Let’s Talk 6 G

Patrick Hindle, Editor, Microwave Journal
December 12, 2018

In June, the first 5G specification was finalized as 5G NR phase I (Release 15) and next year will see the completion of phase II for the 5G NR specification. 5G started in the U.S. this October, when Verizon released the first commercial 5G service with the deployment of mmWave Fixed Wireless Access service in several cities. AT&T started the deployment of the first standards-based 5G mobile service in November, and T-Mobile plans to start in the first half of 2019. It is surprising that the first two deployments in the U.S. use mmWave technology, which was deemed too expensive and short-range to be viable a few years ago. Although it will be several years before 5G becomes prevalent to consumers around the world, we have to ask what is next?

At September’s Mobile World Congress Americas 2018, FCC Commissioner Jessica Rosenworcel suggested that 6G could feature terahertz (THz) frequency networks and spatial multiplexing with multiple simultaneous beams of data transfer with a high level of network densification. This could be accomplished with miniaturized base stations embedded ubiquitously in the environment everywhere. While Rosenworcel said these technologies are far away, spectrum policies need rethinking now in advance of 6G including valuation, auctions and distribution.

Rosenworcel suggested dynamic sharing rather than the binary licensed/unlicensed model. She also proposed a blockchain approach to spectrum management. She said that instead of having a centralized database to support shared access in specific spectrum bands, we could explore the use of blockchain as a lower-cost alternative. With the emergence of blockchain technology being used in wireless applications, we will explore 5G and blockchain as a technology track at EDI CON China 2019 in Beijing in April as it relates to an open wireless network. It will be interesting to see where this technology is headed and the benefits to using it with 5G networks.

As I attended several 5G events this year, a few advanced technologies stood out as potentials for 6G. At the Brooklyn 5G Summit in April, NYU students were performing channel sounding testing using 140 GHz signals produced by Virginia Diodes’ sources. NYU led the way for 5G mmWave implementations with some of the first studies to develop propagation models, and seem to be doing the same for 6G with these projects. Nokia was demonstrating a single chip 90 GHz phased array at the Summit as well, so I look for these upper mmWave to lower THz frequencies being potential technologies for 6G.

At the University of Oulu’s Center for Wireless Communications, they have €250 million of funding over the next eight years for project 6Genesis: 6G-Enabled Wireless Smart Society & Ecosystem. Their charter is to think outside the box for the wireless vision for 2030. The 6Genesis project is led by the University of Oulu in collaboration with Nokia, the VTT Technical Research Center of Finland, Aalto University, Business Oulu and the Oulu University of Applied Sciences. The low latency of 5G, several milliseconds, may not be good enough for 6G and using 100 to 1000 GHz signals will be needed to handle data rates up to terabit/s speeds so they will explore how these goals might
be possible.

In the 6Genesis promo video, they envision an intelligent personal edge, an augmented reality interface using AI and cloud computing to deliver personalized data to your palm. Sensor to AI fusion would enable smart clothing, ambient measurements and individual health monitoring. Autonomous vehicles and ships, smart materials, holographic interfaces, intelligent cities, smart buildings, bio-centric identity for security and more would all become reality. Pretty cool stuff, but seems more likely 2050 before we reach this level of sophistication in our communication networks and data management systems.

In May, Tektronix/IEMN and Nippon Telegraph and Telephone Corporation (NTT) both announced development of 100 Gbps “wireless fiber” solutions. Each took a different route, with Tektronix and IEMN (a French research laboratory) demonstrating a single carrier wireless link with a 100 Gbps data rate signal at 252 to 325 GHz per the recently published IEEE 802.15.3d standard, while NTT used a new principle, Orbital Angular Momentum (OAM) multiplexing at 28 GHz with MIMO technology.

The Tektronix/IEMN demonstration used advanced data coding, THz photonics and wideband and linear devices to enable ultra-fast wireless connections in the 252 to 325 GHz band, according to the release. The purpose of the new 802.15.3d standard is to provide for low complexity, low-cost, low-power consumption, very high data rate wireless connectivity among devices and in the future “low THz” bands.

NTT successfully demonstrated for the first time 100 Gbps wireless transmission OAM multiplexing in order to achieve terabit-class wireless transmission to support demand for future wireless systems. It was shown in a laboratory environment that dramatic increases in transmission capacity can be achieved by signals using this new principle of OAM multiplexing in combination with widely used MIMO technology. NTT conducted transmission experiments at a distance of 10 m in the laboratory operating in the 28 GHz frequency band. Eleven data signals each at a bit rate of 7.2 to 10.8 Gbps were simultaneously generated and carried by multiple OAM-multiplexed signals, thereby achieving large-capacity wireless transmission at a total bit rate of 100 Gbps.

Software-defined radio (SDR) has been around for many years but is now starting to become commercialized. The U.S. agency DARPA is running the Spectrum Collaboration Challenge in the world’s largest channel emulator test bed called the Colosseum to further this technology. We published a deep technical piece on this effort as the cover feature in our September issue. The project will see how AI and SDR technology can be brought together in a large scale test with 256 radio inputs and outputs. In order to better use our existing spectrum, perhaps our 6G phones will listen to what frequencies are being used in real-time and use unoccupied frequencies to better utilize this scarce resource.

6G is likely to be a combination of higher frequencies (mmWave and perhaps THz), integration of blockchain and AI in SDRs and possibly new modulation schemes and techniques to achieve vast improvements in capacity, throughput and latency.