User Equipment Distance Estimation via Discovery Message Power
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Solution Overview
Problem
Current device-to-device communication systems face limitations in estimating geographical distance between user equipment due to network load increases and signal reception failures, especially in public safety applications where network coverage is limited.
Innovation Solution
A method that allows user equipment to estimate geographical distance through direct communication by transmitting a discovery message with embedded transmission power information, enabling distance determination independent of network reception quality and reducing network load, using transmission power calibration information and radio cell-specific settings to adjust transmission power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If device-to-device communication systems use centralized network-based distance determination, then location-based services can be provided, but network load increases with increasing number of relative distances to be determined
Solution Approach 1:
The patent extracts the distance determination function from the centralized network and implements it locally at the user equipment. Each device independently calculates distance using the formula d = 10^((PL - 120)/20), where PL is the path loss derived from received signal strength and transmitted power. This extraction eliminates the need for network-based distance calculation, thereby reducing network load while maintaining reliable location-based services.
Solution Approach 2:
The system enables user equipment to perform self-service distance determination without network intervention. Devices autonomously measure received signal strength, retrieve transmitted power information from discovery messages, calculate path loss, and determine distance independently. This self-service mechanism reduces dependency on network resources while ensuring continuous location-based service availability.
2Adaptability or versatility
If device-to-device communication relies on network coverage for distance estimation, then centralized control is maintained, but usage is limited due to reception failures or weak signals
Solution Approach 1:
The patent segments the distance determination process into independent device-level operations rather than network-dependent operations. Each device locally processes discovery messages, measures signal strength, retrieves transmit power, and calculates distance independently. This segmentation enables operation in areas with weak or failed network signals, as the critical function is distributed to individual devices rather than relying on centralized network processing.
Solution Approach 2:
The system performs preliminary actions by embedding transmitted power information directly in discovery messages before distance calculation is needed. Devices pre-retrieve this power information along with signal strength measurements, enabling immediate local distance computation without requiring subsequent network queries. This preliminary preparation ensures reliability even when network coverage is unavailable during the actual distance determination.
3Adaptability or versatility
If transmission power levels vary between user equipment, then communication flexibility is improved, but distance estimation accuracy deteriorates without calibration
Solution Approach 1:
The patent addresses power level variations by dynamically adjusting the distance estimation calculation based on the actual transmitted power parameter. Devices retrieve the specific transmit power value from discovery messages and use it to calculate path loss and distance. This parameter adaptation ensures that distance estimation remains accurate regardless of whether devices transmit at high or low power levels, maintaining precision while preserving transmission flexibility.
Data Source
Figure 1~2
AI summary
A method for estimating a geographical distance between at least two user equipments includes: generating, by a first user equipment, a discovery message, wherein the discovery message comprises a transmission power information; transmitting, by the first user equipment, the discovery message using a common air interface of the first user equipment and the second user equipment, using the level of transmission power; receiving, by the second user equipment, the discovery message comprising the transmission power information and determining a level of reception power; and determining, by the second user equipment, based on the received transmission power information and the determined level of reception power, an estimation related to the geographical distance between the first user equipment and the second user equipment, or to a range of the geographical distance out of a plurality of different ranges of the geographical distance between the first user equipment and the second user equipment.