UE-Specific TDD Frame HARQ Feedback Timing
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Solution Overview
Problem
In full duplex radio (FDR) systems, interference issues such as intra-device self-interference, UE to UE inter-link interference, and BS to BS inter-link interference occur due to simultaneous transmission and reception in the same time and frequency resources, which affect the efficiency of HARQ ACK/NACK feedback in wireless communication systems.
Innovation Solution
A method and apparatus for transmitting HARQ ACK/NACK feedback using a UE-specific Time Division Duplex (TDD) frame, where the UE receives a downlink control channel in a corresponding subframe and transmits the feedback in an uplink subframe located at least four subframes after the corresponding subframe, utilizing a UE-specific TDD frame structure with both UE-common and UE-specific subframe intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full duplex radio (FDR) is used to allow simultaneous transmission and reception in the same time and frequency resources, then system capacity is doubled, but intra-device self-interference, UE to UE inter-link interference, and BS to BS inter-link interference occur
Solution Approach 1:
The patent segments the TDD frame structure into UE-common subframe intervals and UE-specific subframe intervals. This segmentation allows different UEs to have customized uplink-downlink configurations in their specific subframes while maintaining common subframes for synchronized operations, thereby enabling full duplex operation for some UEs without causing interference to others.
Solution Approach 2:
The patent applies local quality by configuring UE-specific TDD frames where individual UEs can have different uplink-downlink subframe assignments tailored to their channel conditions and service requirements. This allows each UE to optimize its transmission and reception timing locally, reducing self-interference and inter-user interference while maintaining overall system capacity.
2Loss of time
If HARQ ACK/NACK feedback is transmitted quickly to improve communication efficiency, then latency is reduced, but interference management becomes more difficult in FDR systems
Solution Approach 1:
The patent implements dynamic TDD configuration where the uplink-downlink subframe assignments can be adjusted in real-time based on channel conditions, traffic patterns, and interference levels. This dynamic adjustment allows the system to optimize HARQ feedback timing for each UE individually, achieving low latency while managing interference through flexible resource allocation.
Solution Approach 2:
The patent uses preliminary action by pre-configuring UE-specific TDD frames with designated uplink subframes for HARQ feedback transmission. These pre-allocated resources ensure that feedback can be transmitted quickly when needed while avoiding conflicts with other UEs' transmission and reception schedules, thus managing interference proactively.
3Object-generated harmful factors
If UE-specific TDD frames are used to optimize individual UE performance, then interference is reduced, but frame structure complexity increases
Solution Approach 1:
The patent achieves universality by designing a TDD frame structure that serves multiple functions: UE-common subframes provide synchronized downlink transmission and coordination for all UEs, while UE-specific subframes enable individualized uplink-downlink configurations. This multi-functional design reduces self-interference through proper timing separation while avoiding excessive complexity by reusing common frame elements across all UEs.
Data Source
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AI summary
A method for a terminal transmitting a hybrid automatic repeat request (HARQ) ACK/NACK feedback by using a terminal-specific TDD frame in a wireless communication system may comprise the steps of: receiving a downlink control channel from a corresponding subframe of the terminal-specific TDD frame; and transmitting a HARQ ACK/NACK for the downlink control channel from an uplink subframe that is the most adjacent to the corresponding subframe among subframes coming after at least four subframes from the corresponding subframe.