Adaptive CRC Length Selection for 3GPP NR Control Data
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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 size of uplink and downlink control information (UCI/DCI) in 3GPP New Radio (NR) networks, which can span up 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 error detection and correction, and a scaling factor can be applied to adjust the CRC length according to error detection or correction requirements, ensuring effective error detection and correction across a wide range of UCI/DCI sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing CRC length of 8 bits is used, then the overhead is small, but the error detection capability is insufficient for larger UCI/DCI sizes in NR networks
Solution Approach 1:
The patent implements dynamic CRC length adaptation where the CRC polynomial length is selected based on the size of the data block being protected. For NR control information ranging from 1 to 500 bits, the system dynamically chooses appropriate CRC lengths (e.g., 10, 12, 16, 24 bits) rather than using a fixed 8-bit CRC, thereby maintaining adequate error detection capability matched to the data size while optimizing overhead.
Solution Approach 2:
The patent changes the parameter of CRC polynomial length to match different data sizes. By selecting from multiple CRC polynomial lengths (degree 10, 12, 16, 24) based on the information bit length, the system adapts the error detection capability to the actual needs of each transmission, improving reliability without unnecessarily increasing overhead for all transmissions.
2Reliability
If a longer CRC length is used to cover the full UCI size range, then the error detection capability improves, but the overhead increases
Solution Approach 1:
The patent manages system complexity by establishing clear parameter relationships between data size and CRC length. The system uses defined thresholds and selection criteria to map UCI sizes (1-500 bits) to appropriate CRC polynomial degrees, making the adaptation process systematic rather than arbitrary. This structured approach maintains reliability while controlling the complexity of the adaptation mechanism.
3Adaptability or versatility
If the CRC length is fixed, then the implementation is simple, but it cannot effectively address the wide range of UCI/DCI sizes in NR
Solution Approach 1:
The patent implements dynamic CRC length selection based on the actual size of the control information being transmitted. Rather than using a fixed CRC length, the system adaptively chooses the appropriate CRC polynomial degree (10, 12, 16, or 24) according to the UCI/DCI block size, thereby achieving versatility across the wide NR size range while keeping the adaptation logic relatively simple through defined selection criteria.
Solution Approach 2:
The patent changes the CRC polynomial length parameter to match different UCI size requirements. By establishing clear mapping relationships between data size ranges and CRC lengths, the system achieves adaptability without introducing excessive complexity, as the selection follows systematic rules rather than requiring complex decision-making processes.
Data Source
AI summary
The application relates to the adaptation 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.