Polar Code CRC Interleaving for Early-Termination Decoding
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Solution Overview
Problem
The finite-length performance of polar codes under successive cancellation decoding is not competitive with other modern channel coding schemes like LDPC and Turbo codes, and the two-step decoding process with CRC codes is sub-optimal and increases decoding latency.
Innovation Solution
A specific bit-interleaver with a predetermined interleaving pattern is applied between a linear outer code and a polar inner code, enabling early termination of decoding and single-step decoding that accounts for the structure of both codes, reducing latency and false-alarm probability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-step decoding process with CRC codes is used, then error detection capability is improved, but decoding latency increases
Solution Approach 1:
The patent applies preliminary action by performing CRC checking on partial decoded data before the complete decoding process finishes. The receiver calculates CRC values incrementally as data is decoded, allowing early error detection without waiting for the entire two-step decoding process to complete, thus reducing decoding latency while maintaining error detection capability
Solution Approach 2:
The patent changes the parameter of CRC checking from a final-stage operation to an incremental operation performed during the decoding process. By modifying when and how CRC values are calculated (from post-decoding to during-decoding), the system achieves early error detection without incurring the full latency penalty of the traditional two-step process
2Device complexity
If polar codes are used with successive cancellation decoding, then decoding complexity is reduced, but finite-length performance deteriorates
Solution Approach 1:
The patent merges the CRC error detection function with the successive cancellation decoding process by performing incremental CRC checking during decoding. This combination allows the system to maintain the low complexity of successive cancellation decoding while improving finite-length performance through early error detection, avoiding the need for more complex decoding algorithms
Data Source
AI summary
According to some embodiments, a method of operation of a wireless transmitter in a wireless communication network comprises: encoding a set of information carrying data bits u of length K with a linear outer code to generate a set of outer parity bits p along with the data bits u; interleaving the set of outer parity bits p and the data bits u using a predetermined interleaving mapping function that depends on the number of data bits K and is operable to distribute some bits of the set of parity bits p in front of some data bits u; and encoding the interleaved bits using a Polar encoder to generate a set of encoded bits x. Various interleaving mapping functions are disclosed.