18 April 2018
Researchers at the National Institute of Standards and Technology (NIST) are continuing to explore new antenna measurement methods, this time focusing on the future of 5G wireless communication systems.
NIST has developed a ‘Large Antenna Positioning System’ (LAPS) which features two robotic arms designed to position smart or adaptable antennas. The idea is these can be mounted on base stations that handle signals to and from huge numbers of devices. Future 5G systems will operate at higher frequencies and offer more than 100 times the data-carrying capacity of today’s mobiles, while connecting billions of mobile broadband users in complex, crowded signal environments.
Among its “many special capabilities”, NIST says the LAPS can test transmissions to and from antennas located on fast-moving mobile devices, which requires coordination between the timing of communication signals and robot motion.
“Measurements of antenna signals are a great use for robotics,” NIST electronics engineer, Jeff Guerrieri, explains. “The robotic arms provide antenna positioning that would be constrained by conventional measurement systems.”
NIST researchers says they are still validating the performance of the LAPS and are just now beginning to introduce it to industry. The system was described at a European conference last week.
Today’s mobile devices, such as cell phones, consumer Wi-Fi systems and public safety radios, mostly operate at frequencies below 3GHz, a crowded part of the spectrum. Next-generation mobile communications are starting to use the more open frequency bands at mm wavelengths (30-300GHz), but these signals are easily distorted and more likely to be affected by physical barriers such as walls or buildings. Solutions will include transmitter antenna arrays with tens to hundreds of elements that focus the antenna power into a steerable beam that can track mobile devices.
NIST hopes the LAPS will help foster the development of 5G wireless and spectrum-sharing systems. It also believes that the dual-robot system will aid researchers in understanding the interference problems created by ever-increasing signal density.
LAPS is the next generation of NIST’s Configurable Robotic Millimeter-Wave Antenna (CROMMA) Facility, which has a single robotic arm. NIST says CROMMA has become a “popular” tool for high-frequency antenna measurements and companies that integrate legacy antenna measurement systems are starting to use robotic arms in their product lines, facilitating the transfer of this technology to companies like The Boeing Co.
But, while CROMMA can measure only physically small antennas, NIST developed the LAPS concept – a dual robotic arm system, one robot in a fixed position and the other mounted on a large linear rail slide – to accommodate larger antennas and base stations.
The system was designed and installed by NSI-MI technologies. The LAPS also has a safety unit, including radar designed to prevent collisions of robots and antennas within the surrounding environment, and to protect operators.
According to NIST, LAPS’ measurement capabilities for 5G systems include flexible scan geometries, beam tracking of mobile devices and improved accuracy, and repeatability in mobile measurements.
The LAPS has replaced NIST’s conventional scanners and will be used to perform near-field measurement of basic antenna properties for aerospace and satellite companies requiring precise calibrations and performance verification. The near-field technique measures the radiated signal very close to the antenna in a controlled environment and, using mathematical algorithms developed at NIST, calculates the antenna’s performance at its operating distance, known as the far field.
The ultimate goal for the LAPS however, is to perform dynamic, over-the-air tests of future 5G communication systems. Initial validation shows that basic mechanical operation of the LAPS is within the specified design tolerances for still and moving tests to at least 30GHz. Final validation is ongoing.