Low Overhead TRS Pattern for High Mobility Frequency Tracking
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Solution Overview
Problem
Conventional tracking reference signals (TRS) are inadequate for reliable frequency tracking in high mobility scenarios, such as high-speed trains, due to maximum Doppler shift exceeding the maximum pull-in range for carrier frequency offset estimation.
Innovation Solution
A low-overhead TRS pattern is implemented, where TRS symbols have varying bandwidths or discontinuous tone allocations, with a higher time density and potentially lower frequency density, to enhance frequency tracking without increasing signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional TRS is used for frequency tracking, then the signaling overhead is low, but the frequency tracking reliability deteriorates in high mobility scenarios due to maximum Doppler shift exceeding the maximum pull-in range
Solution Approach 1:
The patent applies dynamics by making the TRS pattern configurable and adaptable to different mobility scenarios. The TRS pattern can be dynamically selected or adjusted based on the UE's mobility state, allowing the system to optimize frequency tracking performance for high Doppler shifts while maintaining low overhead for stationary or low-mobility scenarios. This dynamic adaptation resolves the contradiction by enabling reliability improvement only when and where needed.
Solution Approach 2:
The patent changes key parameters of the TRS including bandwidth, tone allocation, and time density to improve frequency tracking in high mobility scenarios. By adjusting these parameters, the TRS can accommodate larger Doppler shifts while maintaining acceptable overhead. The configurable nature of these parameters allows the system to optimize the balance between reliability and overhead based on actual channel conditions.
2Measurement precision
If the TRS bandwidth is increased to improve frequency tracking in high mobility scenarios, then the frequency tracking performance improves, but the signaling overhead increases
Solution Approach 1:
The patent applies local quality by allowing different TRS symbols within the same TRS pattern to have different bandwidths and tone allocations. This enables targeted enhancement of frequency tracking capability in specific frequency regions where it is most needed, rather than uniformly increasing bandwidth across all TRS symbols. The selective adjustment of local TRS properties improves measurement precision without proportionally increasing overall overhead.
Solution Approach 2:
The patent implements partial action by selectively increasing TRS bandwidth or adjusting tone allocation only for specific TRS symbols that are most critical for frequency tracking in high mobility scenarios. Rather than uniformly increasing all TRS parameters, the system applies enhanced parameters only where necessary to achieve the required frequency offset estimation precision, thereby limiting the increase in signaling overhead.
3Adaptability or versatility
If the time density of TRS symbols is increased to improve frequency tracking, then the frequency tracking range increases, but the signaling overhead increases
Solution Approach 1:
The patent applies dynamics by making the time density of TRS symbols configurable based on mobility scenarios. The system can dynamically adjust the number of TRS symbols per slot and their spacing to achieve the required frequency tracking range for different Doppler conditions. This dynamic configuration allows the system to expand tracking range only when high mobility is detected, maintaining low overhead for other scenarios.
Solution Approach 2:
The patent implements multi-functionality by designing a TRS pattern that can serve multiple purposes through configurable parameters. The same TRS infrastructure can adapt to provide both wide frequency tracking range for high mobility and efficient low-overhead operation for low mobility by changing the time density and pattern configuration. This universal design resolves the contradiction by enabling the system to achieve different performance levels using the same basic mechanism.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine a tracking reference signal (TRS) pattern to be used for receiving a TRS. The TRS pattern may indicate a plurality of TRS symbols of the TRS, one or more TRS symbols of the plurality of TRS symbols having a bandwidth that is different than a bandwidth of at least one other TRS symbol of the plurality of TRS symbols, or having a discontinuous tone allocation. The UE may receive the TRS based at least in part on the TRS pattern. Numerous other aspects are provided.