Polar Code Decoding With Frozen Bits for Payload Length Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In radio communication systems using Polar codes for downlink control channels, there is a challenge in identifying payload lengths during decoding, which can lead to false alarm rates and incorrect identification of control information.
Innovation Solution
The proposed solution involves modifying the encoding process to include specific frozen bit sequences and CRC initialization methods that allow the reception side to easily identify payload lengths, thereby reducing false detection rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Polar codes are used for downlink control channels, then error correction performance near Shannon limit is achieved, but payload length identification becomes difficult leading to false alarm rates
Solution Approach 1:
The patent applies preliminary action by pre-defining frozen bit sequences corresponding to different payload lengths before transmission. The base station prepares multiple frozen bit sequences in advance, each associated with a specific payload length, and selects the appropriate sequence based on the actual payload length. This allows the reception side to identify payload length by matching received frozen bit sequences against known sequences, solving the identification problem without affecting the error correction performance of Polar codes.
Solution Approach 2:
The patent introduces frozen bit sequences as an intermediary mechanism to bridge the gap between Polar code encoding and payload length identification. These frozen bit sequences serve as a mediator that carries implicit length information without interfering with the primary error correction function. By using this intermediary, the system enables payload length identification while maintaining the integrity and performance of the Polar code structure.
2Adaptability or versatility
If frozen bits are scrambled using UE-ID for blind detection, then user-specific detection capability is improved, but complexity of decoding process increases
Solution Approach 1:
The patent applies local quality by applying UE-ID scrambling only to specific frozen bits rather than the entire code block. This selective scrambling targets only the necessary portion (frozen bits) to provide user-specific detection capability, while leaving other parts of the data unchanged. This approach maintains adaptability for user identification while minimizing the increase in decoding complexity by limiting the scrambling operation to a specific subset of bits.
3Measurement precision
If CRC initialization uses non-zero state, then payload differentiation capability is improved, but compatibility with existing LTE methods is reduced
Solution Approach 1:
The patent applies parameter changes by modifying the initial state parameter of the CRC register from the conventional zero state to a non-zero state. This parameter change enables the CRC to differentiate between payloads of different lengths more effectively, as the non-zero initial state creates distinct CRC values for different payload configurations. While this improves payload differentiation capability, it does represent a deviation from existing LTE methods that use zero initialization, potentially requiring separate implementation considerations.
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A communication apparatus includes an encoding unit configured to generate a second coded bit sequence by encoding according to a second encoding scheme a frozen bit sequence and a second bit sequence that includes a first bit sequence and a first coded bit sequence generated from encoding the first bit sequence according to a first encoding scheme; and a transmission unit configured to transmit a transmission signal generated from the second coded bit sequence. The communication apparatus determines the second coded bit sequence on the basis of a length of the second bit sequence.