The next generation of cellular technology, referred to as fifth generation, or 5G, will come with some new technical challenges from a physical coverage perspective. With the addition of millimeter wavelengths (mmWave) for the 5G NR (New Radio) solution being developed and ready for mass deployment beginning in the summer of 2020, several amazing techniques will be provisioned to enhance the signal coverage and make this mmWave optimized for better coverage.
To overcome this shorter range of these mmWave carriers and the make the signal more robust even in these shorter ranges, there are several innovative techniques planned to enhance the signals. These techniques include beamforming.
Beamforming is the application of multiple radiating elements transmitting the same signal at an identical wavelength and phase, which combine to create a single antenna with a longer, more targeted stream which is formed by reinforcing the waves in a specific direction. The general concept was first employed in 1906 for trans-oceanic radio communications.
The more radiating elements that make up the antenna, the narrower the beam. An artifact of beamforming is side lobes. These are essentially unwanted radiation of the signal that forms the main lobe in different directions. Poor engineering of antenna arrays would result in excessive interference by a beamformed signal’s side lobe. The more radiating elements that make up the antenna, the more focused the main beam is and the weaker the side lobes are.
While digital beamforming at the baseband processor is most commonly used today, analog beamforming in the RF domain can provide antenna gains that mitigate the lossy nature of 5G millimeter waves.
To enhance beamforming, several other techniques will be added, these include beam steering, beam switching, and MIMO.
Beam steering and beam switching
Beam steering is achieved by changing the phase of the input signal on all radiating elements. Phase shifting allows the signal to be targeted at a specific receiver. An antenna can employ radiating elements with a common frequency to steer a single beam in a specific direction. Different frequency beams can also be steered in different directions to serve different users. The direction a signal is sent in is calculated dynamically by the base station as the endpoint moves, effectively tracking the user. If a beam cannot track a user, the endpoint may switch to a different beam.
This granular degree of tracking is made possible by the fact that 5G base stations must be significantly closer to users than previous generations of mobile infrastructures.
Multiple input and multiple output (MIMO) antennas have long been a feature of commercial public wireless and Wi-Fi systems, but 5G demands the application of massive MIMO. To increase the resiliency (signal-to-noise ratio / SNR) of a transmitted signal and the channel capacity, without increasing spectrum usage, a common frequency can be steered simultaneously in multiple directions.
The successful operation of MIMO systems requires the implementation of powerful digital signal processors and an environment with lots of signal interference, or “spatial diversity”; that is a rich diversity of signal paths between the transmitter and the receiver.
The diversity of arrival times, as the signal is bounced from different obstacles, forms multiple time-division duplexing (TDD) channels that can deliver path redundancy for duplicate signals or increase the channel capacity by transmitting different parts of the modulated data. First conceived of in the 1980s, there are a few differences between classic multi-user MU-MIMO and Massive MIMO, but fundamentally it is still the large number of antennas employed and the large number of users supported. The degree of MIMO is indicated by the number of transmitters and the number of receivers, i.e. 4×4.
As 5G NR emerges in the next year and beyond, users will be able to connect in places and ways they could never do before with older cellular technology generations. The advent of 5G NR promises stunningly higher data rates, ultra low latency, and many other incredible features such as Edge Computing that will provide a unique consumer experience like never enjoyed with past generations. Beamforming promises to make these user experiences powerful and exciting.
Rajiv. (2019). What are small cells in 5G technology. RF Page. https://www.rfpage.com/what-are-small-cells-in-5g-technology/
About the Author:
Michael Martin has more than 35 years of experience in systems design for broadband networks, optical fibre, wireless, and digital communications technologies.
He is a business and technology consultant. Over the past 15 years with IBM, he has worked in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He is a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN: TSX).
Martin currently serves on the Board of Directors for TeraGo Inc (TGO: TSX) and previously served on the Board of Directors for Avante Logixx Inc. (XX: TSX.V).
He has served as a Member, SCC ISO-IEC JTC 1/SC-41 – Internet of Things and related technologies, ISO – International Organization for Standardization, and as a member of the NIST SP 500-325 Fog Computing Conceptual Model, National Institute of Standards and Technology.
He served on the Board of Governors of the University of Ontario Institute of Technology (UOIT) [now OntarioTech University] and on the Board of Advisers of five different Colleges in Ontario. For 16 years he served on the Board of the Society of Motion Picture and Television Engineers (SMPTE), Toronto Section.
He holds three master’s degrees, in business (MBA), communication (MA), and education (MEd). As well, he has three undergraduate diplomas and five certifications in business, computer programming, internetworking, project management, media, photography, and communication technology. He has earned 15 badges in next generation MOOC continuous education in IoT, Cloud, AI and Cognitive systems, Blockchain, Agile, Big Data, Design Thinking, Security, and more.