Experiment No.: -7Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Objective: -Implement a GSM case study. Theory: GSM is a standard developed by the European Telecommunications Standards Institute to describe protocols for 2G digital cellular networks used by mobile devices such as smartphones and tablets. The GSM network can be broadly divided into four categories: mobile station (MS) base station subsystem (BSS) networking and switching subsystem (NSS) operating and support subsystem (OSS) Simplified diagram of the GSMS network architectureMobile station:The Mobile Stations (MS), Mobile Equipment (ME) or as they are better known, cell phones or cell phones are the section of a GSM cellular network that the user sees and uses. In recent years their size has decreased dramatically while the level of functionality has increased significantly. An added benefit is that the time between charges is significantly increased. The mobile phone is made up of numerous elements, although the two main elements are the main hardware and the SIM. The hardware itself contains the main elements of the mobile phone, including the display, the case, the battery and the electronics used to generate the signal and process the data receiver and to transmit. It also contains a number known as International Mobile Equipment Identity (IMEI). This is installed in the phone during production and “cannot” be changed. The network accesses it during registration to see if the equipment has been reported stolen. The SIM or Subscriber Identity Module contains the information that provides the user's identity to the network. It contains a variety of information including a number known as International Mobile Subscriber Identity (IMSI). Base Station Subsystem (BSS) The BSS is composed of two parts: The Base Transceiver Station (BTS) The Base Station Controller (BSC) The BTS and BSC communicate through the specified Abis interface, allowing operations between vendor-made components different. The radio components of a BSS can consist of four to seven or nine cells. A BSS can have one or more base stations. The BSS uses the Abis interface between BTS and BSC. A separate high-speed line (T1 or E1) is then connected from the BSS to the Mobile MSC. The Base Transceiver Station (BTS) The BTS hosts the radio transceivers that define a cell and manages the radio connection protocols with the MS. In a large urban area, a large number of BTSs can 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 transmission power defines the size of a cell. Each BTS has 1 to 16 transceivers, depending on the density of users in the cell. Each BTS acts as a single cell. It also includes the following functions: The Base Station Controller (BSC) The BSC manages radio resources for one or more BTSs. Manages radio channel setup, frequency hopping and handovers. The BSC is the connection between the mobile phone and the MSC. The BSC also translates the 13 Kbps voice channel used on the radio link into the standard 64 Kbps channel used by the public switched telephone network (PSDN) or ISDN. Assign and release frequencies and time slots for MS. The BSC also handles handover between cells. Controls the power transmission of the BSS and MS in its area. The function of the BSC is to allocate the necessary time slots between BTS and MSC. It is a switching device that manages radio resources. Additional features include: Network Switching Subsystem (NSS) The architecture of the GSM systemcontains a variety of different elements and is often referred to as the core network. It provides the main control and interface for the entire mobile network. The main elements within the core network include: Mobile Services Switching Center (MSC): The main element within the core networkThe overall architecture area of ​​the GSM network is the Mobile Switching Services Center (MSC). The MSC acts as a normal switching node within a PSTN or ISDN network, but also provides additional functionality to meet the needs of a mobile user. These include recording, authentication, call location, inter-MSC transfers and call routing to a mobile subscriber. It also provides an interface to the PSTN so that calls can be routed from the mobile network to a phone connected to a landline. Interfaces with other MSCs are provided to allow calls to mobile phones on different networks. Home Location Register (HLR): This database contains all administrative information about each subscriber along with their last known location. In this way the GSM network is able to route calls to the corresponding base station for the Member State. When a user turns 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 turned on) it periodically records itself to ensure that the network (HLR) is aware of its last location. There is one HLR per network, although for operational reasons it may be distributed across various sub-centres.Visitor Location Register (VLR): contains information selected by the HLR which allows the selected services to be provided for the individual subscriber. The VLR can be implemented as a separate entity, but is commonly implemented as an integral part of the MSC, rather than as a separate entity. In this way access becomes faster and more convenient. Equipment Identity Register (EIR): The EIR is the body that decides whether a given mobile device can be admitted to the network. Each mobile equipment has a number known as International Mobile Equipment Identity. This number, as mentioned above, is installed in the equipment and is checked by the network during registration. Depending on the information contained in the EIR, the mobile phone can be assigned one of three states: allowed on the network, blocked access or monitored for problems. Authentication Center (AuC): The AuC is a protected database that contains the secret key also contained in the user's SIM card. It is used for authentication and encryption on the radio channel.Gateway Mobile Switching Center (GMSC): The GMSC is the point to which an ME termination call is initially routed, without any knowledge of the location of the MS. The GMSC therefore has the task of obtaining the MSRN (Mobile Station Roaming Number) from the HLR based on the MSISDN (Mobile Station ISDN number, the "directory number" of an MS) and routing the call to the correct MSC visited . The "MSC" part of the term GMSC is misleading, as gateway operation requires no connection to an MSC. SMS Gateway (SMS-G): SMS-G or SMS gateway is the term used to collectively describe the two Short Message Services Gateways defined in the GSM standards. The two gateways handle messages directed in different directions. The SMS-GMSC (Short Message Service Gateway Mobile Switching Centre) is used for short messages sent to an ME. The SMS-IWMSC (Short Message Service Inter-Working Mobile Switching Centre) is used for short messages originating from a mobile phone on that network. The SMS-GMSC role is similar to that of the GMSC, while SMS-IWMSC provides a fixed access point to the Short Message.