Dedicated Reference Signal Scrambling for MU-MIMO Interference
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Solution Overview
Problem
In LTE-A systems, UEs from different cells use cell-specific scrambling code sequences, leading to interference issues when multiple-cell MU-MIMO is employed, as they cannot obtain scrambling code sequences from other cells, hindering DRS interference suppression and channel estimation precision.
Innovation Solution
A method and apparatus for a base station to determine whether UEs participating in MU-MIMO belong to the same cell or cell group, configuring them to use cell-specific or cell group-specific scrambling code sequences, respectively, and sending configuration information to enable accurate DRS transmission and interference suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cell-specific scrambling code sequences are used for UEs from different cells, then single-cell MU-MIMO performance is optimized, but DRS interference suppression between cells deteriorates
Solution Approach 1:
The patent changes the parameter of scrambling code sequence initialization from cell-specific to UE-specific (or group-specific). By initializing the scrambling code sequence with a unique value for each UE or UE group rather than using cell-specific initialization, the system enables UEs to generate different scrambling sequences even within the same cell, thereby suppressing DRS interference between cells while maintaining single-cell MU-MIMO performance
Solution Approach 2:
The patent segments the scrambling code sequences by introducing UE-specific or group-specific initialization values. This segmentation allows different UEs to use distinct scrambling sequences, creating orthogonality or near-orthogonality between DRS from different cells, thus enabling interference suppression while preserving the benefits of cell-specific optimization
2Object-affected harmful factors
If UE-specific scrambling code sequences are introduced to suppress DRS interference, then DRS interference suppression improves, but system complexity increases
Solution Approach 1:
The patent applies universality by using a unified UE-specific initialization mechanism that works across both single-cell and multi-cell MU-MIMO scenarios. The same UE-specific scrambling code generation method serves multiple purposes: suppressing DRS interference between cells, maintaining compatibility with existing LTE infrastructure, and providing a scalable solution that works for any number of UEs and cells without requiring separate mechanisms
Solution Approach 2:
The system enables UEs to self-generate their scrambling code sequences using their own unique initialization values provided by the network. Each UE independently generates its scrambling sequence without requiring complex coordination or management from the network side, thereby reducing system complexity while achieving interference suppression
Data Source
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AI summary
The present invention provides a method and apparatus for transmitting a dedicated reference signal(DRS), the method includes: determining, by a base station, whether user equipments(UEs) participating in multiple users-multiple input multiple output(MU-MIMO) at the same physical resource block((B) belong to the same cell, if yes, configuring that the UEs adopt a cell-specific scrambling code sequence; otherwise, configuring that the UEs located in the cells belonging to the same cell group adopt a cell group-specific scrambling code sequence; sending, by the base station, configuration information to the UE, and sending a DRS to the UE by using the scrambling code sequence configured for the UE; an initialization code of the cell-specific scrambling code sequence is determined according to an identity of the cell in which the UE is located; an initialization code of the cell group-specific scrambling code sequence is determined according to an identity of the cell group. According to the present invention, the UE can restrain DRS interferences between different cells when receiving the DRS and improve the precision of the channel estimation.