3D Pilot Allocation for UAV–Ground UE Interference Control
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Solution Overview
Problem
In 5G cellular networks with massive MIMO arrays, pilot contamination occurs due to limited orthogonal pilots, leading to inter-cell interference, especially with UAVs experiencing Line Of Sight (LOS) signal propagation, which significantly reduces transmission data rates and causes interference between ground UEs and UAVs.
Innovation Solution
The system divides available pilots into orthogonal subsets and allocates distinct subsets to UAVs and ground UEs, using three-dimensional spatial location and angle of arrival information to minimize interference by optimizing pilot allocation, and adjusts pilot patterns based on flight altitude to enhance channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If orthogonal pilots are allocated to different UEs, then channel estimation accuracy is improved, but the number of available orthogonal pilots is limited by channel coherence length, causing pilot reuse and inter-cell interference
Solution Approach 1:
The patent segments the pilot resource space by dividing available pilots into multiple subsets, where each subset is allocated to specific types of UEs (ground UEs or UAVs). This segmentation allows the system to manage pilot contamination by ensuring that UAVs and ground UEs use orthogonal pilot subsets, thereby eliminating mutual interference while maintaining sufficient pilots for channel estimation within the coherence length constraint
Solution Approach 2:
The patent introduces a new dimension for pilot allocation by considering the three-dimensional spatial characteristics (including altitude) of UEs. By allocating pilots based on vertical dimension (UAV flight altitude) in addition to horizontal position, the system creates orthogonal pilot assignments that exploit spatial separation, allowing UAVs at different altitudes to use different pilot subsets without interference
2Productivity
If pilot reuse occurs among different cells, then system capacity is improved, but inter-cell interference increases due to pilot contamination
Solution Approach 1:
The patent applies local quality by assigning different pilot subset allocation strategies to different UE types and locations. Ground UEs in cell-center regions are allocated from one subset pool, while UAVs are allocated from another subset pool based on their flight altitude and spatial position. This localized differentiation allows pilot reuse within each subset pool while preventing interference between pools
3Productivity
If UAVs and ground UEs share the same pilot resources, then spectrum utilization is improved, but interference between UAVs and ground UEs significantly reduces transmission data rate
Solution Approach 1:
The patent segments the pilot resource pool into distinct subsets for UAVs and ground UEs, ensuring orthogonal allocation between these two UE types. This segmentation eliminates interference while maintaining high spectrum utilization by fully utilizing the available pilot subsets for both UE categories without overlap
Solution Approach 2:
The patent implements dynamic pilot allocation that adapts to UAV flight altitude and spatial position. As UAVs move vertically or horizontally, the system dynamically determines which pilot subset to allocate based on real-time spatial characteristics, ensuring continuous orthogonal separation from ground UEs while maximizing spectrum usage
Data Source
AI summary
The present invention provides an electronic device and method for wireless communications, and a computer readable storage medium. The electronic device comprises: a processing circuit, configured to divide an available pilot frequency into a plurality of orthogonal subsets, and allocate a pilot frequency in a first subset for an unmanned aerial vehicle (UAV) device, wherein the first subset is different from a second subset allocated for another UAV device in an adjacent sector of a different cell, and is different from a third subset allocated for a ground UE located in the same sector as the UAV device.