Implementation of Tail-bitten termination in a convolutional encoder

I'm trying to impelement a convolutional encoder with the structure as follows. The input u1 an u2 are Bernoulli binary.

The initial state S of the of the registers s1,s2,s3 is [0 0 0], and I want to run the encoder once, get the end state S' of s1,s2,s3, then set the end state S' as the initial state for the next convolutional encoder with the same structure.

Simulink applies a convolutional encoder block, with the input and output (ISt and FSt)to set and save the initial and end state of the registers.

But I have no idea how to set the parameters of Trellis structure, the structure in figure 3-12 seems not available to be set by using poly2trellis( )function.

[Xiaotian Yu]

I tried to build this structure, but I don't know how to set the initial state and save the final state of the delay block.

Answer 1

[Ganapathi Subramanian R]

Hi Xiaotian Yu,

It is my understanding that you are working with convolution encoder block and would like to know how to set the Trellis structure.

The ‘poly2trellis’ function is used to convert convolution code polynomials to trellis structure. Please refer to the below documentation for more information about ‘poly2trellis’ function.

https://www.mathworks.com/help/comm/ref/poly2trellis.html

Verifying the validity of the trellis structure can be done using the ‘istrellis’ function. Kindly refer to the below documentation for further information regarding ‘istrellis’ function.

https://www.mathworks.com/help/comm/ref/poly2trellis.html

Please refer the below documentation for further information regarding implementation of Tail Biting Convolutional Coding.

https://www.mathworks.com/help/comm/ug/tail-biting-convolutional-coding.html