Sidelink TDOA Positioning Using Anchor Server RSTD Values
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently determining the location of user equipment (UE) without the assistance of a base station or location service server, particularly in sidelink communication scenarios where latency and resource allocation are critical, such as in vehicle-to-everything (V2X) applications.
Innovation Solution
The proposed method employs a sidelink Time Difference of Arrival (S-TDOA) technique, where a target UE transmits positioning reference signals (PRS) to multiple servers, and an anchor server calculates and communicates the reference signal time difference (RSTD) values and absolute positions of these servers to determine the target UE's location, minimizing reliance on higher-layer signaling and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional location determination methods using base station assistance are used, then location accuracy can be maintained, but system complexity and latency increase
Solution Approach 1:
The patent extracts the location determination function from the base station network and relocates it to the UE side. The UE autonomously performs location determination by measuring RSTD values from multiple anchor UEs and calculating its position based on these measurements, eliminating the need for base station assistance and reducing system complexity.
Solution Approach 2:
The UE performs self-location by autonomously measuring reference signal time differences from multiple anchor UEs and calculating its own position. This self-service approach eliminates dependency on network infrastructure for location determination, reducing latency and system complexity.
2Reliability
If base station or location service server assistance is used, then location determination reliability is improved, but communication overhead and resource allocation complexity increase
Solution Approach 1:
The patent extracts the location determination function from the network infrastructure and implements it at the UE level. The UE measures RSTD values directly from anchor UEs and performs location calculation autonomously, eliminating the need for complex communication with base stations or location servers while maintaining reliability.
Solution Approach 2:
The patent introduces anchor UEs as intermediaries that provide reference signals for location measurement. These anchor UEs act as mediators between the target UE and the location determination process, enabling reliable location measurement without requiring complex network infrastructure or additional communication overhead.
3Loss of time
If direct UE-to-UE communication is used for positioning, then latency is reduced, but measurement precision requirements increase
Solution Approach 1:
The patent merges multiple measurement functions into a single RSTD measurement process. By measuring the time difference of arrival from multiple anchor UEs simultaneously and combining these measurements for location calculation, the system achieves both low latency and sufficient precision without requiring separate high-precision measurements for each parameter.
Solution Approach 2:
The patent performs preliminary synchronization and anchor UE selection before the actual location measurement. Anchor UEs are pre-identified and synchronized, allowing the target UE to directly measure RSTD values without preliminary network coordination, thus reducing latency while maintaining measurement precision through pre-established reference frames.
Data Source
AI summary
According to an embodiment of the present disclosure, a method of performing sidelink communication by a first device is provided. The method may include the steps of: transmitting a PRS to multiple servers; receiving, from one anchor server among the multiple servers, information relating to RSTD values indicating differences between time points at which the multiple servers have received the PRS and information relating to an absolute position of each of the multiple servers; and determining a position of the first device on the basis of the information relating to the RSTD values and the information relating to the absolute position of each of the multiple servers.