Radio Signal Fingerprint Compression Using Significant DCT Coefficients
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Solution Overview
Problem
The existing network-based positioning systems face challenges in efficiently storing and managing large volumes of radio fingerprint data, particularly in indoor environments, due to the need for three-dimensional data processing and the substantial storage requirements of comprehensive fingerprint databases, which can render positioning solutions unfeasible.
Innovation Solution
The method involves transforming radio image data into the frequency domain using discrete transforms like DCT, selecting significant coefficients, and encoding these indices based on their probability of occurrence to achieve compression, allowing for reduced storage and bandwidth requirements while maintaining positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If comprehensive fingerprint databases are stored in three-dimensional format for indoor positioning, then positioning accuracy is improved, but storage space requirements increase substantially
Solution Approach 1:
The patent extracts and stores only the most significant DCT coefficients rather than the complete fingerprint database. By transforming the radio map data into frequency domain and selecting only coefficients above a certain threshold, the system maintains positioning accuracy while dramatically reducing storage requirements from full 3D databases to a compressed subset of essential features.
Solution Approach 2:
The patent changes the representation parameters of the fingerprint data by applying Discrete Cosine Transform (DCT) to convert spatial domain data into frequency domain coefficients. This parameter transformation allows the same information to be represented more compactly, enabling efficient compression while preserving the essential characteristics needed for accurate indoor positioning.
2Measurement precision
If complete radio fingerprint data is transmitted to mobile devices, then positioning accuracy is improved, but bandwidth requirements increase
Solution Approach 1:
The system extracts and transmits only the significant DCT coefficients to mobile devices rather than complete fingerprint databases. This extraction approach maintains the essential positioning information while reducing transmission data volume, thereby lowering bandwidth requirements without compromising positioning accuracy.
Solution Approach 2:
The patent transforms the transmitted data parameters from raw spatial fingerprint data to compressed frequency domain coefficients. This parameter change enables the same positioning information to be transmitted using fewer bits, reducing bandwidth consumption while preserving accuracy.
3Measurement precision
If three-dimensional data processing is implemented for indoor positioning, then vertical direction estimation is improved, but data processing complexity increases
Solution Approach 1:
The patent extracts the essential vertical positioning information through DCT transformation, where the frequency domain representation naturally captures three-dimensional spatial characteristics. By working with the transformed coefficients rather than raw 3D data, the system maintains vertical direction estimation capability while simplifying the processing requirements.
4Quantity of substance
If compression is applied to radio data, then storage and bandwidth requirements are reduced, but data processing time increases
Solution Approach 1:
The patent performs the computationally intensive DCT transformation and coefficient selection in advance during the database construction phase. This preliminary action creates a pre-compressed representation that can be quickly retrieved and used during actual positioning operations, shifting the processing time burden to an offline setup stage rather than real-time positioning.
Data Source
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AI summary
An apparatus obtains a set of radio data comprising signal strength related values for radio signals transmitted by a transmitter with an association of each signal strength related value with a representation of a geographical location. The apparatus applies a frequency transform to the obtained set of radio data to obtain transform coefficients, each transform coefficient comprising a transform index and an associated transform value. The apparatus selects a subset of transform indices having more significant transform values than the remaining transform indices and compresses the transform indices by encoding each transform index exploiting a probability of occurrence of an index value of a respective transform index. The same or another apparatus decodes the compressed transform indices again for use in position operations.