Polar Code Bit Mapping for Unequal Error Protection in XR Streams
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Solution Overview
Problem
Existing wireless communication systems struggle to provide unequal error protection for critical aspects of extended reality (XR) and video streams, leading to potential errors in less important bits and affecting user experience.
Innovation Solution
Implementing unequal error protection polar codes by sorting information bits based on priority and mapping them to reliable bit-channels, ensuring critical bits are encoded with higher reliability, thereby reducing the impact of errors on user perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all information bits are encoded with equal protection, then the encoding process is simple, but critical bits may suffer from errors affecting user experience
Solution Approach 1:
The patent applies local quality by differentiating the encoding protection level for different information bits based on their importance. Critical bits (e.g., DC coefficients, low-frequency transform coefficients) are mapped to more reliable polar code bit channels, while less critical bits are mapped to less reliable channels. This selective differentiation of encoding quality resolves the contradiction by providing enhanced reliability for critical bits without unnecessarily complicating the encoding of all bits equally.
Solution Approach 2:
The patent segments the information bits into different priority groups based on their importance to user experience. By dividing the bit stream into critical and non-critical segments and applying different mapping strategies to each segment, the system achieves selective error protection. This segmentation approach allows the encoding process to focus computational resources on protecting only the most important bits, rather than treating all bits uniformly.
2Reliability
If critical bits are prioritized in encoding, then error protection for important data improves, but the encoding and decoding process becomes more complex
Solution Approach 1:
The patent applies preliminary action by performing bit prioritization and mapping to reliable channels before the actual encoding process. The transmitter预先 identifies which bits are critical (based on their position in the transform coefficient stream) and assigns them to the most reliable polar code bit channels in advance. This preliminary organization of bits based on importance reduces the complexity during the main encoding process, as the sorting and mapping are completed beforehand in a systematic manner.
Solution Approach 2:
The patent changes the mapping parameter between information bits and polar code bit channels based on the importance of each bit. Instead of using a fixed mapping scheme, the system dynamically adjusts which information bit maps to which bit channel position, prioritizing critical bits for positions with lower error rates. This parameter change in the mapping relationship enables selective error protection while maintaining a structured encoding process.
3Reliability
If unequal error protection is implemented, then user experience for critical data improves, but the system requires more sophisticated encoding schemes
Solution Approach 1:
The patent implements local quality by applying different error protection levels to different portions of the data stream based on their importance. Critical transform coefficients (such as DC and low-frequency AC coefficients that have the greatest impact on perceived video quality) are mapped to polar code bit channels with higher reliability, while less important coefficients are mapped to channels with lower reliability. This localized differentiation of protection quality achieves superior decoding success for critical data without requiring uniformly sophisticated encoding for all data.
Solution Approach 2:
The patent introduces asymmetry in the error protection scheme by creating an unequal mapping between information bits and bit channels based on bit importance. The mapping is asymmetric in that critical bits are preferentially assigned to reliable channels while non-critical bits are assigned to less reliable channels. This asymmetric approach resolves the contradiction by providing targeted enhanced protection where needed rather than symmetric uniform protection across all bits.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. Polar coding involves assigning bits to different bit-channels, and encoding the bits such that certain bit-channels (e.g., polar channels) are polarized to increased reliability, while other bit-channels are polarized to decreased reliability. To ensure that polar codes for extended reality (XR) and video applications have increased reliability for the aspects of an XR stream or video code that are most important, the information bits of a stream may be sorted based on priority or importance. Then the sorted information bits may be mapped to the most reliable bit-channels of a polar encoder. Any errors in the transmission may therefore be most likely to occur in the less important bits. Accordingly, in the case of XR, the information bits that are most important to user experience/perception are the most likely to be successfully received and decoded at the receiver.