Uplink Reference Signal Beam Configuration for Hidden Node Interference
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Solution Overview
Problem
In high-frequency wireless communication systems, especially in unlicensed millimeter wave bands, the large latency caused by beam scanning during uplink positioning leads to interference from hidden node devices, which cannot be detected through listen-before-talk operations. Additionally, the uplink and downlink channels do not have reciprocity, making it difficult to configure uplink reference signals effectively.
Innovation Solution
The proposed solution involves a network device instructing a user equipment to send uplink reference signals using a first set of beams, measuring transmission quality metrics, and then switching to a second set of beams if the quality is below a threshold. This configuration avoids interference from hidden node devices by updating the beam directions dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If beam scanning is performed during uplink positioning in high-frequency wireless communication systems, then directional transmission throughput is improved, but transmission latency increases causing interference from hidden node devices
Solution Approach 1:
The network device performs beam measurement and identifies suitable beams for uplink reference signal transmission before the actual positioning process. By pre-configuring the user equipment with appropriate beam directions based on downlink measurements or network device measurements, the system avoids time-consuming beam scanning during positioning, thus reducing latency while maintaining directional transmission benefits
Solution Approach 2:
The network device measures transmission quality metrics of uplink reference signals in different beam directions and uses this feedback information to determine the second set of beams. This feedback mechanism allows the system to adaptively select optimal beams for positioning, ensuring high throughput while minimizing latency by avoiding unnecessary beam scanning
2Area of stationary object
If uplink reference signals are transmitted in all beam directions, then positioning coverage is improved, but interference from hidden node devices increases
Solution Approach 1:
Instead of transmitting uplink reference signals in all beam directions uniformly, the network device identifies and selects specific beam directions that have acceptable transmission quality metrics. By applying different transmission configurations to different beam directions based on their local quality characteristics, the system maintains positioning coverage in viable directions while avoiding interference-prone directions where hidden nodes are present
Solution Approach 2:
The system dynamically changes beam direction parameters based on measured transmission quality metrics. When certain beam directions exhibit poor quality indicating hidden node interference, the network device adjusts the beam configuration to exclude those directions, thereby changing the transmission parameters adaptively to balance coverage and interference avoidance
3Reliability
If listen-before-talk operation is used to detect hidden nodes, then collision avoidance is improved, but detection capability against hidden node interference is insufficient
Solution Approach 1:
The network device acts as an intermediary that performs beam measurement and quality assessment on behalf of the user equipment. By having the network device measure transmission quality metrics of uplink reference signals in different beam directions, the system indirectly detects the presence of hidden nodes without requiring the user equipment to perform complex detection operations, thus improving detection capability while maintaining reliability
Data Source
AI summary
A method for a network device in a wireless communication system, comprising: instructing a user equipment to send uplink reference signals to the network device using a first set of beams; measuring transmission quality metrics of the uplink reference signals sent in each beam direction of the first set of beams; and instructing the user equipment to send uplink reference signals to the network device for uplink positioning using a second set of beams based at least on a transmission quality metric of an uplink reference signal sent in at least one beam direction of the first set of beams being lower than a threshold. The second set of beams enables the user equipment to avoid sending uplink reference signals in beam directions that are interfered by a communication link of a hidden node device. The hidden node device is unknown to the network device and the user equipment.