5G is coming! What is a “G”? It refers to the generation of wireless capability. Prior generations:
- 1G delivered analog voice only. Think clunkly, big cell phones of the 80s. Ran at about 2Kbps. Was used from 1974 to 1984.
- 2G introduced digital voice. Started being implemented in early 1980s and was used until the late 90s. Speed was 14-64Kbps. Was first digital wireless generation. Could support texting in addition to voice.
- 3G brought mobile data with much faster speeds of around 2Mbps. Used from around 1990 – 2002.
- 4G LTE ushered in the era of mobile Internet. Began roll out in 2000. Can run as high as 200Mbps (usually much slower than that).
5G will be super fast – as high as 20gbps. That is 100x times faster than 4G. An HD move that takes about an hour to download on 4G will be downloaded in a few seconds with 5G speeds. 5G will likely start being rolled out in 2019 or 2020. In addition, as we move into the “internet of things” and billions of devices are connected to the internet 5G will use smart technology to optimize the connections with those billions of gadgets.
It is physics Friday – here’s what 5G in terms of how these much great speeds and capacities are achieved. Note, that because 5G doesn’t actually exist yet, there are no concrete details about what 5G will actually be.
A bit of needed background: Wireless technology transmits data over radio waves. AM and FM are very low frequencies (AM is at 880KHz while FM is 87.5 to 108.0 MHz) while current cell phones operate on much higher frequencies (LTE uses 700 MHz to 2.1 GHz). Why? Because the information conveyed via the sine waves carries the information needed to communicate and transmit data. The more frequent the sine waves per second, the greater the amount of information that can be conveyed. 5G is expected to use between 30GHz and 300 GHz which are referred to as “millimeter waves” because that is how much space there is between those sine waves. As a comparison, AM waves are about the length of a football field and FM waves are about the length of a house. So, millimeter waves can convey many multitudes of information given the vastly increased number of sine waves per second. Here’s a good picture:
So, why wouldn’t we use electromagnetic spectrum higher than 300GHz and convey even more information? That hits the primary challenge of moving up the spectrum: As you move to higher frequencies the laws of physics say that the energy of your signal dissipates inversely proportional to the square of the increase. This explains how you can hear an A.M. station hundreds of miles away and how a single FM transmitter can reach an entire city, but we need cell phone towers all over the place – the higher frequencies of mobile phones result in a signal that loses its strength quickly as distance grows.
How will 5G work around this immutable law of physics? A number of technologies will hope to solve this problem:
- Small Cells: THese are small portable, minature base stations that require minimal power to operate and can be placed every 250 meters and all throughout cities. Because the frequency of the signal being transmitted are so small, the attenaes on these base stations can be very small as well.
- Massive MIMO: Today’s 4G LTE base stations support about a dozen attennas (8 transmitters and 4 receivers). MIMO stands for “multiple input multiple output.” This technology should allow base stations to support about 100 attennas per base station.
- Beamforming: Today’s cellular attennas transmit in all directions. This creates interference. The new attennas will not transmit in all directions but will direct signals to individual users.
- Full Duplex: Current technology allows signals to travel one direction- like a walkie-talkie a basic cellular attenna can only do one job at a time: transmit or receive. Full duplex technology allows high speed switches to allow signals to pass each other on the same wave.
Here’s great podcast interview from Scientific American with a Verizon technical person: on this topic: https://www.scientificamerican.com/podcast/episode/5g-wiz-whats-on-the-horizon-for-mobile/