How do smartphones work?
There are many aspects of their technology that are interesting and should be described in a detail. For now, we’d like to explain how smartphones use cellular frequencies.
Cellular frequencies are the sets of frequency ranges that have been assigned for cellular compatible mobile devices, among which the most popular ones are obviously mobile phones. Tablets and laptops can also work on those frequencies if they have the appropriate functions.
The radio frequencies used for cellular networks may differ in some countries. For example, when the first commercial standard was launched in the United States (more than two decades ago), it operated in the 800 MHz frequency band.
Nowadays there are four major frequency bands in the U.S. and they are as follows:
- 698-806 MHz (700 MHz Band)
- 806-849/851-896 MHz (800 MHz Band)
- 1850-1910/1930-1990 MHz (PCS Band)
- 1710–1755/2110–2155 MHz (AWS Band)
Their differences depend on the carrier. Various operators use different bands, T-Mobile often uses PCS or AWS bands, while Verizon goes with an 800 MHz band. What does it mean when some are 800 while others are over two thousand? In general, the lower frequencies provide coverage over a larger area and the higher ones allow service to more customers in a smaller area.
It is not easy to describe one universal system. It often depends on which mobile phone is being used because some smartphones support two or three bands (they are called dual-band or tri-band) but there are many which work fine only in the one band.
The actual frequency used by a particular model of mobile phone can change from place to place because it varies based on the settings of the carrier’s base stations. Switching to another frequency range is unnoticeable because it happens automatically when you are moving with your smartphone, for example, while travelling in the car.
Users don’t usually know which band they are on as it isn’t important to them. Problems may occur when you look at this from the other side, each carrier uses their own cell sites, there is no sharing allowed. This means that if your friend has a mobile phone on a different system and both of you are in the same place, one of you might have a stronger signal than the other.
What is GSM or CDMA? Why do you have 3G or 4G?
There is also another typology of frequency bands in which two technologies dominate: GSM (Global System for Mobiles) and CDMA (Code Division Multiple Access). These two standards are entirely incompatible. Not all carriers using those technologies are equal. A phone which goes well with CDMA may not work best on carrier X but might be perfect on carrier Y. When you check your reception you’ll be able to tell.
Technologies are changing rapidly. There was 1G, 2G, and now 3G and 4G. The newer ones are replacing the former but even if they are still improving, they are operating in the same frequencies. We mentioned the U.S. above but for the rest of the world, the most common bands are named as 800 Mhz, 900 Mhz, 1700 Mhz, 1900 Mhz and 2100 MHz. These are approximate figures, which is why you can find many different typologies of them. The bands in GSM network are as follows: 850 MHz, 900 MHz, 1800 Mhz and 1900 MHz. In the U.S., mobile devices have dual-band capability which supports 850 MHz and 1900 MHz and if someone has that kind of mobile phone, it cannot be used in Europe whereas 900 MHz and 1800 Mhz are supported.
Frequency bands are the most important for the carriers as they have to know how to provide service to an increasing number of customers. Their development is about supporting the best connection and transmission of data. As an average user, you won’t have to delve into the subject (unless you want to) but it is worth noting that your bad reception is coming from somewhere.
If you want to keep up to date with us and our articles (or follow what we’re doing in general) then you can find us via Facebook: Slow Digital
- How Cell Phones Work
- Cell Phone Frequencies / Wireless Communications Devices
- Electromagnetic Spectrum or Frequency Spectrum
- Bands and Frequencies
- Smartphone Bands Explained
All images used are CC0 1.0 Universal (CC0 1.0).