LDPC Decoder Broadcast Messaging to Eliminate Echo Computation
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Solution Overview
Problem
High-speed signal processing systems face challenges in implementing Low Density Parity Check (LDPC) codes due to the complexity of message passing in the Belief Propagation algorithm, particularly in software implementations and the physical connection requirements for hardware implementations, which result in increased computation time and impractical wire connections within integrated circuits.
Innovation Solution
A method is introduced to compute and broadcast messages by removing echoes of previous messages in each node, allowing for a simplified message calculation and reduced physical connections, enabling the use of a bus architecture instead of individual connections, which reduces the number of wire connections and complexity in hardware implementations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional message passing algorithm is used in LDPC decoding, then decoding accuracy is maintained, but the number of wire connections and device complexity increase significantly
Solution Approach 1:
The patent merges the message passing function into a broadcast architecture where a single broadcast bus replaces multiple individual wire connections between nodes. The message passing algorithm is adapted to use broadcast messages that are received by all neighboring nodes simultaneously, reducing the physical connection infrastructure while maintaining the decoding functionality.
Solution Approach 2:
The broadcast bus serves multiple functions: it carries messages from variable nodes to check nodes, from check nodes to variable nodes, and supports multiple iterations of the decoding algorithm. This universal communication channel replaces the need for dedicated point-to-point connections, significantly reducing device complexity.
2Reliability
If traditional message passing algorithm is used in LDPC decoding, then decoding accuracy is maintained, but computation time increases
Solution Approach 1:
The patent pre-organizes the message passing schedule to avoid redundant computations. By planning the broadcast sequence in advance and eliminating echo messages (messages that would return to the sending node without adding new information), the algorithm reduces the number of iterative steps required while maintaining decoding accuracy.
Solution Approach 2:
The patent extracts and removes echo messages from the message passing process. These are messages that would simply return to the originating node and provide no new information. By taking out these redundant messages, the computation time is reduced while the essential decoding functionality is preserved.
3Measurement precision
If individual connections are used between nodes, then message passing accuracy is maintained, but physical layout complexity increases
Solution Approach 1:
The patent combines multiple individual connection paths into a single broadcast bus infrastructure. This merging of physical connections simplifies the layout from a mesh-like structure with many interconnections to a more compact design where all nodes connect to a shared communication medium, reducing layout complexity while maintaining message passing capability.
Data Source
AI summary
In a decoder implementing a belief propagation algorithm for iteratively decoding a Low Density Parity Check (LDPC) encoded data block, a method of computing messages to be sent by a first node of the decoder to at least one neighbor node of the decoder. The method comprises: processing messages received by the first node to remove an echo of a previous message sent by the first node to the at least one neighbor node in a previous iteration, to yield corresponding modified messages; computing a message for a current iteration using the modified messages; and broadcasting the computed message for the current iteration to each of the at least one neighbor nodes.