QC-LDPC Decoder Partial Cyclic Shifters for Lower Area and Power
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Solution Overview
Problem
Existing LDPC code decoders require complex and power-consuming full cyclic shifters to handle the full range of shift values, which limits their efficiency and increases latency, while partial shifters are less efficient due to limited support for shift values.
Innovation Solution
A decoder architecture using multiple configurable partial cyclic shifters that support only a subset of shift values, allowing for simultaneous message passing between variable-node and check-node circuitry, with the ability to assign different shifters for different message sets, and incorporating full cyclic shifters for unsupported values, enabling efficient processing and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full cyclic shifters are used to handle the full range of shift values, then error correction capability is maintained, but area and power consumption increase
Solution Approach 1:
The decoder is divided into multiple processing units, each handling a specific subset of shift values. Instead of one large full cyclic shifter, the system uses several smaller partial cyclic shifters that work in parallel, reducing the area of each individual unit while maintaining overall functionality through coordinated operation.
Solution Approach 2:
Each processing unit uses a partial cyclic shifter that handles only a portion of the total shift value range rather than requiring full-range shifters. By distributing different subsets of shift values across multiple units, the system achieves complete coverage with smaller, more area-efficient components.
2Reliability
If full cyclic shifters are used to handle the full range of shift values, then error correction capability is maintained, but power consumption increases
Solution Approach 1:
The power consumption is distributed across multiple partial cyclic shifters instead of concentrating it in a single full cyclic shifter. Each partial shifter consumes less power individually, and the overall system power consumption is reduced due to the efficiency gains from specialized smaller units working in parallel.
Solution Approach 2:
By using partial cyclic shifters that handle only specific subsets of shift values, each unit performs fewer operations and consumes less power. The system achieves full error correction capability through the coordinated action of multiple low-power partial shifters rather than high-power full shifters.
3Productivity
If partial cyclic shifters are used to reduce area and power consumption, then decoder efficiency improves, but support for full range of shift values is limited
Solution Approach 1:
The complete range of shift values is segmented into multiple subsets, with each partial cyclic shifter dedicated to handling a specific subset. This segmentation allows each unit to be optimized for its specific range while collectively covering the entire required spectrum, maintaining versatility through modular architecture.
Solution Approach 2:
Multiple partial cyclic shifters work together as a universal system that can handle any shift value within the full range. By assigning different subsets of shift values to different units and coordinating their operation, the system achieves multi-functionality equivalent to full shifters while maintaining the efficiency benefits of partial specialization.
4Speed
If partial cyclic shifters are used to reduce area and power consumption, then clock rate can be increased, but latency may increase due to multiple shifters
Solution Approach 1:
The decoding process is segmented into parallel operations across multiple processing units. While each unit processes a subset of messages, the parallel execution of multiple units compensates for the overhead of coordinating between them, allowing higher clock rates to be achieved without significant latency penalty.
Solution Approach 2:
Multiple partial cyclic shifters are merged into a coordinated system where their combined output achieves the same functionality as a single full shifter. The merging of results from parallel units eliminates the need for sequential processing, maintaining low latency while enabling higher clock rates through parallel operation.
Data Source
AI summary
A decoder includes variable-node circuitry, check-node circuitry and a Message Passing (MP) module, which includes multiple configurable partial cyclic shifters that each supports only a partial subset of shift values out of a full range of shift values 0 . . . L-1. The variable-node circuitry and check-node circuitry are configured to exchange messages with one another in accordance with a parity check matrix that represents a respective Quasi-Cyclic (QC)-Low Density Parity Check (LDPC) Error Correcting Code (ECC) and that includes L-by-L sub-matrices, and to process the exchanged messages to decode a given code word that was encoded using the QC-LDPC ECC. The MP module is configured to schedule the variable-node circuitry and check-node circuitry that are interconnected in accordance with a respective sub-matrix to exchange L messages simultaneously by assigning a given partial cyclic shifter to shift the L messages cyclically a number of positions that depends on a structure of the respective sub-matrix.