MIMO Scheduler Selection Using QR Orthogonality and Fairness
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Solution Overview
Problem
In cooperative MIMO networks, selecting which active user equipment (UEs) to serve during the same time slot is challenging due to potential interference and the complexity of computing optimal combinations of UE and spatial dimension groupings, which can exceed the computational resources of baseband units.
Innovation Solution
A baseband unit or central processing system treats spatial dimensions as virtual UEs, determining channel strengths and ordering UEs based on fairness metrics, and using QR decomposition to select orthogonal UE and spatial dimension groupings, reducing computational complexity by separating UE selection from precoder calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optimal combinations of UE and spatial dimension groupings are computed to minimize interference and maximize throughput, then network performance is improved, but computational complexity exceeds the resources of baseband units
Solution Approach 1:
The patent segments the user selection process into multiple stages: first identifying a candidate set of users based on channel conditions, then selecting the final subset from this candidate set. This segmentation reduces the computational complexity by breaking down the combinatorial optimization problem into manageable steps that can be executed within baseband unit resources while still achieving near-optimal network throughput.
2Object-affected harmful factors
If spatial orthogonality measurements are performed for all UE combinations to minimize interference, then interference reduction is achieved, but computational burden increases significantly
Solution Approach 1:
The patent performs preliminary actions by first ordering users based on channel strength metrics before conducting detailed spatial orthogonality measurements. This preliminary sorting allows the system to focus computational resources on evaluating only the most promising user combinations, significantly reducing the overall computational burden while still achieving effective interference minimization through orthogonal spatial dimension selection.
Data Source
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AI summary
Aspects of the disclosure relate to a selection scheme implemented by a scheduler in a multiple-input multiple-output (MIMO) network to identify which users to schedule simultaneously during the same time slot. For downlink communications and a particular frequency wholeband or sub-band, the scheduler can determine downlink channel information for channels between base stations and UEs. The scheduler can then determine a strength of the channels, order the UEs using a fairness metric based on the channel strengths, and compute one or more QR decompositions to identify whether a spatial dimension of a UE is roughly or approximately orthogonal to spatial dimension(s) of other UEs selected to be served during a time slot being scheduled. If the spatial dimensions are roughly or approximately orthogonal, the scheduler selects the UE to be served at the same time as other UEs already selected. Uplink UE selection features are also disclosed.