Polar Channel Encoding with Interleaved CRC for Early Stop Decoding
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Solution Overview
Problem
In wireless communications systems, polar codes used for channel encoding often require multiple decoding attempts in blind detection scenarios, leading to significant decoding delays and energy consumption due to the lack of an early stop mechanism in CRC decoding processes.
Innovation Solution
A distributed cascaded cyclic redundancy check (CRC) mechanism is introduced, which allows for early termination of decoding by interleaving CRC bits among information bits and using a prestored interleaving sequence, reducing encoding and decoding delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional CRC encoding is used without distributed interleaving, then the encoding structure is simple, but decoding cannot stop early leading to increased decoding delay and energy consumption
Solution Approach 1:
The patent divides the CRC bits into multiple groups and distributes them among information bits through interleaving. Instead of placing all CRC bits at the end, the CRC bit sequence is segmented and interleaved with information bits, enabling the decoder to check CRC conditions incrementally and stop early when detection fails, thus reducing decoding delay while managing complexity through structured segmentation
Solution Approach 2:
The patent performs interleaving of CRC bits and information bits during the encoding phase before transmission. By preliminarily distributing CRC bits among information bits in a predetermined pattern, the decoder can immediately begin early stop detection without waiting for complete decoding, as the CRC check positions are already in place to enable incremental verification
2Reliability
If multiple decoding attempts are performed in blind detection scenarios, then decoding reliability improves, but energy consumption increases significantly
Solution Approach 1:
The patent implements a feedback mechanism where CRC check results are continuously monitored during the decoding process. When the CRC condition is not satisfied at any intermediate stage, the decoder immediately stops and feeds back the failure result, preventing unnecessary continuation of decoding attempts. This feedback-driven early stop capability maintains reliability by ensuring successful decodings are verified while eliminating wasteful energy consumption from failed decoding attempts
3Productivity
If CRC bits are distributed among information bits through interleaving, then early stop capability is enabled, but the encoding process becomes more complex
Solution Approach 1:
The patent performs the interleaving of CRC bits and information bits during the encoding phase using predetermined patterns. By preliminarily arranging bits in the interleaved structure before transmission, the complexity of the interleaving operation is concentrated in the encoding phase rather than during decoding, enabling the decoder to simply follow the known pattern for early stop detection and thus improving decoding speed while managing complexity through advance preparation
Solution Approach 2:
The patent changes the structural parameter of bit arrangement from conventional sequential ordering to an interleaved distribution pattern. By transforming the bit sequence structure during encoding, the system enables incremental CRC verification during decoding, improving decoding speed through early stop capability while the parameter transformation is performed once during encoding rather than repeatedly during decoding
Data Source
AI summary
A channel encoding method and apparatus. The method includes: obtaining A to-be-encoded information bits; mapping the A to-be-encoded information bits and L CRC bits to a first bit sequence based on an interleaving sequence, where the L CRC bits are obtained based on the A to-be-encoded information bits and a CRC polynomial, the interleaving sequence is obtained from a prestored interleaving sequence table or is obtained based on a maximum-length interleaving sequence, A+L is less than or equal to Kmax, and Kmax is a length of the maximum-length interleaving sequence; and encoding the first bit sequence. In this way, not only an encoding delay can be reduced, but also decoding has an early stop capability, so that decoding can end in advance, thereby reducing a decoding delay.