Signal Isolation via Dual-Reference Correlation in Wireless Location

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Solution Overview

Problem

In spread-spectrum wireless communications networks, low uplink radio transmission power and high frequency reuse cause co-channel interference, making it difficult to detect and identify radio signals of interest for wireless location systems.

Innovation Solution

A two-phase correlation process is employed, where a reference signal and a second reference signal are correlated with the received signal at a cooperative sensor station to identify the signal of interest by comparing peak ratios based on predetermined gain factors, allowing for the isolation of the signal of interest from interfering signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If low uplink radio transmission power and high frequency reuse are used, then network capacity and spectral efficiency are improved, but co-channel interference increases making signal detection difficult

Engineering Contradiction:

Improvenetwork capacityVSAvoidsignal detection difficulty

Core Design Contradiction:

ProductivityVSDifficulty of detecting and measuring

Solution Approach 1:

The received signal is segmented into multiple correlation outputs corresponding to different mobile stations. Each correlation operation separates a specific signal component from the composite received signal, allowing individual signal processing and identification despite the presence of co-channel interference from multiple sources

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Reference signals serve as intermediaries between the received composite signal and the target signal components. By correlating the received signal with known reference signals, the system can extract and identify specific mobile station signals from the interfered composite signal

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If correlation processing is performed to identify signals, then signal detection accuracy is improved, but processing complexity increases

Engineering Contradiction:

Improvesignal identification accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Reference signals are prepared in advance and stored for correlation processing. This preliminary preparation allows the correlation operation to efficiently identify target signals without requiring complex real-time signal generation or processing, reducing computational complexity while maintaining detection accuracy

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method effectively identifies and isolates the signal of interest, enhancing the accuracy of location estimation in wireless location systems by mitigating co-channel interference and improving the determination of the time of arrival.

Implementation Method 1

the first reference signal and the second reference signal are correlated (or cross-correlated) with the signal received at the cooperative sensor station

Methodology Applied

Scientific EffectCorrelation:

Data Source

PatentUS8737452B2Identification and isolation of radio signals for a wireless location system

Publication Date: 2014.05.27 QUALCOMM INC

AI summary

In an overlay, network-based, Wireless Location System, LMUs typically co-located with BTSs, are used to collect uplink radio signaling for use in TOA, TDOA and/or AoA positioning methods. In a UMTS, the dual nature of the uplink allows for identification of the correct uplink signal even in the presence of co-channel interference from other UMTS mobile devices.