RSSI Location Accuracy via AP Clustering and SSN Bitmap Analysis
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Solution Overview
Problem
Existing methods for determining the location of a device in a wireless network using Received Strength of Signal Indicator (RSSI) are inaccurate due to variations in transmission power, especially when devices switch between power save modes, leading to location errors.
Innovation Solution
The method involves clustering Access Points (APs) based on Starting Sequence Number (SSN) and bitmap combinations, using relative RSSI values to mitigate transmission power variations, and determining a final location by merging probable locations from these clusters, potentially incorporating Machine Learning for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RSSI values are used directly for location determination, then the process is simple, but location accuracy deteriorates due to transmission power variations
Solution Approach 1:
The patent segments the set of access points into multiple clusters based on SSN and bitmap combinations. Each cluster represents a specific transmission power state, allowing the system to handle power variations by processing clusters separately rather than treating all APs uniformly. This segmentation enables accurate location determination within each power state cluster while maintaining manageable processing complexity.
Solution Approach 2:
The patent changes the parameter used for location determination from raw RSSI values to relative RSSI values (differences between clusters). This parameter transformation eliminates the need to know absolute transmission power levels, as the relative differences remain consistent even when transmission power varies. The system uses SSN and bitmap as additional parameters to identify and group APs with similar transmission characteristics.
2Measurement precision
If transmission power variations are accounted for using multiple parameters, then location accuracy improves, but the complexity of data processing increases
Solution Approach 1:
The patent makes the SSN and bitmap fields serve multiple functions: they identify transmission power states, enable clustering of APs, and provide the basis for creating relative RSSI measurements. This multi-functionality reduces the need for separate tracking mechanisms for each parameter, as the same data structures serve both power state identification and location calculation purposes.
Solution Approach 2:
The patent creates a simplified representation of the physical environment by copying AP data into cluster structures organized by SSN and bitmap. Instead of processing raw data from all APs simultaneously, the system creates clustered copies grouped by transmission characteristics, making the data more manageable and easier to process for location determination.
Data Source
AI summary
Transmission (Tx) power variation mitigation for Received Strength of Signal Indicator (RSSI) location may be provided. RSSI data for a station may be received from a plurality of Access Points (APs). The RSSI data may include a RSSI value determined from a Block Acknowledgement (BA) packet and a Starting Sequence Number (SSN) and a bitmap of the BA packet. The plurality of APs may be clustered into one or more clusters based on a combination of the SSN and the bitmap. One or more APs having a same combination of the SSN and the bitmap are clustered into one cluster. A probable location of the station may be determined in each of the one or more clusters based on RSSI values received from the one or more APs of each of the one or more clusters. A final location of the station may be determined based on merging probable locations from the one or more clusters.