Orthogonal Pilot Allocation for Massive MIMO Edge Interference
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Solution Overview
Problem
In wireless communication networks, especially in massive MIMO systems, pilot signal transmission faces significant interference due to the reuse of non-orthogonal resources by user equipment in neighboring cells, which contaminates channel estimation and limits system performance.
Innovation Solution
A method where network nodes classify user equipment as edge or center based on signal attenuation, allocating orthogonal resources such that edge user equipment in one cell does not share resources with adjacent cells, while center user equipment can reuse resources from other cells, thereby reducing interference and increasing resource availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-universal pilot reuse is used to reduce pilot contamination, then channel estimation accuracy is improved, but the number of user equipment that can be trained and served is significantly limited
Solution Approach 1:
The patent applies local quality by differentiating resource allocation between cell edge user equipment and cell center user equipment. Cell edge UEs are allocated orthogonal pilots to avoid contamination, while cell center UEs can reuse pilots from other cells. This localized differentiation resolves the contradiction by applying strict orthogonality only where contamination is problematic (cell edges) while allowing resource reuse where it benefits capacity (cell centers).
Solution Approach 2:
The patent segments the set of orthogonal pilots into multiple subsets and allocates different subsets to different cells for cell edge user equipment. This segmentation allows neighboring cells to use different pilot subsets, eliminating pilot contamination at cell edges while still allowing cell center UEs to access all pilots, thus resolving the contradiction between estimation accuracy and system capacity.
2Productivity
If universal pilot reuse is used to increase system capacity, then resource utilization is improved, but pilot contamination increases and degrades channel estimation
Solution Approach 1:
The patent applies local quality by implementing different pilot allocation strategies for different user equipment locations. Cell center UEs benefit from universal pilot reuse (high capacity), while cell edge UEs use orthogonal pilot subsets (high accuracy). This spatially-dependent allocation resolves the contradiction by allowing resource reuse where contamination is minimal while preventing it where contamination is severe.
Solution Approach 2:
The patent segments the pilot resource pool into multiple orthogonal subsets and assigns different subsets to different cells for cell edge users. This segmentation enables controlled pilot reuse: cell center UEs can access all subsets (increasing capacity), while cell edge UEs are restricted to their assigned subset (maintaining accuracy). This resolves the contradiction between system capacity and estimation accuracy.
3Reliability
If orthogonal resources are allocated to all user equipment to eliminate interference, then signal quality is improved, but resource availability decreases and throughput is limited
Solution Approach 1:
The patent applies local quality by providing orthogonal resources specifically to cell edge user equipment where interference is most problematic, while allowing cell center user equipment to share resources. This targeted approach maintains signal quality for vulnerable users while enabling resource reuse that boosts overall throughput, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent segments the orthogonal resource set into multiple subsets and allocates them selectively to cell edge UEs across different cells. This segmentation ensures that cell edge users (who need high signal quality) receive orthogonal resources, while cell center users (who can tolerate some interference) share resources freely, thus resolving the contradiction between signal quality and throughput.
Data Source
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AI summary
A method of allocating orthogonal resources, a computer program for so doing, a network node and network control node are disclosed. One method comprises determining user equipment within a radio cell of the network node that are considered to be edge user equipment located towards an edge of the radio cell and user equipment that are considered to be centre user equipment located towards a centre of the radio cell. Allocating a subset of the set of resources to the edge user equipment and allocating resources from the set of resources that are not allocated to the edge user equipment to the centre user equipment; and indicating to at least some adjacent network nodes that the subset of the resources is not available to the adjacent network node for allocation to edge user equipment.