Configurable DCI CRC Length for Lower PDCCH Control Overhead
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies due to the use of fixed-length cyclic redundancy check (CRC) in downlink control information (DCI) messages, leading to increased overhead and processing burdens, particularly for messages with small payloads.
Innovation Solution
Implementing configurable CRC lengths based on the type of blind detection, radio network temporary identifier (RNTI), and total quantity of blind decodes, allowing for reduced CRC lengths in certain scenarios, especially for UEs supporting two-stage PDCCH blind detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed-length CRC is used in DCI messages, then reliability of error detection is maintained, but control signaling overhead increases
Solution Approach 1:
The patent applies dynamics by making the CRC length configurable rather than fixed. The network entity can dynamically adjust the CRC length (e.g., 16, 24, or 32 bits) based on the specific DCI message characteristics, search space type, and blind detection configuration, allowing the system to adapt between reliability and overhead requirements for different scenarios
Solution Approach 2:
The patent changes the parameter of CRC length from a fixed value to a configurable parameter. By allowing the CRC length to vary (16, 24, or 32 bits) based on message payload size, search space type, and blind detection type, the system optimizes the balance between error detection capability and signaling overhead for each specific transmission scenario
2Ease of manufacture
If fixed-length CRC is used in DCI messages, then simplicity of implementation is maintained, but processing burden increases
Solution Approach 1:
The patent applies local quality by configuring different CRC lengths for different local scenarios within the system. Specifically, the CRC length is adjusted based on the search space type (common vs. UE-specific), blind detection type (one-stage vs. two-stage), and message characteristics, allowing each local configuration to have optimally tailored error detection processing
Solution Approach 2:
The system dynamically determines the appropriate CRC length based on the specific transmission scenario, including the type of blind detection configured and the search space being monitored. This dynamic approach allows UEs to process only the necessary number of CRC bits for each DCI message, reducing overall processing burden while maintaining implementation feasibility through standardized configuration procedures
3Quantity of substance
If shorter CRC length is used, then control signaling overhead is reduced, but error detection accuracy decreases
Solution Approach 1:
The patent changes the CRC length parameter based on the specific transmission scenario. For DCI messages with smaller payloads or in two-stage blind detection scenarios, a shorter CRC (16 bits) reduces overhead while maintaining sufficient error detection capability. For messages requiring higher reliability or in one-stage blind detection, longer CRC lengths (24 or 32 bits) are configured to maintain higher error detection accuracy
Solution Approach 2:
Different error detection accuracy levels are applied locally to different scenarios. The system configures appropriate CRC lengths based on the specific requirements of each search space and message type, ensuring that error detection accuracy is optimized for each local context rather than uniformly applied across all transmissions
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may perform cyclic redundancy check (CRC) techniques to support accurate detection and decoding of downlink control messages. In some aspects, the UE may monitor a first search space for a first downlink control message, and may receive the first downlink control message which includes a first set of CRC bits having a first length. The UE may support different configurable lengths for CRC based on different characteristics of the first search space. In some aspects, the first length of the first set of CRC bits may be based on a first blind detection type associated with the first search space, a first radio network temporary identifier (RNTI) associated with the first search space, or both. The UE may then perform a redundancy check of the first downlink control message using the first length of CRC bits.