Turbo-Code Block Segmentation for Controllable Decoding Latency
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Solution Overview
Problem
Channel coding techniques, such as turbo-codes and LDPC codes, face challenges in reducing decoding latency in wireless communication systems like WLAN and WPAN, which limits their use in packet-based transmission systems due to high latency and performance trade-offs.
Innovation Solution
A method of encoding and decoding data using blocks-oriented codes, where blocks are segmented into sub-blocks to match desired decoding latency, allowing for flexible block sizes and interleaving patterns to optimize decoding speed and throughput, enabling controlled latency and maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If block size is increased to improve throughput, then decoding latency increases
Solution Approach 1:
The patent divides a large data block into multiple sub-blocks of smaller sizes. Each sub-block is decoded separately and in parallel, which reduces the decoding latency for each individual sub-block while maintaining the overall throughput by processing multiple sub-blocks simultaneously. This segmentation approach resolves the contradiction by allowing the system to handle large data volumes (high throughput) without suffering from the quadratic increase in decoding latency that would result from decoding a single large block.
2Loss of time
If block size is reduced to decrease latency, then throughput decreases
Solution Approach 1:
The patent employs parallel processing of multiple sub-blocks to ensure continuous decoding operation. While one sub-block is being decoded, other sub-blocks are being prepared or transmitted. This continuous pipeline operation maintains high throughput despite using smaller block sizes, as the decoder remains constantly utilized without idle periods. The parallel architecture allows multiple decoding operations to overlap in time, preserving productivity while benefiting from reduced latency per sub-block.
3Reliability
If iterative decoding is used to improve performance, then decoding latency increases
Solution Approach 1:
The patent implements a dynamic stopping criterion for the iterative decoding process. Instead of always performing a fixed number of iterations, the decoder monitors the convergence of the decoding algorithm and terminates early when sufficient reliability is achieved. This dynamic adaptation allows the system to maintain high decoding performance while significantly reducing latency in cases where full convergence is not necessary, thus resolving the contradiction between reliability and latency.
Data Source
AI summary
To control a decoding latency, larger blocks are nonequally segmented into smaller ones. The decoding process starts directly after reception of the first small block. The latency is defined by the latency of the last small block decoding. Changing the number of iterations during the turbo-code decoding also permits control of the decoding latency.