MU-MIMO Precoding Matrix Selection for Interference Reduction
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Solution Overview
Problem
In MU-MIMO systems, efficient precoding to minimize user interference requires high-granularity channel feedback and complex scheduling, leading to increased control information overhead.
Innovation Solution
A wireless communication apparatus and method that uses a channel estimation unit to select user equipment pairs and determines a precoding matrix to make channel response matrices orthogonal, reducing interference without increasing control information overhead by applying the precoding matrix only to one user equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If precoding is used to minimize user interference in MU-MIMO systems, then user interference is reduced, but control information overhead increases due to high-granularity channel feedback requirements
Solution Approach 1:
The patent extracts only the essential precoding information needed for interference mitigation, rather than feeding back complete high-granularity channel state information. The base station determines precoding matrices and feeds back only the necessary control information to user equipment, reducing overhead while maintaining interference reduction benefits
Solution Approach 2:
The patent changes the parameter granularity of feedback information from fine-grained channel state information to coarser precoding matrix indicators. This parameter transformation reduces the amount of control information while preserving the essential functionality for interference minimization through precoding
2Reliability
If high-granularity channel feedback is implemented for effective precoding, then precoding performance improves, but system complexity increases due to complicated scheduling procedures
Solution Approach 1:
The base station performs preliminary determination of precoding matrices based on available channel information before scheduling decisions are finalized. This preliminary action allows the system to maintain good precoding performance while simplifying the scheduling complexity, as the precoding configuration is prepared in advance rather than requiring complex real-time coordination
Solution Approach 2:
The patent implements partial precoding optimization by applying precoding matrices selectively to user equipment pairs where it provides the most benefit, rather than requiring complex scheduling for all users. This partial action approach maintains precoding performance where needed while reducing overall system complexity
Data Source
AI summary
Interference between users in an MU-MIMO system is minimized by effective precoding, without increasing an overhead of control data. In a wireless communication system in which multiplex communication is possible between multiple UE1, UE2, and BS, a channel estimation and precoding selection unit 539 in BS estimates channels from the respective UE1, UE2 to the BS, determines a precoding matrix P from a projection matrix to make the two channel response matrices orthogonal or nearly orthogonal, and feeds back the precoding matrix P to UE2, and executes precoding on only UE2 of the two. A precoding unit 524 in the UE2 employs the precoding matrix P that has been notified to perform precoding of a data stream, and sends the precoded data stream to the BS.