Dynamic Coherence Signaling for TDD Channel Reciprocity
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Solution Overview
Problem
In TDD wireless communication systems, the reciprocity between uplink and downlink channels is not accurately maintained due to phase and amplitude mismatches in transmit/receive chains, leading to performance degradation in MU-MIMO and CoMP-JT schemes, especially with phase discontinuity issues during uplink MIMO transmissions.
Innovation Solution
Implementing dynamic signaling for coherence levels and Tx/Rx coherence status to ensure phase calibration among antenna ports, allowing for adaptive operation based on UE capability and reporting changes in coherence group configurations to maintain optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If channel reciprocity is assumed in TDD systems, then downlink channel can be estimated from uplink transmission, but phase and amplitude mismatches in transmit/receive chains cause estimation inaccuracies
Solution Approach 1:
The patent changes the operational parameters of the transmit and receive chains by introducing phase compensation values and calibration factors. The system dynamically adjusts phase and amplitude parameters to correct mismatches between uplink and downlink channels, thereby improving channel estimation accuracy while maintaining reciprocity reliability.
Solution Approach 2:
The patent implements feedback mechanisms where the network node receives coherence group configuration information from the UE and uses this feedback to adjust phase compensation and calibration parameters. This closed-loop feedback system continuously monitors and corrects phase/amplitude mismatches, resolving the contradiction between measurement precision and reliability.
2Productivity
If phase calibration is performed among antenna ports, then MIMO performance is improved, but system complexity increases due to dynamic coherence group configuration
Solution Approach 1:
The patent segments the antenna ports into coherence groups, where each group contains antenna ports with similar phase characteristics. This segmentation allows phase calibration to be performed independently within each group, improving MIMO performance while managing system complexity through modular configuration rather than treating all antenna ports as a single complex unit.
Solution Approach 2:
The patent applies local quality by performing phase calibration and coherence group configuration locally within each coherence group rather than globally across all antenna ports. This localized approach improves MIMO performance for each group while reducing overall system complexity by limiting the scope of calibration operations to manageable subsets of antenna ports.
3Measurement precision
If dynamic coherence level signaling is implemented, then channel reciprocity accuracy is enhanced, but uplink overhead increases
Solution Approach 1:
The patent applies partial action by signaling coherence group configuration information only when changes occur, rather than continuously transmitting full coherence state data. This selective signaling approach enhances channel reciprocity accuracy by providing necessary updates while minimizing uplink overhead by avoiding redundant transmissions.
Solution Approach 2:
The patent extracts and signals only the essential coherence group configuration information that is necessary for maintaining accurate channel reciprocity, rather than transmitting complete coherence state data. This extraction approach enhances measurement precision by providing critical information while reducing uplink overhead by eliminating unnecessary data transmission.
Data Source
AI summary
According to an example embodiment, a method is provided including: receiving, at a user equipment from a network node, a coherence group configuration, wherein the group coherence group configuration indicates at least: one or more transmit groups, wherein each transmit group includes one or more transmit ports of the user equipment, and wherein the one or more transmit ports in each group are coherent; and one or more receive groups, wherein each receive group includes one or more receive ports of the user equipment, and wherein the one or more receive ports in each group are coherent; determining a change in the coherence group configuration; and transmitting information indicating the change to the network node.