|Published (Last):||9 March 2017|
|PDF File Size:||13.20 Mb|
|ePub File Size:||19.75 Mb|
|Price:||Free* [*Free Regsitration Required]|
Protocols 5. Speech and Channel Coding 6. Mobility Management 7. Radio Resource Management 8. Call Management 9. GSM Security Billing Procedures Overview GSM Evolution Introduction to Cellular Systems 7.
Radio Resource Management 2. Architecture Overview 8. Mobility Management 3. Services 9. Connection Management 4. The Air Interface Security 5. GSM Protocols Billing Procedures Overview 6. Speech and Channel Coding Introduction to Cellular Systems In early networks, the emphasis was to provide radio coverage with little consideration for the number of calls to be carried.
As the subscriber base grew, the need to provide greater traffic capacity had to be addressed. Introduction to Cellular Systems While first generation systems used a cellular structure and frequency re-use patterns, digital systems developed this concept to include multi-layer cellular patterns microcells and macrocells. The greater immunity to interference inherent in digital transmission allowed tighter frequency re-use patterns to be implemented.
This includes a brief explanation of the different network subsystems and a description of the functionality of the elements within each of the se subsystems. It is registered by the network operator and optionally stored in the AuC for validation purposes.
It is assigned to the subscriber by the network operator at registration and is stored in the SIM. The purpose of LAs is covered later in this course. However, the CI is only unique within a specific Location Area. Architecture Overview The two parts of the mobile station allow a distinction between the actual equipment and the subscriber who is using it. Architecture Overview The IMEI may be used to block certain types of equipment from accessing the network if they are unsuitable and also to check for stolen equipment.
They are distinguished primarily by their power output rating. The radio equipment of a BSS may support one or more cells. A BSS may consist of one or more base stations, where an A-bis-interface is implemented.
The actual physical link may be microwave, optical fibre or cable. Planning of these links may be done using a tool such as Connect 2. Signalling between the registers uses Signalling System No.
When a Mobile Station MS enters a new location area it starts a registration procedure. This data item will be used to call the station. A PLMN may contain one or several physical HLRs depending on the number of mobile subscribers, the capacity of the equipment and the organization of the network. However, even if the HLR comprises geographically separated hardware, it logically forms a single virtual database.
Supplementary services parameters need not all be stored in the HLR. However, it is considered safer to store all subscription parameters in the HLR even when some are stored in a subscriber card.
This information is used to page the subscriber when they have an incoming call. The procedures used for authentication and ciphering are described more fully in the security section of this course and in the ETSI GSM Architecture Overview The GMSC routes calls out of the network and is the point of access for calls entering the network from outside. The terminal is not allowed to connect to the network. The mobile equipment may be classified as "white listed", "grey listed" and "black listed" and therefore may be stored in three separate lists.
The EIR contains, as a minimum, a "white list" Equipment classified as "white listed". There is an optional implementation that may be used by the operator to control access to the network by certain types of equipment or to monitor lost or stolen handsets. The interface also allows control of the radio equipment and radio frequency allocation in the BTS. This interface is specified in the Architecture Overview This procedure occurs whenever an MS roams to another location area.
The main service provided to the mobile subscriber is the capability to set up or to receive calls within the whole service area. To support this, the location registers have to exchange data. The VLR informs the HLR of the location of a mobile station managed by the latter and provides it either at location updating or at call set-up with the roaming number of that station.
Exchanges of data may occur when the mobile subscriber requires a particular service, when he wants to change some data attached to his subscription or when some parameters of the subscription are modified by administrative means.
For that purpose the MSCs have to exchange data to initiate and then to realize the operation. After the handover operation has been completed, the MSCs will exchange information to transfer A-interface signalling as necessary.
The protocol used to transfer the data over this interface is not standardized. Here is a screen shot from Asset showing the site database of a small network: Sites 22 and 23 are connected in a star configuration to the BSC. Sites 25, 26 and 27 are connected in a chain. These bearer services carrying end-to-end teleservices. As teleservices are end-to-end, they are generally transparent to the IWF. They represent the functionality of layers 1 to 3 of the OSI 7-layer model.
Both circuit switched BS and packet switched BS data bearer services are supported. The transparent mode services provide a circuit-switched connection between the TE and the IWF module.
They are generally constant bit rate and are only forward error protected FEC. Non-transparent mode services are protected by level 2 error protection over the air interface using a Radio Link Protocol RLP. Non-transparent mode operation generally offers a more reliable transmission path but at lower potential data rates than transparent mode services.
The distinction is only important when operating outside the PLMN i. The distinction is whether the data should be handled as the equivalent of 3. The last two categories of bearer services shown in the diagram above refer to services which enable switching between voice and data during a session.
These teleservices are generally end-to-end user applications and are therefore transparent to their transporting bearer services. Consequently, it cannot be offered to a customer as a stand alone service, only in association with a basic teleservice. The same supplementary service may be applicable to a number of teleservices.
Both asynchronous BS and synchronous BS options are available and each data rate other than bps synch can operate in transparent or non - transparent mode see Section 3. A mobile can send a message either to another MS or into the fixed network as an Email for example. SMSCB messages are generally broadcast only in a specific network region. An MS cannot initiate such a message and does not acknowledge receipt of one.
These messages differ from standard SMS messages in that they are only 92 characters long. However, procedures exist to concatenate up to 15 SMSCB messages using a special reassembly mechanism.
Messages can be initiated in the fixed or mobile network and delivered to either the fixed or mobile network. The SME may be located in the fixed network, a mobile station, or another service centre.
Home Location Register The HLR is a database used for permanent storage and management of subscriptions and service profiles. The HLR also informs the SMSC, which has previously initiated unsuccessful short message delivery attempts to a specific mobile station, that the mobile station is now recognized by the mobile network to be accessible.
Mobile Switching Centre The MSC performs the switching functions of the system and controls calls to and from other telephone and data systems.
Visitor Location Register The visitor location register VLR is a database that contains temporary information about subscribers.
404 Not Found
Aircom International, a mobile network planning and optimisation consultancy, has won a contract with Vietnamese mobile network operator Vinaphone to provide RF network planning, design support and surveying activities for the expansion of Vinaphone's GSM network. The deal, which comes on the back of a commercial bidding procedure, will see Aircom deliver a range of consultancy services, including network planning and formal on-the-job training, to Vinaphone. It is expanding its existing GSM network to boost subscriber numbers and provide service coverage to all nationwide districts through the installation of an extra 5, base transmission stations BTS. With Aircom's support, Vinaphone wants to have some 9, optimised BTS installed on its network by the end of the year. Comments powered by CComment.
Three steps: Scanning a QR-code: Find your way to a press release without typing. Use the QR-code shown on the print version of each press release to get redirected to the corresponding page on PresseBox with your smartphone without typing the URL manually. Everything you need is an web-enabled mobile phone or smartphone with a built-in camera and a QR-code reading software. QR stands for Quick Response - with one step you can quickly reach a website. QR-codes work like bar codes, which you can find on your milk carton, for example. A software decrypts the QR-code and directs you to a web page - so you do not even need to know the web address to reach it.