HARQ-ACK Feedback Bit Determination for TDD Carrier Aggregation
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Solution Overview
Problem
In LTE-A systems with carrier aggregation, determining the correct number of bits for HARQ-ACK feedback information is challenging when TDD uplink-downlink configurations of multiple Component Carriers (CCs) are different, leading to potential interference and inefficient resource usage.
Innovation Solution
The method involves determining the number of downlink subframes corresponding to HARQ-ACK feedback information in each CC based on received PDCCH, UL DAI, PDSCH subframes, and HARQ-ACK bundling window size, allowing for accurate transmission and efficient resource allocation even when CCs have different TDD configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple aggregated CCs use the same uplink-downlink configuration, then the system structure is simple, but interference occurs when CCs have different TDD configurations
Solution Approach 1:
The patent segments the HARQ-ACK feedback information by CC, determining the number of downlink subframes for each CC independently based on its specific TDD configuration. This allows each CC to be handled separately despite using the same physical resources, preventing interference while maintaining structural simplicity.
Solution Approach 2:
The patent applies local quality by determining the number of bits for HARQ-ACK feedback separately for each CC according to its specific TDD configuration characteristics. Each CC receives customized feedback allocation based on its local configuration rather than a uniform approach, eliminating interference while keeping the overall system simple.
2Device complexity
If the number of bits for HARQ-ACK feedback is determined uniformly for all CCs, then the determination process is simple, but PUSCH resources are wasted
Solution Approach 1:
The patent makes the HARQ-ACK feedback bit determination dynamic by calculating the number of bits for each CC based on its specific TDD configuration and the actual number of downlink subframes. This dynamic adaptation ensures accurate resource allocation without waste, while the process remains manageable through systematic calculation methods.
Solution Approach 2:
The patent changes the parameter of HARQ-ACK feedback bit allocation from a uniform fixed value to a variable value determined by each CC's TDD configuration characteristics. This parameter adaptation allows precise resource matching for each CC, preventing waste while maintaining a systematic determination approach.
3Productivity
If HARQ-ACK feedback information is bundled across multiple subframes, then the feedback can be transmitted efficiently, but the timing relationship becomes complex
Solution Approach 1:
The patent segments the HARQ-ACK feedback timing determination by CC, calculating the number of downlink subframes for each CC independently. This segmentation maintains the bundling efficiency while managing timing complexity through systematic, per-CC calculations rather than a unified complex timing approach.
Data Source
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AI summary
The disclosure provides a method for transmitting hybrid automatic repeat request acknowledgement, HARQ-ACK, feedback information by a user equipment, UE, in a wireless communication system. The disclosure also provides method for receiving HARQ-ACK and a User Equipment and Base station.