Non-overlapping Dynamic Modulation Coding for THP Signal Separation
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Solution Overview
Problem
Existing modulation techniques, such as Tomlinson-Harashima Precoding and Dynamic Modulation Coding, face challenges in maintaining signal level separation after modulo operations, particularly in multi-level Pulse-Amplitude Modulation (PAM) constellations, which affects receiver differentiation and error propagation in high-speed data transmission over unshielded or shielded twisted pair cables.
Innovation Solution
A non-overlapping Dynamic Modulation Coding scheme is introduced, utilizing distinct Pulse-Amplitude Modulation constellations with different levels that remain separated after modulo operations, specifically using Tomlinson-Harashima Precoding with modulo K*M, where K is an integer greater than or equal to two, ensuring signal levels are maintained without overlap, and incorporating a compensation signal to ensure output within desired intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If overlapping subsets of PAM constellations are used for Dynamic Modulation Coding, then variable bit rates and different levels of error resistance are achieved, but signal level separation is lost after modulo operations affecting receiver differentiation
Solution Approach 1:
The PAM constellation levels are segmented into non-overlapping subsets for different modulation orders. For example, PAM-16 uses levels {±1, ±3, ..., ±15}, PAM-8 uses {±7, ±11, ±13, ±15}, PAM-4 uses {±3, ±13, ±11, ±15}, and PAM-2 uses {±1, ±9, ±7, ±15}. This segmentation ensures that after modulo operations in THP, the signal levels from different constellations remain distinguishable at the receiver, solving the contradiction between adaptability and measurement precision.
2Device complexity
If Tomlinson-Harashima Precoding with modulo operation is applied, then spectral shaping and receiver complexity reduction are achieved, but signal level overlap occurs affecting transmission reliability
Solution Approach 1:
The invention applies local quality by assigning specific non-overlapping level subsets to different modulation orders within the THP framework. Each PAM constellation (PAM-16, PAM-8, PAM-4, PAM-2) is assigned distinct levels that maintain separation after modulo K*M operations. This local differentiation at the signal level maintains transmission reliability while preserving the complexity benefits of THP precoding.
3Manufacturing precision
If large DFE coefficients are used in Tomlinson-Harashima Precoding, then spectral shaping is improved, but Decision Feedback Equalizer error propagation increases
Solution Approach 1:
The non-overlapping constellation design is applied preliminarily before the THP modulo operation. By pre-assigning distinct level subsets to different PAM constellations, the system prepares the signal structure in advance to prevent error propagation. This preliminary structuring ensures that even with large DFE coefficients for spectral shaping, errors do not propagate across constellation boundaries, maintaining reliability while achieving precise spectral shaping.
Data Source
AI summary
A Tomlinson-Harashima Precoding (THP) transmitter transmits data modulated by non-overlapping Dynamic Modulation Coding (DMC) to a receiver. In order to enable the receiver to differentiate between the different modulations of the DMC, a novel non-overlapping DMC is used. The constellations of the non-overlapping DMC are selected such that the result of the modulo operation of the THP maintains the signal levels, belonging to the different constellations, separated.