NR V2X Synchronization Signal Blocks for High-Doppler Vehicle Links
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Solution Overview
Problem
The challenge in V2X communication systems is the large Doppler shift due to high relative speeds between vehicles, which affects the transmission and reception of synchronization signals, leading to signal quality degradation and inefficiencies in communication.
Innovation Solution
The method involves dynamically adjusting the transmission characteristics of VSSBs, including carrier frequency, subcarrier spacing, and reference signal time domain density to counteract Doppler shift effects, ensuring effective communication between vehicle-mounted devices and receiving terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the transmission period of VSSB is set to 160ms with fixed frame structure, then the overhead is reduced, but the ability to counteract large Doppler shift in high-speed V2X scenarios is insufficient
Solution Approach 1:
The patent applies dynamics by making the VSSB transmission characteristics adjustable rather than fixed. Specifically, the subcarrier spacing, cyclic prefix length, and reference signal density can be dynamically changed based on the detected Doppler shift magnitude, allowing the system to adapt to different vehicle speeds while maintaining low overhead in normal conditions
Solution Approach 2:
The patent changes physical parameters of the VSSB transmission including subcarrier spacing (e.g., 15kHz, 30kHz, 60kHz), cyclic prefix length (normal or extended), and reference signal time-domain density based on the detected Doppler shift. These parameter changes enable the system to maintain signal quality across varying speed conditions
2Measurement precision
If the reference signal time domain density is increased to counteract Doppler shift, then the signal detection accuracy improves, but the overhead increases
Solution Approach 1:
The patent dynamically adjusts the reference signal time-domain density parameter based on the detected Doppler shift magnitude. When large Doppler shift is detected, the reference signal density is increased to improve detection accuracy; when Doppler shift is small, the density is reduced to minimize overhead
3Reliability
If the subcarrier spacing is increased to handle high Doppler shift, then the resistance to frequency offset improves, but the time resolution and synchronization precision may be affected
Solution Approach 1:
The patent dynamically selects the subcarrier spacing based on the detected Doppler shift magnitude. For high-speed scenarios with large Doppler shift, larger subcarrier spacing (e.g., 60kHz) is selected to resist frequency offset; for low-speed scenarios, smaller subcarrier spacing (e.g., 15kHz) is used to maintain better time resolution and synchronization precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the efficiency and immediacy of communication by ensuring accurate detection and synchronization of reference signals, thereby improving communication quality and reducing synchronization time between vehicles.
Implementation Method 1
the speed of one vehicle with respect to another vehicle is almost two times of its own speed, which makes the Doppler shift larger
Data Source
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AI summary
Provided are a method and apparatus for sending a reference signal, a method and apparatus for receiving a reference signal, vehicle user equipment (UE), and a terminal. The method for sending a reference signal comprises: determining transmission configuration information of a synchronization signal block VSSB in an NR V2X system, the transmission configuration information comprising: a sending period of the VSSB and a time domain position of a VSSB sending time window in the sending period; and sending, according to the transmission configuration information, N VSSB within the VSSB sending time window which appears periodically, N being an integer greater than or equal to 1, and each VSSB comprising: a primary sidelink synchronization signal (PSSS), a secondary sidelink synchronization signal (SSSS), a physical sidelink broadcast channel (PSBCH), and a demodulation reference signal (DMRS). The use of the method for sending a reference signal provided in the present disclosure can ensure quick time domain synchronization between a vehicle-mounted device and a receiving terminal in an NR V2X system.