Mobile Device Location via Timing Advance Step Changes
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Solution Overview
Problem
Conventional methods for 'drive' testing mobile communications devices on high-speed trains face challenges due to difficulty in obtaining GPS signals and the inability to accurately indicate marker positions, leading to limited accuracy in determining the location of mobile devices.
Innovation Solution
A method utilizing timing advance information from mobile communications networks to identify step changes in timing advance values, allowing for the determination of precise location markers by analyzing patterns in timing advance data, which are then used to interpolate intermediate locations along a known path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS signals are used for location determination in drive testing on high-speed trains, then location accuracy can be maintained under normal conditions, but GPS signals become difficult to obtain inside trains and at high speeds
Solution Approach 1:
The patent uses timing advance information from mobile communications base stations as an intermediary to determine location. Instead of directly relying on GPS signals that are blocked inside trains, the system uses the timing advance parameter (which reflects signal propagation time from base station to mobile device) as a mediator to indirectly calculate position along the train trajectory, thereby resolving the signal obstruction problem.
Solution Approach 2:
The patent replaces the GPS satellite-based electromagnetic positioning system with a terrestrial mobile communication network-based timing measurement system. By substituting the GPS mechanical/satellite system with the mobile network's timing advance mechanism, the system achieves location determination that works reliably inside trains where GPS signals are blocked.
2Productivity
If conventional drive testing methods are used on high-speed trains, then testing can be performed, but the speed of motion makes it practically impossible to indicate marker positions with sufficient accuracy
Solution Approach 1:
The system uses the mobile device's own timing advance measurements with respect to known base station locations to automatically determine its position. Instead of requiring external operators to manually indicate marker positions (which is impossible at high speeds), the system self-determines location through automated timing advance analysis, enabling accurate positioning despite high train speeds.
Solution Approach 2:
The patent continuously measures timing advance values throughout the drive test and continuously calculates position along the trajectory. This continuous automated positioning replaces discontinuous manual marker indication, maintaining measurement precision throughout the entire high-speed test without requiring intermittent human intervention that cannot keep up with train speed.
3Measurement precision
If timing advance information is used for location determination, then accurate location markers can be identified along the trajectory, but timing advance values are quantised which limits precision
Solution Approach 1:
The patent performs preliminary actions by collecting multiple timing advance measurements at different locations along the train trajectory before final position calculation. By gathering timing advance data points in advance and analyzing patterns of change, the system can identify precise location markers even though individual timing advance values are quantized, effectively compensating for the quantization limitation through pre-collected data analysis.
Data Source
AI summary
A method of locating a mobile communications device, in particular on a known path, the mobile device communicating with a mobile communications network infrastructure including a plurality of base stations, communications between the mobile device and the base station to which it is attached having a timing advance to compensate for a time taken for a radio signal to reach the base station from the mobile device, the method comprising: reading a time ordered sequence of messages captured from said communications between the mobile device and said network infrastructure; reading timing advance information from said captured messages; identifying a step change in timing advance using said timing advance information; and determining a location of said mobile devices, in particular on said path, at a time of said step change.