Joint DM-RS and PT-RS Scheduling for Phase Noise Mitigation
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Solution Overview
Problem
Existing wireless communication systems face challenges in managing phase noise at high carrier frequencies, particularly in mmWave frequencies, where phase tracking reference signals (PT-RS) are needed to mitigate phase noise-induced errors, and there is a need for efficient joint design with demodulation reference signals (DM-RS) to reduce pilot contamination and resource overhead.
Innovation Solution
A joint scheduling method for DM-RS and PT-RS is implemented, where the position of PT-RS is dependent on the position of DM-RS, optimizing resource allocation and reducing overall reference signal overhead while maintaining estimation quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PT-RS and DM-RS are scheduled independently with separate resource allocation, then each reference signal can be optimized for its specific function, but the total reference signal overhead increases and pilot contamination occurs
Solution Approach 1:
The patent combines PT-RS and DM-RS into a joint scheduling framework where both reference signals share the same time-frequency resources. The PT-RS is mapped to specific resource elements within the DM-RS structure, allowing phase noise estimation and channel demodulation to occur simultaneously using integrated resource allocation, thereby reducing total overhead while maintaining estimation accuracy.
Solution Approach 2:
The joint scheduling design enables certain reference signal resources to serve multiple functions. The scheduled reference signals simultaneously provide channel estimation for demodulation and phase noise tracking, allowing a single resource allocation to fulfill multiple reference signal purposes and reduce the quantity of dedicated resources needed.
2Reliability
If PT-RS time density is increased to improve phase noise tracking at high carrier frequencies, then phase noise mitigation performance improves, but the resource consumption and overhead increase
Solution Approach 1:
The patent applies different time densities of PT-RS locally based on the specific carrier frequency and channel conditions. At high carrier frequencies where phase noise is severe, higher PT-RS time density is applied in those specific frequency regions and time slots, while lower density is used in regions with better conditions, optimizing the balance between mitigation performance and resource consumption.
Solution Approach 2:
The PT-RS time density is made dynamic and configurable based on scheduled modulation and coding schemes (MCS) and channel conditions. The system can adaptively adjust the density of PT-RS transmissions in response to changing phase noise characteristics, increasing density when phase noise is severe and decreasing it when conditions are favorable, thereby optimizing resource usage.
Data Source
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AI summary
A method, network node and wireless device in a wireless communication system for one of transmitting and receiving a phase-tracking reference signal, PT-RS. The method includes obtaining information about a position in a time domain of a scheduled first demodulation reference signal, DM-RS, in a slot, and one of transmitting and receiving the PT-RS within the slot, the position of the PT-RS depending on the position in the time domain of the scheduled first DM-RS.