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5G MIMO close-up with blue sky and clouds at the background
5G MIMO close-up with blue sky and clouds at the background


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      Tony Montalvo, Fellow and VP of Technology, Automotive, Communications, and Aerospace
      Tony Montalvo,

      Fellow and VP of Technology, Automotive, Communications

      Analog Devices

      Author Details
      Tony Montalvo
      Tony Montalvo joined Analog Devices in Raleigh, NC in 2000. He’s been the vice president of technology for Automotive, Communications, and Aerospace since 2020. Before that, he was director of technology for the Communications Business Unit since 2017 and a fellow since 2012. Before joining Analog Devices, Tony led the RF IC group at Ericsson, Inc., and was involved with the design of flash memories at Advanced Micro Devices. He received a B.S. in physics from Loyola University, New Orleans in 1985, an M.S.E.E. from Columbia University in 1987, and a Ph.D. from North Carolina State University in 1995 where he is also an adjunct professor and a member of their Electrical and Computer Engineering Alumni Hall of Fame.
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      5G brings well-known opportunities: faster, more reliable networks and new business models. As technologists, though, we must identify the challenges and develop solutions so that those opportunities can be realized. Here are three areas I see as key to making the 5G vision a reality.


      The deployment of 5G is coincident with the virtualization of the network architecture. The benefits of virtualization—a nimble network that’s easy to upgrade and maintain—do not extend to the radio unit (RU). At some point, the virtual world has to meet the real world and, in the case of the cellular network, that’s at the RU.

      The higher speed and improved energy efficiency of 5G have a lot to do with the deployment of massive MIMO RUs. Where legacy radios had two or four antennas, a massive MIMO radio may have 64. With these antennas, technologists can implement techniques such as beamforming and multi-user MIMO, which dramatically improve the spectral efficiency of the network.

      Massive MIMO technology wouldn’t be possible without dramatic improvements in radio technology. Analog Devices, Inc. (ADI) has been deeply involved in the RU since the 2G days and has created some of the core technologies that make 5G possible. Radio channel density has increased by an order of magnitude in the last decade, and power per channel has fallen by an order of magnitude in the same period.

      But it’s not just the chips. ADI views the RU system holistically and applies our expertise to minimize system cost, size, and weight at the system level. For example, the antenna filters in a massive MIMO RU may account for 30% to 40% of the volume of the box. We architect the system such that the filter’s complexity is reduced by up to 50% compared to competitive solutions.

      5G MIMO at the countryside crossroads


      Where there used to be one or two frequency bands in any region, there can now be dozens. The increasing complexity of the network is apparent to anyone who, like me, spends a lot of time staring at towers while on long road trips (“Look at that one kids … at least eight bands!”). This increase in the number of bands has created the need for a single RU that simultaneously supports multiple bands.

      But it’s not just the number of bands that are the issue. There used to be just macro radios on large towers, but now there are a multitude of macro radio variations, indoor and outdoor small cells in very high density deployments, and massive MIMO devices with up to 64 antennas, all in both traditional cell frequencies (sub 6 GHz) and millimeter wave frequencies.

      To meet this challenge, ADI’s products are specifically designed with flexibility in mind. A single ADI RF transceiver family, for example, can create R&D leverage by being applicable to all sub 6 GHz network deployments including small cells, macrocells, and massive MIMO.

      5G MIMO with the waves of bands


      Coincident with the deployment of 5G is the development of a new ecosystem—the Open Radio Access Network, or O-RAN. O-RAN disaggregates the network so that network operators can have flexibility in how they build their networks. As is often the case, with flexibility comes complexity.

      The complexity of the RU and the limited availability of skilled RF and signal processing engineers is a risk to the development of the O-RAN ecosystem. ADI’s role is to simplify the RU by providing a complete and highly optimized signal chain and power solution that contract manufactures can quickly bring to production.

      All in all, addressing these technology challenges will ensure that players in this new open ecosystem will have a scalable platform on which to build their products. Delivering O-RAN to the world clearly requires innovations across the communications ecosystem, and radio technology is foundational to delivering against each of these advances. A combination of integrating, simplifying, and democratizing radio units will lower the barriers for new entrants to create new value in the communications ecosystem.

      O-RAN enabling network operators to have flexibility
      O-RAN enables network operators to have flexibility in how they build their networks, and ADI’s role is to simplify the RU with a complete signal chain and power solution.