Supporting the 5G Network

Information connectivity continues to evolve, as does wireless technology. The first wave of information connectivity disruption happened decades ago in our homes and businesses through wired telephony and the early Internet via dial-up modems. Since then, the development of communication networks has been superseded by wireless mobile technology connecting people instead of places. Today, there are over seven billion mobile devices in the world connecting over 3.8 billion people. The next era will connect things. It has been well published that within the next decade we expect to connect at least 10 times the number of things as people, representing another sea of change.

This next era, the so called Internet of Things (IoT) or even the Industrial Internet of Things (IIoT), will drive the development of new wireless technologies supporting the underlying infrastructure defined in 5G network standards currently being conceptualized. The promise of increased information bandwidth and faster response times (low latency) for real-time wireless control, all with minimal power consumption, makes for highly attractive yet very challenging system performance goals. While the technical requirements necessary to make 5G and the IoT a commercial success are very demanding, the economic potential and business opportunities are enormous.

5G networks will likely be based on multi-radio access technology (Multi-RAT) using existing cellular base stations to ensure broad coverage and high-mobility and interspersed small cells for capacity and indoor service. These future networks use a combination of small cell + macrocell base stations, as well as cellular + Wifi with considerable research into using Wifi for cellular traffic offloading. Although there is not yet full agreement on which technology will address the 5G challenge, researchers are converging on four vectors:

• Massive MIMO (Multiple Input Multiple Output): explores a dramatic increase in the number of antennas a base station employs for mobile device coverage and high-speed backhaul links
• Network densification: includes space (e.g., dense deployment of small cells to achieve greater coverage using more nodes) and spectral (utilizing larger portions of radio spectrum in diverse bands)
• 5G waveforms: looks to improve bandwidth utilization through structural improvements of signals and modulation techniques
• Millimeter wave frequencies: will exploit new spectrum (3 to 300 GHz) frequency ranges, once considered too exotic for commercial use, to provide very large bandwidths capable of delivering multi-Gbps data rates, as well as the opportunity for extremely dense spatial reuse to increase capacity

System performance will require that the radio components function as mini-systems with ever-increasing levels of integration. The challenges in the integrated circuits and system design include the nonlinear distortion of power amplifiers, phase noise, IQ imbalance, highly directional antenna design, etc. Fortunately, advancements in microwave and signal processing technologies such as Gallium Nitride transistors, heterogeneous “More-than-Moore” integration, new millimeter-wave Silicon ICs, and advanced antenna integration/electronic beam-steering will enable new wireless technologies standards such as 802.11ax and Wi-Gig.

The challenge for product development teams targeting 5G/IoT opportunities will be to shorten the design cycle and reduce failure through proper up-front planning, realistic radio block performance specification, outlining detailed circuit requirements, verification via electromagnetic (and possible multi-physics) simulation, and early prototype testing with the ability to incorporate results back into the system simulation. For organizations of any size, the top-down/bottom-up approach calls for design tool integration that includes a system-level understanding of overall performance based on data representing individual components from a range of simulation and/or measurement sources.

Managing the design project through system simulation helps guide the early development process and allows integrators to generate a link budget (accounting for losses and gains through the signal chain), define the component specifications, and monitor the overall performance. Design detail from circuit/electromagnetic (EM) simulation and/or measurement is added as it becomes available. A design platform that supports system-level data management of circuit/EM simulation and/or measurement-based results should be able to directly access this data through tool interoperability. The electrical design phase is best served by a unified design platform that integrates physical design.

The integration of simulation technologies, physical design, and verification will help design teams achieve greater first pass success, however they will still need to rely on a combination of simulation and prototype testing to validate assumptions made before fabrication and to convince others of design viability.

Gary Xu, Director of Research at Samsung, recently showcased one of the first public demonstrations of a prototype for a 5G FD-MIMO (Full Dimensional MIMO) base station. The demo comprised of a small base station containing the FD-MIMO antenna array and four NI USRP RIO software receivers which emulated four “5G” handled terminals. Samsung’s new 3D beam forming algorithms was a key technology. The prototype demonstrated that 3D beamforming enabled higher throughput and an increase in the number of supported users. In this instance, the system improved from enabling 2 Mbps (megabits per second) for one user to 25 Mbps for four users by using 3D beamforming.

In terms of simulation, recent work from Université du Québec à Rimouski (UQAR) students, led by Dr. Chan-Wang Park, provides an example of simulation and test data being applied together in a 5G design. The design team developed a 6 W, 1 GHz power amplifier (PA) for use with 5G MIMO multi-carrier signals. Because they wanted to linearize the PA in the future, the team intended to correct the nonlinearity of the PA by using a neural network pre-distortion linearizer, volterra or polynomial pre-distortion linearizer.

The design team was able to achieve first-pass PA design success through detailed circuit/EM co-simulation using Microwave Office and AXIEM, imported multi-harmonic source and load pull data, and the RF PXIe platform programed with LabVIEW for fast test results of the PCB-based prototype. The team was able to develop a simplified solution for future (5G MIMO) telecommunication system standards using a pre-distortion linearizer.

Together, these interoperable design-prototype-test platforms will give design teams the power and flexibility to realize the high-frequency electronics that will drive 5G and IoT.