5G and the History of Cellular Networks


There is a conspiracy theory floating around, and being circulated by people who should know better, that 5G causes [insert ailment here].  Some people take this conspiracy so far as to blame 5G for COVID-19.

We need to talk a bit about RF history here.  I've been interested in radio frequencies and technology for most of my life, both personally and professionally.  When I was a teenager, I became interested in radio scanners and found the radio spectrum fascinating, in terms of all of the information that was literally in the air around us, and the different behavior of different frequency bands.  Using my scanner, I could pick up all kinds of signals from police, fire, corporate radio systems, security, and even cordless phones and cellular phones, not that I did so.  This led to obtaining my amateur radio license in 1996.  As an amateur "ham" radio operator I learned to use VHF and UHF repeaters, direction finding, and volunteered with the county Emergency Management Agency (EMA) and I participated in exercises as well as real events such as missing persons searches.  Before I had a cell phone, I used autopatch which used amateur radio repeaters to patch in an amateur radio to the telephone system to make phone calls.

At the time, cellular telephones existed and operated on the AMPS (Advanced Mobile Phone System) network in the frequency ranges of 824-849Mhz and 869-894MHz.  This is what was later called 1G or "first generation" cellular phone systems.  These were analog systems (like most radio systems of the day) that used up to 3 watts and had fairly good penetration of buildings and foliage at those frequencies, up to 15 miles.  In order for this system to work, "cellular" radios were installed on radio towers to provide coverage to certain areas, and the system was sophisticated enough to 'hand off' your call to the next radio when you drove from one cell to another.  Still, in those days, dropped calls were frequent as the signals weakened at the greater distances near the edges of the cells.  Two frequencies were used, one for each party of the conversation.  These were known as channel pairs and allowed for full duplex communication, in other words, both parties could speak at the same time like a traditional telephone.  That was just enough bandwidth to provide frequencies for two carriers per market, with each carrier receiving 21 control channels (to control which phones use which frequencies, and for cellular radios to communicate with one another to coordinate hand-offs) and 395 voice channel pairs.  This means that no more than 395 simultaneous calls were possible per carrier in a given cell.  During the early days of cellular phone systems, when few people had cell phones, this wasn't a huge issue, but in time, that would change.

The next iteration of ceullar technology, or 2G, was the conversion of AMPS to D-AMPS or "digital AMPS" which utilizes TDMA, which stands for Time Division Multiple Access. PDC, iDEN, and PHS are other examples of TDMA systems.  GSM is a system that combines TDMA with frequency hopping and wideband transmission to minimize interference.   In a TDMA system, which is digital and not analog, frequencies can be shared among multiple simultaneous calls, by sending voice data in rapid succession, thereby allowing more calls to be handled, and also required less power in a cell phone.  Since 2G is digital, it also allowed the use of SMS and MMS messages. GPRS was also used on these networks to allow other data such as emails to be sent across the network, albeit with limited bandwidth.  As the FCC allocated additional frequency bands, such as 1900MHz, these were utilized as well.  At higher frequencies, more bandwidth is available for calls and data, but the harder it is to penetrate objects such as walls, trees, and even air, so range is limited the higher in frequency that you go.  2G systems provided up to 64kbps of bandwidth.

3G added additional radio spectrum primarily around 2.1GHz which provided for greater bandwidth, but again with the caveat that it has poorer penetration than lower frequencies.  CDMA or Code Division Multiple Access came along around this time, even in some late 2G systems, which works similarly to TDMA but uses spread-spectrum technology thus spreading out the communications over multiple frequencies which can be a bit more secure.  3G can transfer data as fast as 2Mbps.

4G utilizes even more frequency bands including those around 600MHz, 700MHz, 1.7GHz, 2.3GHz, and 2.5GHz.  The lower frequencies added to 4G provide much better penetration, but have limited bandwidth.  There have been multiple iterations of 4G including some called LTE or long term evolution, which is essentially an improvement within the same generation of technology.  This allocation of higher frequencies provide the much higher data transmission capacity allowing 4G to reach 100Mbps, and higher in certain circumstances.

5G adds even more frequency bands, this time even high including some as high as 28GHz and 39GHz.  If you've been paying attention so far, you know that at frequencies that high, you can't penetrate much at all, certainly nothing with water in it like skin or trees or foliage.  This is why most of the 5G systems have massive data transmission capabilities, as high as 10Gbps in close range, but even several hundred feet away, lose bandwidth rapidly.  The exception is T-Mobile which utilizes 600MHz for much of their 5G system, meaning they will have good range, but far less bandwidth.

