Spectral and power shaping mapper for high data rate signalling

Abstract

A spectral and power shaping mapper for high data rate signaling modem functions in a first mode having spectral and power shaping and using convolutional encoding, a second mode having power shaping, a third mode having power shaping using convolutional encoding, and a fourth mode having straight-forward mapping. Based on data rates and other criteria, incoming bits are grouped together, with a first subgroup of bits used in the first mode to generate two sign vectors (and in the other modes a single vector), a second subgroup of bits used in conjunction with an appended bit in the first, second and third modes to generate at least two magnitude manipulation vectors, and a third subgroup of bits used in a modulus converter to generate a plurality of quotients. The quotients and magnitude manipulation vector(s) are used to select one, two or four sequences of constellation points from a multidimensional constellation depending on mode. The sequences of selected points are combined with the sign vector(s) to generate, one, two or four sequences of octets for a shaping selector. In the first and third modes, the shaping selector employs a convolutional encoder state machine which uses criteria such as lowest cost paths and/or lowest average power in order to select which sequence of octets to output. In the second mode, selection is based on power only. In the fourth mode, the generated octets are output as there is no choice of octets.