Recursive Phase Vector Subspace Estimation for Wireless Client Localization

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Solution Overview

Problem

Current location techniques using Angle-of-Arrival (AoA) measurements in wireless communications face accuracy issues due to missed packets, erroneous measurements, and client device mobility, which conventional methods fail to adequately address, leading to reduced location accuracy.

Innovation Solution

The implementation of a recursive phase vector subspace estimation method that identifies and corrects for missing and erroneous AoA measurements by generating a phase observation matrix, computing an estimated subspace matrix, and reconstructing phase vectors, thereby improving location accuracy for both static and mobile client devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional AoA measurement techniques are used for location determination, then location functionality is provided, but location accuracy deteriorates when packets are missed, erroneous measurements occur, or client devices are mobile

Engineering Contradiction:
Improvelocation accuracyVSAvoidmeasurement reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the processor compares reconstructed phase vectors with originally received phase vectors to identify discrepancies. When errors or missing values are detected, the system uses recursively updated subspace information to correct these measurements, feeding the corrected data back into the location calculation process. This continuous feedback loop maintains measurement reliability while preserving location accuracy.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs preliminary subspace estimation and reconstruction of phase vectors before final location determination. By pre-processing the phase measurements to correct errors and fill missing values using recursive subspace methods, the system prepares improved measurement data in advance, ensuring both reliability and accuracy are maintained before the critical location calculation step.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If phase vectors are updated frequently to track mobile clients, then tracking accuracy improves, but computational complexity and processing time increase

Engineering Contradiction:
Improvetracking accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs dynamic subspace tracking where the signal subspace is recursively updated as new phase vectors arrive from mobile clients. Instead of recalculating the entire subspace from scratch, the system dynamically adapts the subspace estimate using incoming measurements, allowing accurate tracking of mobile devices while reducing computational burden through incremental updates rather than full recalculations.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If recursive phase vector subspace estimation is implemented to correct measurement errors, then location accuracy improves, but computational processing requirements increase

Engineering Contradiction:
Improvelocation accuracyVSAvoidcomputational processing power
Core Design Contradiction:
Measurement precisionVSPower

Solution Approach 1:

The system maintains continuous subspace estimation and phase vector reconstruction through recursive updates. By continuously processing incoming phase vectors through the established subspace model, the system keeps the location determination process active and accurate without requiring periodic full recalculations, thereby improving location accuracy while managing computational power requirements through efficient continuous operation.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentUS11714154B2Using recursive phase vector subspace estimation to localize and track client devices
Publication Date: 2023.08.01 CISCO TECHNOLOGY INC
  • US11714154B2 patent drawing
  • US11714154B2 patent drawing
  • US11714154B2 patent drawing

AI summary

Techniques for determining a location of a client device using recursive phase vector subspace estimation are described. One technique includes receiving a plurality of angle-of-arrival (AoA) measurements from a plurality of access points (APs). Each AoA measurement includes a plurality of entries for phase values measured from a signal received from a client device at the plurality of APs. At least one AoA measurement of the plurality of AoA measurements that includes at least one of: (i) one or more entries with missing phase values and (ii) one or more entries with erroneous phase values is identified, based on a recursive phase estimation. The plurality of AoA measurements are updated based on the identified at least one AoA measurement. The location of the client device is determined, based on the updated plurality of AoA measurements.