MU-MIMO User Pairing via Dual-Stream CQI Feedback
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Solution Overview
Problem
In MU-MIMO scenarios, the low probability of successful codebook-based orthogonal pairing leads to inefficient radio resource utilization, and inaccurate CQI feedback due to single-user scheduling interference, resulting in inappropriate codebook selection and degraded system performance.
Innovation Solution
Implementing dual-stream scheduling in the TM4 mode, where UEs feed back PMIs and CQIs for dual codewords, allowing the base station to group users with similar PMIs and compute scheduling priorities to determine optimal user pairing combinations, thereby improving resource allocation and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If codebook-based orthogonal pairing is used in MU-MIMO, then user pairing is performed, but the probability of successful pairing is very low leading to wasted radio resources
Solution Approach 1:
The patent changes the pairing parameters from traditional codebook-based orthogonal pairing to dual-stream scheduling with dual codewords. By introducing CQI feedback for both first and second codewords and using scheduling priorities based on these feedbacks, the system achieves more reliable pairing while improving radio resource utilization through dual-user scheduling capability.
2Measurement precision
If single-user scheduling CQI feedback is used in MU-MIMO, then channel quality is measured, but interference between users causes inaccurate CQI feedback leading to inappropriate codebook selection
Solution Approach 1:
The patent implements feedback mechanisms where user equipment provides CQI feedback for both first and second codewords in dual-stream scheduling. This feedback information is used by the base station to calculate scheduling priorities and select appropriate codebooks, thereby achieving accurate channel quality measurement even in the presence of multi-user interference.
3Reliability
If dual-stream scheduling with dual codewords is implemented, then user pairing success probability increases, but system complexity increases
Solution Approach 1:
The patent segments the scheduling process into distinct components: receiving CQI feedback for first and second codewords, calculating scheduling priorities separately for each codeword, determining user pairing combinations, and selecting codebooks. This segmentation of the dual-stream scheduling process into manageable steps reduces the overall system complexity while maintaining high pairing success probability.
Data Source
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AI summary
Embodiments of the present invention provide a method for multi-user scheduling in a MIMO system, and an apparatus. A base station receives PMIs, and CQIs of first codewords and second codewords, where the PMIs and the CQIs are fed back by N UEs; groups UEs whose PMIs are the same into one pairing group to divide the N UEs into M pairing groups; determines, for each pairing group, a user pairing combination of the pairing group according to a CQI of a first codeword of each UE in the pairing group and a CQI of a second codeword of each UE in the pairing group; and determines an optimal user pairing combination from M user pairing combinations. In subsequent scheduling, the base station schedules two UEs in the optimal user pairing combination simultaneously. In the method, UEs whose PMIs are the same are grouped into one pairing group, to increase a probability of successful UE pairing in each pairing group.