Polar Code Sub-channel Mapping for Wireless Control Channels
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Solution Overview
Problem
Existing wireless communication systems face challenges in balancing the service needs of users with good channel quality and those at the cell edge, particularly in terms of block error probability and decoding latency for control channels.
Innovation Solution
The proposed solution involves mapping different information to different Polar code sub-channels based on channel quality and information characteristics, allowing control information for users with worse channel quality to be allocated to better sub-channels, thereby reducing the need for repetition and improving decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control channels are separately encoded with one code block of TBCC for each channel (LTE approach), then the block error probability for cell edge users is improved through 8 times repetition, but the overhead is relatively high
Solution Approach 1:
The patent applies local quality by differentiating the encoding approach based on user channel quality. Users are divided into two groups: cell-edge users (first group) receive separately encoded control channels with higher repetition factors for reliable decoding, while cell-center users (second group) share a common control channel with lower overhead. This localized quality adjustment resolves the contradiction by providing high reliability only where needed rather than uniformly across all users.
Solution Approach 2:
The patent segments the user population into two distinct groups based on channel quality metrics. The first group (cell-edge users) receives dedicated encoded control channels with 8 times repetition, while the second group (cell-center users) shares a common control channel. This segmentation allows the system to optimize overhead by avoiding redundant encoding for users who don't require it, thereby resolving the contradiction between reliability and overhead.
2Quantity of substance
If control channels are combined with one code block of TBCC (WiMAX approach), then the overhead is reduced with only one CRC appended, but all users must decode all control channels which negatively impacts cell edge users' ability to efficiently decode their control information
Solution Approach 1:
The patent implements local quality by providing differentiated control channel structures tailored to user locations. Cell-edge users receive separately encoded control channels with user-specific scrambling, enabling them to quickly identify and decode only their relevant control information without processing all control channels. Cell-center users share the common control channel. This approach maintains low overhead while restoring decoding efficiency for cell-edge users.
Solution Approach 2:
The patent segments control channels into two types: separately encoded control channels for cell-edge users and a common control channel for cell-center users. This segmentation allows cell-edge users to efficiently decode their specific control information without being burdened by all control channels, thereby improving decoding efficiency while maintaining reduced overhead through the shared common control channel.
3Reliability
If 8 times repetition is applied to guarantee cell edge user performance, then the block error probability is improved, but the decoding latency increases
Solution Approach 1:
The patent applies partial action by providing 8 times repetition only to cell-edge users who require it for reliable decoding, while cell-center users receive control channels without such extensive repetition. This selective application of repetition reduces the average decoding latency across the system while maintaining the necessary reliability for cell-edge users, thereby resolving the contradiction between reliability and latency.
Data Source
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AI summary
Various aspects of the disclosure relate to mapping different information to different sub-channels. For example, information for different users may be mapped to different Polar code sub-channels. In some aspects, the mapping may be unbalanced in that different information is mapped to different sub-channels according to the quality (e.g., in terms of error probability) of the sub-channels and a criterion associated with the information. For example, control information for users that are experiencing the worst channel quality (e.g., in a wireless communication channel) may be mapped to the Polar code sub-channels that have the best quality.