Trellis Coded Modulation using Partially Overlapped Signal Sets of Non-equiprobable Signaling

Masayuki ARIYOSHI  Iwao SASASE  

IEICE TRANSACTIONS on Communications   Vol.E79-B   No.9   pp.1242-1247
Publication Date: 1996/09/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Personal Communications)
Category: Modulation, Equalization and interference cancellation technologies
trellis coded modulation,  signal points overlapping,  non-equiprobable signaling,  

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In conventional trellis coded modulation (TCM), higher-ary modulation scheme combining with a convolutional code is employed not to expand the transmitted bandwidth. This forces the system to be attended with signal constellation expansion and increasing the average signal power. As the solutions to avoid signal constellation expansion, TCM systems using totally overlapped signal sets (TO-TCM and RU-TCM) were proposed. These schemes can realize a coded modulation system without signal constellation expansion and achieve more coding gain compared with the conventional TCM. However, a problem that the systems with totally overlapped signal sets might be catastrophic has been remained. In this paper, we propose a novel TCM system using partially overlapped signal sets of non-equiprobable signaling (PO-TCM-NE). This scheme employs the partially overlapped signal constellation to control increasing signal points, and to avoid catastrophic error propagation. The non-equiprobable signaling is employed to reduce average signal power. Coding gain of the proposed PO-TCM-NE is considerably improved in consequence the average signal power is reduced much lower than that of other TCM systems with equiprobable signaling.