Table of Contents

## How does Viterbi decoder work?

A Viterbi decoder uses the Viterbi algorithm for decoding a bitstream that has been encoded using a convolutional code or trellis code. There are other algorithms for decoding a convolutionally encoded stream (for example, the Fano algorithm).

## What is Viterbi decoding in digital communication?

The Viterbi algorithm is based on the Maximum-Likelihood decoding technique. The main purpose of the decoder is to select the code word with the minimum distance between the received signal and the code word. The Viterbi algorithm can use either hard or soft decisions.

**What is the purpose of the Viterbi algorithm?**

The purpose of the Viterbi algorithm is to make an inference based on a trained model and some observed data. It works by asking a question: given the trained parameter matrices and data, what is the choice of states such that the joint probability reaches maximum?

**What is difference between sequential decoding and Viterbi decoding?**

Sequential decoding offers the advantage that its computational complexity is independent of the encoder constraint length. This is in contrast to Viterbi decoding in which the computational complexity increases exponentially with the encoder constraint length.

### Is Viterbi algorithm recursive?

Abstrucf-The Viterbi algorithm (VA) is a recursive optimal solu- tion to the problem of estimating the state sequence of a discrete- time finite-state Markov process observed in memoryless noise.

### Is Viterbi algorithm greedy?

The Viterbi algorithm is not a greedy algorithm. It performs a global optimisation and guarantees to find the most likely state sequence, by exploring all possible state sequences. An example of a greedy algorithm is the one for training a CART.

**What is traceback depth?**

The traceback depth influences the decoding delay. The decoding delay is the number of zero symbols that precede the first decoded symbol in the output. For the continuous operating mode, the decoding delay is equal to the number of traceback depth symbols.

**How do turbo codes work?**

Turbo codes are a much more developed way of integrating information redundancy. They are based on the transmission of the initial message in three copies. The first copy is the raw, non-encoded information. The second is modified by encoding each bit of information using an algorithm shared by the coder and decoder.

#### What are the three basic problems of Hmms?

HMM provides solution of three problems : evaluation, decoding and learning to find most likelihood classification.

#### Where are convolutional codes used?

The convolutional coding has been one of the most widely used error corrections in digital wireless communication. Therefore, the Viterbi decoding algorithm must be implemented efficiently in a pipelined/systolic fashion.

**Which method is used most for convolutional decoding?**

The most popular decoding algorithm for convolutional codes is perhaps the Viterbi algorithm. Although widely adopted in practice, the Viterbi algorithm suffers from a high decoding complexity for convolutional codes with long constraint lengths.

**What is a Viterbi trellis?**

The Viterbi algorithm finds the maximum-likelihood code sequence x(D) using a diagram called a trellis. In Section 4.1, we saw that a convolutional encoder can be represented by a state diagram. The trellis diagram shows every possible sequence of state transitions of the state diagram.