Polar Code Version Bit Mapping for PBCH Soft Combining
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Solution Overview
Problem
In 5G wireless communications, existing methods for encoding polar codes in the Long Term Evolution (LTE) system face challenges in explicitly conveying version information for soft combining of physical broadcast channel (PBCH) segments, leading to increased power consumption due to blind detection requirements.
Innovation Solution
A polar code encoding method that maps bits to indicate version information, using a polar code encoder to scramble and permute encoded bits, allowing explicit transmission of version information while enabling soft combining without blind detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If version information is transmitted using existing LTE polar code encoding methods, then PBCH segments can be transmitted, but the version information cannot be explicitly conveyed, requiring blind detection at the receiver which increases power consumption
Solution Approach 1:
The patent extracts version information as a separate entity from the payload data and allocates dedicated bit positions specifically for version indication. This allows the receiver to directly read version information without performing blind detection across multiple hypotheses, thereby reducing power consumption while ensuring version information is explicitly conveyed.
Solution Approach 2:
The patent segments the encoded bit structure into distinct functional parts: payload data bits and version information bits. By dividing the code structure this way, version information can be independently extracted and processed, enabling the receiver to avoid exhaustive blind detection and reducing computational energy consumption.
2Loss of information
If blind detection is used to determine version information, then version information can be obtained, but detection complexity and power consumption increase
Solution Approach 1:
The patent performs preliminary action by pre-allocating specific bit positions for version information in the encoded stream before transmission. This allows the receiver to directly access version information at known positions without needing to perform complex blind detection algorithms, thereby reducing detection complexity and power consumption.
3Device complexity
If polar codes are used for PBCH transmission, then encoding complexity is reduced, but version information indication capability is lost
Solution Approach 1:
The patent makes the polar code structure multi-functional by designing it to simultaneously carry both payload data and version information. By incorporating version indication capability into the standard polar code framework, the system maintains low encoding complexity while gaining the additional function of explicit version information transmission.
Data Source
AI summary
A polar code encoder is configured to: map q bits to q positions of q sub-channels, where q is a positive integer, and the q bits are used to indicate a version of encoded codeword; map K-q information bits to K-q positions for the K-q information bits, K is an integer, K>q; and perform polar encoding over an input vector u0N-1, comprising the q bits and the K-q information bits, with the length of N, N is an integer, N>=K and scramble with scrambling vector over the polar encoded bits, where the scrambling vector is associated to the q sub-channels or the scrambling vector is associated to a special frozen bit which is corresponding to the q sub-channels.