Overlay Location System for LTE Idle Device Identification
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Solution Overview
Problem
Obtaining uplink TDOA measurements in LTE or LTE-A networks is challenging due to the unique radio air interface characteristics, which differ from other systems like GSM, CDMA, or UMTS, and existing methods struggle to identify mobile devices effectively, especially when they are idle or not actively transmitting their identifiers.
Innovation Solution
A system combining passive radio network monitors and passive wired monitors to obtain triggering information and mobile identity, utilizing Location Measurement Units (LMUs) to detect and cache Random Access Preamble messages, and then using uplink and downlink signals to determine UE identity and perform location estimates, enabling network-based techniques like U-TDOA, AOA, and POA for accurate mobile device location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional identification methods are used in LTE networks, then device identification is simple when devices are actively transmitting, but device identification fails when devices are idle or not actively transmitting identifiers
Solution Approach 1:
The system performs preliminary caching of Random Access Preamble messages and device identifiers during the random access procedure before actual communication begins. This allows the overlay location system to have identification data ready in advance, enabling location of idle devices that would otherwise not transmit identifiable signals.
Solution Approach 2:
The patent introduces an overlay location system as an intermediary layer between the LTE network and location services. This intermediary captures and processes signaling messages (Random Access Preamble, RAR, Connection Request) that contain device identifiers, enabling identification of devices without requiring them to be in active communication mode.
2Productivity
If LTE network architecture is used, then network performance and data rates are improved, but obtaining uplink TDOA measurements becomes challenging due to unique radio air interface characteristics
Solution Approach 1:
The patent segments the location measurement function into a separate overlay system that operates independently from the LTE network core. The overlay location system intercepts and processes uplink signals (Random Access Preamble on PRACH) separately from the main data transmission path, allowing TDOA measurements without interfering with LTE performance.
Solution Approach 2:
An overlay location system acts as an intermediary between LTE user equipment and the core network, capturing signaling messages during the random access procedure. This intermediary approach enables TDOA measurement extraction without requiring modifications to the LTE air interface or core network architecture.
3Measurement precision
If overlay location system is implemented, then location determination accuracy is improved, but system complexity increases due to integration of passive radio monitors and wired monitors
Solution Approach 1:
The overlay location system is designed to be multi-functional, handling multiple location determination techniques (TDOA, AOA, POA) and working with different device states (idle, active, handover). This universal approach consolidates various monitoring functions into a single system, managing complexity through unified architecture rather than separate specialized systems.
Data Source
AI summary
In an overlay, network-based, wireless location system, passive network probes and Location Measurement Units, typically co-located with eNodeB's, are used to collect identity information and radio signaling both in the forward and reverse channels for use in power-based, timing-based and/or angle-based positioning methods in Long Term Evolution (LTE) and LTE-Advanced wireless communications networks.