Two-Level Decorrelated Coded Modulation on the $D_4$ Lattice
2026-08-17 • Information Theory
Information Theory
AI summaryⓘ
The authors introduce a new way to send data called two-level decorrelated coding (TLDC) that works with a special structure called the D4 lattice. Their method uses two steps: first shaping the signal and then decoding in two parts, which makes it easier and faster to figure out the sent message. By making parts of the data in the second step almost independent, it allows for parallel processing and better error correction choices. They tested their method with popular error-correcting codes and found it can make communication about 0.5 dB more efficient compared to current best methods for certain signal sizes.
Two-level decorrelated codingD4 latticeVoronoi shapingCoded modulationTwo-stage decodingError correction codesBit-interleaved coded modulationPolar codesAWGN16-QAM
Authors
Leopold Bertholet, Chloe Makdad, Stephen Mackes, Daniel Chew, Matthew Robinso
Abstract
We propose \textit{two-level decorrelated coding} (TLDC), a novel coded modulation scheme for the $D_4$ lattice that combines Voronoi shaping with a two-stage decoding process to achieve lattice shaping and coding gains at low complexity. In TLDC, the decoded values of the first level allow the several random variables in the second level to become approximately uncorrelated. The resulting independence of the variables in level two permits decoding in parallel or consolidation into a larger codeword, enhancing performance. TLDC supports flexible choice of FEC within each level. Using bit-interleaved or multi-level polar codes at each level, the resulting coded modulation scheme exhibits a gain of up to 0.5 dB over analogous state-of-the-art coded modulation schemes on a 16-QAM under AWGN at block sizes of 64 and 1024 bits.