5 GHz Band LTE-LAA Signal Selection for Use as the Unintended Signal in ANSI C63.27 Wireless Coexistence Testing

Area of Science:

• Electromagnetic Compatibility
• Wireless Communication Systems
• Radio Frequency Engineering

Background:

• Wireless coexistence is crucial for reliable communication, especially in shared frequency bands like the 5 GHz spectrum.
• License Assisted Access (LAA) technology utilizes unlicensed spectrum, necessitating investigation into its impact on existing wireless systems.
• The U.S. Food and Drug Administration (FDA) conducts research to ensure the safety and efficacy of wireless medical devices.

Purpose of the Study:

• To investigate the wireless coexistence impact of License Assisted Access (LAA) signals.
• To evaluate the performance of IEEE 802.11ac devices when subjected to LAA interference.
• To analyze the internal system states of LAA during coexistence testing and inform risk management.

Main Methods:

• Utilized a software-defined radio platform to generate realistic LAA signals.
• Employed a standardized radiated anechoic chamber method for testing wireless coexistence.
• Tested the impact on an equipment under test (EUT) using IEEE 802.11ac in the 5 GHz band.

Main Results:

• LAA signals exhibit a mutual coexistence impact in the 5 GHz band.
• Maximum channel time occupancy and highest modulation and coding scheme (MCS) for LAA create the most significant coexistence challenges.
• Observed an inverse relationship between LAA transmit/wait times and successful channel access under challenging coexistence scenarios.

Conclusions:

• Selecting LAA signals with maximum channel time occupancy and highest MCS intensifies coexistence issues.
• Challenging coexistence scenarios adversely affect LAA's ability to access channels.
• Risk management for wireless coexistence in medical devices should incorporate findings from such coexistence testing.