MIMO Scheduler Spatial Orthogonality UE Selection
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Solution Overview
Problem
Cooperative MIMO networks face challenges in efficiently selecting active UEs and spatial dimensions for simultaneous service within a time slot due to limitations in the number of spatial dimensions available, leading to potential interference and reduced capacity and throughput.
Innovation Solution
A scheduler is implemented to determine downlink channel information, order receive antenna elements based on channel strengths, and select them for service if spatial orthogonality with other elements exceeds a threshold, optimizing the selection process to maximize capacity and throughput within power constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of spatial dimensions is increased to serve more UEs simultaneously, then the network capacity and throughput are improved, but the device complexity and interference management become worse
Solution Approach 1:
The patent changes the parameter of spatial orthogonality measurement to select UEs for simultaneous service. By measuring and selecting UEs with sufficiently orthogonal spatial channels (above a threshold), the system can serve more users without proportionally increasing complexity, as the orthogonality metric provides a systematic way to manage spatial resource allocation.
Solution Approach 2:
The patent segments the spatial dimensions into distinct orthogonal channels that can be independently allocated to different UEs. By decomposing the spatial domain into orthogonal components, the system can manage each spatial channel separately, reducing overall complexity while increasing total capacity.
2Productivity
If more UEs are selected for simultaneous service in a time slot, then the throughput is improved, but the interference between spatial elements increases
Solution Approach 1:
The patent converts the potentially harmful spatial interference into a useful selection criterion. By measuring spatial orthogonality and selecting UEs with high orthogonality values, the system identifies combinations of UEs that naturally exhibit low mutual interference. The interference problem is transformed into a benefit by using orthogonality measurement to guide UE selection.
Solution Approach 2:
The patent performs preliminary spatial orthogonality measurements and UE ordering before actual resource allocation. By pre-evaluating and ranking UEs based on their spatial channel characteristics, the system prepares an optimal selection sequence that minimizes interference from the outset, rather than dealing with interference issues during resource allocation.
3Reliability
If spatial orthogonality threshold is increased to reduce interference, then the signal quality is improved, but the number of UEs that can be served simultaneously decreases
Solution Approach 1:
The patent implements a dynamic threshold mechanism where the spatial orthogonality requirement is adjusted based on current system conditions. The threshold is not fixed but adapts to balance signal quality and user capacity, allowing the system to serve more UEs when conditions permit while maintaining adequate signal quality through flexible threshold management.
Solution Approach 2:
The patent applies a threshold that may be lower than ideal orthogonality would suggest, accepting partial orthogonality to serve more UEs. By allowing some degree of non-orthogonality (excessive action in terms of user admission), the system prioritizes overall throughput while managing interference through advanced signal processing rather than strict orthogonality requirements.
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 uplink communications and a particular frequency wholeband or sub-band, the scheduler can obtain uplink channel information for channels between base stations and UEs. The scheduler can then determine a strength of the channels using the uplink 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.