MU-MIMO DM-RS Port Allocation for Better Channel Estimation
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Solution Overview
Problem
Existing MU-MIMO systems face performance trade-offs in channel estimation due to interference between DM-RS ports, leading to reduced throughput and fairness, especially in partially loaded scenarios.
Innovation Solution
A dynamic DM-RS port allocation scheme using Orthogonal Variable Spreading Factor (OVSF) codes and partial port occupancy (P-Poi) signaling, combined with VSFOCC despreading and DFT interpolation, to enhance channel estimation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If orthogonal cover codes (OCC) based on Walsh spreading are used to separate users or layers in MU-MIMO, then channel estimation can be performed, but interference between pilots occurs when reference signals occupy the same time-frequency resources
Solution Approach 1:
The patent changes the spreading factor parameter dynamically based on the number of active ports. When the number of active ports is less than the maximum supported ports, a reduced spreading factor is applied to generate partial port occupancy information, allowing the system to adapt the code structure to the actual load and reduce interference.
Solution Approach 2:
The system transitions from static OCC allocation to dynamic port allocation where the spreading factor and code selection are adjusted in real-time based on the number of active MU-MIMO ports. This dynamic adaptation allows optimal separation of pilots under varying system conditions.
2Measurement precision
If the spreading factor is reduced to increase the number of distinct channel estimates, then channel estimation quality improves, but the system complexity increases
Solution Approach 1:
The patent modifies the spreading factor parameter based on the actual number of active ports rather than using a fixed maximum spreading factor. This parameter adaptation increases the number of distinct channel estimates available for estimation, improving quality without requiring complex receiver processing.
Solution Approach 2:
The system generates partial port occupancy information that enables the receiver to self-adapt to the actual number of active ports. The reduced spreading factor allows the receiver to efficiently identify and process only the active ports, reducing complexity while improving estimation quality.
3Productivity
If fixed DM-RS port allocation is used to simplify resource management, then system operation is simple, but throughput and fairness are reduced in partially loaded scenarios
Solution Approach 1:
The patent implements dynamic port allocation where the spreading factor and code assignment are adjusted based on the actual number of active MU-MIMO ports. This allows the system to optimize throughput for partially loaded scenarios while maintaining simple operation through automated adaptation.
Solution Approach 2:
The system changes the spreading factor parameter dynamically to match the load conditions. When fewer ports are active, a reduced spreading factor is applied, increasing the number of distinct channel estimates and improving both throughput and fairness without requiring complex manual configuration.
Data Source
AI summary
A method and system for improving channel estimation for multi-user, multiple-input, multiple-output (MU-MIMO) systems through dynamic DM-RS port allocation in a 5G New Radio network is provided. The method comprises of allocating, by a Scheduler aware UE port allocation unit, one or more MU-MIMO ports to a plurality of code division multiplexing (CDM) groups for a plurality of UE users, performing, by a code selection unit, a code selection based on a number of allocated MU-MIMO ports, determining, by a spreading factor unit, a spreading factor allocated for each of the MU-MIMO ports in each of the plurality of CDM groups, determining, by a signalling unit, a Downlink Control Information (DCI) signalling of a Partial Port Occupancy (P-Poi) transmission for each UE and obtaining, by a channel estimation unit, channel estimates at the receiver through VSFOCC de-spreading based on the P-POI assigned for each of the MU-MIMO ports.