Patent ID: 9231705
Filing Date: 2016-01-05
CPC Classification: H04B,H04L

Claim Text:
1. A transmitter for generating a composite modulated signal from first and second independent information-containing signals for transmission over a communications link to a remote receiver where the first and second information-containing signals are to be reconstructed, the transmitter comprising: (a) a first information-containing signal source characterized by a first data rate and encoding onto a first signal constellation symbols of the first information-containing signal according to a first modulation scheme, the first modulation scheme mapping each one of the symbols of the first signal onto a corresponding one of a plurality of constellation points of the first signal constellation, each one of the constellation points of the first signal constellation representing a corresponding one of a first plurality of symbols employed in the first signal; (b) a second information-containing signal source characterized by a second data rate, lower than the first data rate, and encoding onto a second signal constellation symbols of the second information-containing signal according to a second modulation scheme, the second modulation scheme mapping each one of the symbols of the second signal onto a corresponding one of a plurality of constellation points of the second signal constellation, each one of the constellation points of the second signal constellation representing a corresponding one of a second plurality of symbols employed in the second signal; and (c) a processor operatively coupled to the first and second signal sources and arranged to encode onto a composite signal constellation the symbols of the first and second signals according to a composite modulation scheme, wherein the processor is arranged so that: (d) the composite signal constellation includes all constellation points of the first signal constellation except for one omitted constellation point, the omitted constellation point corresponding to a designated carrier symbol among the first plurality of symbols; (e) the composite signal constellation includes, at a location of the omitted constellation point, a scaled replica of the second signal constellation; (f) the composite modulation scheme (i) maps each one of the symbols of the first signal, except for the designated carrier symbol, onto a corresponding one of the constellation points of the first signal constellation included in the composite signal constellation, (ii) maps the designated carrier symbol of the first signal onto one of the constellation points of the replica of the second signal constellation included in the composite signal constellation, and (iii) maps each one of the symbols of the second signal onto a corresponding one of the constellation points of the replica of the second signal constellation included in the composite signal constellation; (g) each one of the constellation points of the first signal constellation included in the composite signal constellation represents a corresponding one of the first plurality of symbols, except for the designated carrier symbol; and (h) each symbol of the second signal is mapped onto the corresponding constellation point of the replica of the second signal constellation only when the designated carrier symbol of the first signal is encoded onto the composite signal constellation, so that each one of the constellation points of the replica of the second signal constellation represents both (i) a corresponding one of the second plurality of symbols and (ii) the designated carrier symbol of the first plurality of symbols.