Viterbi decoder block decoding - Trellis termination and tail biting
Author: Xilinx

Data encoded in this way generally is decoded with a Viterbi decoder, which operates by constructing a trellis of state probabilities and branch metrics. The transmitted data is often terminated with a number of zeros to force the encoder back to the zero state. This allows the decoder to start decoding from a known state, however, extra symbols have to be transmitted over the channel.