MIMO Scheduler UE Selection via Spatial Orthogonality
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Solution Overview
Problem
Cooperative MIMO networks face challenges in efficiently selecting active user equipment (UEs) to serve simultaneously within a time slot due to limitations in spatial dimensions, leading to potential interference and reduced capacity and throughput.
Innovation Solution
A scheduler system determines downlink channel information, orders receive antenna elements based on channel strengths, and selects UEs to be served by transmit antenna elements if spatial orthogonality and interference criteria are met, using QR decomposition to identify orthogonal spatial dimensions and adjust thresholds dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple UEs are selected to be served simultaneously within a time slot, then the system throughput and capacity increase, but spatial interference increases and spatial dimensions become limited
Solution Approach 1:
The patent applies spatial dimensionality by selecting UEs based on their spatial orthogonality characteristics. The scheduler identifies UEs whose channel vectors are orthogonal or near-orthogonal in the spatial domain, allowing simultaneous service in different spatial directions. This transforms the single-dimensional time slot into a multi-dimensional spatial resource allocation problem, enabling multiple UEs to be served concurrently without mutual interference.
Solution Approach 2:
The patent implements local quality by evaluating and selecting UEs with specific local spatial characteristics. Each UE's channel vector is assessed for its spatial orthogonality relative to already-selected UEs. The scheduler prioritizes UEs that exhibit favorable local spatial properties (high orthogonality) for simultaneous service, while excluding those that would create spatial interference. This localized spatial quality assessment enables selective multi-UE service within the same time slot.
2Reliability
If UE selection is performed based on spatial orthogonality to minimize interference, then signal quality improves, but computational complexity increases due to QR decomposition requirements
Solution Approach 1:
The patent applies preliminary action by pre-computing the QR decomposition of the channel matrix before UE selection. The Q matrix from the QR decomposition is stored and reused for evaluating spatial orthogonality of multiple candidate UEs. This preliminary computation avoids redundant decomposition operations during the actual selection process, significantly reducing real-time computational complexity while maintaining accurate spatial orthogonality assessment for signal quality optimization.
Data Source
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 using uplink channel information for channels between base stations and UEs. The scheduler can then determine a strength of the channels using the downlink channel information, 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.