PT-RS Subcarrier Configuration With Lower NR Signaling Overhead
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Solution Overview
Problem
Existing signaling methods for configuring Phase Tracking Reference Signals (PT-RS) in New Radio (NR) networks result in scheduling restrictions and high overhead, particularly due to the use of explicit 'PTRS-RE-offset' signaling, which limits DM-RS subcarrier allocation and requires excessive bit indications.
Innovation Solution
A method that transmits a configuration message with a bit field indicating a relative subcarrier offset for PT-RS within the subset of DM-RS subcarriers, allowing flexible allocation and reducing signaling overhead by restricting PT-RS subcarriers to the subset used by DM-RS ports, thus avoiding scheduling restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If explicit PTRS-RE-offset signaling is used to configure PT-RS subcarrier position, then PT-RS can be positioned to avoid DC subcarrier collision, but scheduling restrictions occur because DM-RS must use the same subcarrier indicated by PTRS-RE-offset
Solution Approach 1:
The patent segments the subcarrier allocation by dividing it into two independent parts: DM-RS subcarrier allocation and PT-RS subcarrier allocation. DM-RS can be scheduled on any subcarrier according to normal resource allocation rules, while PT-RS is specifically positioned on the subcarrier indicated by PTRS-RE-offset to avoid DC collision. This segmentation allows each signal type to be optimized independently without mutual constraint.
Solution Approach 2:
The patent introduces an intermediary mechanism where the PTRS-RE-offset parameter serves as a dedicated mediator for PT-RS positioning. Instead of forcing DM-RS to adapt to PT-RS positioning requirements, the system uses this intermediary parameter to independently control PT-RS subcarrier selection, allowing DM-RS to maintain its scheduling freedom while PT-RS achieves optimal positioning.
2Adaptability or versatility
If PTRS-RE-offset is signaled with full range (0-11) to allow flexible PT-RS positioning, then PT-RS can avoid DC subcarrier, but signaling overhead increases requiring 4 bits per indication
Solution Approach 1:
The patent changes the parameter representation by introducing PTRS-RE-offset as a dedicated signaling parameter with specific semantic meaning. Instead of using generic resource allocation fields, this specialized parameter directly indicates the PT-RS subcarrier offset, enabling compact and unambiguous signaling. The parameter can be efficiently encoded based on the actual range of values needed, reducing overhead compared to general-purpose allocation schemes.
3Reliability
If PT-RS is configured with independent subcarrier allocation to avoid DC collision, then PT-RS performance is improved, but device complexity increases due to separate configuration management
Solution Approach 1:
The patent merges the PT-RS configuration into the existing DM-RS configuration framework by using the same PTRS-RE-offset parameter that is already part of the DM-RS configuration. This integration allows the system to manage PT-RS positioning without creating entirely separate configuration mechanisms, thereby reducing complexity while maintaining the ability to independently control PT-RS subcarrier allocation to avoid DC collision.
Data Source
AI summary
A technique for transmitting and receiving a configuration message for a phase tracking reference signal, PT-RS, on a radio channel between a radio access node and a radio device is described. The radio channel comprises a plurality of subcarriers in a physical resource block, PRB. A subset of the subcarriers in the PRB is allocated to a demodulation reference signal, DM-RS. As to a method aspect of the technique, the configuration message is transmitted to the radio device. The configuration message comprises a bit field that is indicative of at least one subcarrier allocated to the PT-RS among the subset of subcarriers allocated to the DM-RS.