MU-MIMO Scheduling via Submodular Virtual User Segmentation
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Solution Overview
Problem
Current MU-MIMO scheduling with linear transmit precoding in mmWave systems is limited by the intractable combinatorial nature of the problem, restricting algorithm design to simple greedy heuristics that do not exploit underlying structures.
Innovation Solution
A computer-implemented method for downlink scheduling in MU-MIMO systems that identifies a transmit precoder and receive beamformer combination maximizing the difference between submodular set functions, allowing for improved scheduling by forming virtual users and optimizing achievable transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple greedy heuristics are used for MU-MIMO scheduling, then device complexity is reduced, but productivity is limited due to inability to exploit underlying problem structure
Solution Approach 1:
The patent segments the MU-MIMO scheduling problem by introducing virtual users that combine multiple actual users with receive beamformers. This segmentation transforms the intractable combinatorial problem into a more manageable form that can be solved with improved algorithms while maintaining reasonable complexity.
Solution Approach 2:
The patent changes the problem parameters by formulating the scheduling objective as maximizing the difference between two submodular set functions. This parameter transformation enables the use of more sophisticated algorithms that exploit the underlying structure of the problem, improving scheduling efficiency without excessive complexity increase.
2Productivity
If sophisticated algorithms exploiting problem structure are used, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent introduces virtual users as an intermediary concept that bridges actual users and receive beamformers. This intermediary formulation allows sophisticated algorithms to exploit problem structure and improve scheduling efficiency while keeping the implementation complexity manageable through the structured virtual user framework.
Data Source
AI summary
A computer-implemented method is provided for downlink scheduling in a MU-MIMO telecommunication system. The method includes identifying for each of multiple virtual users which collectively form a ground set of virtual users, a respective transmit precoder and receive beamformer combination that maximizes a difference between two submodular set functions applied over the ground set of virtual users, from among a plurality of combinations formed from a respective one of a plurality of transmit precoders and a respective one of a plurality of receive beamformers. The method includes transmitting data from at least some multiple virtual users, based on a downlink transmission schedule determined from the respective transmit precoder and receive beamformer combination identified for the at least some multiple virtual users. The ground set is formed from respective combinations of multiple actual users and the plurality of receive beamformers. The functions correspond to an achievable virtual user transmission rate.