TDD Flexible Subframe Reconfiguration via Pseudo-Uplink Grants
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Solution Overview
Problem
Current TDD communication systems face challenges in dynamically adapting uplink and downlink configurations to optimize data capacity based on changing traffic patterns without disrupting HARQ transmission timing.
Innovation Solution
The system identifies flexible subframes within an initial uplink-downlink configuration and reconfigures them using pseudo-uplink grants or RRC signaling, allowing for dynamic changes from uplink to downlink subframes without altering HARQ acknowledgment timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If TDD UL-DL configuration is reconfigured to adapt to changing traffic patterns, then data capacity is improved, but HARQ transmission timing may be disrupted
Solution Approach 1:
The patent segments the TDD frame into different subframe types (fixed uplink subframes, fixed downlink subframes, and flexible subframes). This segmentation allows selective reconfiguration of only the flexible subframes while maintaining the timing of fixed subframes, thereby preserving HARQ transmission timing while still enabling data capacity adaptation.
Solution Approach 2:
The patent introduces dynamic reconfiguration capability where the eNodeB can change the UL-DL configuration of flexible subframes based on current traffic conditions. This dynamic adjustment allows the system to adapt to changing data traffic patterns while maintaining stability in the overall HARQ timing framework through controlled reconfiguration procedures.
2Productivity
If flexible subframes are reconfigured from uplink to downlink, then downlink data capacity is improved, but uplink transmission opportunities are reduced
Solution Approach 1:
The patent applies local quality by treating different subframes differently - fixed uplink subframes maintain their uplink function for guaranteed uplink transmission opportunities, while flexible subframes can be dynamically assigned to downlink based on traffic conditions. This localized differentiation optimizes downlink capacity when needed while preserving uplink reliability through fixed subframe allocation.
Solution Approach 2:
The patent changes the parameter of subframe directionality from static to dynamic for flexible subframes. By allowing the UL-DL configuration parameter to change based on traffic conditions, the system can optimize downlink capacity when traffic demands it while maintaining the ability to restore uplink transmission opportunities when needed.
3Adaptability or versatility
If reconfiguration signaling is transmitted to the UE, then subframe configuration is updated, but signaling complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-identifying and marking flexible subframes during the initial configuration phase. This preliminary identification eliminates the need for complex reconfiguration signaling later, as the eNodeB only needs to indicate which pre-identified flexible subframes should be reconfigured, rather than specifying entire configuration changes from scratch.
Solution Approach 2:
The patent uses the flexible subframe identification as an intermediary mechanism that simplifies reconfiguration signaling. Instead of transmitting complete reconfiguration details, the system uses the pre-established flexible subframe markers as intermediaries to convey reconfiguration intent, thereby reducing signaling complexity while maintaining configuration flexibility.
Data Source
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AI summary
Methods, systems, and devices are described for reconfiguring a user equipment (UE) to operate in a reconfigured TDD UL-DL configuration. An initial uplink- downlink (UL-DL) configuration for TDD communication may be provided for communication between an e Node B and a UE. One or more subframes within each frame transmitted using the initial UL-DL configuration may be identified as flexible subframes. The identification of flexible subframes may permit the identification of timing for HARQ transmissions that does not change when a reconfiguration takes place. A different UL-DL configuration may be transmitted to the UE, in which at least one flexible subframe is to be changed from an uplink subframe to a downlink subframe. The different UL-DL configuration may be transmitted by, for example, a pseudo-uplink grant to the UE, which indicates that the UE is to reconfigure one or more flexible subframes from uplink to downlink transmission.