Picture a household journey. Your spouse is on the phone setting up activities to do at the destination, your teenage daughter is streaming music and chatting with her pals on her phone, and her more youthful brother or sister is playing an online game with his pals. All those separate discussions and information streams are communicated over the cellular network, apparently all at once. You most likely take this for given, however have you ever questioned how the cellular system can handle all those activities at the very same time, from the very same cars and truck?
How does it work when everybody in your car is utilizing cellular voice and information service at the very same time, therefore are a number of the people in the cars and trucks around you?
Interacting all those messages
Picture using a sheet of paper to write messages to 100 various buddies, one personal message for each person. The several gain access to technology utilized in 3G networks is like writing every message to each of your friends using the entire sheet of paper, so all the messages are composed on top of each other.
The number of colored pens is fixed, so if you desire to send out messages to more people than the number of colored pens you have, you will need to begin blending colors. Now when a pal applies their unique lenses, they will see a bit of the messages to other pals. They wont see enough to read the other messages, but the overlap may be enough to blur the message intended for them, making it more difficult to check out.
The several access technology used by 3G networks is called Code Division Multiple Access, or CDMA. It was created by Qualcomm creator Irwin M. Jacobs with a number of other prominent electrical engineers. The technique is based on the concept of spread spectrum, an idea that can be traced back to the early 20th century. Jacobs 1991 paper showed that CDMA can increase the cellular capability manyfold over systems at the time.
CDMA lets all cellular users send out and receive their signals at all times and over all frequencies. So if 100 users wish to start a call or use a cell service at around the exact same time, their 100 signals will overlap with each other over the whole cellular spectrum for the whole time they communicate.
The overlapping signals create disturbance. CDMA resolves the disturbance issue by letting each user have an unique signature: a code series that can be used to recuperate each users signal. The code corresponds to the color in our paper analogy. The codes can overlap if there are too lots of users on the system at the exact same time. This causes disturbance, which gets worse as the variety of users boosts.
Pieces of time and spectrum
Rather of enabling users to share the whole cellular spectrum at all times, other multiple access techniques divide gain access to by time or frequency. Each connection can last over several time slots spread out in time, however each time slot is so brief– a matter of milliseconds– that the cellphone user does not perceive the disturbances from alternating time slots.
The division can likewise be performed in frequency. Each connection is provided its own frequency band within the cellular spectrum, and the connection is constant for its period. This frequency slicing strategy is frequency division several gain access to (FDMA).
In our paper analogy, tdma and fdma are like dividing the paper into 100 strips in either dimension and writing each private message on one strip. FDMA would be, for instance, horizontal strips, and TDMA would be vertical strips. With private strips, all messages are separated.
4G/LTE and 5G networks use Orthogonal Frequency Division Multiple Access (OFDMA), an extremely efficient combination of FDMA and TDMA. In the paper analogy, OFDMA resembles drawing strips along both dimensions, dividing the entire paper into many squares, and designating each user a different set of squares according to their information need.
Various strategies for sharing access to wireless network resources. Entropy 2019, 21( 3 ), 273, CC BY-SA
End of the line for 3G
Now you have a standard understanding of the distinction between 3G and the later 4G/LTE and 5G. You may still reasonably ask why 3G requires to be closed down. It ends up that due to the fact that of those differences in the gain access to innovation, the 2 networks are developed utilizing totally different equipment and algorithms.
3G handsets and base stations run on a wideband system, meaning they use the entire cellular spectrum. 4G/LTE and 5G operate on narrowband or multi-carrier systems, which utilize slices of the spectrum. These 2 systems require totally different sets of hardware, from the antenna on the cell tower to the components in your phone.
If your phone is a 3G phone, it can not connect to a 4G/LTE or 5G tower. For a long while, the cellular provider have actually been keeping their 3G networks going while developing an entirely different network with brand-new tower equipment and servicing new handsets using 4G/LTE and 5G. Envision bearing the cost of operating two different networks at the very same time for the same purpose. Ultimately, one has to go. And now, as the providers are beginning to deploy 5G systems in earnest, that time has come for 3G.
Written by Mai Vu, Associate Professor of Electrical and Computer Engineering, Tufts University.
This article was very first released in The Conversation.
The sun is setting on 3G networks. Credit: Ted/Flickr, CC BY-NC
On February 22, 2022, AT&T began switching off its 3G cellular network. T-Mobile is arranged to turn its off on July 1, 2022, and Verizon is slated to do the same on December 31, 2022.
The huge bulk of cellphones in service run on 4G/LTE networks, and the world has actually started the shift to 5G, however as lots of as 10 million phones in the U.S. still rely on 3G service. In addition, the cellular network functions of some older devices like Kindles, iPads, and Chromebooks are connected to 3G networks. Likewise, some older internet-connected systems like home security, automobile navigation, and entertainment systems, and solar panel modems are 3G-specific. Consumers will need to update or replace these systems.
So why are the telecommunications providers turning off their 3G networks? As an electrical engineer who studies cordless communications, I can explain. The answer begins with the distinction between 3G and later innovations such as 4G/LTE and 5G.
Rather of permitting users to share the entire cellular spectrum at all times, other several access techniques divide access by time or frequency. Department over time develops time slots. Each connection can last over numerous time slots spread out in time, however each time slot is so brief– a matter of milliseconds– that the mobile phone user does not perceive the interruptions from alternating time slots. Think of bearing the cost of operating 2 different networks at the very same time for the same function. And now, as the providers are beginning to deploy 5G systems in earnest, that time has come for 3G.
