Gsm system architecture pdf

Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Abdelsalam Hantash. A short summary of this paper. Download Download PDF. Translate PDF. The development of this architecture is not only in terms of infrastructure but also in the terms of software and coding to encrypt and secure the data. The 3G — 4G transition is only for data speed, keeping the voice constant.

While using the telecom service when we are on move, it is at the BTS that the handover takes place. Handovers occur to ensure that we are connected to the network even when we are moving. BSC is responsible for making the handover. MSC has 4 main elements: a. In HLR we find out whether the subscriber is eligible for a few services like able to make international calls and etc. All the blocked IMEI are in black list. The BTS houses the radio transceivers that define a cell and handles the radio link protocols with the MS.

In a large urban area, a large number of BTSs may be deployed. The BTS corresponds to the transceivers and antennas used in each cell of the network. A BTS is usually placed in the center of a cell. Its transmitting power defines the size of a cell. Each BTS has between 1 and 16 transceivers, depending on the density of users in the cell. Each BTS serves as a single cell. It handles radio channel setup, frequency hopping, and handovers. It assigns and releases frequencies and time slots for the MS.

The BSC also handles intercell handover. It is a switching device that handles the radio resources. The Network switching system NSS , the main part of which is the Mobile Switching Center MSC , performs the switching of calls between the mobile and other fixed or mobile network users, as well as the management of mobile services such as authentication. The HLR is a database used for storage and management of subscriptions.

The HLR is considered the most important database, as it stores permanent data about subscribers, including a subscriber's service profile, location information, and activity status. These include registration, authentication, call location, inter-MSC handovers and call routing to a mobile subscriber.

It also provides an interface to the PSTN so that the mobile communications calls can be routed from the mobile network to a phone connected to a landline. Interfaces to other MSCs are provided to enable calls to be made to mobiles on different networks.

Home Location Register HLR : This database contains all the administrative information about each subscriber along with their last known location. When a user switches on their phone, the phone registers with the network and from this it is possible to determine which BTS it communicates with so that incoming calls can be routed appropriately. Even when the phone is not active but switched on it re-registers periodically to ensure that the network HLR is aware of its latest position.

There is one HLR per network, although it may be distributed across various sub-centres to for operational reasons. The VLR can be implemented as a separate entity, but it is commonly realised as an integral part of the MSC, rather than a separate entity. In this way access is made faster and more convenient. Each mobile equipment has a number known as the International Mobile Equipment Identity. This number, as mentioned above, is installed in the equipment and is checked by the network during registration.

Dependent upon the information held in the EIR, the mobile may be allocated one of three states - allowed onto the network, barred access, or monitored in case its problems. It is used for authentication and for ciphering on the radio channel. The two gateways handle messages directed in different directions. The BTS is the defining element for each cell.

The BTS communicates with the mobiles and the interface between the two is known as the Um interface with its associated protocols. It manages the radio resources and controls items such as handover within the group of BTSs, allocates channels and the like. It communicates with the BTSs over what is termed the Abis interface. Mobile station Mobile stations MS , mobile equipment ME or as they are most widely known, cell or mobile phones are the section of a GSM mobile communications network that the user sees and operates.

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