Coded modulation with unequal error protection
First Claim
1. Apparatus for channel coding successive groups of data elements, said apparatus comprisingredundancy coding means for redundancy encoding a first group of data elements to generate a first redundancy coded group of data elements and for identifying one of a plurality of supersymbols of a predetermined channel symbol constellation in response to the first redundancy coded group of data elements, each supersymbol being comprised of a respective plurality of symbols forming a subset of the constellation, andmeans for selecting an individual one of the symbols of the identified supersymbol at least in response to a second group of data elements, and for applying to a communication channel a signal representing the selected symbol,the minimum distance between the symbols within at least one of the supersymbols being a) less than the maximum intrasubset distance for said constellation and b) greater than the minimum distance between the symbols of the constellation as a whole, and said at least one supersymbol having at least two symbols in at least one quadrant of the constellation.
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Accused Products
Abstract
Digital signals, such as digitized television signals, are subjected to a source coding step followed by a channel mapping step. The source coding step causes the signal to be represented by first and second data streams. The first stream carries data regarded as more important and the second carries data regarded as less important. In the channel mapping step, the mapping is such that the data elements of the various data streams have differing probabilities of being erroneously detected at the receiver. The channel mapping step includes at least one multi-level coding step. The signal constellations used in the channel mapping step are partitioned into supersymbols, in which the distance between the symbols of at least ones of the supersymbols is less than a parameter referred to as the maximum intra-subset distance (MID). Additionally, in some constellations, the minimum distance between at least ones of the symbols of at least one of the supersymbols is greater than the minimum distance between the symbols of the constellation as a whole while, again, still being less than the MID. The first data stream is used to identify a sequence of supersymbols, while the second data stream is used to select particular symbols from the identified supersymbols.
72 Citations
17 Claims
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1. Apparatus for channel coding successive groups of data elements, said apparatus comprising
redundancy coding means for redundancy encoding a first group of data elements to generate a first redundancy coded group of data elements and for identifying one of a plurality of supersymbols of a predetermined channel symbol constellation in response to the first redundancy coded group of data elements, each supersymbol being comprised of a respective plurality of symbols forming a subset of the constellation, and means for selecting an individual one of the symbols of the identified supersymbol at least in response to a second group of data elements, and for applying to a communication channel a signal representing the selected symbol, the minimum distance between the symbols within at least one of the supersymbols being a) less than the maximum intrasubset distance for said constellation and b) greater than the minimum distance between the symbols of the constellation as a whole, and said at least one supersymbol having at least two symbols in at least one quadrant of the constellation.
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6. Apparatus for channel coding successive groups of m+k data bits associated with respective symbol intervals, said apparatus comprising
means for redundancy encoding during each said interval m of the bits of one of the groups to generate a redundancy coded group of r bits, r> - m,
means for identifying a particular one of 2r supersymbols of a predetermined channel symbol constellation as a function of the values of said r bits, each of said supersymbols being comprised of a plurality of symbols forming a subset of said constellation, and means for generating a signal representing a selected one of the channel symbols of the identified one supersymbol, the selection being performed as a function of the values of the other k bits of said one group, the minimum distance between the symbols within at least one of the supersymbols being a) less than the maximum intrasubset distance for said constellation and b) greater than the minimum distance between the symbols of the constellation as a whole, and said at least one supersymbol having at least two symbols in at least one quadrant of said constellation. - View Dependent Claims (7, 8, 9, 10)
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11. Apparatus for use in a receiver which receives intelligence communicated to said receiver by a transmitter, said transmitter being adapted to channel code successive groups of m+k data bits associated with respective symbol intervals via the steps, performed for each said interval, of a) redundancy encoding m of the bits of one of the groups using a first predetermined code to generate a redundancy coded group of r bits, r>
- m;
b) identifying a particular one of 2r supersymbols of a predetermined channel symbol constellation as a function of the values of said r bits, each of said supersymbols being comprised of a plurality of symbols forming a subset of said constellation assigned thereto and the minimum distance between the symbols within at least one of the supersymbols being i) less than the maximum intrasubset distance for said constellation and ii) greater than the minimum distance between the symbols of the constellation as a whole, and said at least one supersymbol having at least two symbols in at least one quadrant of the constellation;
c) generating a signal representing a selected one of the channel symbols of the identified one supersymbol, the selection being performed as a function of the values of the other k bits of said one group; and
d) communicating said signal to said receiver over a communication channel;said apparatus comprising means for receiving said signal from said channel, and means for recovering said intelligence from the received signal, said recovering being carried out in response to information stored in said receiver about said first predetermined code, about said constellation, and the manner in which said symbols are assigned to their respective supersymbols. - View Dependent Claims (12, 13, 14)
- m;
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15. A method comprising the steps of
redundancy encoding a first group of data elements to generate a first redundancy coded group of data elements, identifying one of a plurality of supersymbols of a predetermined channel symbol constellation in response to the first redundancy coded group of data elements, each supersymbol being comprised of a respective plurality of symbols of the constellation forming a subset, selecting an individual one of the symbols of the identified supersymbol at least in response to a second group of data elements, and applying to a communication channel a signal representing the selected symbol, the minimum distance between the symbols within at least one of the supersymbols being a) less than the maximum intrasubset distance for said constellation and b) greater than the minimum distance between the symbols of the constellation as a whole, and said at least one supersymbol having at least two symbols in at least one quadrant of said constellation.
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16. A method of channel coding successive groups of m+k data bits associated with respective symbol intervals, said method comprising the steps, performed for each said interval, of
redundancy encoding m of the bits of one of the groups to generate a redundancy coded group of r bits, r> - m,
identifying a particular one of 2r supersymbols of a predetermined channel symbol constellation as a function of the values of said r bits, each of said supersymbols being comprised of a plurality of symbols of said constellation forming a subset, and generating a signal representing a selected one of the channel symbols of the identified one supersymbol, the selection being performed as a function of the values of the other k bits of said one group, the minimum distance between the symbols within at least one of the supersymbols being a) less than the maximum intrasubset distance for said constellation and b) greater than the minimum distance between the symbols of the constellation as a whole, and said at least one supersymbol having at least two symbols in at least one quadrant of said constellation.
- m,
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17. A method for use in a receiver which receives intelligence communicated to said receiver by a transmitter, said transmitter being adapted to channel code successive groups of m+k data bits associated with respective symbol intervals via the steps, performed for each said interval, of a) redundancy encoding m of the bits of one of the groups using a first predetermined code to generate a redundancy coded group of r bits, r>
- m;
b) identifying a particular one of 2r supersymbols of a predetermined channel symbol constellation as a function of the values of said r bits, each of said supersymbols being comprised of a plurality of symbols forming a subset of said constellation assigned thereto and the minimum distance between the symbols within at least one of the supersymbols being i) less than the maximum intrasubset distance for said constellation and ii) greater than the minimum distance between the symbols of the constellation as a whole, and said at least one supersymbol having at least two symbols in at least one quadrant of said constellation;
c) generating a signal representing a selected one of the channel symbols of the identified one supersymbol, the selection being performed as a function of the values of the other k bits of said one group; and
d) communicating said signal to said receiver over a communication channel;said method comprising the steps of receiving said signal from said channel, and recovering said intelligence from the received signal, said recovering being carried out in response to information stored in said receiver about said first predetermined code, about said constellation, and the manner in which said symbols are assigned to their respective supersymbols.
- m;
Specification