# Documentation

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# lteUCIDecode

PUCCH format 2, 2a, and 2b transmission UCI decoding

## Syntax

``ucibits = lteUCIDecode(cw,n)``

## Description

example

````ucibits = lteUCIDecode(cw,n)` returns a vector of decoded UCI bits, `ucibits`, resulting from decoding the soft bit column vector, `cw`, where the output vector, `ucibits`, is expected to contain `n` bits. `ucibits` is a column vector of CQI/PMI or RI bits (UCI), representing the CQI/PMI or RI information fields described in TS 36.212, Section 5.2.3.3 [1]. `n` must be between 1 and 13. The decoder uses a maximum likelihood approach assuming that `cw` has been demodulated using `ltePUCCH2Decode` whose input had already been equalized to best restore the originally transmitted complex values. If multiple decoded UCI bit vectors have a likelihood equal to the maximum, UCIBITS will be a matrix where each column represents one of the equally likely bit vectors ```

## Examples

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Decode UCI bits representing RI=3 using N=2 bits. According to TS 36.212, Table 5.2.2.6-6 this maps to the set of input bits `[1;0]`.

```cw = lteUCIEncode([1;0]) softBits = double(cw)/sqrt(2); decodedUciBits = lteUCIDecode(softBits, 2) ```
```cw = 20x1 int8 column vector 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 decodedUciBits = 2x1 logical array 1 0 ```

The decoded UCI bits match the input bits.

## Input Arguments

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Codeword of soft bits, specified as a numeric column vector.

Data Types: `logical` | `double`

Number of bits, specified as a scalar integer from 1 to 11.

Data Types: `double`

## Output Arguments

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Decoded UCI bits, returned as a logical column vector. UCI bits are CQI/PMI or RI information.

Data Types: `logical`

## References

[1] 3GPP TS 36.212. “Multiplexing and channel coding.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA). URL: http://www.3gpp.org.