Multi-Network Positioning Using Weighted Time Differences
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Solution Overview
Problem
Current positioning methods in cellular communication systems, especially those relying on base station and mobile phone signal transmission time, face inaccuracies due to obstructions and limited base station availability, leading to poor location estimation accuracy.
Innovation Solution
A positioning method and system that utilize multiple cellular networks by measuring and weighting time differences between base stations, employing a formula J=∑j=1Nswj∑i=1Njwij[(X-X0j-X-Xij)-cΔtij]2 to estimate the mobile phone's position, incorporating a time difference measuring module in UE and a time delay correction module in SRNC or SAS, and including a position calculating module for optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If positioning is performed using traditional base station signal transmission time in a single cellular network, then the positioning process is simple, but the positioning accuracy deteriorates due to obstructions and limited base station availability
Solution Approach 1:
The patent combines positioning measurements from multiple cellular networks (e.g., WCDMA and TD-SCDMA) into a unified positioning system. The mobile terminal performs time difference of arrival (TDOA) measurements across base stations from different networks, and the location server integrates these measurements to calculate position, thereby improving accuracy through diversified signal sources while managing complexity through standardized processing procedures
2Measurement precision
If multiple base stations are used to improve positioning accuracy, then the positioning precision improves, but the system complexity and difficulty of detecting and measuring increases
Solution Approach 1:
The patent enables the mobile terminal to perform universal TDOA measurements across base stations from different cellular networks by supporting multiple radio access technologies. The measurement process and calculation methodology remain consistent regardless of which network's base stations are used, allowing the system to leverage multiple networks without proportionally increasing measurement complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances positioning accuracy by leveraging multiple networks, accounting for signal obstructions and base station limitations, and provides a more precise location estimation by using weighted time differences and optimization techniques.
Implementation Method 1
As the velocity of radio waves is equal to the speed of light (c), the distance between the mobile phone and the respective base station is di=ti*c (i=1, 2 . . . )
Data Source
AI summary
A positioning method in two or more cellular networks calculates a gradient (grad (J)) of an optimization function for estimating position of UE:J=∑j=1Nswj∑i=1Njwij[(X-X0j-X-Xij)-cΔtij]2,wherein X0j is the position of a reference cell of the jth network, Xij is the position of the ith cell of the jth network, Wij is the weight directly proportional to the downlink signal receiving intensity of the ith cell of the jth network, wj is the weight inversely proportional to the signal code continuing time of the jth network, ∥x−x0∥=√{square root over ((x−x0)2+(y−y0)2+(z−z0)2)}{square root over ((x−x0)2+(y−y0)2+(z−z0)2)}{square root over ((x−x0)2+(y−y0)2+(z−z0)2)} is the Euclidian distance, Nj is the number of non-reference cell of the jth network, Ns is the number of networks, c is the speed of light.