5G cellular ?
The term 5G just means 5th generation digital cellular technology.
To recap, 1G was CDMA (1xRTT) voice and data, 2G was the EVDO CDMA data upgrade, 3G is HSPA (or WCDMA) voice and data, and 4G is LTE data and VoLTE (voice over LTE).
5G is easily confused by and in the media because it can mean one of two things or both. First and foremost, it is basically a new data transmission protocol. A step advancement like each previous "G" generation.
Secondly, it can also be referring to a new frequency band, 28 MHz in Canada. There are a number of frequency bands used for the current HSPA and LTE signals; 600 MHz, 700 MHz, 850 MHz, 1900 MHz, 1700/2100 MHz, 2300 MHz, and 2600 MHz. Any technology can be used in any band. In fact, LTE (4G) is deployed in every band, but HSPA (3G) is only in the 850 & 1900 bands.
Data speeds are not as cut-n-dry as the propaganda leads one to believe. Data throughput (speed) is heavily dependent on frequency band and loading (congestion). The LTE data speed in the lower bands (600, 700, 850) max's out under 20 meg (in best conditions), and in the upper bands (1900, 1700/2100, 2300, 2600) max's out at about 120 meg (in best conditions). I say best conditions, because numerous other factors come into play as well. Such as signal strength and signal to noise ratio. The weaker the signal or greater the noise floor, the slower the speed.
The whole purpose of 5G is two-fold. First, to increase data speeds through newer transmission protocols and equipment. In the current frequency bands, testing in optimal conditions shows increases of almost double the current speeds. And secondly, to use un-used 28 MHz high-frequency spectrum where download speed bandwidth can be maximized and loading minimized. Initially, the manufacturers bragged about how they could achieve 1000 meg (gigabit) download speeds, but are now finding (due to factors outlined below) that 200 meg is a more realistic maximum.
The big media scare is the perceived health concern in the use of this 28 MHz spectrum.
It is a common belief that these radio waves will be harmful to us, causing cancer and other ailments.
the Electromagnetic Spectrum (ie Radio Waves and such)
To understand what 28 GHz millimeter waves are, lets recap the electromagnetic spectrum.
Sound waves, radio waves, microwaves, visible light, infrared, and ultraviolet are all the same type of non-ionizing wave (more on that later). The only difference is the frequency of the wave, its cycles per second, measured in Hertz (Hz). The higher the frequency, the more cycles per second, and inversely, the shorter the wavelength.
Here are some examples . . .
& Non-ionizing waves
Above 30 PHz are the X-rays, gamma rays, etc. These are also what's know as ionizing waves because their wavelength is so short, shorter than the size of an atom actually, that they can actually knock electrons out of an atom, making the atom more positive, hence ionized. These are the waves that can disrupt cell structure and cause DNA damage leading to mutations and cancers.
Everything below roughly 30 PHz are non-ionizing waves. They do not cause cell damage. They pass right through us harmlessly.
Microwave ovens work by agitating the atoms in the food, which causes them to bounce around more, which, due to atomic friction causes heat dissipation. There is no "radiation".
millimeter waves and 5G cellular
Because of the very short wavelength, these waves do not travel very far in free air (in comparison to lower frequencies at the same power). They are also very susceptible to anything in the air. Cloud, fog/mist, rain, snow, wood, even your hand will all degrade or block the signal. In best case testing, these signals only travel 300-500 feet. Also, because of the very high frequency, they are very directional. Essentially, the transmitting and receiving antennas have to be lined up perfectly. One thing the manufacturers of the equipment are finding is that they'll need an antenna on every side of the phone to track the signal from the tower. And the tower will have to employ some kind of beaming/tracking to maintain a direct path to the phone.
Due to the nature/physics of the 28 GHz millimeter waves, it is impossible to achieve wide-ranging cellular coverage with them like we enjoy today with the existing systems. This technology will only be deployed in key small areas were return on investment can be maximized by the maximum number of users. Simple economics says there is no way the carriers will spend hundreds of thousands of dollars to deploy a tower/radio on each streetlight to get signal to 2-3 houses (which can't penetrate the walls anyway) with no guarantee of financial return. With a range of only a few hundred feet and the signal being degraded by pretty much anything in it's path, its ubiquitous use could not and never be achieved.