Method for polar decoding with dynamic successive cancellation list size and polar decoder
AssigneeTelefonaktiebolagget LM Ericsson (Publ)
InventorsAng Feng, Ailing Xie, Yushi Zhang
Life of this patent
Estimating the term…
Abstract
It provides a method (300) for polar decoding a received signal into a number, N, of bits with Successive Cancellation List, SCL. The method (300) includes: at the i-th level of a binary tree for decoding the i-th bit of the N bits, where 1≤i≤N: when the i-th bit is an information bit, calculating (310) a path metric for each of 2*Li-1 candidate paths at the i-th level, where Li-1 is an SCL size at the (i−1)-th level and L0=1; setting (320) an SCL size at the i-th level, Li, based on Li-1 and a statistical distribution of the path metrics calculated for the 2*Li-1 candidate paths; and selecting (330) Li surviving paths from the 2*Li-1 candidate paths based on their respective path metrics.
Claims9
A method performed by a polar decoder for polar decoding the method comprising:
- receiving, from a demodulator, a demodulated radio signal;
- and
- decoding the demodulated radio signal into a number, N, of bits with Successive Cancellation List by:
- determining, by a processor of the polar decoder, at the i-th level of a binary tree for decoding the i-th bit of the N bits, where 1≤i≤N, and when the i-th bit is an information bit by:
- calculating, by the processor, a path metric for each of 2*Li-1 candidate paths at the i-th level, where Li-1 is an SCL size at the (i−1)-th level and L0=1, the calculating the path metric for each of 2*Li-1 candidate paths comprises, for each of the 2*Li-1 candidate paths:
- calculating a Logarithmic Likelihood Ratio, LLR, and calculating, by the processor, the path metric based on the LLR;
- setting, by the processor, an SCL size at the i-th level, Li, based on and a statistical distribution of the path metrics calculated for the 2*Li-1 candidate paths;
- and
- selecting, by the processor, Li surviving paths from the 2*Li-1 candidate paths based on their respective path metrics;
- determining a difference between the largest and the smallest of the path metrics calculated for the 2*Li-1 candidate paths, and dynamically setting Li based on the difference;
- and
- when the i-th bit is a frozen bit:
- setting, by the processor, Li to be equal to Li-1 and determining Li surviving paths for the frozen bit.
A polar decoder comprising:
- a processor;
- and
- memory, the memory including instructions executable by the processor whereby the polar decoder is configured to perform a method for polar decoding a demodulated radio signal received from a demodulator into a number, N, of bits with Successive Cancellation List, SCL by:
- determining at the i-th level of a binary tree for decoding the i-th bit of the N bits, where 1≤i≤N, and when the i-th bit is an information bit by:
- calculating a path metric for each of 2*Li-1 candidate paths at the i-th level, where Li-1 is an SCL size at the (i−1)-th level and L0=1, the calculating the path metric for each of 2*Li-1 candidate paths comprises, for each of the 2*Li-1 candidate paths:
- calculating a Logarithmic Likelihood Ratio, LLR, and calculating the path metric based on the LLR;
- setting an SCL size at the i-th level, Li, based on Li-1 and a statistical distribution of the path metrics calculated for the 2*Li-1 candidate paths;
- and
- selecting Li surviving paths from the 2*Li-1 candidate paths based on their respective path metrics;
- determining a difference between the largest and the smallest of the path metrics calculated for the 2*Li-1 candidate paths, and dynamically setting Li based on the difference;
- and
- when the i-th bit is a frozen bit:
- setting Li to be equal to Li-1 and determining Li surviving paths for the frozen bit.
A computer program product comprising a non-transitory computer readable storage medium having computer program instructions stored thereon, the computer program instructions comprising:
- when executed by a processor in a polar decoder, causing the polar decoder to perform a method for polar decoding a demodulated radio signal received from a demodulator into a number, N, of bits with Successive Cancellation List, SCL, the method including:
- determining at the i-th level of a binary tree for decoding the i-th bit of the N bits, where 1≤i≤N, and when the i-th bit is an information bit by:
- calculating a path metric for each of 2*Li-1 candidate paths at the i-th level, where Li-1 is an SCL size at the (i−1)-th level and L0=1, the calculating the path metric for each of 2*Li-1 candidate paths comprises, for each of the 2*Li-1 candidate paths:
- calculating a Logarithmic Likelihood Ratio, LLR, and calculating the path metric based on the LLR;
- setting an SCL size at the i-th level, Li, based on Li-1 and a statistical distribution of the path metrics calculated for the 2*Li-1 candidate paths;
- and
- selecting Li surviving paths from the 2*Li-1 candidate paths based on their respective path metrics;
- determining a difference between the largest and the smallest of the path metrics calculated for the 2*Li-1 candidate paths, and dynamically setting Li based on the difference;
- and
- when the i-th bit is a frozen bit:
- setting Li to be equal to Li-1 and determining Li surviving paths for the frozen bit.
Dependencies are inferred from the claim text.