GSM Architecture

   
A GSM Architecture is a complex structure to understand. It is made of many small units working in a harmonious way. To better understand the GSM architecture, divide all the units in four categories.

    First is the mobile station which is actually a mobile phone itself. It works by communicating with the other parts of the base station.

    Second is the Base Station System which is made up of two parts;

Base transceiver Station (BTS)

It is responsible for the wireless communication between mobile and its relevant network. It is possible through a radio interface. This base transceiver station is based on a radio and an antenna.

Base Station Controller (BSC)

Base Station Controller provides the control. It directs the function and establishes connection between BTS and MSC. The functions like cell configuration, handover, and RF power level controls are processed in Base station control. MSC also controls some of BSC functions.

    Third part is based on the Switching System of GSM. Following are the functions performed by the Switching System;

Switching System of GSM

Mobile Services Switching (MSC) Center initiates the system. It’s like you turn on the switch and device starts working. Similarly when caller dial the number, this switching center activates the process by toll ticketing, interfacing network, synchronizing signals and other necessary functions to make call happen. MSC is responsible to where this call has to send. There are two types of registers which comes up to help the MSC for the right ID. These registers are;

Home locator Register (HLR) & Visitor Locator Register (VLR) in GSM

First Home Locator Register receives the signals and response whether it contains the specific number’s information. Home Locator Register has a complete database of the consumers and all subscriptions are managed and updated here. It has a complete profile of subscriber like service mode, registered address and status mode.


If caller input data is not located in HLR then it goes to Visitor’s Location Register (VLR). This register is filled with the temporary data files related to the subscribers. These files provide information about a roamer mobile which occasionally travels from one MSC to the other. Visitor Locator Register saves the MSC’s time and supplied it the relevant information.

Authentication Center (AUC) in GSM

When Mobile Service Switching Center locate the user’s ID from HLR or VLR, this authentication center gives the authentication that whether the received information are true or not hence less chances of cheating.


Next gate to cross to carry on the further process is Equipment Identity register which stores information about mobile equipment ID so it restricts the calls from unauthenticated number and lessens the cases of stealing.

And now the information reached at the message center (MXE). It is a node responsible for receiving data, voice or fax. It’s time to hit the target as reached at the Mobile Service Node (MSN). It is responsible for the intelligent network services accessing the Gateway Mobile Switching Center (GMSC). It is a node working as a bridge between two networks to interconnect.


Ultimately MSC approaches GSM Interworking Unit (GIWU) which is the combination of hardware and software and work as a unit by synchronizing the whole information. This GIWU makes you chose between message and dialogue mode. 

    The fourth and last part of this GSM Architecture is Operation and Support System (OSS). Being a monitoring and scheming body, it works as an operative unit. Basically this OSS unit is responsible to monitor the whole process and provides support for the centralization, covers the local and regional operations and retains the GSM network in its running condition. 

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"Remember Me When You Raise Your Hand For Dua"
Raheel Ahmed Khan
System Engineer
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