Binary Cyclic Decoder

Decode systematic cyclic code to recover binary vector data

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Libraries:
Communications Toolbox / Error Detection and Correction / Block

Description

The Binary Cyclic Decoder block recovers a message vector from the codeword vector of a binary systematic cyclic code. For more information, see Binary Cyclic Coding.

For proper decoding, the parameter values in this block must match those in the corresponding Binary Cyclic Encoder block.

Examples

Create Binary Cyclic Code in Binary Format Using Simulink

This example shows how to model a simple encoder and decoder using appropriate vector lengths for the code and message.

The cm_binary_cyclic model includes these blocks:

• Bernoulli Binary Generator block with Samples per frame set to 4 to match the binary cyclic encoder message length

• Binary Cyclic Encoder block with default parameter values

• Binary Cyclic Decoder block with default parameter values

• Error Rate Calculation block with Output data set to Port

• Display block connected to the output port of the Error Rate Calculation block

To display the vector length of signals in the model, go to Debug > Diagnostics > Information Overlays > Signals and select Signal Dimensions. The connector lines show the signal attributes. To compile the model, press Ctrl+D. Run the model to display the error rate statistics.

Ports

Input

In — Encoded message

binary column vector

Encoded message, specified as a binary column vector signal containing N elements. The Codeword length N parameter determines N. This port is unnamed on the block mask.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean

Output

Out — Decoded message

column vector

Decoded message, returned as a column vector signal containing K elements and having the same data type as the input port, In. The Message length K, or generator polynomial parameter determines K. This port is unnamed on the block mask.

Parameters

To edit block parameters interactively, use the Property Inspector. From the Simulink^® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Codeword length N — Codeword length

7 (default) | positive integer

Codeword length, specified as a positive integer. For more information, see Binary Cyclic Coding. The codeword length is also the input vector length.

Message length K, or generator polynomial — Message length of systematic cyclic code

4 (default) | positive integer | binary vector | polynomial character vector

Message length of the systematic cyclic code or an (N–K)-degree generator polynomial, where N is the Codeword length N parameter value.

• When this parameter is an integer, the block uses the output of cyclpoly(N,K,'min') as the generator polynomial for the code.

• When this parameter is a vector, the vector must represent an (N–K)-degree generator polynomial.

For more information, see Binary Cyclic Coding.

Block Characteristics

Data Types	Boolean | double | fixed point | integer | single
Multidimensional Signals	no
Variable-Size Signals	no

More About

Binary Cyclic Coding

For cyclic codes, the codeword length N must have the form 2^M–1, where M is an integer greater than or equal to 3. Cyclic codes have algebraic properties that allow a generator polynomial to determine the coding process completely. This generator polynomial is a degree-(N–K) divisor of the polynomial x^N–1.

You can determine the systematic cyclic coding scheme in one of two ways:

• To create an [N,K] code, enter N and K as the first and second parameters, respectively. The algorithm uses cyclpoly(N,K,'min') to compute the appropriate generator polynomial.

• To create a code with codeword length N and a particular degree-(N–K) binary generator polynomial, enter N as the first parameter and a binary vector as the second parameter. The vector must represent the generator polynomial by listing its coefficients in order of ascending exponents. To create cyclic generator polynomials in binary vector form, use the cyclpoly function. You can also specify the polynomial as a character vector, for example, 'D^3 + D + 1'. For more information, see Representation of Polynomials in Communications Toolbox.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a