Multiplexed coded modulation with unequal error protection
AssigneeAT&T Bell Laboratories
InventorsHong Y. Chung, Jin-Der Wang, Lee-Fang Wei
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Abstract
Unequal error protection is provided for an HDTV signal by separately coding each one of the classes of information in the HDTV signal by using a conventional coded modulation scheme and then time-division-multiplexing the various coded outputs for transmission. In particular, each class of information is separately coded by a 4-dimensional 8-state trellis code and a uniformly-spaced (QAM) signal constellation.
Claims32
A method for processing an information signal, the information signal being comprised of a plurality of classes of information, the method comprising the steps of:
- separately coding each one of the plurality of classes of information using a separate coded modulation scheme to provide a coded output, such that one of the plurality of classes of information has more error protection than the remaining ones of the plurality of classes of information, where each one of the plurality of coded outputs comprises a plurality of signal points taken from a signal point constellation and where the signal point constellation of at least one of the coded modulation schemes is different from the signal point constellations of the remaining coded modulation schemes;
- and
- multiplexing the plurality of coded outputs for transmission.
A method for providing unequal error protection for an information signal, the information signal being comprised of a plurality of classes of information, the method comprising the steps of:
- assigning each one of the plurality of classes of information to a coded modulation scheme such that at least one of the plurality of classes of information is assigned to a different coded modulation scheme than the remaining ones of the plurality of classes of information;
- assigning a time interval to each one of the plurality of coded modulation schemes such that at least one of the plurality of coded modulation schemes is assigned to a different time interval than the remaining ones of the plurality of coded modulation schemes;
- and
- separately coding each one of the plurality of classes of information using the assigned coded modulation scheme in the assigned time interval to provide a coded output for transmission such that at least one of the plurality of classes of information has more error protection than the remaining ones of the plurality of classes of information;
- where each one of the coded outputs comprises a plurality of signal points taken from a signal point constellation and where the signal point constellation of at least one of the coded modulation schemes is different from the signal point constellations of the remaining coded modulation schemes.
Apparatus for processing an information signal, the information signal being comprised of a plurality of classes of information, the apparatus being comprised of:
- source encoding means responsive to the information signal for providing the plurality of classes of information;
- coding means responsive to the plurality of classes of information for separately coding each one of the plurality of classes of information using a separate coded modulation scheme to provide a coded output for each one of the plurality of classes of information such that at least one of the plurality of classes of information has more error protection then the remaining ones of the plurality of classes of information, where each one of the coded outputs comprises a plurality of signal points taken from a signal point constellation and where the signal point constellation of at least one of the coded modulation schemes is different from the signal point constellations of the remaining coded modulation schemes;
- and
- means for multiplexing the plurality of coded outputs for transmission.
Apparatus for decoding a received signal, the received signal representing a stream of signal points, the apparatus being comprised of:
- means for demultiplexing the stream of signal points to provide a plurality of coded outputs, where each one of the plurality of coded outputs comprises a portion of the signal points from the stream of signal points and represents a class of information wherein one said coded outputs provides more error protection to its class of information than the remainder of said coded outputs to their classes of information;
- a plurality of means for decoding, where each one of the plurality of means for decoding decodes one of the plurality of coded outputs to provide one of the plurality of classes of information;
- and
- means for source decoding the plurality of classes of information to provide an information signal.
Dependencies are inferred from the claim text.