Recursive Modulation Decoding Without Interleavers in LDGM Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing digital communication systems using recursive modulation schemes with Irregular Repeat Accumulate (IRA) codes require additional interleavers, increasing complexity and cost due to the need for three-component decoders and complex control logic, which is not efficient for systems employing Low Density Generator Matrix (LDGM) codes with recursive modulation.
Innovation Solution
A communication system that employs a joint recursive modulator and accumulator soft decoder without a de-interleaver, using a trellis-based algorithm for demodulation and decoding, which simplifies the transmitter and receiver architecture by eliminating the need for additional interleavers and combining the accumulator decoder with the soft demodulator, thereby reducing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional interleavers are used in systems with recursive modulation schemes and IRA codes, then decoding performance is improved, but device complexity increases due to three-component decoders and complex control logic
Solution Approach 1:
The patent combines the accumulator decoder and soft demodulator into a single integrated component. This merging eliminates the need for separate interleavers and reduces the decoder from three components to two, thereby maintaining decoding performance while significantly reducing device complexity and control logic requirements
Solution Approach 2:
The patent extracts and eliminates the additional interleavers from the system architecture. By removing these redundant components while maintaining the essential decoding functionality through the integrated accumulator decoder and soft demodulator, the system achieves the same performance with reduced complexity
2Reliability
If additional interleavers and three-component decoders are implemented, then error correction capability is enhanced, but manufacturing cost increases
Solution Approach 1:
By merging the accumulator decoder and soft demodulator into one integrated unit, the patent reduces the total number of components that need to be manufactured and assembled. This consolidation maintains error correction capability while lowering implementation costs through reduced component count and simplified manufacturing processes
3Measurement precision
If de-interleavers are included in the demodulator, then signal recovery accuracy is improved, but the number of components and system complexity increase
Solution Approach 1:
The patent integrates the de-interleaving function directly into the accumulator decoder and soft demodulator, eliminating the need for separate de-interleaver components. This functional integration maintains signal recovery accuracy while reducing the overall number of components in the system
Solution Approach 2:
The integrated accumulator decoder and soft demodulator performs multiple functions simultaneously: decoding, demodulation, and de-interleaving. This multi-functionality eliminates the need for separate dedicated components for each function, thereby maintaining signal recovery accuracy while reducing system complexity
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Methods and apparatus for use in communication systems using recursive modulation schemes with a Low Density Generator Matrix code (including an irregular repeat accumulate (IRA) code) are described that have reduced complexity and thus reduced cost compared to prior art systems. A communication system is described in which the transmitter concatenates a low density generator matrix code with an accumulator followed by a recursive modulator in order to eliminate the use of an interleaver, and in which the receiver combines the decoder for the accumulator and the soft demodulator into a single joint decoder in order reduce the number of components and complexity. Another variation is also described in which the transmitter is further simplified by eliminated the accumulator altogether, and in which the receiver is further simplified by replacing the joint decoder with a soft demodulator prior to the LDGM soft decoder.