CoMP TAE FAE Compensation via UE Feedback
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Solution Overview
Problem
In Coordinated Multipoint Transmission (CoMP) systems, time alignment error (TAE) and frequency alignment error (FAE) between antenna ports pose significant challenges, leading to increased frequency selectivity and precoding performance issues, as existing methods struggle to accurately compensate for these errors, especially in wideband precoding and joint transmission scenarios.
Innovation Solution
A user equipment (UE) with measuring and feedback units measures internal and external TAE/FAE and feeds back the data to transmission point devices, which then compensates for these errors using a determining and compensating unit, averaging feedback from multiple UEs to enhance accuracy and effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CoMP transmission is implemented with multiple transmission point devices, then system throughput and coverage are improved, but TAE and FAE between antenna ports increase significantly
Solution Approach 1:
The patent implements a feedback mechanism where the UE measures TAE and FAE values from multiple transmission point devices and feeds back this information to the network side. The network then uses this feedback to adjust the precoding matrices and compensation parameters, creating a closed-loop system that continuously optimizes alignment precision despite the presence of multiple transmission points.
Solution Approach 2:
The patent dynamically adjusts compensation parameters based on measured TAE and FAE values. The system changes precoding matrix indices, modifies compensation parameters for each antenna port, and updates transmission parameters in response to measured alignment errors, enabling adaptive compensation for varying synchronization conditions across multiple transmission points.
2Productivity
If wideband precoding is used to improve spectral efficiency, then data rate increases, but frequency selectivity due to TAE deteriorates precoding performance
Solution Approach 1:
The patent applies different compensation strategies to different frequency bands and antenna ports. Instead of a uniform compensation approach, the system measures and compensates TAE and FAE specifically for each antenna port and frequency sub-band, allowing optimized precoding parameters to be applied locally where needed while maintaining overall system performance.
Solution Approach 2:
The patent implements dynamic precoding matrix selection and compensation parameter adjustment based on real-time TAE and FAE measurements. The system transitions from static wideband precoding to dynamic precoding that adapts to changing synchronization conditions, selecting appropriate precoding matrices and compensation parameters for each transmission point device based on measured alignment errors.
3Ease of manufacture
If DMRS-based precoding technique is used, then channel estimation is simplified, but FAE and TAE compensation becomes difficult at UE side
Solution Approach 1:
The patent introduces reference signals as intermediaries to facilitate TAE and FAE measurement. Instead of directly measuring alignment errors from data signals, the system uses dedicated reference signals transmitted from multiple antenna ports that can be independently processed by the UE to extract synchronization information, making the measurement process feasible despite the simplified channel estimation approach.
Solution Approach 2:
The patent segments the measurement task by measuring TAE and FAE for each antenna port separately using reference signals transmitted from individual ports. This segmentation allows the UE to process alignment information from each transmission point independently, overcoming the limitation of DMRS-based approaches where the composite channel from multiple points makes differentiation difficult.
4Measurement precision
If CRS-based or CSI-RS-based precoding technique is used, then FAE and TAE can be estimated, but system complexity increases
Solution Approach 1:
The patent makes the reference signals serve multiple functions: they are used for channel estimation, precoding matrix selection, and simultaneously for TAE and FAE measurement. This multi-functionality reduces the need for separate dedicated measurement signals and procedures, thereby reducing overall system complexity while maintaining precise alignment estimation capability.
Data Source
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AI summary
The present invention discloses a user equipment (UE) (100), comprising: a first measuring unit (1 10) adapted to measure time alignment error (TAE) and/or frequency alignment error (FAE) for antenna ports belonging to transmission point devices in Coordinated Multipoint Transmission (CoMP), the TAE including internal TAE and/or external TAE; and a first feedback unit (120) adapted to feedback the measured internal TAE, and/or external TAE, and/or FAE to at least one of the transmission point devices. The present invention provides a simple, direct and efficient approach for measuring and feeding back the cell-specific internal TAE and/or the UE-specific external TAE/FAE by UE and compensating the TAE/FAE by the transmission point device in the CoMP transmission, so that the CoMP transmission can properly operate.