For sure, you often hear the expression ” cell phone “. Have you ever wondered why a mobile phone is called a cell phone? In this article, we will talk about the history of cellular communications and how it works.
The History of Mobile Phones
American journalist Robert Sloss predicted the appearance of “mobile phones” back in 1910. The first new technology was adopted by the police – in 1921, law enforcement officers in Detroit received information from dispatchers via radio communication in the range of 2 MHz, and by 1940, mobile phones were already working in 10,000 police cars across the country. And in 1946, the first public mobile telephone was installed in St. Louis. Communication was carried out on two bands-150 and 450 MHz.
In 1957, Moscow engineer Kupriyanovich introduced the LC-1 mobile phone. The prototype “mobile phone” weighed three kilograms and allowed you to call 25-30 km in the district.
The following year, Kupriyanovich presented a noticeably more advanced model of the LK-1-weighing only half a kilogram and the size of a box of cigarettes.
Around the same time, specialists of the Voronezh research Institute of Communications developed the world’s first system of automatic (previously, subscribers were connected manually) mobile communication “Altai”. By 1970, it was operating in 30 cities of the USSR at frequencies of 150 and 330 megahertz. Each city was served by a single base station, with a range of 50 to 100 km, and calls were made to “Altai” telephones, city and long-distance / international numbers.
Modern cellular communication systems appeared in the United States in 1978 when Chicago began testing the first such system for 2 thousand subscribers in the 800 MHz band. The city received its first commercial cellular phone system in October 1983 from AT&t. And the first commercially successful cellular network was the Finnish Autoradiopuhelin (ARP, “Automobile radiotelephone”). By 1986, it was used by more than 30 thousand subscribers.
How Mobile Communication Works
The modern cellular network consists of base stations – multi-frequency VHF transceivers, evenly distributed over the entire coverage area. Externally, they look like huge towers of red or white color with special equipment.
Vertical parts of the antenna are responsible for mobile communication, while circular parts provide communication with the controller. The range of the base station is 35 kilometers (but this is not the limit, see below). Each base station has six service sectors, with one sector receiving up to 70 phone calls at a time. Multiply 6 by 70 and you will understand why no one can reach you on New Year’s eve:).
Adjacent stations never operate in the same band – otherwise interference cannot be avoided.
Where did the name “cellular communication” come from
What about the honeycomb? Basic networks are used a lot, circles-radii are superimposed on each other and together form a network resembling a honeycomb. Hence the name of the technology – “cellular communication”. A group of seven cells is called a cluster.
This approach gives the mobile subscriber several advantages at once. First, the “dense” location of mobile cellular cells ensures uninterrupted communication – unlike landline communications, we are not tied to a single line. Secondly, the mobile (or cellular) phone automatically moves away from the station with the highest signal attenuation to the lowest, i.e. it provides the best quality of communication. A handover controller is responsible for the” seamless ” transition from the old station to the new one.
Now let’s look at how everything works from the subscriber’s side. A functioning cell phone always scans the airwaves for a signal from the base station. When the signal is found, the cell sends its unique identification code to the station. Then the periodic exchange of radio packets via analog or digital Protocol (for example, CDMA, GSM, UMTS) begins. The communication channel from the station to the subscriber is called DownLink (“downlink”), from the subscriber to the station – UpLink (“uplink») When you call someone, the phone contacts the station and asks them to allocate a voice channel. The station sends the signal to the controller, which sends it to the switchboard. If the subscriber uses a different cellular operator, the request goes to “his” switch. if he is on the same network as you, the switch will find the subscriber itself and direct the call to him.
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