“6G is currently at a stage where thought leaders from academia and industry are proposing possibilities, making bold dreams, and imagining what the world will be like 10 or 20 years from now. Listening to futuristic use cases like the Tactile Internet, it’s easy to get caught up in the excitement of defining the next generation of cellular communication standards, in pursuit of new technologies that push the boundaries of human cognition.
6G is currently at a stage where thought leaders from academia and industry are proposing possibilities, making bold dreams, and imagining what the world will be like 10 or 20 years from now. Listening to futuristic use cases like the Tactile Internet, it’s easy to get caught up in the excitement of defining the next generation of cellular communication standards, in pursuit of new technologies that push the boundaries of human cognition. But in many ways, our industry is still waiting to deliver on the promise of 5G, and with wider deployments and the next phase of 5G enhancements still well underway, we can’t help but ask: why talk about 6G already?
The evolution of “G” in the communication industry
Beginning with the first realization of cell phone calling in 1973, which we later called “1G,” our industry has observed cellular technology evolve on a roughly 10-year cycle. The 4G timeline unfolded between 2000 and 2010. 3GPP has been working on 5G standardization since 2015, but by that time academic research institutions were already well under way, with the New York University Wireless Research Center (NYU Wireless) and the EU 5G Research Project Group (METIS) established in 2012. The first phase of standardization was completed in Release 15 in 2018, with field testing in 2019 and expanded deployment starting in 2020. The model looks stable today, with ongoing early 6G research supporting a 2025 standardization launch and a 2030 or even earlier deployment timeline. While the scenario of consumers buying the first 6G products may seem out of reach, academic and industry researchers at the forefront of these cycles are already experimenting and building an understanding of the key technologies that will be critical to standardization.
What can 6G offer?
The International Telecommunication Union, which once set the goals for 5G in the IMT-2020 standard, is now working on a vision for 6G under the umbrella of the Network 2030 Focus Group. They generalized performance vectors (including throughput, reliability, coverage, latency, energy efficiency, cost, and massive connectivity) into three 5G use cases: enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and Ultra-Reliable Low-Latency Communications (URLLC) to support numerous applications across multiple industries. 6G is expected to expand on these vectors, driving the further development of existing applications while introducing new use cases and business models. These include holographic interactive communications for fully immersive 3D experiences, and tactile internet for real-time remote operation through auditory, visual and haptic feedback. These application examples illustrate the importance of sensing for 6G: it is the foundation of all interactions and simulations with the physical environment, and its potential extends to a wide range of fields such as digital health care, autonomous driving, and more.
Feasible technologies for enabling 6G
As we look at the possibilities and promise of 6G, four candidate technologies stand out in terms of business opportunity and viability:
① Joint communication and sensing
The 6G experience requires more data and more contextual awareness and awareness, and joint communication and perception is all about exploring how to combine them. Self-driving vehicles, for example, have extremely complex sensing systems that fuse together a range of data from cameras, lidar and radar sensors through machine learning algorithms. Advanced communication systems in these vehicles use cellular networks to transmit info and entertainment information, environmental and performance data, and vehicle-to-everything communications. Researchers working in sensing are looking to new communication techniques to help improve their results, such as orthogonal frequency division multiplexing (OFDM) waveforms or multiple-input multiple-output (MIMO) phased arrays; while those working in communications are looking at Here comes the opportunity to gain more data bandwidth in the vast spectrum allocated by radar. The extent to which these two traditionally separate functions will merge in the future will depend on regulatory and technological factors, but it is this combination that is underlying what defines 6G.
The continued need for larger data bandwidths is driving researchers to explore underutilized spectrum in the sub-terahertz band. The frequency band between 90 GHz and 300 GHz provides many times the spectrum currently used for cellular communications. 3GPP has set aside 21.2 GHz above 100 GHz for consideration for 6G. Path loss at higher frequencies, one of the biggest barriers to advancing into the sub-terahertz band, can be mitigated by matching the attenuation characteristics of the band to the appropriate application. For example, use high-attenuation bands for high-security applications, limiting the distance a signal can travel. In addition, the inverse relationship between frequency and antenna size provides a way to overcome path loss: as frequency increases, the geometry and spacing of the antenna decreases, allowing more elements to fit in the same space, to get more gain. While current 5G mmWave deployments are delayed and expansion into sub-terahertz bands seems premature, leading industry and academia researchers are already exploring it as a way to significantly increase network capacity.
③ Evolution of MIMO
MIMO has great potential across many different use cases and frequency bands and will continue to evolve based on the popular multi-antenna technology. Beamforming is the key to overcoming sub-terahertz path loss, and multi-user MIMO greatly improves spectral efficiency in the most widely used sub-8 GHz bands. Distributed MIMO breaks up a large antenna array into multiple smaller, geographically separated radio heads, and is especially interesting for frequencies below 8 GHz, where the size of the antenna becomes very large. The expansion of MIMO includes more system antennas for more users, and more precise directional beam steering, designed to increase cell capacity and provide enhanced positioning services.
④ Artificial intelligence and machine learning
A fourth technology that plays an important role is artificial intelligence and machine learning (AI/ML). As complexity increases and we try to squeeze every bit of bandwidth out of the available spectrum, it becomes increasingly difficult to optimize communication systems using traditional signal processing methods. Machine learning provides a solution to this complexity. AI/ML-driven design or adaptation seeks to dynamically optimize link performance, which can be improved through features such as automatic spectrum allocation, beam management, and RF non-ideal cancellation. Deploying AI/ML at the application layer can optimize quality of service (QoS), taking into account application-specific needs as well as environmental factors such as latency or energy efficiency. The availability of large open datasets for AI/ML wireless communication research and training will play an important role in 6G development.
Find the killer app
While these 6G candidates all offer multiple possibilities, their survival will inevitably depend on commercial applications. The costs of developing and deploying these technologies are high, the multi-billion-dollar investments require huge, predictable returns, and raise the age-old question: “What’s the killer app?”
At recent global events, we’ve relied heavily on online connections and virtual experiences – many of us have a whole new appreciation for reliable, high-speed internet. In addition to including popular tech buzzwords (technologies like immersive XR) and key performance indicators (like 1 Tb/s data rate), the 6G discussion also includes social and sustainable development goals, as well as “connectivity for everyone.” As we work to continue building 5G beyond enhanced mobile broadband, and the definitions of 6G begin to coalesce, the answers to these business and societal questions may be just as important as the technical ones.