Trellis Shaping on LDPC-Coded Modulation DMT Systems

Abstract

A transmitter in a Digital Subscriber Line (DSL) system includes a rate encoder configured to generate a first set of encoded bits using a set of least significant bits, a trellis shaper configured to generate a second set of encoded bits using a most significant bit and the first set of encoded bits, a first constellation mapper configured to generate a first point described by integer coordinates in a complex plane based on the first set of encoded bits obtained from the rate encoder, a second constellation mapper configured to generate a second point described by integer coordinates in the complex plane after interleaving two bits from the second set of encoded bits obtained from the trellis shaper, and a merger module configured to merge the first point with the second point to generate a symbol. The symbol represents a third point described by integer coordinates in the complex plane.

What is claimed is: 
     
         1 . A transmitter in a Digital Subscriber Line (DSL) system, comprising:
 a rate encoder configured to generate a first set of encoded bits using a set of least significant bits, wherein the first set of encoded bits contains at least one more bit than the set of least significant bits;   a trellis shaper operably coupled to the rate encoder, wherein the trellis shaper is configured to generate a second set of encoded bits using a most significant bit and the first set of encoded bits;   a first constellation mapper operably coupled to the rate encoder, wherein the first constellation mapper is configured to generate a first point described by integer coordinates in a complex plane based on the first set of encoded bits obtained from the rate encoder;   a second constellation mapper operably coupled to the trellis shaper, wherein the second constellation mapper is configured to generate a second point described by integer coordinates in the complex plane after interleaving two bits from the second set of encoded bits obtained from the trellis shaper; and   a merger module operably coupled to the first constellation mapper and the second constellation mapper, wherein the merger module is configured to merge the first point with the second point to generate a symbol, wherein the symbol represents a third point described by integer coordinates in the complex plane.