.2. An Mbit value of 20, 21, or 22 corresponds to PUCCH format 2, 2a, or 2b, respectively, as described in TS 36.211 [1], Table 5.4-1.

Example: [ ] indicates that no HARQ are transmitted in the subframe.

## Output Arguments

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PUCCH format 2 DRS values, returned as a numeric matrix. The symbols for each antenna are in the columns of `seq`, with the number of columns determined by the number of PUCCH resource indices specified in `chs``.``ResourceIdx`.

 Note:   The standard does not support format 2a or 2b transmission with extended cyclic prefix. If the `ack` setting corresponds to format 2a or 2b transmission and extended cyclic prefix is set for `ue``.``CyclicPrefixUL`, the function returns an empty matrix for `seq`.

Data Types: `double`
Complex Number Support: Yes

PUCCH format 2 information, returned as a structure array with elements corresponding to each transmit antenna and containing these fields. When configured for format 2a or 2b transmission with extended cyclic prefix, the `info` structure contains all fields, but each field is empty.

Reference signal cyclic shift for each OFDM symbol, returned as a two-column vector. (α)

PUCCH base sequence group number for each slot, returned as two-column vector. (u)

PUCCH base sequence number for each slot, returned as two-column vector. (v)

PUCCH resource indices for each slot, returned as two-column vector. (n')

Cell-specific cyclic shift for each OFDM symbol, returned as vector. (${n}_{cs}^{cell}$)

Modulated data symbols, returned as a vector. There is one element for each OFDM symbol. (z)

Example: [0.7071 + 0.7071i,...]

Orthogonal sequence for each slot, returned as a 4-by-2 numeric matrix. ($\overline{w}$)

Example: [1.000 + 1.000i,...]

Data Types: `struct`

## References

[1] 3GPP TS 36.211. "Physical Channels and Modulation." 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA). URL: http://www.3gpp.org.