Apparatus and method for trellis encoding data for transmission in digital data transmission systems

A process for Trellis encoding a plurality of payload bits into a constellation point, comprising:

• receiving a plurality of payload bits;
• convolutionally encoding a combination of said payload bits into one or more additional bits by applying said payload bits to different inputs of a convolutional encoder and also applying a modified bit to an input of said convolutional encoder, said modified bit being generated by exclusive-ORing one of said payload bits with an output bit from an intermediate stage of said convolutional encoder, said convolutional encoding step resulting in output of one or more additional bits;
• and
• mapping the combination of at least some of said payload bits in an unmodified state, said modified bit and said one or more additional bits into a constellation point, wherein said process for Trellis encoding is performed upon multiple pluralities of said payload bits successively, and wherein said step of convolutional encoding comprises introducing a certain dependency between successive constellation points generated from said successive plurality of payload bits such that only certain patterns or permissible sequences of constellation points are permitted, said patterns or permissible sequences capable of being modelled in a receiver's Viterbi decoder as a Trellis code.

A process for Trellis encoding a plurality of payload bits into a constellation point, comprising:

• receiving a plurality of payload bits;
• convolutionally encoding a combination of said payload bits into one or more additional bits by applying said payload bits to different inputs of a convolutional encoder and also applying a modified bit to an input of said convolutional encoder, said modified bit being generated by exclusive-ORing one of said payload bits with an output bit from an intermediate stage of said convolutional encoder, said convolutional encoding step resulting in output of one or more additional bits;
• and
• mapping the combination of at least some of said payload bits in an unmodified state, said modified bit and said one or more additional bits into a constellation point, wherein said step of mapping includes the steps of receiving a control signal that indicates whether a normal mode or a fallback mode is to be implemented wherein said normal mode maps said plurality of payload bits, said modified bit and said one or more additional bits into a constellation point in a constellation of points that is larger than a constellation of possible points would be if only the original payload bits were mapped into a constellation, and said fallback mode mapping said plurality of bits in an unmodified payload state, said modified bit and said one or more additional bits into a constellation point in a constellation of points that is larger than the constellation of points that are possible in said normal mode.

A process for Trellis encoding a plurality of payload bits into a constellation point, comprising:

• receiving a plurality of payload bits;
• convolutionally encoding a combination of said payload bits into one or more additional bits by applying said payload bits to different inputs of a convolutional encoder and also applying a modified bit to an input of said convolutional encoder, said modified bit being generated by exclusive-ORing one of said payload bits with an output bit from an intermediate stage of said convolutional encoder, said convolutional encoding step resulting in output of one or more additional bits;
• and
• mapping the combination of at least some of said payload bits in an unmodified state, said modified bit and said one or more additional bits into a constellation point, wherein the step of convolutionally encoding is characterized by parity check polynomials given in octal form as follows:
• h3=04, h2=10, h1=06, h0=23, d^2_free=5.0, Nfree=1.68, and wherein the nonlinear term is given by D^2[y0(S).AND.D^(−1)y0(D)].