Architecture and Working Of GSM Networks
We have already read about how GSM technology had taken over mobile communication technologies and grown to over 214 countries around the world, including the networks Lao Shinawatra Telecom in Laos are to name few. Now it is important to learn how GSM networks work and what the the architecture of GSM networks is. GSM networks consist of thee major systems: SS, which is known to be The Switching System; BSS, which is also called The Base Station; and the Operation and Support System for GSM networks.
Below all three systems are defined in details with sub systems of each system.
The Switching System
The Switching system is very operative system in which many crucial operations are conducted, SS systems holds five databases with in it which performs different functions. If we talk about major tasks of SS system it performs call processing and subscriber related functions. These five databases from SS systems are HLR, MSC, VLR, AUC and EIR. Let’s study each database in detail and learn what functions this little systems performs.
HLR- Home Location Register:
HLR is database, which holds very important information of subscribers. It is mostly known for storing and managing information of subscribers. It contains subscriber service profile, status of activities, information about locations and permanent data of all sorts. When new connections are purchased, these subscribers are registered in HLR of mobile phone companies.
MSC- Mobile Services Switching Center:
MSC is also important part of SS, it handles technical end of telephony.It is build to perform switching functionality of the entire system. It’s most important task is to control the calls to and from other telephones, which means it controls calls from same networks and calls from other networks. Toll ticketing, common channel signaling, network interfacing etc are other tasks which MSC is responsible for.
VLR- Visitor Location Register:
VLR performs very dynamic tasks; it is database which stores temporary data regarding subscribers which is needed by Mobile Services Switching Center-MSC VLR is directly connected to MSC, when subscribe moves to different MSC location, Visitor location register – VLR integrates to MSC of current location and requests the data about subscriber or Mobile station ( MS ) from the Home Location Register –HLR. When subscriber makes a call the Visitor location register-VLR will have required information for making call already and it will not required to connect to Home Register Location – HRL again.
AUC- Authentication Center:
AUC is small unit which handles the security end of the system. Its major task is to authenticate and encrypt those parameters which verify user’s identification and hence enables the confidentiality of each call made by subscriber. Authentication center – AUC makes sure mobile operators are safe from different frauds most likely to happen when hackers are looking for even smallest loop wholes in systems.
EIR – Equipment Identity Register:
EIR is another important database which holds crucial information regarding mobile equipments. EIR helps in restricting for calls been stolen, malfunctioning of any MS, or unauthorized access. AUC – Authentication center and EIR- Equipment Identity registers are either Stand-alone nodes or some times work together as combined AUC/EIR nodes for optimum performance.
The Base Station System (BSS)
The base station system have very important role in mobile communication. BSS are basically out door units which consist of iron rods and are usually of high length. BSS are responsible for connecting subscribers (MS) to mobile networks.All the communication is made in Radio transmission.The Base station System is further divided in two systems. These two systems, they are BSC, and BTS. Let’s study these two systems in detail.
BTS – The Base Transceiver Station:
Subscriber, MS (Mobile Station) or mobile phone connects to mobile network through BTS; it handles communication using radio transmission with mobile station. As name suggests, Base transceiver Station is the radio equipment which receive and transmit voice data at the same time. BSC control group of BTSs.
BSC – The Base Station Controller:
The Base Station normally controls many cells, it registers subscribers, responsible for MS handovers etc. It creates physical link between subscriber (MS) and BTS , then manage and controls functions of it. It performs the function of high quality switch by handover over the MS to next BSC when MS goes out of the current range of BTS, it helps in connecting to next in range BTS to keep the connection alive within the network. It also performs functions like cell configuration data, control radio frequency in BTS. Data moves to MSC-Mobile switching center after BSC done processing it. MSC is switching center which acts as bridge between different mobile networks.
Note: This image is graphical explanation of GSM Architecture and Working of GSM Networks
The Operation and Support System (OSS)
OMC- Operations and maintenance center is designed to connect to equipment of MSC- Mobile Switching Center and BSC-Base Station Controller. The implementation of OMC is called OSS-The Operations and Support System.OSS helps in mobile networks to monitor and control the complex systems.The basic reason for developing operation and support system is to provide customers a cost effective support and solutions. It helps in managing, centralizing, local and regional operational activities required for GMS networks.
Maintaining mobile network organization, provide overview of network, support and maintenance activities are other important aspects of Operation and Support System