Apparatus and method for processing a Quadrature Amplitude Modulated (QAM) signal

A receiver for receiving a Quadrature Amplitude Modulation (QAM) modulated bitstream containing phasor points represented in a QAM constellation, said receiver comprising:

• a first decoder for decoding the QAM modulated bitstream with respect to a Quaternary Phase Shift Keying (QPSK) constellation to produce a decoded bitstream;
• a second decoder, coupled to said first decoder, for decoding the QAM modulated bitstream with respect to a QPSK constellation within a subset region of the QAM constellation defined by said first decoder;
• a delay, coupled to said second decoder, for applying a delay;
• and
• a reencoder, coupled to said first decoder, for generating information relating to said subset region defined by said first decoder.

A receiver for receiving a Quadrature Amplitude Modulation (QAM) modulated bitstream containing phasor points represented in a QAM constellation, said receiver comprising:

• a first decoder for decoding the QAM modulated bitstream with respect to a Quaternary Phase Shift Keying (QPSK) constellation to produce a decoded bitstream;
• a second decoder, coupled to said first decoder, for decoding the QAM modulated bitstream with respect to a QPSK constellation within a subset region of the QAM constellation defined by said first decoder;
• and
• an outer decoder, coupled said first decoder, for decoding said decoded bitstream from said first decoder.

A method of decoding a Quadrature Amplitude Modulation (QAM) signal having a plurality of QAM phasor points represented in a QAM constellation diagram having "n" hierarchical levels of Quaternary Phase Shift Keying (QPSK) constellation, said method comprising the steps of:

• a) using a first decoder to decode a first hierarchical level of the QAM signal with respect to a QPSK constellation to produce a decoded signal;
• b) using a second decoder to decode a second hierarchical level of the QAM signal with respect to a QPSK constellation, within a subset region of the QAM constellation defined by said first decoder;
• wherein
• additional decoders are used to decode additional hierarchical levels of the QAM signal.

A method of decoding a Quadrature Amplitude Modulation (QAM) signal having a plurality of QAM phasor points represented by a QAM constellation diagram having "n" hierarchical levels of Quaternary Phase Shift Keying (QPSK) constellation, said method comprising the steps of:

• a) using a first decoder to decode a first hierarchical level of the QAM signal with respect to a QPSK constellation to produce a decoded signal;
• and
• b) using a second decoder to decode a second hierarchical level of the QAM signal with respect to a QPSK constellation, within a subset region of the QAM constellation defined by said first decoder;
• further comprising the steps of:
• a1) applying a delay to the QAM signal;
• and
• a2) encoding said decoded signal from said first decoder to generate information relating to said subset region defined by said first decoder.

A method of decoding a Quadrature Amplitude Modulation (QAM) signal having a plurality of QAM phasor points represented by a QAM constellation diagram having "n" hierarchical levels of Quaternary Phase Shift Keying (QPSK) constellation, said method comprising the steps of:

• a) using a first decoder to decode a first hierarchical level of the QAM signal with respect to a QPSK constellation to produce a decoded signal;
• and
• b) using a second decoder to decode a second hierarchical level of the QAM signal with respect to a QPSK constellation, within a subset region of the QAM constellation defined by said first decoder;
• further comprising the step of:
• c) using a third decoder to decode said decoded signal from said first decoder.