ACK/NACK Feedback Configuration for Mixed TDD-FDD Carrier Aggregation
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Solution Overview
Problem
In LTE TDD or FDD systems, especially with carrier aggregation, existing methods fail to provide a solution for acknowledging or negative acknowledging data transmission when TDD carriers with different uplink and downlink subframe configurations are aggregated, or when an FDD and a TDD carrier are aggregated, leading to inability to feed back ACK/NACK information on the primary carrier.
Innovation Solution
A method and device that select a timing relationship and configure a subframe and channel resource for ACK/NACK feedback, allowing feedback on a secondary carrier when the primary carrier's subframe is an uplink subframe, balancing feedback loads across carriers and subframes, and enabling flexible ACK/NACK feedback even in systems with different subframe configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ACK/NACK transmission method is used, then the method is simple and applicable to same-configuration carrier aggregation, but it cannot provide ACK/NACK feedback when TDD carriers with different uplink and downlink subframe configurations are aggregated
Solution Approach 1:
The patent applies dynamics by making the ACK/NACK feedback configuration adaptable rather than fixed. The network device dynamically selects timing relationships from multiple options based on the specific carrier aggregation scenario, allowing the system to adjust to different TDD and FDD configuration combinations while maintaining reliable feedback
Solution Approach 2:
The patent changes the timing relationship parameters between downlink subframes and ACK/NACK feedback subframes. By selecting from multiple timing relationships with different K1 values (e.g., K1=4, K1=5, K1=6), the system adapts to different carrier configurations and ensures that ACK/NACK feedback can always be transmitted on an appropriate uplink subframe
2Ease of operation
If ACK/NACK feedback is restricted to primary carrier only, then the feedback mechanism is simple, but feedback cannot be transmitted when primary carrier subframe is not available
Solution Approach 1:
The patent makes the feedback mechanism universal by enabling ACK/NACK feedback on both primary and secondary carriers. The network device can configure multiple timing relationships that map to different carriers, allowing the system to universally handle feedback transmission regardless of which carrier is available, thus maintaining both simplicity and reliability
Solution Approach 2:
The patent introduces secondary carriers as intermediary resources for ACK/NACK feedback. When the primary carrier is unavailable (e.g., its subframe is downlink instead of uplink), the system uses pre-configured timing relationships to redirect feedback to appropriate subframes on secondary carriers, ensuring feedback transmission availability without complicating the basic mechanism
3Adaptability or versatility
If multiple timing relationships are configured for different carriers, then flexible ACK/NACK feedback is enabled, but the configuration complexity increases
Solution Approach 1:
The patent segments the timing relationship configuration into carrier-specific relationships. Each carrier is assigned its own timing relationship(s) between downlink subframes and ACK/NACK feedback subframes, allowing independent optimization for each carrier's characteristics while maintaining overall system flexibility without overwhelming complexity
Data Source
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AI summary
The present invention discloses a method and device for transmitting ACK/NACK indication information. A network-side device configures at least two carriers for a UE; transmits PDCCH information to the UE; selects one of at least two timing relationships as a first timing relationship; determines a corresponding third uplink subframe and first carrier; indicate related information corresponding to the third uplink subframe and the first carrier to the UE; in the third uplink subframe of the first carrier, determines a first channel resource, and indicates the first channel resource to the UE; and receives an ACK/NACK fed back by the UE on the allocated resource.