ACK/NACK Resource Determination in Carrier Aggregation
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Solution Overview
Problem
Current wireless communication systems face challenges in effectively transmitting and receiving ACK/NACK signals, particularly in determining resources for ACK/NACK signal transmission, preventing downlink grant resource blocking, and reducing signaling overhead.
Innovation Solution
A method and apparatus for transmitting ACK/NACK signals in a wireless communication system, where a user equipment (UE) receives downlink control information including fields for transmit power control and resource allocation, and uses these to determine ACK/NACK resources, with specific offset information used based on the carrier aggregation configuration, allowing for efficient resource allocation and reduced overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACK/NACK resource indication information is transmitted through downlink control information, then the ACK/NACK resource can be determined, but signaling overhead increases
Solution Approach 1:
The patent reuses existing downlink control information fields (first field for transmit power control, second field for resource allocation) to convey ACK/NACK resource indication information. By making these existing fields serve multiple functions, the patent avoids adding dedicated signaling for ACK/NACK resource indication, thereby reducing signaling overhead while ensuring reliable resource determination.
2Productivity
If carrier aggregation is implemented, then system capacity increases, but resource allocation complexity increases
Solution Approach 1:
The patent applies different field interpretations based on the carrier on which downlink data is received. When downlink data is received on the first carrier, the third field contains ACK/NACK resource indication information. When downlink data is received on the second carrier, the first field contains ACK/NACK resource indication information. This localized adaptation allows the system to handle multiple carriers efficiently without requiring a completely different resource allocation mechanism for each carrier.
3Loss of information
If multiple fields are used for control information, then information completeness improves, but processing complexity increases
Solution Approach 1:
The patent employs dynamic field interpretation where the meaning and content of downlink control information fields change based on the carrier aggregation configuration and the carrier on which downlink data is received. The system dynamically determines which field contains ACK/NACK resource indication information, allowing flexible information conveyance without requiring fixed, dedicated fields for each type of information, thus balancing completeness with processing simplicity.
Data Source
AI summary
A method is presented for transmitting an acknowledgement/negative acknowledgement (ACK/NACK) signal by a user equipment (UE) in a wireless communication system. The UE is configured with a primary cell (PCell) and a secondary cell (SCell). The UE receives downlink control information (DCI) via a physical downlink control channel (PDCCH). The DCI including a first field for transmit power control information and a second field for ACK/NACK resource offset information. The UE receives downlink data via a physical downlink shared channel (PDSCH) based on the DCI. The UE transmits an ACK/NACK signal for the downlink data using an ACK/NACK resource. When the downlink data is received on the PCell, the ACK/NACK resource is determined by adding a lowest resource index of the PDCCH and a value of the ACK/NACK resource offset information. When the downlink data is received on the SCell, the first field includes ACK/NACK resource indication information.