Mobile communications systems around the world use a wide range of frequencies.
The microwaves are applied, which length is from 10 cm to 1 m. This range includes wave frequency from 300 MHz to 3 GHz.
The same frequency band is also used TV, Wi-Fi and Bluetooth. there are those that have been allocated specifically for mobile phones among the band.
Historically, the radio waves used in mobile communications systems in the Americas, Europe, Africa and Asia, are different from each other.
technology and frequency standards
The first technology standard applied in the USAfor commercial use was AMPS 800 MHz band. In northern Europe, was first introduced NMT-450 technology, the range of which was 450 MHz.
Along with the growing popularity of mobilephone manufacturers are faced with a problem: they can not provide services to more people. They had to develop the existing system and to introduce a new standard with the other frequency bands.
In Japan and some European countries appearedTACS standard with a range of 900 MHz. The GSM standard, instead of NMT-450 technology, also used a range of 900 MHz. As demand and cell phone market, providers have acquired a license to use the 1800 MHz band.
Lower frequencies allow providers to cover a larger area of the zone, and the higher frequencies allow connection of a larger number of customers in a smaller size.
Modern technology standards
The current generation of mobile devices operates mainly in GSM standard. Also gaining popularity UMTS standard. Some countries apply formats ELT technology, 3G, 4G.
Each standard or format uses a frequency band of the two frequencies. Low frequency band transmits information to the mobile station device, and the high - from the station to the mobile.
Many phones GPS standards cover threeFrequency range: 900, 1800, 850 or 1900 MHz, 1800 1900 MHz. This so-called tri-band phones or the tri-band device. With such a phone is convenient to travel around the world, and it does not require replacement when
moving to another country.
Mobile networks may use different formats, the same frequency. An example is the 800 MHz range used by at least four different formats.
The amount of frequencies available for usemobile devices is limited. This should be considered when the number of users increase. This means that the base station can provide a limited number of people, and the communication network is required to constantly expand.
Cell phone providers in major Russian operate at frequencies of 900 MHz and 1800 MHz. This Megafon, Beeline, MTS use both range and TELE 2 only 1800 MHz.