Multi-Panel MU-MIMO Scheduling With Reduced Panel-UE Search
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Solution Overview
Problem
Conventional single-user scheduling algorithms for multi-user multiple-input multiple-output (MU-MIMO) systems with panel-based spatial configurations face challenges in optimizing UE selection and analog beam assignment due to high beam management overheads and exponential complexity, especially with practical-size codebooks, limiting their effectiveness in next-generation communication systems.
Innovation Solution
A network entity schedules MU-MIMO transmissions by determining a reduced set of panel-to-UE assignments using a proportionately fair (PF) metric, computing PF metrics based on estimated throughput and channel quality indicators, and selecting an entry with maximum summed PF metric for scheduling, while optimizing digital precoding to mitigate inter-UE interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional single-user scheduling algorithms are used for MU-MIMO systems with panel-based spatial configurations, then UE selection and analog beam assignment can be performed, but computational complexity becomes exponential and beam management overhead increases
Solution Approach 1:
The patent segments the scheduling process into distinct phases: analog beam selection based on channel quality indicators, followed by digital precoding optimization. This segmentation allows the complex joint optimization problem to be decomposed into manageable sub-problems, reducing exponential complexity to polynomial complexity while maintaining scheduling performance
Solution Approach 2:
The patent performs preliminary analog beam selection based on channel quality indicators before digital precoding. This preliminary action establishes an initial feasible solution that constrains the subsequent digital precoding search space, thereby reducing the overall computational complexity from exponential to polynomial
2Ease of manufacture
If practical-size codebooks are used in panel-based spatial MU-MIMO systems, then system implementation becomes feasible, but UE separation by both analog and digital precoding becomes challenging
Solution Approach 1:
The patent introduces an intermediary digital precoding stage that operates between analog beam selection and final transmission. This intermediary digital precoder refines the UE separation by optimizing the precoding weights based on the selected analog beams and channel state information, thereby achieving precise UE separation even with practical-size codebooks
3Reliability
If brute-force search is used to jointly optimize UE selection and analog beam assignment, then sum of PF metric is maximized, but complexity becomes exponential with number of panels
Solution Approach 1:
The patent segments the joint optimization problem into sequential steps: first selecting analog beams based on channel quality indicators, then optimizing digital precoding weights. This segmentation transforms the exponential brute-force search into a polynomial complexity algorithm while maintaining sufficient optimization accuracy for practical systems
Solution Approach 2:
The patent performs partial optimization by focusing digital precoding optimization on the subset of UEs selected by analog beam pairing, rather than searching through all possible UE combinations. This partial action achieves near-optimal performance with significantly reduced computational complexity
Data Source
AI summary
An apparatus, at a network entity, for scheduling multi-user multiple-input multiple-output (MU-MIMO) transmissions to a co-scheduled set of user equipment (UEs) from an antenna array comprising multiple panels is disclosed. The apparatus comprises: a processor; a memory communicatively coupled to the processor; and executable instructions code stored in the memory, which when executed by the processor, cause the processor to: determine a reduced set of entries of panel-to-UE assignment from among multiple combinations of panel-to-UE assignment; and select, from within the reduced set, an entry of the panel-to-UE assignment for scheduling, based on a proportionately fair (PF) metric, wherein a panel-to-UE assignment is a mapping of the panels assigned to transmit to a selection of the UEs using associated serving beams configured for transmission to the respective UEs.