Mobile Communication System
Mobile Communication System is a radio signal based communication system or network that cover a specific area with a base station and stations are connected with wire, fiber or it can be wireless and all the base station and other station is control through switching center. In this communication system, covered area is similar like a cell, that’s why sometime it called Cellular Network also. Each of the cell or base station give access for mobile services. Base stations are communicate mobile devices with Radio transmission dishes. For communicate one mobile device with other mobile device in network covered are of a cell, All the mobile devices are first connect with the base station of the cell and base station send signal to the switching center then the switching center connect the another mobile device through the base station of device location.
There are many different kinds of Mobile communication System:
- Nordic Mobile Telephone (NMT)
- Advanced Mobile Phone System (AMPS)
- Total Access Communication Systems (TACS)
- Nordic Mobile Telephony (NMT)
- American Digital Cellular (ADC)
- Global System for Mobile Communication (GSM)
- Digital Cellular System (DCS) 1800
- Japanese Personal Digital Cellular (PDC)
- Personal Communications Service (PCS) 1900 – Canada
- Personal Communications Service (PCS) – USA
Among the all over the world, GSM (Global System for Mobile) is most popular mobile communication system. GSM is second generation (2G) Standard Communication System for mobile network. It is basically based on on the time division multiple access (TDMA) system technology. With this technology , GSM user can use digital signaling and voice channels. Using TDMA, a narrow band that is 30 kHz wide and 6.7 milliseconds long is split time-wise into three time slots. GSM used different kinds of frequency carrier band like, 900 MHz band for normal GSM communication, 1800 MHz for giver the network user swelling number support and 1900Mhz for better down-link. GSM is now one of the growing fastest wireless technology all over the world. GSM technology is now third generation (3G) standard legacy network. Technological evaluation of GSM is remarkable.
General Packet Radio Service (GPRS), Enhanced Data for GSM Evolution (EDGE), Universal Mobile Telecommunication System (UMTS), High Speed Packet Access (HSPA), Long Term Evolution (LTE), Al those technology make GSM so popular. There are many advance feature of GSM like Clear voice quality, international rooming, Spectral flexibility, Tight security, Data support, Subscriber Identity Module (SIM) cards.
For allowing multiple user, all the Mobile communication system use some method of technology for sharing the system concurrently. There are three method of technology is used commonly and they are :-
- FDM Frequency Division Multiplexing
- TDMA Time Division Multiple Access
- CDMA Code Division Multiple Access
Frequency Division Multiplexing: In FDM technology, available frequency are divided into many channels. Each and every communication use a channel for communicate. If in any area, all the channels are busy then this technology not allow other user for make a call. FDM operates much like the channel button on your television set. The AMPS and NAMPS mobile telephone systems utilize FDM.
Time Division Multiple Access: In TDMA system, Encoded voice signal is converted into digital and send the data via RF(radio frequency). In time division multiple Access technology, frequency are send in different length of wave and it change in every 2 second slot and each 30khz frequency are divided into three time slot. D-AMPS, D-AMPS 1900, GSM, PCS and iDEN systems are all use TDMA technology.
Code Division Multiple Access :In a CDMA system, voice is encoded in digital signal and divided into small packets. These packets are tagged with “codes.” and they are mixed with all of the other packets of traffic in the local CDMA network. when they are routed towards their destination. The receiving system only accepts the packets with the codes destined for it.this is one of the smartest technology for mobile communication.
Mobile Communication System Architecture:
The Switching System : The switching system is very operative system in which many crucial operation are conducted. There are five database from SS and they are : HLR, MSC, VLR, AuC and EIR.
HLR : Home Location Register
MSC : Mobile Service Switching Center
VLR : Visitor Location Register
AUC : Authentication Center
EIR : Equipment Identity Register
BSS: Base Stataion Subsystem
BTS: The Base Station Center
There are some related system of Mobile comunication System and they are :
- Mobile IP network
- Access points
- Ad hoc
- Sensor networks
- Mobile Computing Systems Network