Dynamic TDD Configuration for Legacy UE Interference
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Solution Overview
Problem
Legacy UEs in LTE TDD systems are incompatible with dynamic TDD DL-UL reconfiguration, leading to interference issues and inaccurate signal quality measurements due to differences in understanding TDD configurations between legacy and new UEs, which affects system performance and scheduling flexibility.
Innovation Solution
A dynamic TDD configuration method that selects a subset of allowable configurations based on the current TDD configuration, ensuring that downlink subframes are not dynamically converted to uplink subframes, thereby avoiding interference and maintaining compatibility with legacy UEs, using criteria such as avoiding UL HARQ interference with new UEs' DL transmissions and ensuring accurate DL channel quality measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic TDD configuration is implemented, then traffic adaptation capability is improved, but compatibility with legacy UEs deteriorates
Solution Approach 1:
The patent segments the TDD configuration into two parts: a semi-static configuration transmitted via system information that legacy UEs can follow, and a dynamic configuration transmitted via physical layer signaling that new UEs can utilize for traffic adaptation. This segmentation allows the system to support both legacy and new UEs simultaneously with different capability levels.
Solution Approach 2:
The patent introduces an intermediary mechanism where the base station transmits both semi-static TDD configuration information (visible to all UEs) and dynamic TDD configuration information (interpreted only by new UEs with enhanced capability). This intermediary approach allows legacy UEs to operate reliably while new UEs benefit from dynamic traffic adaptation.
2Productivity
If downlink subframes are dynamically converted to uplink subframes, then uplink traffic capacity is improved, but interference with legacy UEs increases
Solution Approach 1:
The patent applies local quality by allowing dynamic subframe conversion only for specific subframes that do not affect legacy UE operations. The base station identifies which downlink subframes can be dynamically converted to uplink without causing HARQ interference or measurement inaccuracies for legacy UEs, thereby locally optimizing uplink capacity without global disruption.
Solution Approach 2:
The patent employs preliminary anti-action by pre-identifying and protecting critical downlink subframes that must remain as downlink to maintain legacy UE compatibility. Before implementing dynamic conversion, the system determines which subframes are safe to convert, preventing harmful interference in advance rather than correcting it afterward.
3Reliability
If TDD configuration is changed via system information modification, then legacy UE compatibility is maintained, but reconfiguration speed deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-transmitting the semi-static TDD configuration via system information, which legacy UEs use immediately. Meanwhile, the base station prepares and transmits dynamic configuration adjustments via faster physical layer signaling, enabling new UEs to adapt quickly without waiting for system information modification cycles.
Solution Approach 2:
The patent introduces dynamics by implementing a dual-layer configuration system where the semi-static layer provides stability for legacy UEs through traditional system information updates, while the dynamic layer enables rapid reconfiguration for new UEs through physical layer signaling, achieving both reliability and speed.
4Adaptability or versatility
If dynamic reconfiguration is implemented, then traffic flexibility is improved, but measurement accuracy for legacy UEs deteriorates
Solution Approach 1:
The patent segments measurement references into two categories: cell-specific reference signals (CRS) that legacy UEs use for accurate channel quality measurements based on the semi-static configuration, and dedicated reference signals for new UEs that support dynamic configuration. This segmentation ensures legacy UEs maintain measurement accuracy while new UEs benefit from traffic flexibility.
Solution Approach 2:
The patent uses copying by providing legacy UEs with a copy of the stable semi-static TDD configuration for measurement purposes, separate from the dynamic configuration used for actual data transmission. This allows legacy UEs to perform accurate measurements on a consistent configuration baseline while the system dynamically adapts to traffic conditions.
Data Source
AI summary
Accordingly, the present disclosure is directed to a dynamic time division duplex (TDD) configuration method and a base station using the same method. According to one of the exemplary embodiments, the present disclosure is directed to A dynamic TDD configuration method, applicable to a base station, and the method includes the steps of transmitting a current time division duplex (TDD) configuration, selecting a dynamic TDD configuration based on the current TDD configuration after transmitting the current TDD configuration, and transmitting the dynamic TDD configuration, wherein, the dynamic TDD configuration is a subset of an allowable set comprising one or more possible TDD configurations by which each downlink subframe of the current TDD configuration is not re-configured to a uplink subframe by the dynamic TDD configuration selected from the allowable set.