Cross-Carrier Signaling for Multi-Carrier Fallback Reliability
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Solution Overview
Problem
Current wireless communication systems face challenges in reliably sending control information to user equipment (UE) during fallback operations, especially when the operating mode of the UE is unknown or undergoing reconfiguration, leading to potential missed data transmissions and performance degradation.
Innovation Solution
The implementation of cross-carrier signaling with specific DCI formats, including a cross-carrier indicator field, allows UEs to monitor and receive control information on one carrier to support data transmission on another, ensuring reliable communication by maintaining at least one common DCI format before and after reconfiguration, and restricting blind decodes to reduce the number of fallback carriers and search spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-carrier signaling is implemented with multiple DCI formats to support multi-carrier operation, then the system can support data transmission on multiple carriers, but the complexity of monitoring and detecting DCI formats increases
Solution Approach 1:
The patent segments the DCI format monitoring by dividing search spaces into common search spaces and UE-specific search spaces, and further dividing carriers into fallback carriers and non-fallback carriers. This segmentation allows the UE to monitor different DCI formats in different search spaces on different carriers, reducing the overall complexity of multi-carrier DCI monitoring while maintaining adaptability.
Solution Approach 2:
The patent applies preliminary action by configuring the UE with fallback operation support before actual data transmission. The UE is pre-configured with DCI formats to monitor on fallback carriers, and the base station pre-assigns search spaces and carriers. This preliminary configuration enables the UE to reliably receive control information even during reconfiguration events, reducing complexity during critical transitions.
2Reliability
If the UE monitors for multiple DCI formats with different sizes to support fallback operation, then control information can be reliably sent during reconfiguration, but the number of blind decodes increases
Solution Approach 1:
The patent applies local quality by making DCI format sizes carrier-specific and search space-specific rather than uniform across all carriers. Different carriers have different DCI format sizes based on their specific configurations (fallback vs. non-fallback, common vs. UE-specific search spaces). This allows the UE to optimize blind decode operations by knowing the expected DCI size for each specific carrier and search space combination, reducing the overall number of blind decodes needed while maintaining reliability.
Solution Approach 2:
The base station performs preliminary action by pre-configuring the UE with specific DCI formats and their sizes for each carrier and search space before data transmission begins. This preliminary configuration includes providing information about which DCI formats to monitor on which carriers, allowing the UE to prepare the appropriate number and types of blind decode operations in advance, rather than having to handle all possible formats dynamically.
3Reliability
If fallback operation is supported on all carriers with all search spaces, then control information delivery is maximally reliable, but the system complexity and processing overhead increase
Solution Approach 1:
The patent segments fallback operation support by designating specific carriers as fallback carriers and specific search spaces as fallback search spaces, rather than enabling fallback operation universally across all carriers and search spaces. This segmentation allows the system to concentrate reliability measures where they are most needed while maintaining processing efficiency on other carriers, thus balancing reliability with productivity.
Solution Approach 2:
The patent applies partial action by implementing fallback operation support selectively on certain carriers and search spaces rather than on all carriers and search spaces. This partial implementation provides sufficient reliability for critical control information while avoiding the excessive processing overhead that would result from universal fallback support, thus optimizing the balance between reliability and productivity.
Data Source
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AI summary
Techniques for supporting fallback operation in a multi-carrier communication system are described. In one aspect, a UE may determine at least one first downlink control information (DCI) format to monitor on a first carrier. The UE may monitor for the first DCI format(s) on the first carrier to detect DCI sent to the UE. The UE may receive a reconfiguration message related to communication on a plurality of carriers by the UE with cross-carrier signaling, and may determine at least one second DCI format to monitor on the first carrier based on the reconfiguration message. The UE may monitor for the first DCI format(s) and the second DCI format(s) on the first carrier after receiving the reconfiguration message.