Adaptive CRC Length for 3GPP NR UCI Error Detection
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Solution Overview
Problem
The existing cyclic redundancy check (CRC) length of 8 bits used in LTE is insufficient for the larger uplink control information (UCI) sizes in 3GPP New Radio (NR) networks, which can range from 1 bit to 500 bits, affecting error detection and correction capabilities.
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 number of bits and those greater than the threshold, and a scaling factor can be applied to adjust the CRC length for error detection and correction requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing CRC length of 8 bits is used for LTE UCI, then the error detection capability is sufficient for LTE UCI sizes, but the error detection capability becomes insufficient for larger NR UCI sizes ranging from 1 bit to 500 bits
Solution Approach 1:
The patent implements a dynamic CRC length selection mechanism where the CRC polynomial length is adjusted based on the UCI size. For UCI sizes up to 11 bits, a 6-bit CRC is used; for UCI sizes from 12 to 500 bits, an 11-bit CRC is used. This dynamic adaptation resolves the contradiction by making the error detection capability sufficient for both small and large UCI sizes while maintaining system versatility.
Solution Approach 2:
The patent changes the CRC parameter (polynomial length) from a fixed 8 bits to variable lengths (6 bits or 11 bits) based on the UCI size. This parameter change enables the system to achieve adequate error detection capability for different UCI size ranges, resolving the contradiction between maintaining sufficient error detection and adapting to varying UCI sizes in NR networks.
2Reliability
If a longer CRC polynomial length is used to cover the full UCI size range, then the error detection capability improves, but the CRC overhead increases
Solution Approach 1:
The patent applies parameter changes by selecting different CRC polynomial lengths (6 bits or 11 bits) based on the UCI size. This avoids using a uniformly long CRC for all sizes, thereby maintaining adequate error detection capability while minimizing CRC overhead for smaller UCI sizes where a 6-bit CRC suffices.
Solution Approach 2:
The dynamic selection of CRC length based on UCI size ensures that the system uses the minimum necessary CRC overhead to achieve sufficient error detection capability. For small UCI sizes (≤11 bits), a 6-bit CRC provides adequate protection with minimal overhead, while for larger UCI sizes (12-500 bits), an 11-bit CRC provides sufficient protection without unnecessarily increasing overhead for all cases.
Data Source
AI summary
According to some embodiments, a method for use in a wireless transmitter comprises: determining an amount of data to transmit; determining a cyclic redundancy check (CRC) polynomial length based on the amount of data to transmit; encoding the data using a CRC of the determined polynomial length; and transmitting the encoded data. According to some embodiments, a method for use in a wireless receiver comprises: receiving encoded data from a wireless transmitter; determining an amount of data received in the encoded data; determining a CRC polynomial length based on the amount of data; and decoding the received encoded data using a CRC of the determined polynomial length. In particular embodiments, the data to transmit comprises control channel data or user data, and the encoding uses Polar codes or low-density parity check (LDPC) codes.