Mobile Device Group Delay Calibration via Closed Loop
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Solution Overview
Problem
Current wireless communication systems face challenges in accurately determining group delay, which affects the precision of positioning measurements such as Round Trip Time (RTT), due to variations in processing delays within mobile devices.
Innovation Solution
The implementation of closed loop calibration techniques, including near field radiated and conducted closed loops, to measure and calibrate transmission and reception group delay in mobile devices, accounting for propagation delays and component-specific delays for increased accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closed loop calibration techniques are implemented to measure and calibrate group delay, then positioning measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent performs group delay calibration measurements in advance before actual positioning operations. The calibration process pre-determines the group delay characteristics of the device's RF components, storing these values for later use in positioning calculations. This preliminary action separates the complex measurement process from routine positioning, improving accuracy without significantly impacting operational complexity.
Solution Approach 2:
The closed loop calibration technique uses feedback by measuring the actual group delay through transmitted and received signals, then using this measured information to compensate for delays in positioning calculations. The system continuously monitors and adjusts for delay variations, creating a feedback mechanism that improves measurement precision while managing system complexity through software-based compensation.
2Measurement precision
If propagation delay between antennas is included in calibration, then group delay accuracy is improved, but measurement complexity increases
Solution Approach 1:
The patent segments the total delay measurement into distinct components: propagation delay between antennas and processing delay through RF components. By separating these elements and measuring them independently, the system can accurately account for each contribution to the total group delay without overwhelming measurement complexity. The propagation delay is calculated based on known antenna spacing and signal speed.
Solution Approach 2:
The patent uses a closed loop calibration signal as an intermediary to measure both propagation delay and processing delay. This calibration signal traverses the same RF path as positioning signals, serving as a mediator that allows the system to infer actual group delay characteristics without requiring separate complex measurements for each signal type.
3Measurement precision
If multiple antenna pairs are used for calibration, then calibration accuracy is improved, but calibration time increases
Solution Approach 1:
The patent combines calibration measurements across multiple antenna pairs into a unified calibration process. By simultaneously or sequentially measuring group delay through multiple antenna combinations and averaging or synthesizing the results, the system achieves higher calibration accuracy while managing the time required. The closed loop structure allows efficient reuse of measurement data across different antenna pairs.
Data Source
AI summary
The transmission and reception group delay in a front end structure of a mobile device may be determined using closed loop calibration. The closed loop may be a near field radiated closed loop between pairs of antennas in an antenna array of the mobile device. The delay based on time of transmission and time of reception may be measured for a plurality of pairs of antennas, from which the transmit and receive group delay within a single path may be determined. The propagation delay of the signal between antennas may be included in the group delay calibration for increased accuracy. In another implementation, a conducted closed loop, e.g., in the transceiver or in a radio frequency switching network may be used to calibrate the group delay. Pre-characterization of the delay caused by components between the closed loop and antennas may be included in the group delay calibration for increased accuracy.