Stack-Effect Compensation Model for Wireless Terminal Elevation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for estimating the elevation of a wireless terminal within a structure, such as a building, are inaccurate due to the stack effect, which causes differences in air pressure and temperature between indoors and outdoors, leading to errors in elevation estimation, especially in emergency situations where precise location is crucial.
Innovation Solution
A stack-effect compensation model is developed to account for the neutral pressure plane and its variations within a structure, using barometric pressure and temperature measurements from both indoor and outdoor sources to refine elevation estimates, allowing for accurate location determination of wireless terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If barometric pressure measurements are used to estimate elevation of a wireless terminal within a structure, then elevation estimation can be performed without external positioning systems, but the stack effect causes inaccurate elevation estimates due to temperature differences between indoor and outdoor air
Solution Approach 1:
The patent changes the parameter used for elevation estimation from raw barometric pressure to a compensated pressure value that accounts for the stack effect. By introducing a temperature-based compensation parameter, the system adjusts the pressure measurement to reflect what the pressure would be without the stack effect, thereby improving both accuracy and reliability of elevation estimates within structures
Solution Approach 2:
The patent introduces an intermediary compensation mechanism that mediates between the outdoor barometric pressure measurement and the indoor elevation estimation. The compensation model, based on temperature differences, acts as an intermediary factor that corrects the pressure measurement to account for the stack effect, enabling reliable elevation estimation despite the presence of this physical phenomenon
2Productivity
If the stack effect is ignored in elevation estimation, then the calculation process remains simple and fast, but elevation estimates become increasingly inaccurate in tall buildings and structures with significant temperature differences
Solution Approach 1:
The patent modifies the calculation by introducing a temperature-based compensation parameter that adjusts the barometric pressure measurement. This parameter change enables the system to maintain simple and fast calculations while significantly improving elevation estimation accuracy in structures where the stack effect is present, thus resolving the contradiction between calculation speed and measurement precision
3Measurement precision
If a stack-effect compensation model is developed using multiple measurements, then elevation estimation accuracy improves, but the complexity of the system increases due to the need for multiple measurements and model development
Solution Approach 1:
The patent applies preliminary action by pre-developing the stack-effect compensation model using multiple measurements taken during a calibration phase. Once the model is established, it can be applied repeatedly to subsequent elevation estimations without requiring additional complex measurements or calculations, thus improving accuracy while minimizing the increase in system complexity during normal operation
Solution Approach 2:
The system performs self-service by automatically developing and applying the compensation model without requiring external intervention. The wireless terminal or network entity autonomously collects measurements, develops the model, and uses it for elevation estimation, reducing the operational complexity despite the enhanced accuracy
Data Source
AI summary
A technique for developing a stack-effect compensation model that is representative of a structure, such as a particular building, and of generating an estimate of the elevation of a wireless terminal inside the structure by using the model. The technique includes estimating information related to one or more neutral pressure planes within the structure, at which the difference between the indoor barometric pressure and the outdoor barometric pressure is essentially zero. The technique leverages pressure and temperature measurements that are provided by one or more wireless terminals that are regularly present in the building. The stack-effect compensation model includes a parameter that represents, for each of a plurality of uncompensated elevations, the height of the particular uncompensated elevation above a neutral pressure plane. The location engine uses this height-information parameter from the compensation model, in order to develop the estimate of the elevation of the wireless terminal.