Apparatus and method for decoding turbo TCM using coset mapping

A turbo TCM decoder, comprising:

• means for converting a received signal to signal bits of QPSK mode by using an I-axis coordinate and a Q-axis coordinate on a constellation of the received signal;
• means for performing a phase sector quantization on the received signal by using the I-axis coordinate and the Q-axis coordinate;
• means for determining coded data by decoding the signal bits of QPSK mode;
• means for delaying the quantized signal from the phase sector quantization means;
• and
• means for determining un-coded data by using the delayed quantized signal and the determined coded data,
• wherein a relation of the I-axis coordinate and the Q-axis coordinate with a phase of the received signal is determined by a rotational transformation using the phase of the received signal,
• wherein said rotational transformation using the phase of the received signal is determined by:
• x′=√{square root over (2)} cos(2(φ−φ))
• y′=√{square root over (2)} sin(2(φ−φ)),
• wherein x′ and y′ are coordinates of input symbols for converting the received signal to the signal bits of QPSK mode, φ is a phase rotation constant and φ is a phase of the received signal, and
• wherein said means for determining the coded data by decoding the signal bits of QPSK mode includes:
• a first decoding unit configured to decode the signal bits of QPSK mode;
• and
• a second decoding unit configured to decode an output of the first decoding unit.