GSM_SANAT_Ppt
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The document provides an overview of the Global System for Mobile Communications (GSM), detailing its architecture, which includes the Mobile Station Subsystem, Base Station Subsystem, and Network Switching Subsystem, along with their components and functions. It describes the GSM specifications, such as frequency bands, as well as key elements like the Mobile Equipment Identity (IMEI), Subscriber Identity Module (SIM), handovers, and databases like the Home Location Register (HLR) and Visitor Location Register (VLR). The document also touches on GSM network protocols and the operation of the Public Switched Telephone Network (PSTN).
GSM_SANAT_Ppt
- 1. Global System for Mobile Communications Prepared by: Sanat Varasada Florida Polytechnic University, Lakeland, Florida
- 2. About GSM Global System for Mobile communication (GSM) is a cellular standard developed to improve voice services and data delivery.
- 3. GSM Specifications GSM 900 Mobile to BTS (uplink): 890-915 MHz BTS to Mobile(downlink):935-960 MHz Bandwidth : 25 MHz GSM 1800 Mobile to BTS (uplink): 1710-1785 MHz BTS to Mobile(downlink) 1805-1880 MHz Bandwidth : 75 MHz
- 4. GSM architecture…. 1. MSS (Mobile Station Sub-system) # ME (Mobile Equipment) # SIM (Subscriber Identity Module) 2. BSS (Base Station Sub-system) # BTS (Base Transceiver Station) # BSC (Base Station Controller) 3. NSS (Network Station Sub-system) # MSC (Main Switching Center) & more….
- 6. 1. Mobile Station Subsystem(MSS) The Mobile Station is made up of two entities: i. Mobile Equipment (ME) ii. Subscriber Identity Module (SIM)
- 7. . i. Mobile Equipment (ME):- The ME is the hardware used by the subscriber to access the network. The hardware has an identity number associated with it, which is unique for that particular device and permanently stored in it. This identity number is called the International Mobile Equipment Identity (IMEI)
- 8. • IMEI Structure TAC: It indicated that the particular device was approved by a national GSM approval body. FAC: It identified the company that had built and assembled the device. SNR: It assigned by manufacturer SP: Check digit It uniquely characterizes a mobile station and gives clues about the manufacturer and the date of manufacturing.
- 9. The SIM is a card which plugs into the ME. This card identifies the MS subscriber and also provides other information regarding the service that subscriber should receive. The subscriber is identified by an identity number called the International Mobile Subscriber Identity (IMSI). SIM also contain PIN, PUK and ICCID number. Mobile Equipment may be purchased from any store but the SIM must be obtained from the GSM network provider. Without the SIM inserted, the ME will only be able to make emergency calls. ii. Subscriber Identity Module(SIM):-
- 10. 2. BSS(Base Station Subsystem) Base Station Subsystem is composed of two parts: i. Base Transceiver Station (BTS) ii. Base Station Controller (BSC)
- 11. i. Base Transceiver Station (BTS):- A base transceiver station (BTS) is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. It transmits and receives RF signals from & to MS. The area covered by one BTS is called as cell.
- 12. Cell concept • Areas divided into cells – Each cells served by its own antenna – Served by base station consisting of transmitter, receiver, and control unit – Band of frequencies allocated – Cells set up in hexagonal pattern
- 13. Why hexagonal cell ?
- 14. Cell planning Macro cell: 1 – 20 mile. Normally the site location is on a hilltop or rooftop. Micro cell: 0.5 – 1.5 mile. Normally site location is on the building or under a roof. Pico cell: Up to 0.3 mile. It’s use for small coverage area. Normally located inside the building.
- 16. Approaches to cope with Increasing capacity • Cell Splitting • Cell Sectoring Why cell splitting and sectoring? As users increases channel capacity decreases Both techniques are needed to provide extra channels
- 17. • Cell sectoring The sectoring is done by Replacing a single Omni-directional antenna with 3 direction antennas (120 degree) or with 6 directional antennas (60 degree) at the base station by several directional antenna.
- 18. • Cell splitting Cell splitting is the process of splitting a cell into smaller cells. The splitting is usually done on demand, when in a certain cell there is too much blocking of calls.
