Fifth generation (or 5G) wireless communications systems, expected to roll out later this year, include a wide range of new technologies, many of which will be much faster and carry far more data than today’s technologies.
As the nation’s measurement authority, the National Institute of Standards and Technology (NIST) is helping to create the technologies and methods that industry can use to build and evaluate 5G systems.
Entirely new devices and approaches are needed for 5G. That’s because many 5G systems will operate at much higher (millimeter wave) frequencies and offer more than 100 times the speed and data-carrying capacity of today’s cellphones, all while connecting billions of mobile broadband users in ever-more-crowded signal environments. NIST is focusing mainly on this category of 5G technology.
Industry’s first 5G standards, ratified in late 2017, define technologies for the use of frequency bands up to 52.6 gigahertz (GHz). Today’s cellphones operate below 3 GHz. By using new frequency bands over 3 GHz with efficient advanced technologies, 5G systems will help optimize the use of the electromagnetic spectrum, a scarce resource.
Forecasts call for 5G wireless to transmit voice, data and images in many new ways. For instance, cellphones may talk to each other directly, with their signals skipping base station antennas on cell towers entirely. Base stations, the network hubs that receive and transmit signals, may serve a high density of short communications links in many directions.
Signal strength and frequency may be varied much faster than they are today, and specific bands of frequencies may be allocated to different categories of users at different times. “Smart” antennas may choose different directions for transmitting and receiving data, or form beams to track moving users, to help expand channel capacity and extend range.
The development of these technologies will support not only future cellphones and public safety radios but also wearable devices, the internet of things, the smart grid, smart homes, next-generation automotive technologies and smart manufacturing.
In keeping with NIST’s role of assisting industry by creating a measurement infrastructure that is traceable, or linked, to national or international standards, the Communications Technology Laboratory (CTL) is developing measurements, tests and standards for systems that are intelligent, fast and nimble enough to support 5G wireless.
Because there are so many possible novel 5G systems, CTL needs to measure many things:
NIST has a long history of pioneering antenna measurements. CTL’s innovations include the world’s first robotic-arm antenna testing system.
Recently, CTL introduced an antenna test range designed specifically for 5G measurements.
Signal distortion in complex transmitters, receivers and the instruments used to characterize them is much larger at millimeter wave frequencies than it is at frequencies used by conventional cellphones. CTL provides measurement services that help correct these distortions and link these high-speed signal measurements to fundamental physical quantities.
Precise evaluations of complex, high-speed signals and systems require the use of new techniques to quantify measurement uncertainties. To meet this need, CTL staff developed a software tool, the NIST Microwave Uncertainty Framework, which allows users to build uncertainty models of instruments and systems and use simulations to help estimate uncertainty. This provides a link between fundamental physical quantities (such as the meter, the second, and the volt) and communications system metrics such as bit-error rate.
To help convene all 5G participants and generate the most widely useful results, NIST launched the 5G mmWave Channel Model Alliance to accelerate the development and use of accurate measurements and models. To date, the alliance has brought together more than 130 participants from academia, industry and other government organizations. The alliance has a shared database that provides all members with methodology, best practices and channel-model test results. The output of NIST’s research and the alliance is being incorporated into the development of standards, specifications and best practices benefitting the entire industry.