Coded modulation with unequal error protection
First Claim
1. A method comprising the steps ofencoding a first group of data elements to generate a first expanded group of data elements,identifying one of a plurality of supersymbols of a predetermined channel symbol constellation in response to the first expanded group of data elements, each supersymbol being comprised of a respective plurality of symbols of the constellation,selecting an individual one of the symbols of the identified supersymbol at least in response to a second group of data elements, andapplying to a communication channel a signal representing the selected symbol,the minimum distance between at least ones of the symbols of at least one of the supersymbols being the same as the minimum distance between the symbols of the constellation as a whole.
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Accused Products
Abstract
Digital signals, such as digitized television signals, are subjected to a source coding step in which a class of "most important" data elements represents a proportionately greater amount of the information to be communicated than the rest of the data elements. This is followed by a constellation mapping step which is carried out in such a way that those data elements have a lower probability of being erroneously detected at the receiver than the others. The constellation mapping step uses coded modulation in order to provide enhanced noise immunity for the "most important" data element class.
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Citations
35 Claims
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1. A method comprising the steps of
encoding a first group of data elements to generate a first expanded group of data elements, identifying one of a plurality of supersymbols of a predetermined channel symbol constellation in response to the first expanded group of data elements, each supersymbol being comprised of a respective plurality of symbols of the constellation, 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 at least ones of the symbols of at least one of the supersymbols being the same as the minimum distance between the symbols of the constellation as a whole.
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8. 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
encoding m of the bits of one of the groups to generate an expanded 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, 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 of each supersymbol being the same as the minimum distance between the symbols of the constellation as a whole. - View Dependent Claims (9, 10, 11, 12, 13, 14)
- m,
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15. 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) encoding m of the bits of one of the groups using a first predetermined code to generate an expanded 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 of said constellation assigned thereto and the minimum distance between the symbols of each supersymbol being the same as the minimum distance between the symbols of the constellation as a whole;
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. - View Dependent Claims (16, 17, 18)
- m;
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19. Apparatus for channel coding first and second streams of data elements, said apparatus comprising
means for encoding said first stream of data elements to generate a first expanded stream of data elements, means for identifying a sequence of supersymbols of a predetermined channel symbol constellation in response to the first expanded stream of data elements, means for selecting an individual one of the symbols of each supersymbol of said sequence at least in response to said second stream of data elements, and means for applying to a communication channel a signal representing the selected symbols, the minimum distance between at least ones of the symbols of at least one of the supersymbols being the same as the minimum distance between the symbols of the constellation as a whole.
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26. Apparatus operative during each of a succession of symbol intervals for channel coding respective groups of m+k data bits, said apparatus comprising,
means for encoding m of the bits of one of the groups to generate an expanded 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 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 of each supersymbol being the same as the minimum distance between the symbols of the constellation as a whole. - View Dependent Claims (27, 28, 29, 30, 31, 32)
- m,
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33. An arrangement for use in a receiver which receives intelligence communicated to said receiver by a transmitter, said transmitter including apparatus for a) encoding a first stream of the data elements using a first predetermined code to generate a first expanded stream of data elements;
- b) identifying a sequence of supersymbols of a predetermined channel symbol constellation in response to the first expanded stream of data elements, the minimum distance between at least ones of the symbols of at least one of the supersymbols being the same as the minimum distance between the symbols of the constellation as a whole;
c) encoding a second stream of data elements using a second predetermined code to generate a second expanded stream of data elements;
d) selecting an individual one of the symbols of each supersymbol of said sequence at least as a function of the second expanded stream of data elements; and
d) means for applying to a communication channel a signal representing the selected symbols,said arrangement comprising means for receiving the signal from the communication channel, and means for carrying out a maximum likelihood decoding operation on the received signal to recover said first stream of data elements and for carrying out a second maximum likelihood decoding operation on the received signal to recover said second stream of data elements. - View Dependent Claims (34, 35)
- b) identifying a sequence of supersymbols of a predetermined channel symbol constellation in response to the first expanded stream of data elements, the minimum distance between at least ones of the symbols of at least one of the supersymbols being the same as the minimum distance between the symbols of the constellation as a whole;
Specification