DMRS Transmission Power Configuration for LTE-A Channel Estimation
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Solution Overview
Problem
In LTE-A systems, the existing pilot signal designs, such as CRS, lead to increased overhead and interference due to non-orthogonal pilot frequencies in MU-MIMO scenarios, necessitating a more efficient method for channel estimation that reduces signaling overhead and enables channel estimation without network-side notifications.
Innovation Solution
Configuring the transmission power of DMRS at each layer to be the same and setting a constant ratio between DMRS and data transmission power in user terminals, allowing for channel estimation without network-side notifications, thereby simplifying control signaling and improving channel estimation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Common Reference Signal (CRS) is used for pilot frequency measurement, then channel estimation can be performed, but signaling overhead increases and interference cannot be estimated in MU-MIMO scenarios
Solution Approach 1:
The patent extracts the pilot signal function from the common CRS to a dedicated DMRS specifically for demodulation. This separation allows the pilot frequency measurement function to be performed by DMRS without requiring additional CRS notifications, thereby reducing signaling overhead while maintaining channel estimation capability.
Solution Approach 2:
The DMRS is designed to serve multiple functions: it acts as both the demodulation reference signal and the pilot frequency measurement signal. This multi-functionality eliminates the need for separate CRS notifications and enables channel estimation without increasing signaling overhead.
2Adaptability or versatility
If multiple CRSs are used in MU-MIMO, then channel estimation can be performed for multiple users, but orthogonality of pilot frequency cannot be realized and interference cannot be estimated
Solution Approach 1:
The patent segments the pilot signal resources by assigning different orthogonal DMRS sequences to different users in MU-MIMO scenarios. This segmentation enables each user to have dedicated pilot resources, achieving orthogonality and allowing interference estimation through the orthogonal structure.
Solution Approach 2:
The patent introduces orthogonality in the sequence domain for DMRS, adding a new dimension of differentiation beyond frequency and time resources. This allows multiple users to share the same time-frequency resources while maintaining orthogonality through orthogonal sequences, enabling both multi-user support and interference estimation.
3Loss of information
If DMRS is mapped according to available rank information, then overhead can be reduced in self-adaptive manner, but transmission power configuration becomes complex when total layer number is odd
Solution Approach 1:
The patent changes the power configuration parameter from layer-specific variable power to a constant ratio between DMRS and data transmission power. This parameter change simplifies the transmission power configuration by eliminating the need for complex layer-by-layer power management, while the self-adaptive overhead reduction is maintained through rank-based DMRS mapping.
Data Source
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AI summary
The present disclosure discloses a transmission power configuration method for a Demodulation Reference Signal (DMRS), and the method comprises: configuring the ratio between transmission power of a DMRS at each layer in a Resource Element (RE) and transmission power of data at a corresponding layer to be a constant value. Meanwhile, the present disclosure discloses a transmission power configuration apparatus for the DMRS. The present disclosure greatly improves the correct rate of data frame decoding, and improves decoding performance. The present disclosure enables the network side not need to notify a UE of the corresponding relationship between transmission power of DMRS at each layer and transmission power of data at the corresponding layer, which simplifies the overhead of the control signalling in the network side. As the corresponding relationship between transmission power of DMRS at each layer and transmission power of data at the corresponding layer is configured in the UE, the UE can implement channel estimation without waiting for the notification from the network side, which improves the channel estimation efficiency.