DMRS Port Allocation for MU-MIMO Channel Estimation
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Solution Overview
Problem
The performance of MU-MIMO systems is limited due to lower channel estimation performance caused by limited orthogonal DMRS ports and high Multi-User Interference (MUI) after increasing the number of MU-MIMO transmission layers, which restricts the full utilization of multi-antenna performance at base stations.
Innovation Solution
A method and device for notifying and determining DMRS ports or mapping relationships by sending indication information, including Radio Resource Control (RRC) signaling, physical layer New Data Indication (NDI) bits, and DMRS pilot scrambler configuration information, to allocate and configure DMRS port groups, enhancing channel estimation and supporting dynamic switching between SU-MIMO and MU-MIMO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of MU-MIMO transmission layers is increased, then system capacity is improved, but channel estimation performance deteriorates due to limited orthogonal DMRS ports
Solution Approach 1:
The patent extends the DMRS port indexing from a single dimension to multiple dimensions by introducing group indices and intra-group port indices. This allows orthogonal DMRS ports to be identified by a combination of group index and port index within the group, effectively increasing the total number of orthogonal ports available for channel estimation in multi-layer MU-MIMO transmissions.
Solution Approach 2:
The patent segments the DMRS ports into multiple groups, where each group contains a subset of orthogonal ports. This segmentation allows the system to manage a larger total number of ports by organizing them into manageable groups, enabling support for more transmission layers while maintaining orthogonal channel estimation capabilities.
2Productivity
If the number of MU-MIMO transmission layers is increased, then system capacity is improved, but Multi-User Interference (MUI) increases
Solution Approach 1:
By extending port identification to multiple dimensions (group index and intra-group port index), the patent enables orthogonal separation of DMRS ports across more users and layers. This increased orthogonality reduces Multi-User Interference by ensuring that channel estimation references for different users remain statistically independent even as the number of simultaneous transmission layers increases.
3Quantity of substance
If more bits are used for representing joint coding of layers, ports and scramblers, then orthogonal DMRS ports for more MU-MIMO receiving ends are supported, but terminal complexity is improved
Solution Approach 1:
The patent segments the port identification into two parts: group index and intra-group port index. This segmentation allows the terminal to process port information in smaller, more manageable units rather than handling a single large port index, thereby reducing terminal complexity while supporting a larger total number of orthogonal DMRS ports through the combined indexing scheme.
Solution Approach 2:
The patent transforms the single-dimension port indexing into a two-dimensional indexing system (group index, intra-group port index). This dimensional transformation allows the system to support more orthogonal ports without proportionally increasing the complexity of port management at the terminal, as the indexing is naturally divided into hierarchical levels.
4Adaptability or versatility
If DCI resources are increased to notify all scenarios with extended joint coding, then dynamic switching of SU-MIMO/MU-MIMO is supported, but DCI resources are unnecessarily wasted
Solution Approach 1:
The patent introduces a transmission mode indication dimension that allows the system to select between different DMRS port notification methods. When multi-layer MU-MIMO is not active, the system can use the legacy single-table method, avoiding the overhead of the extended joint coding. When multi-layer MU-MIMO is required, the extended method with group indices is activated, thus supporting dynamic switching without wasting DCI resources in scenarios where the extended capability is not needed.
Data Source
AI summary
A method and device for notifying and determining De Modulation Reference Signal (DMRS) ports or a mapping relationship is provided. The method includes: a sending end sends indication information to a receiving end in a Transmission Mode (TM), and the sending end indicates allocation information about DMRS ports or a mapping relationship according to the indication information, and the indication information includes at least one of the following: Radio Resource Control (RRC) signaling, physical layer New Data Indication (NDI) bit, and DMRS pilot scrambler configuration information nscid. A problem of influence on a performance of a Multi-User Multiple-Input Multiple-Output (MU-MIMO) system caused by lower channel estimation performance due to limited orthogonal DMRS ports for MU-MIMO transmission and high Multi-User Interference (MUI) after increment of a total number of MU-MIMO transmission layers is solved, thereby increasing orthogonal DMRS ports for MU-MIMO transmission on a basis of improving base station configuration flexibility during MU-MIMO transmission, effectively inhibiting MUI during channel estimation, and improving channel estimation performance.