Back in 2004 I was an engineer for a Wireless Internet Service Provider (WISP).  We provided high speed wireless Internet access to clients out to a range of 50 miles from our transceiver using licensed MMDS spectrum that operated at 2.5GHz.  The problem with this frequency range, is we had to use directional antennas and line of sight for the system to work.  Any trees or hills in the way would interfere with the signal.  Even rain would cause attenuation of the signal to varying degrees.  I lived in an area, along with hundreds of potential clients, within our coverage area, but permeated with trees, so there was no good way to provide our desperately needed high speed Internet service to that area with our existing MMDS system.  So I engineered another system whereby we provided bandwidth to a radio tower in the area via our MMDS system, and then retransmitted it over another system made by Airspan, an Israeli company, which operated on the license free 900MHz spectrum using FHSS, or frequency hopping spread spectrum, similar to GSM mentioned above.  The lower 900MHz system, even though it operated on considerably less power, was able to penetrate trees and other foliage much better than the MMDS system and we were able to provide high speed Internet via this system to hundreds of new clients.

There are a number of conspiracy theories running rampant about 5G and none of them I have heard have any basis in reality.  As we have seen, while the higher frequencies used by 5G allow significantly higher bandwidth, which makes it valuable for a number of technologies such as video, it requires smaller cells and many more transceivers to provide usable coverage from that system.  5G at millimeter wave frequencies penetrate matter and even air very poorly.  With this knowledge, you should know right off the bat that most of the conspiracy theories are inherently impossible because the signal cannot even penetrate your skin, unless the transmitter is using extremely high power and you are within feet of it.  An example of such high power and proximity is a microwave oven, which operates around 2.45GHz and uses massive amounts of power in a faraday cage of a thousand watts or more to have enough power to vibrate molecules and warm up your food.  As all RF engineers and technicians know, the same can happen to human tissue, so you don't want to be right next to an antenna putting out high power or you could sustain skin burns or damage to your eyes, but that's the worst it can do.  All radio frequency energy is non-ionizing radiation, meaning that it has insufficient energy to break chemical bonds or remove electrons, so it cannot damage DNA or RNA.  Ionizing radiation, which only exists on the other side of visible light and ultraviolet in the spectrum, such as X-Rays and Gamma Rays have the energy to do this.  Ionizing radiation starts at 30 Petahertz.  One Petahertz is one million Gigahertz, so radio frequency energy in the Megahertz and Gigahertz range is no where even remotely close to the frequencies required to generate ionizing radiation.




Note that WiFi operates on frequencies very similar to your microwave oven, but WiFi uses no more than 100mW or a thousand times less power than your microwave oven.  You can sit next to your WiFi transceiver for your entire life with no ill effects.  

Some conspiracy theories say 5G is the same as the systems used by the military to drive people away from areas.  Obviously, this is not the case- what good would it do to spend millions of dollars to deploy a system that will drive your customers away.  Active Denial Systems used by the military operate around 95GHz and use up to 100KW of power to heat the surface of the skin on a human, consistent with what we have discussed here.  Think of a giant heat light being pointed at you, which makes you want to get out of the area.  Even at that massive power level, these systems can only penetrate the skin by 1/64 of an inch.

Some have said that 5G is causing the COVID-19 coronavirus.  I don't really know where to start there, other than to say that makes no sense whatsoever.  Viruses spread through physical contact.  5G radio waves do not have the ability to penetrate your skin, much less create biological entities.  COVID-19 is spreading rapidly in areas where 5G has never been deployed.  Quarantine and hygiene procedures would be ineffective if COVID-19 were spread through radio waves.  Some have said that RADAR caused the Spanish Flu in 1918, despite that fact that RADAR wasn't deployed until 1939.  Some have said that 5G makes "oxygen molecules oscillate" and "alters the orbital properties" of oxygen molecules thus depriving humans of oxygen and causing asphyxiation.  Aside from the obvious fact that killing your customers is not a very good business strategy, this can be easily disproven by sitting in a room with a 5G device and monitoring your oxygen saturation levels.  Some claim that 5G is responsible for DNA mutations, mitochondrial damage, cancer, heart palpitations, memory and cognitive problems, sperm changes and infertility, headaches, tinnitus, ADHD, anxiety, depression, heart disease, diabetes, and just about any other ailment you can think of, while offering zero evidence to support their claims.  Some make the bizarre claim that Schumann resonance signals are interrupted by millimeter wave RF energy.  Schuman resonance signals are simply ELF frequencies that bounce between the ground and the ionosphere, just like HF signals that amateur radio operators use all the time to talk to one another around the world.  These frequencies are nowhere near millimeter wave frequencies used by 5G systems.  Some claim that the frequencies affect the body's ability to produce vitamin D.  Vitamin D is produced by the body as a result of exposure to sunlight (ultraviolet rays) and it can also be ingested.  UV light energy is completely unaffected by frequencies used by 5G.

These are just a few of the absolutely ridiculous claims I have heard regarding 5G technology and the frequencies on which they operate.  I hope this provides you with the background to refute these claims as absurd on their face.  5G is nothing more than the next iteration of cellular technology, that will provide more bandwidth to an increasingly bandwidth-hungry world.

Comments

Popular posts from this blog

Coronavirus / COVID-19

Normalcy Bias