Turbo coding is one of the great achievement in the
field of communication systems and signal processing. It is
embedded in most of the European standardizations for the
radio access networks of start-of-art cellular radio technologies.
A Turbo-Decoder consists of two soft-in soft-out component
decoders, which exchange information (soft-values) in an
iterative process. Turbo-Decoder can be implemented using
different algorithm, but Maximum A Posteriori decoding
algorithm (MAP) is high Bit Error Rate (BER) performance,
nearer to Shannon limit. However, decoding with a fixed
number of iterations may lead to excessive processing,
penalizing battery operated terminals while fewer iterations are
sometimes sufficient. It is necessary to stop the decoding
process at an appropriate moment to reduce the computational
time, latency and power dissipation. Sign difference ratio (SDR)
presents a simple and efficient criterion for stopping the
iteration process in turbo-decoding with a negligible
degradation of the error performance. In this paper MATLAB
simulated results of turbo decoder are implemented using MAP
decoder and it