Mobile Unit Interference Mitigation via Time Segmentation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Wireless Local Area Networks (WLANs) experience interference from Real Time Location Systems (RTLS) due to shared power amplifiers and antennas, which can overwhelm WLAN receivers and disrupt data communication operations.

Innovation Solution

Implementing a mobile device with a co-located RF radio and radio tag that operates during inactive time intervals of the RF radio or reserves exclusive airtime using standard protocol interfaces like IEEE 802.11, minimizing interference by segregating time for RTLS signal transmissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If RTLS and WLAN share common power amplifiers and antennas, then device complexity is reduced, but WLAN receivers are overwhelmed by RTLS signals causing interference

Engineering Contradiction:

Improvedevice complexityVSAvoidinterference

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the operation time of RTLS and WLAN by introducing inactive time intervals for the RF radio, allowing the radio tag to transmit RTLS signals only during these segmented time periods when WLAN is not active, thereby eliminating signal overlap and interference

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic action by establishing a repeating cycle where the RF radio alternates between active and inactive time intervals, with the radio tag periodically transmitting RTLS signals during the inactive intervals, creating a rhythmic pattern that prevents continuous interference

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If RTLS signals are transmitted continuously, then location tracking precision is improved, but WLAN data communication is disrupted

Engineering Contradiction:

Improvelocation tracking precisionVSAvoiddata communication reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent uses periodic action to schedule RTLS signal transmission during inactive time intervals of the RF radio, maintaining location tracking capability through regular periodic transmissions while ensuring WLAN communication reliability by avoiding continuous transmission that would cause disruption

Inventive Principle:

Principle #19Periodic action

3Reliability

If RF radio is kept active continuously, then WLAN data communication reliability is maintained, but RTLS signal transmission opportunities are reduced

Engineering Contradiction:

Improvedata communication reliabilityVSAvoidRTLS signal transmission duration

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent segments the time domain into active intervals for WLAN and inactive intervals for RTLS, allowing the RF radio to be fully active during WLAN communication while the radio tag transmits RTLS signals during the segmented inactive intervals, thus maintaining both functions without conflict

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8169991B2Interference mitigation in mobile units having location transmitters

Publication Date: 2012.05.01 SYMBOL TECHNOLOGIES LLC

AI summary

A mobile device for data communications has a radio circuit for data communications with a wireless network access point and a radio tag for transmitting location-identifying radio signals. The radio circuit and the radio tag are co-located on a circuit board or are commonly powered. The operation of the radio circuit and the radio tag are segregated in time to avoid interference. Standard wireless network interface protocol functions are exploited to identify time intervals in which the radio circuit is inactive for data communications. These time intervals are used to operate the radio tag to transmit the location-identifying radio signals.