Indoor Localization Signal Synthesis for Temporary Absence
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Solution Overview
Problem
Current localization methods for mobile terminal devices indoors, such as WLAN-based RSS fingerprinting, face inaccuracies due to unreliable signal reception and temporary absence of radio transmitters, leading to erroneous penalty values and poorer position estimation.
Innovation Solution
An apparatus and method that post-process measurement packets by temporarily synthesizing signal characteristics of radio transmitters not recently receivable, allocating their last known signal characteristics for up to 0.5 seconds, and using low-pass filtering to smooth signal variations, thereby improving correspondence calculations between current and reference packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RSS fingerprinting is used for localization, then the method can be implemented with available WLAN infrastructure, but localization accuracy deteriorates due to temporary signal absences and noise causing erroneous penalty values
Solution Approach 1:
The system performs preliminary actions by maintaining a history of recently received signal characteristics from radio transmitters and proactively synthesizing this information to fill gaps when signals are temporarily absent. Instead of waiting for signal absence to cause errors, the system pre-prepares compensatory data using previously stored signal characteristics, thereby preventing localization accuracy deterioration before it occurs.
Solution Approach 2:
The invention applies beforehand cushioning by creating a temporal buffer of signal characteristics that cushions against the harmful effects of temporary signal absences and noise. When a transmitter's signal is not detected, the system uses the buffered historical signal characteristics to maintain accurate correspondence calculations, preventing the localization system from suffering accuracy losses due to transient signal problems.
2Measurement precision
If signal characteristics are strictly required at current measurement time, then measurement precision is maintained, but reliability deteriorates due to temporary signal absences causing erroneous penalty values
Solution Approach 1:
The system introduces an intermediary mechanism that bridges the gap between current measurement requirements and historical signal data. When a radio transmitter's signal is temporarily absent, the intermediary synthesizes information from previously received signal characteristics to provide the necessary data for correspondence calculations. This intermediary approach allows the system to maintain measurement precision while ensuring reliability by preventing erroneous penalty values during signal absences.
3Measurement precision
If strict matching of current measurement values with reference values is performed, then measurement precision is maintained, but localization accuracy deteriorates due to temporary signal absences
Solution Approach 1:
The system performs preliminary synthesis of signal characteristics from historical data before the strict matching process occurs. When current measurements are unavailable due to signal absences, the synthesized values from previously received characteristics are prepared in advance and used in the matching process. This preliminary action ensures that the strict matching maintains its precision while working with reliable, gap-free data, thereby improving position estimation reliability.
Solution Approach 2:
The invention applies beforehand cushioning by preparing compensatory signal characteristic values from historical data before the matching process. This cushioning layer protects the strict matching operation from the harmful effects of temporary signal absences, ensuring that the matching process always has valid data to work with and can maintain its precision while achieving reliable position estimates.
4Device complexity
If radio transmitters are removed from measurement packets immediately when not receivable, then device complexity is reduced, but localization accuracy deteriorates due to temporary signal absences
Solution Approach 1:
The system performs preliminary synthesis of signal characteristics and maintains an extended presence of radio transmitters in measurement packets beyond their immediate reception. Instead of immediately removing transmitters when signals are absent, the system proactively maintains them using synthesized values from historical data for a predetermined period. This preliminary action prevents premature removal, maintaining localization accuracy while managing complexity through structured synthesis rather than immediate deletion.
Solution Approach 2:
The invention applies beforehand cushioning by extending the presence of radio transmitters in measurement packets using synthesized signal characteristics from historical data. This cushioning prevents the harmful effect of immediate removal, allowing the system to maintain accurate correspondence calculations during temporary signal absences. The predetermined period extension provides a buffer that maintains localization accuracy while the structured synthesis approach manages processing complexity.
Data Source
AI summary
An apparatus (30) for determining a correspondence of a position (21) with a reference position (24), wherein radio signals of stationary radio transmitters (22) are receivable at the position, comprising a means (32) for determining an identification of a certain radio transmitter (22e) and for determining a signal characteristic of a radio signal of the certain radio transmitter at a first time tls wherein the identification and the signal characteristic of the radio signal of the certain radio transmitter represent at least part of a measurement packet (MP) for the position (21), a means (36) for post-processing the measurement packet (MP) to obtain a post-processed measurement packet (MP') for the position (21) wherein the means for post-processing is implemented to synthesize the signal characteristic of the certain radio transmitter, starting from the first time (t1) up to a second time (t2) after the first time (t1), for which the identification of the certain radio transmitter (22e) cannot be determined, when the first time (t1) was the last time before the second time (t2) when the identification of the certain radio transmitter (22e) was determinable, and when a time duration (?t) of more than or equal to 0.5 seconds lies between the first and second times, and a means (38) for comparing the post-processed measurement packet (MP') with at least one previously determined reference measurement packet (RP) for the reference position (24) to determine the correspondence.