Adaptive CRC Length Selection for Wireless Channel Reliability
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in managing cyclic redundancy check (CRC) lengths, particularly in LTE, where a fixed CRC length for all data channels is inefficient, leading to increased overhead for less demanding traffic types like VoIP, and higher false alarm probabilities in 5G requirements for ultra-high reliability.
Innovation Solution
The method involves determining the CRC field size based on explicit or implicit indications for each transmission, allowing for varying CRC lengths (e.g., 24-bit or 36-bit) depending on traffic types, data packet sizes, and other parameters, such as transport block sizes, UE capabilities, and scheduling types, to optimize overhead and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed CRC length is used for all data channels, then system complexity is reduced, but overhead increases for less demanding traffic types and false alarm probability increases
Solution Approach 1:
The patent implements dynamic CRC length selection where the CRC length is adjusted based on traffic type, transport block size, and reliability requirements. Different CRC lengths (e.g., 16-bit, 24-bit, 32-bit) are selectively applied to different data channels and traffic types, allowing the system to adapt CRC configuration to specific communication scenarios rather than using a fixed length for all channels.
Solution Approach 2:
The patent changes the CRC length parameter based on multiple factors including traffic type (voice, data, signaling), transport block size thresholds, and required reliability levels. The system selects from multiple possible CRC length values to optimize the balance between overhead and false alarm probability for each specific transmission scenario.
2Reliability
If a longer CRC length is used, then false alarm probability is reduced, but overhead increases
Solution Approach 1:
The patent applies different CRC lengths to different local contexts - specific data channels, traffic types, and transport block sizes receive appropriately tailored CRC lengths. For example, voice traffic with small transport blocks uses shorter CRC lengths to minimize overhead, while critical data transmissions with larger blocks use longer CRC lengths to reduce false alarm probability, optimizing the local characteristics of each transmission.
Solution Approach 2:
The system dynamically changes the CRC length parameter based on transport block size thresholds and traffic type characteristics. When transport block size exceeds certain thresholds or when high reliability is required, longer CRC lengths are selected; otherwise, shorter CRC lengths are used to minimize overhead, achieving optimal parameter configuration for each transmission scenario.
3Quantity of substance
If a shorter CRC length is used, then overhead is reduced, but false alarm probability increases
Solution Approach 1:
The patent implements dynamic adaptation of CRC length based on real-time transmission characteristics. The system evaluates traffic type, transport block size, and channel conditions to dynamically select the appropriate CRC length, switching between shorter and longer CRC lengths as conditions change, thereby balancing overhead and false alarm probability adaptively rather than using a static configuration.
Solution Approach 2:
The system adjusts the CRC length parameter based on transport block size and traffic type. For small transport blocks with voice traffic, shorter CRC lengths are applied to reduce overhead since the absolute overhead impact is smaller. For larger transport blocks or critical data, longer CRC lengths are used despite increased overhead to maintain acceptable false alarm probabilities.
Data Source
AI summary
Certain aspects of the present disclosure provide methods and apparatus for managing cyclic redundancy check field lengths in wireless communications. An exemplary method generally includes determining a size of a cyclic redundancy check (CRC) field, from a plurality of possible sizes for a given type of physical wireless channel, to be used for a transmission to be sent on the physical wireless channel, and performing communication based on the transmission on the physical wireless channel with the CRC field of the determined size.