TRELLIS-CODED MODULATION FOR LINEAR DISTORTION CHANNELS

Abstract

Introduction: Real communication channels used for high-speed data transmission are characterized by substantial linear distortions leading to a significant decrease in the effectiveness of the known coded modulation techniques developed for distortion-free channels. This means that a modified coded modulation technique should be created, which would take into account the channel distortions. Purpose: Using multidimensional signal sets to build up multilevel trellis-coded modulation constructions with multidimensional constellations and multi-stage decoding, matched to the channels with linear distortions, and study of their main characteristics. Results: A new approach was developed to the design of trellis-coded modulation constructions for channels with linear distortions, based on the combination of two techniques: decomposition of the channel into a set of independent memoryless subchannels and time-frequency multilevel coding. The high level of flexibility of the proposed trellis-coded modulation constructions makes it possible to effectively take into account linear channel distortions and compensate for them, due to the rational choice of the number of the subchannels and optimization of the energy distribution between the subchannels. It also provides a wide-range tradeoff between performance and decoding complexity. The relationships between the basic parameters of the proposed class of trellis-coded modulation constructions were obtained in an explicit form. These relationships allow you to provide tradeoffs between the transmission rate, the minimum distance, and the decoding complexity. Examples of multilevel trellis-coded modulation constructions based on multidimensional Barnes — Wall lattices are given. A comparative study showed that as the value of the permissible decoding complexity increases, constructions with larger values of both the number of subchannels and the cardinality of the signal constellation become more preferable. Practical significance: The proposed class of trellis-coded modulation constructions allows you to effectively take into account and to overcome the influence of linear channel distortions common in communication channels used for high-speed data transmission. An additional advantage of these constructions is a relatively small value of the crest factor of transmitted signals and thereby more efficient use of the transmitter's power.