Elevator Access Control via Dynamic Signal Power Segmentation
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Solution Overview
Problem
Modern access control systems for buildings, such as those used in elevator systems, face challenges in precisely localizing a user's mobile communication device within a building, leading to difficulties in determining the floor of the destination call, resulting in inaccurate user location and inefficient navigation.
Innovation Solution
A method involving three communication units where the second and third units verify an identification code and send a confirmation code with a lower transmission power, allowing precise localization of the user within a near field, typically less than 2 meters, ensuring accurate access control and navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple transmitter/receiver units simultaneously emit code sequences for locating the communication means, then the user can be localized within the building, but the code sequences can be superimposed making localization more difficult
Solution Approach 1:
The patent segments the localization process into distinct phases: first transmitting an identification code, then transmitting a confirmation code only after successful verification. This temporal segmentation prevents code sequence superposition by ensuring that at any given moment, only one type of code is being transmitted and processed, eliminating the interference problem while maintaining localization precision.
2Loss of information
If the identification code reaches multiple transmitter/receiver units on different floors, then the user can be identified, but the processing unit cannot distinguish which floor the user is on
Solution Approach 1:
The patent applies local quality by making each transmitter/receiver unit (located on different floors) have a distinct characteristic - specifically, each unit transmits the confirmation code with a floor-specific transmission power level. This allows the processing unit to determine the user's floor by analyzing which confirmation code is received, as each floor's confirmation code has a unique power signature, thereby preserving floor information without increasing discrimination complexity.
Solution Approach 2:
The confirmation code serves as an intermediary that carries floor-specific information from the transmitter/receiver units to the processing unit. Instead of the identification code directly revealing floor information (which would be ambiguous when received by multiple units), the confirmation code acts as a mediator that encodes the floor identity through its transmission characteristics, enabling unambiguous floor determination.
3Measurement precision
If high transmission power is used for the identification code, then the code can be received by multiple floors, but the confirmation code may be received by communication means not in the immediate vicinity
Solution Approach 1:
The patent employs dynamics by varying the transmission power based on the message type and verification status. The identification code is transmitted at a higher power level to reach multiple floors, while the confirmation code is transmitted at a lower, floor-specific power level only after successful verification. This dynamic adjustment of transmission power ensures that confirmation codes are received only by communication means in the immediate vicinity of the correct floor, preventing incorrect location while maintaining the ability to initially reach multiple floors with the identification code.
Data Source
Figure 1
AI summary
An identification code is transmitted at a predetermined power from a mobile telephone (10) to a stationary terminal (20) when a user (30) enters the building. The transmitted identification code is checked with the terminal and an acknowledgement code is transmitted at a transmission power lower than the predetermined transmission power from terminal to mobile telephone. An access code is transmitted from mobile telephone to terminal which is checked with the terminal and access to the building is freed if access code checking is successful.