Wireless Coexistence Testing in the 5 GHz Band with LTE-LAA Signals.

Area of Science:

• Wireless communication
• Electromagnetic compatibility
• Spectrum management

Background:

• Long Term Evolution (LTE) specifications were updated in Release 13 for unlicensed spectrum operation, known as LTE-Licensed Assisted Access (LAA).
• The widespread adoption of LTE-LAA raises concerns about its coexistence impact on incumbent unlicensed spectrum users, including critical wireless medical devices.
• This necessitates revisions to the American National Standards Institute (ANSI) C63.27 standard for evaluating wireless coexistence.

Purpose of the Study:

• To investigate the use of LAA signals for wireless coexistence testing.
• To evaluate the coexistence impact of LAA on incumbent technologies and vice versa.
• To inform updates for the ANSI C63.27 standard.

Main Methods:

• Experimental work conducted at the U.S. Food and Drug Administration's Electromagnetic Compatibility and Wireless Laboratory.
• Deployment of a software-defined radio platform to generate realistic LAA signals.
• Testing using a standardized radiated anechoic chamber method with IEEE 802.11ac as the incumbent technology in the 5 GHz band.

Main Results:

• LTE-LAA signals exhibit mutual coexistence impact within the 5 GHz band.
• The most significant coexistence impact occurs when LAA signals utilize maximum channel time occupancy and the highest modulation and coding scheme (MCS).
• This maximal configuration impacts both the equipment under test (EUT) and the LAA system.

Conclusions:

• LTE-LAA significantly impacts wireless coexistence in the 5 GHz unlicensed band.
• Signal parameters, specifically channel time occupancy and MCS, are critical factors determining coexistence challenges.
• Findings support the need for robust coexistence testing methodologies to ensure reliable operation of diverse wireless devices.