Variable CRC Polynomial Length for 3GPP NR UCI Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing cyclic redundancy check (CRC) length of 8 bits used in 3GPP LTE is insufficient for the larger uplink control information (UCI) sizes in 3GPP New Radio (NR), which can range from 1 bit to 500 bits, necessitating an adaptive solution for effective error detection and correction.
Innovation Solution
An adaptive length CRC is implemented, where the CRC polynomial length is determined based on the amount of data to transmit, with different lengths used for data less than or equal to a threshold (e.g., 19 bits) and greater than the threshold (e.g., 11 bits), and a scaling factor can be applied to adjust the CRC length for error detection or correction requirements, allowing for both error detection and correction capabilities to be tailored to the specific application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the existing CRC length of 8 bits is used, then the system maintains simplicity and compatibility with LTE, but it is insufficient for the larger UCI size range in NR (1 to 500 bits)
Solution Approach 1:
The patent implements dynamic CRC length adaptation where the CRC polynomial degree is adjusted based on the UCI payload size. For small UCI sizes (≤19 bits), a 6-bit CRC is used; for medium sizes (20-500 bits), an 11-bit CRC is used; and for large sizes (>500 bits), a 16-bit CRC is used. This dynamic adjustment ensures adequate error detection capability across the entire UCI size range while maintaining efficiency.
Solution Approach 2:
The patent changes the CRC parameter (polynomial degree/length) according to the UCI size requirements. By modifying the CRC length parameter from fixed 8 bits to adaptive values (6, 11, or 16 bits), the system achieves both versatility in handling different UCI sizes and reliability in error detection for each size category.
2Reliability
If a longer CRC is used to cover the full UCI size range, then error detection capability is improved, but CRC overhead increases
Solution Approach 1:
The patent applies local quality by matching the CRC length to the specific UCI size category rather than using a uniformly long CRC for all cases. Small UCI packets use short CRC (6 bits), medium packets use medium CRC (11 bits), and large packets use long CRC (16 bits). This ensures each packet receives appropriate error detection coverage without paying the overhead cost of unnecessarily long CRC for small packets.
Solution Approach 2:
The system dynamically selects the appropriate CRC length based on the actual UCI payload size, transitioning from static fixed-length CRC to adaptive variable-length CRC. This dynamic approach optimizes the trade-off between error detection reliability and overhead by selecting the minimum necessary CRC length for each transmission.
3Reliability
If different CRC lengths are used for different data sizes, then error detection capability is optimized, but system complexity increases
Solution Approach 1:
The patent segments the UCI size range into distinct categories (small: ≤19 bits, medium: 20-500 bits, large: >500 bits), each associated with a specific CRC length (6, 11, or 16 bits). This segmentation simplifies the decision process compared to continuous adaptation, as the system only needs to determine which segment the UCI size falls into and apply the corresponding CRC length.
Solution Approach 2:
The system changes the CRC parameter (length) based on predefined thresholds of UCI size. By establishing clear boundary conditions (19 bits and 500 bits), the patent makes the parameter selection process straightforward and implementable, reducing complexity while maintaining optimized error detection for each size category.
Data Source
AI summary
The application relates to the adaption of the length of the cyclic redundancy check (CRC) code in the context of 3GPP NR. In 3GPP NR, the length of the uplink and downlink control information (UCI, DCI) significantly varies. Therefore, it is necessary to select a CRC code of appropriate size or length. Accordingly, a method (200) for use in a wireless transmitter comprises: determining an amount of data to transmit (212), determining a cyclic redundancy check (CRC) polynomial length based on the amount of data to transmit (214); encoding the data using a CRC of the determined polynomial length (216); and transmitting the encoded data (216). The data to transmit may not only comprise control channel data but also user data and may be encoded with a Polar code or a low-density parity check (LDPC) code.