Multilevel codes for high-speed voiceband data modem

Abstract

A novel class of multilevel codes is proposed for achieving high coding gain. Multilevel codes composed of two-level codes are investigated from the standpoint of the systematic design of codes. Two-level codes as component codes are shown to be preferable to a combination of conventional one-level codes in coding gain and decoder delay. For a 19.2 kb/s voiceband modem application, this scheme presents a class of coded modulation superior to trellis-coded modulation in simultaneous realization of high coding gain, low/moderate decoder complexity, and short decoding delay.<>