Uplink Reference Signal Allocation by UE Priority
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Solution Overview
Problem
Current cellular systems face challenges in efficiently allocating uplink reference signals, particularly in massive MIMO systems and millimeter-wave frequencies, where pilot contamination and limited orthogonal reference signals lead to interference and reduced capacity, especially when serving a large number of UEs with diverse traffic patterns.
Innovation Solution
A method is introduced to allocate uplink reference signals based on priority levels determined by traffic characteristics, such as burstiness and emergency levels, allowing for orthogonal or non-orthogonal signal allocation to UEs, thereby mitigating pilot contamination and optimizing resource usage across cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If orthogonal reference signals are allocated to UEs in massive MIMO systems, then channel estimation accuracy is improved, but the number of available orthogonal signals is limited leading to interference and reduced capacity
Solution Approach 1:
The patent changes the parameter of reference signal orthogonality from strict orthogonality to controlled non-orthogonality based on UE priority levels. High-priority UEs receive orthogonal signals while lower-priority UEs share non-orthogonal signals, transforming the binary orthogonality parameter into a graded property that resolves the contradiction between estimation accuracy and system capacity
Solution Approach 2:
The patent introduces dynamic priority-based allocation where reference signal orthogonality is not fixed but dynamically assigned based on UE priority levels. The system transitions from static orthogonal allocation to dynamic selective orthogonality, allowing flexible adaptation to different traffic patterns and UE requirements while managing the limited pool of orthogonal signals
2Device complexity
If reference signals are allocated without considering UE priority, then allocation simplicity is maintained, but pilot contamination increases especially in high UE density scenarios
Solution Approach 1:
The patent applies local quality by differentiating reference signal allocation based on UE priority levels. Instead of uniform treatment, the system assigns orthogonal signals to high-priority UEs and non-orthogonal signals to lower-priority UEs, creating localized quality differences that reduce pilot contamination where it matters most while maintaining simplicity for lower-priority users
3Productivity
If non-orthogonal reference signals are used for all UEs, then system capacity is improved through better resource utilization, but channel estimation accuracy deteriorates due to interference
Solution Approach 1:
The patent segments the UE population into different priority levels and applies different reference signal allocation strategies to each segment. High-priority UEs receive orthogonal signals for accurate channel estimation, while lower-priority UEs share non-orthogonal signals, dividing the system into segments with different quality requirements and resolving the contradiction between capacity and accuracy
Data Source
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AI summary
The invention relates to a method for allocating an uplink reference signal to a user equipment, UE, located in a cell area comprising one or a plurality of cells served by one or a plurality of access nodes, comprising the steps of determining one or a plurality of active applications of the UE, determining a traffic characteristic associated to the one or the plurality of active applications, associating a priority level to the UE, wherein the priority level is based on the traffic characteristic, and allocating an uplink reference signal to the UE based on the priority level; the invention further relates to a corresponding access point and a computer program.