Time Frequency Tracking Reference Signal Dynamic Slot Configuration
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Solution Overview
Problem
New Radio (NR) systems face challenges in time and frequency tracking for user equipment (UE) during dynamic slot structures, beam switching, and initial access procedures, particularly in reducing overhead and power consumption, and ensuring accurate synchronization for Ultra-Reliable and Low Latency Communications (URLLC) data transmission.
Innovation Solution
The introduction of a Time/Frequency Tracking Reference Signal (TRS) mechanism that supports dynamic slot structures, enables efficient signaling and configuration for multiple beams, and ensures synchronization during Discontinuous Reception (DRX) and initial access, using TRS bursts with sufficient density and strategic placement within slots to minimize latency and overlap with other signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TRS is transmitted periodically in slots with dynamic structures, then time and frequency tracking accuracy is improved, but slot structure complexity and configuration overhead increase
Solution Approach 1:
The patent implements dynamic slot structures where the number of PDCCH symbols and UL data allocation can vary between slots. The TRS pattern is designed to adapt to these dynamic changes, allowing the system to maintain tracking accuracy while accommodating flexible resource allocation for different service requirements.
Solution Approach 2:
The TRS burst is segmented into multiple TRS signals transmitted across different symbols within a slot. This segmentation allows the TRS to be distributed throughout the slot structure, enabling accurate tracking regardless of the specific slot configuration while reducing the impact of any single symbol being used for other purposes.
2Adaptability or versatility
If multiple TRSs are configured for multi-TRP/multi-panel/multi-BWP operation, then beam switching capability is improved, but signaling overhead increases
Solution Approach 1:
The patent configures multiple TRSs that can serve multiple purposes: time/frequency tracking, beam management, and support for multi-TRP/multi-panel/multi-BWP operations. Each TRS is associated with specific SS blocks and can be used for both tracking and beam switching, reducing the need for separate signaling mechanisms.
Solution Approach 2:
The TRS acts as an intermediary signal that enables the UE to synchronize with new beams during beam switching. By transmitting TRS on different beams and allowing the UE to select the appropriate TRS based on beam quality, the system facilitates beam switching without requiring extensive explicit signaling for each beam transition.
3Measurement precision
If TRS is transmitted with sufficient density, then tracking accuracy is improved, but resource overhead and power consumption increase
Solution Approach 1:
The patent transmits TRS periodically rather than continuously, with TRS bursts occurring at specific intervals. This periodic transmission provides sufficient tracking accuracy by refreshing synchronization information regularly while allowing the system to conserve resources during intervals when TRS is not transmitted, reducing overall power consumption.
Solution Approach 2:
The TRS is transmitted with concentrated density in specific symbols and frequency resources where it is most needed for tracking, rather than uniformly across all resources. This localized high-density transmission achieves effective tracking accuracy while minimizing the total number of resources consumed, thereby reducing power consumption.
Data Source
AI summary
A wireless transmit/receive unit (WTRU) may receive a tracking reference signal comprising resources located in one or more slots. The resources may be located in one or more symbols used for receiving a demodulation reference signal. The one or more symbols in which the resources of the tracking reference signal are located may be within a first five symbols in each of the one or more slots. At least one resource of the received tracking reference signal may be frequency multiplexed with the demodulation reference signal.