Emergency Call Positioning via Assisted-GPS Using the LPP Protocol on Smartwatches

Smartwatches currently lack a precise solution for determining a user's position in emergency scenarios, limiting their effectiveness in critical situations. To address this, this study evaluates Assisted-GPS (A-GPS) with the LTE Positioning Protocol (LPP) to enhance emergency call positioning in Voice over LTE (VoLTE) systems. By leveraging network assistance, AGPS improves accuracy and reduces Time to First Fix (TTFF) compared to traditional GPS. We develop custom source code and use laboratory testbed to simulate real-world emergency call scenario, assessing key metrics such as horizontal positioning accuracy of A-GPS compared to Cell-ID, jitter, message exchange consistency via LPP, signal-to-noise ratio (SNR), network response times, and vertical positioning accuracy. The results show that A-GPS using the LPP protocol improved the location accuracy, achieving an average positioning error of 1.65 meters, in contrast to approximately 700 meters associated with Cell-ID and other methods from the literature. Additionally, the smartwatch response times were approximately 18 seconds meeting the 3GPP 20-second standard for location reporting. These findings highlight the potential of A-GPS and LPP protocol to enhance emergency call positioning.