The solar is setting on 3G networks. Ted/Flickr, CC BY-NC
On Feb. 22, 2022, AT&T is scheduled to show off its 3G mobile community. T-Cellular is scheduled to show its off on July 1, 2022, and Verizon is slated to observe go well with on Dec. 31, 2022.
The overwhelming majority of cellphones in service function on 4G/LTE networks, and the world has begun the transition to 5G, however as many as 10 million telephones within the U.S. nonetheless depend on 3G service. As well as, the mobile community features of some older gadgets like Kindles, iPads and Chromebooks are tied to 3G networks. Equally, some older internet-connected programs like residence safety, automobile navigation and leisure programs, and photo voltaic panel modems are 3G-specific. Shoppers might want to improve or change these programs.
So why are the telecommunications carriers turning off their 3G networks? As {an electrical} engineer who research wi-fi communications, I can clarify. The reply begins with the distinction between 3G and later applied sciences corresponding to 4G/LTE and 5G.
Image a household journey. Your partner is on the cellphone arranging actions to do on the vacation spot, your teenage daughter is streaming music and chatting along with her mates on her cellphone, and her youthful sibling is enjoying a web based sport together with his mates. All these separate conversations and knowledge streams are communicated over the mobile community, seemingly concurrently. You most likely take this as a right, however have you ever ever puzzled how the mobile system can deal with all these actions on the identical time, from the identical automobile?
How does it work when everybody in your automobile is utilizing mobile voice and knowledge service on the identical time, and so are lots of the individuals within the vehicles round you?
The Good Brigade/DigitalVision by way of Getty Pictures
Speaking all these messages
The reply is a technological trick known as a number of entry. Think about utilizing a sheet of paper to write down messages to 100 completely different mates, one non-public message for every individual. The a number of entry expertise utilized in 3G networks is like writing each message to every of your folks utilizing the entire sheet of paper, so all of the messages are written on high of one another. However you’ve a particular set of pens with completely different colours that lets you write every message in a singular shade, and every of your folks has a particular pair of glasses that reveals solely the colour meant for that individual.
Nevertheless, the variety of coloured pens is mounted, so if you wish to ship messages to extra individuals than the variety of coloured pens you’ve, you’ll need to start out mixing colours. Now when a good friend applies their particular lenses, they may see a bit little bit of the messages to different mates. They received’t see sufficient to learn the opposite messages, however the overlap may be sufficient to blur the message meant for them, making it more durable to learn.
The a number of entry expertise utilized by 3G networks is named Code Division A number of Entry, or CDMA. It was invented by Qualcomm founder Irwin M. Jacobs with a number of different distinguished electrical engineers. The approach relies on the idea of unfold spectrum, an concept that may be traced again to the early twentieth century. Jacobs’ 1991 paper confirmed that CDMA can enhance the mobile capability manyfold over programs on the time.
CDMA lets all mobile customers ship and obtain their indicators always and over all frequencies. So if 100 customers want to provoke a name or use a cell service at across the identical time, their 100 indicators will overlap with one another over all the mobile spectrum for the entire time they impart.
The overlapping indicators create interference. CDMA solves the interference downside by letting every person have a singular signature: a code sequence that can be utilized to recuperate every person’s sign. The code corresponds to the colour in our paper analogy. If there are too many customers on the system on the identical time, the codes can overlap. This results in interference, which will get worse because the variety of customers will increase.
Slices of time and spectrum
As an alternative of permitting customers to share all the mobile spectrum always, different a number of entry methods divide entry by time or frequency. Division over time creates time slots. Every connection can final over a number of time slots unfold out in time, however every time slot is so quick – a matter of milliseconds – that the cellphone person doesn’t understand the interruptions from alternating time slots. The connection seems to be steady. This time slicing approach is time-division a number of entry (TDMA).
The division will also be accomplished in frequency. Every connection is given its personal frequency band throughout the mobile spectrum, and the connection is steady for its length. This frequency slicing approach is frequency division a number of entry (FDMA).
In our paper analogy, FDMA and TDMA are like dividing the paper into 100 strips in both dimension and writing every non-public message on one strip. FDMA could be, for instance, horizontal strips, and TDMA could be vertical strips. With particular person strips, all messages are separated.
4G/LTE and 5G networks use Orthogonal Frequency Division A number of Entry (OFDMA), a extremely environment friendly mixture of FDMA and TDMA. Within the paper analogy, OFDMA is like drawing strips alongside each dimensions, dividing the entire paper into many squares, and assigning every person a distinct set of squares in response to their knowledge want.
Totally different methods for sharing entry to wi-fi community assets.
Entropy 2019, 21(3), 273, CC BY-SA
Finish of the road for 3G
Now you’ve a fundamental understanding of the distinction between 3G and the later 4G/LTE and 5G. You would possibly nonetheless fairly ask why 3G must be shut down. It seems that due to these variations within the entry expertise, the 2 networks are constructed utilizing fully completely different tools and algorithms.
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3G handsets and base stations function on a wideband system, that means they use the entire mobile spectrum. 4G/LTE and 5G function on narrowband or multi-carrier programs, which use slices of the spectrum. These two programs want fully completely different units of {hardware}, from the antenna on the cell tower all the way down to the parts in your cellphone.
So in case your cellphone is a 3G cellphone, it can not hook up with a 4G/LTE or 5G tower. For a protracted whereas, the mobile service suppliers have been preserving their 3G networks going whereas constructing a very separate community with new tower tools and servicing new handsets utilizing 4G/LTE and 5G. Think about bearing the price of working two separate networks on the identical time for a similar goal. Ultimately, one has to go. And now, because the carriers are beginning to deploy 5G programs in earnest, that point has come for 3G.
Mai Vu receives funding from Nationwide Science Basis.
