Configured Grant Feedback for Low-Latency NR-U Carrier Aggregation
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Solution Overview
Problem
In 5G NR technologies, user equipment (UE) faces challenges in transmitting uplink data without an explicit physical downlink control channel (PDCCH) grant due to low latency requirements, and there is a need for improved methods to determine resource carriers for feedback in unlicensed spectrum carrier aggregation.
Innovation Solution
The UE and base station employ configured grant configurations to transmit and receive feedback on specific carriers based on predefined settings, using various options for configured grant-deficiency feedback indicator (CG-DFI) feedback, activation/deactivation, and carrier aggregation modes to optimize communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE waits to receive an explicit PDCCH UL grant before transmitting UL data, then the system maintains reliable control signaling, but the transmission latency increases which violates low latency requirements in 5G NR
Solution Approach 1:
The network pre-configures grant parameters (resources, power, modulation) for the UE before data transmission is needed. This preliminary configuration allows the UE to transmit UL data immediately when data arrives without waiting for dynamic PDCCH grants, thus reducing latency while maintaining reliability through pre-established control parameters
2Loss of time
If the UE transmits UL data without receiving an explicit PDCCH grant using configured grant, then transmission latency is reduced, but the UE cannot determine which carriers contain feedback for the transmitted data
Solution Approach 1:
The patent establishes feedback mechanisms where the network sends ACK/NACK responses on specific carriers that the UE can identify through pre-configured carrier associations or DCI indicators. This allows the UE to transmit autonomously while still receiving reliable feedback information about transmission success
Solution Approach 2:
The network uses intermediate signaling elements such as DCI formats or RRC configuration parameters to indicate which carriers will carry feedback for configured grant transmissions. This intermediary information bridges the gap between autonomous transmission and feedback reception
3Productivity
If the system uses configured grant configurations for autonomous UL transmission, then transmission efficiency improves, but the complexity of managing multiple carriers and feedback indicators increases
Solution Approach 1:
The patent creates universal DCI formats and RRC configuration structures that can handle multiple carriers and feedback scenarios through standardized fields. These multi-functional configurations reduce the need for separate management mechanisms for each carrier, thereby reducing overall system complexity while maintaining high transmission efficiency
Data Source
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AI summary
Configured grant operations for new radio (NR) unlicensed spectrum (NR-U) carrier aggregation (CA) are disclosed. In an aspect, a method of wireless communication by a user equipment (UE) may include transmitting uplink (UL) data to a base station according to a configured grant configuration. The method may also include determining a carrier to receive feedback from the base station based on the configured grant configuration. The method may further include receiving feedback from the base station on the carrier in response to the transmitting of the UL data.