PT-RS Time Frequency Density Determination in 5G NR
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Solution Overview
Problem
Current cellular networks face challenges in reliability and capacity, particularly in scenarios with high demand for mobile services and data rates, due to difficulties in exchanging control and performance information between base stations and mobile devices.
Innovation Solution
The implementation of phase tracking reference signals (PT-RS) with specific time and frequency densities, determined based on modulation and coding schemes and resource block thresholds, to optimize communication in 3GPP, NR, and 5G networks, enabling efficient uplink control information transmission without uplink shared channel data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase tracking reference signals (PT-RS) are transmitted with high time density and frequency density to improve phase tracking accuracy in high-demand scenarios, then reliability and measurement precision are improved, but network capacity and spectral efficiency deteriorate due to increased overhead
Solution Approach 1:
The patent implements dynamic adjustment of PT-RS time density and frequency density based on real-time channel conditions, modulation and coding schemes (MCS), and resource block allocation. The network can adaptively configure PT-RS parameters through RRC signaling or DCI, allowing the system to optimize phase tracking accuracy while minimizing overhead impact on network capacity. This dynamic approach enables the system to use higher PT-RS density only when and where phase tracking challenges arise, rather than uniformly across all transmissions.
Solution Approach 2:
The patent changes multiple parameters of PT-RS including time density (frequency of transmission in time domain), frequency density (distribution across frequency resources), and resource element mapping patterns. By adjusting these parameters based on channel quality indicators, MCS levels, and bandwidth allocation, the system achieves optimal balance between phase tracking precision and spectral efficiency. Higher order modulations trigger more frequent PT-RS transmissions, while robust modulations allow reduced density.
2Reliability
If PT-RS transmission overhead is increased to support higher data rates and more users, then reliability is improved, but device complexity and processing requirements worsen
Solution Approach 1:
The patent segments the uplink transmission into multiple resource blocks and applies PT-RS selectively based on local channel conditions in each segment. Rather than uniformly increasing PT-RS density across all resources, the system divides the frequency spectrum into resource blocks and configures PT-RS density per block or per user equipment, reducing overall processing complexity while maintaining reliability in critical segments.
Solution Approach 2:
The patent enables user equipment to autonomously determine appropriate PT-RS configuration based on received channel quality indicators and MCS information from the network. The UE self-adjusts its phase tracking requirements and PT-RS processing based on current transmission conditions, reducing the processing burden on the network while ensuring adequate phase tracking for each user's specific channel conditions.
Data Source
AI summary
Embodiments of a User Equipment (UE), Next Generation Node-B (gNB) and methods of communication are generally described herein. The UE may receive an information element (IE) that includes: a higher layer parameter that indicates a plurality of modulation and coding scheme (MCS) thresholds; and another higher layer parameter that includes a plurality of resource block (RB) thresholds. The UE may determine a time density of phase tracking reference signal (PT-RS) to be transmitted by the UE based at least partly on a comparison between a MCS and the plurality of MCS thresholds. The UE may determine a frequency density of the PT-RS based at least partly on a comparison between a scheduled bandwidth and the plurality of RB thresholds. The UE may encode the PT-RS for transmission in accordance with the determined time density and the determined frequency density.