To be able to characterize a convolutional code, we must characterize how the codeword generation depends both on the k input bits as well as the encoder status, which has 2K−1 possible values. One can find numerous methods to characterize convolutional codes, as well as a tree diagram, state diagram, and trellis diagram.The trellis diagram simplifies the tree representation by merging nodes in the tree in accordance with the same encoder state.