In 2021 the mobile communication system 5G, with all of its advanced technologies, is beginning to see mass adoption.
A high-level overview of 1G to 5G. Image used courtesy of Fizza et al
5G is a high-fidelity data communication medium for streaming services with advanced beamforming technology, operating frequencies around sub-6 GHz and 24 GHz, with open radio architectures that provide opportunities for new market entrants.
However, fifty years ago, the devices were analog-based and weighed nearly 2.5 lbs. So, where did the mobile revolution start, and what integral technologies led the world to 5G?
It All Started in 1973…
5G is made possible because of the world’s first, successful mobile phone call in 1973 made by Martin Cooper on the Motorola DynaTAC prototype. Although it would take another decade for the first 1G cellular network to launch in the United States, it quickly became apparent in the 1970s that a worldwide telecommunications revolution had begun.
An inside look at the DynaTAC phone from 1973. Image used courtesy of Popular Science
Built to run on AMPS (advanced mobile phone system), this mobile telephony device and others like it would usher in a rate of consumer demand unlike any other (with Facebook possibly coming in second).
Looking back, what problems did electrical engineers face over the past five decades, leading us to 5G?
EE’s Ease Generational Growing Pains
Success is its own enemy is a truism that can apply to people as well as technology. Cellular telephony’s popularity led to each generation having one fundamental problem: a scaling user base.
Research data from the Pew Research Center shows that nearly 97% of U.S. residents now possess a cellular device.
Cell service expansion in the U.S. from 2004 to 2020. Image used courtesy of the Pew Research Center
However, mass service expansion began decades earlier, with roughly 12 million subscribers by 1990.
For the first three generations of cellular telephony, consumer demand for digital services, inefficient use of spectrum, and the relentless march towards the smartphone were the major growing pains that EE’s had to address.
The Social Challenge: Mobile Service Demands
1G services, possessing 30 kHz channels based on frequency division duplexing (FDD), could only perform voice calls. Although exciting in 1983, it took less than a decade before consumers would be demanding additional services.
2G, which launched in Finland in 1991, did away with analog phones and brought the world into the digital age. These new digital cell phones had data services, were significantly smaller, and were based upon the GSM standard.
Shortly afterward, the short-messaging-system (SMS) and multimedia services of 2G gave consumers a taste of the media-rich future that 3G would unleash. This future excitement was especially true since 2G provided under 0.5 Mbps while 3G was showing an impressive 14.7 Mbps.
The explosion in data throughput in the mid-90s, alongside growing market penetration, meant a new form of spectral engineering was required.
The Technical Challenge: Spectrum Efficiency
Achieving the maximum throughput for the maximum number of users with minor infrastructure investment is a daunting challenge. Moreover, when considering electromagnetic interference between devices, the shortcomings of 1G FDD modulation become clear.
Today, cellular telephony uses orthogonal frequency division multiplexing (OFDM) with quadrature amplitude modulation (QAM-256) to achieve high spectral efficiency and high bandwidth for data bursts. However, getting from FDD to OFDM required several technological advancements.
In the early 1990s, time-division duplexing (TDD) and code-division multiple access (CDMA) emerged as modulation schemes designed to improve frequency allocation.
CDMA allowed multiple users to share the same frequency allocation utilizing codes. Screenshot used [modified] courtesy of Qualcomm
In addition to modulation changes, several other technical constraints hampered cellular efficacy, including the near-far power problem, cell edge hand-off issues, and multipath. Thankfully, after answering these issues, today’s users seldom experience any signal fade during a call.
Even still, consumers demanded more, and in 2007 Steve Jobs provided “more.”
A Visionary Challenge: Evolution of the Smartphone
Modulation scheme advancements were not the only change that engineers devised over the past decades to improve the physical appeal of the cell phone.
The first digital cell phones were big and blocky with antenna technology which would seem alien today. Advancements in antenna technology allowed for the migration of external whip antennas and loaded-Q stub antennas to the compact planar inverted-F antennas (PEFA) used today.
An example of a PIFA antenna. Image used courtesy of Munzer et al. and MATEC Web of Conferences
In June 2007, the world of communication changed forever with the release of the first generation Apple iPhone. The iPhone was a sleek, ultra-thin (at the time) advanced device that would undo all which came before it.
DynaTAC and iPhone comparison. Image used courtesy of Wired and Ashton Tibbitt
The release of the iPhone immediately redefined the form factor of consumer cellular devices. The external features, including small screens, antennas, and physical buttons, which were so common in the 1990s and early 2000s, were replaced with highly integrated internal antennas and advanced touchscreen technology.
A lot has happened since the first-generation iPhone, and the Internet of Things is shaking up the future.
What is the Future Evolution of Mobile Telephony?
It isn’t easy to know what the future holds for mobile telephony.
The only real way to know the future is to make it. Apple has been known to do this, as has Alphabet (parent company of Google & Android).
The advent of smart wearables, like the Apple Watch, is redefining what connectivity means to consumers. The ability to control your television or your phone from your wrist is new and exciting.
Beyond the consumer, the always-connected Edge awaits. The Edge is where 5G will hopefully shine, allowing for unprecedented automation, real-time decision-making, and business opportunities.
In the final episode of Star Trek TNG, Jonathan de Lancie, the famous Q, uttered an excellent quote that could easily apply to 5G: “See you, out there.”
Interested in other historical articles? Learn more in the articles down below.
History of the Oscilloscope: Oersted’s Laws and Hand Drawn Waveforms
Kirchhoff’s Laws: Laying EE Foundations in Voltage, Current, and Spectroscopy
The History of Vacuum Tubes: An Era Away
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