- 19. ii. Base Station Controller (BSC) The Base Station Controller (BSC) controls the working of one or more Base Transceivers. It handles radio-channel setup, handovers etc. Numbers of BSCs are connected to MSC. Thus BSC is the connection between the mobile station and the Mobile Switching Center (MSC).
- 20. BSS Configurations • chain Configurations • Star configurations • Loop configurations
- 24. Handover - Changing the point of connection while communicating. - In other words, when mobile users travel from one cell to another cell.
- 25. Types of handover • Soft handover: Mobile users move from one BTS to other BTS • Softer handover: Mobile users move from one sector to another sector within one cell. When will a handover occur? When received signal level drops below a certain signal level.
- 26. Improper and Proper handovers Improper handover Proper handover
- 28. 3. NSS(Network Switching Subsystem) 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.
- 29. i. Mobile Switching Centre (MSC) The MSC is included in the GSM system for call-switching. The functions carried out by the MSC are listed below:- Manages communication between GSM and other networks Call setup function and basic switching Call routing Billing information and collection Mobility management - Registration - Location Updating - Handovers
- 30. • permanent database about mobile subscribers in a large service area. • Any administrative action by the service provider or changes made by subscriber is first carried out on the HLR and then update the VLR. data in HLR:- – IMSI number. – Roaming restriction (allowed or not). -- Supplementary services like call forwarding -- Messages waiting data used for SMS ii. Home Location Register (HLR)
- 31. The only way via which HLR communicates with other GSM nodes is Mobile Access Protocol. Other functions defined on the MAP are: - Update HLR and VLR - Fault Recovery - Retrieval of subscriber data during call setup. - Security related data
- 32. iii. Visitor Location Register (VLR) It is a subscriber database containing the information about all the MS currently located in the MSC service area. If MS moves into a new service area, VLR requests the HLR to provide the relevant data and store it, for making the calls for that MS. VLR is always integrated with MSC to avoid the signaling load on the system. The additional data stored in the VLR is listed below: Location updating and registration Updating the mobile subscriber data. Maintain the security of the subscriber by allocating TMSI. Receiving and delivering short messages
- 33. Location update
- 34. iv. Authentication Centre (AUC) Authentication is required at each registration, at each call setup attempt, at the time of location updating, before supplementary service activation, de-activation , registration. -- Providing the authentication key used for authorizing the subscriber access to the associated GSM Network. -- it is linked to the MSC and checks the identity of each user trying to connect. -- Stores IMSI number
- 35. v. Equipment Identity Register (EIR) -- The Equipment Identity Register (EIR) is a database that contains a list of all valid mobile equipment on the network, where its International Mobile Equipment Identity (IMEI) identifies each mobile station. 1. White List Contains those IMEIs which are known to have been assigned to valid MS equipment. 2. Grey List Contains IMEIs of MS which have problems. 3. Black List Contains IMEIs of MS which are to be denied service for some other reason.
- 37. Public Switched Telephone Network (PSTN) The PSTN consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all interconnected by switching centers, thus allowing most telephones to communicate with each other.
- 38. Operation and Maintenance Centre • The centralized operation of the various units in the system and functions needed to maintain the subsystems. • Fault report & alarm handling • Storage of systems software and data • Traffic monitoring • Status reports of networks • Configuration management
- 40. GSM network protocols 1. MAP: Mobile Access Protocol 2. BSSAP: BSS Access Protocol 3. LAP: Link Access Protocol
- 41. GSM control channels BCCH Broadcast Control Channel – Continuously transmitted from the BTS. Contains information about cell identity, frequency etc. FCCH SCH Frequency Correction Channel / Synchronisation Channel – Used to correct/synchronise the frequency (FCCH) + time synchronise to the frame structure. Each cell has a FCCH and a SCH RACH Random Access Channel – Used by the mobile to send a request to the network for access. AGCH Access Grant CHannel – Used by the network to inform the mobile that access has been granted and information about which channel to use PCH Paging Channel – Used by the network to notify users about incoming calls.
- 42. Handover system Between 1 and 2 Inter BTS / Intra BSC ( Soft handover) Between 1 and 3 Inter BSC/ Intra MSC Between 1 and 4 Inter MSC
- 43. Call Detail Recorders • CDRs contain the following information: - Subscriber Identity - Number called - Call Length - Route of call
- 46. 1. GSM in US