HISTORY The Europeans realized this early on, and in 1982 the Conference of European Posts and Telegraphs (CEPT) formed a study group called the Groupe Spécial Mobile (GSM) to study and develop a pan-European public land mobile system. The proposed system had to meet certain criteria:
PURPOSES Good subjective speech quality Low terminal and service cost Support for international roaming Ability to support handheld terminals Support for range of new services and facilities Spectral efficiency ISDN compatibility
GSM network consists of the followingcomponents: Mobile station. The GSM mobile station (ormobile phone) communicates with other parts ofthe system through the base-station system. SIM:Subscriber Identification Module. A SIM cardcontains its unique serial number, internationalunique number of the mobile user (IMSI), securityauthentication and ciphering information,temporary information related to the local network(also temporary local id that has been issued tothe user), a list of the services the user hasaccess to and two passwords (PIN for usual useand PUK for unlocking).
GSM Base station system (BSS). Base transceiver station (BTS). The basetransceiver station (BTS) handles the radiointerface to the mobile station. The basetransceiver station is the radio equipment(transceivers and antennas) Base station controller (BSC). The BSCprovides the control functions and physicallinks between the MSC and BTS. Itprovides functions such as handover, cellconfiguration data and control of RF powerlevels in base transceiver stations. Anumber of BSCs are served by a MSC
GSM Switching SystemMobile services switching center (MSC). TheMSC performs the telephony switching functionsof the system. It also performs such functions asnetwork interfacing, common channel signalling,and others. Home location register (HLR). The HLRdatabase is used for storage and managementof subscriptions. The home location registerstores permanent data about subscribers,including a subscribers service profile, locationinformation, and activity status.
Visitor location register (VLR). The VLRdatabase contains temporary informationabout subscribers that is needed by themobile services switching center (MSC) inorder to service visiting subscribers. Whena mobile station roams into a new mobileservices switching center (MSC) area, thevisitor location register (VLR) connected tothat MSC will request data about themobile station from the HLR, reducing theneed for interrogation of the home locationregister (HLR).
Authentication center (AUC). The AUCprovides authentication and encryptionparameters that verify the users identityand ensure the confidentiality of each call.The authentication center (AUC) alsoprotects network operators from fraud. Equipment identity register (EIR). The EIRdatabase contains information on theidentity of mobile equipment to preventcalls from stolen, unauthorized or defectivemobile stations.
CALL IN PROGRESS-STEPS 1) MS initialization after switched-on 2) Service request 3) Authentication and security 4) MS attach and detach 5) Location update 6) Outgoing voice call 7) Incoming voice call 8) SMS and special services 9) Call hand over
GSM SPECIFICATIONS-1RF SpectrumGSM 900 Mobile to BTS (uplink): 890-915 Mhz BTS to Mobile(downlink):935-960 MhzGSM 1800 Mobile to BTS (uplink): 1710-1785 Mhz BTS to Mobile(downlink): 1805-1880 Mhz
FDMA Frequency Division Multiple Access or FDMA is a channel access method used in multiple-access protocols as a channelization protocol. FDMA gives users an individual allocation of one or several frequency bands, or channels
TDMA Time division multiple access (TDMA) is a channel access method for shared medium networks. It allows several users to share the samefrequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using his own time slot.
1-G 1G (or 1-G) refers to the first-generation of wireless telephone technology, mobile te lecommunications. The 1G system in GSM all power allocation and handoffs strategies were decided by MSC and then executed by BSC.
2-GGSM differs from its predecessors in thatboth signaling and speech channelsare digital, and thus is considered a secondgeneration (2G) mobile phone system. GSM also pioneered a low-cost (to the network carrier) alternative to voice calls, the short message service (SMS, also called "text messaging").
The basic difference is that theinterfernce of MSC is reducedas compared to 1-G thepower and handoff allocationdepends on THE BSC unlessin the case of roaming wherethe MSC’s are different.
2.5-G 2.5 Generation ( Future of GSM) HSCSD (High Speed ckt Switched data) Data rate : 76.8 Kbps (9.6 x 8 kbps) GPRS (General Packet Radio service) Data rate: 14.4 - 115.2 Kbps EDGE (Enhanced data rate for GSM Evolution) Data rate: 547.2 Kbps (max)
HSCSD-High-speed circuit-switched datais the ability to use multiple time slots atthe same time. Using the maximum of fourtime slots, this can provide an increase inmaximum transfer rate of up to 57.6 kbit/s.GPRS – General Packet Radio Service(GPRS) is a packet oriented Mobile DataService available to users of GlobalSystem for Mobile Communications(GSM).
GPRS can be used for services suchas WAP access, SMS, MMS, and forInternet communication servicessuch as email and World Wide Webaccess. 2G cellular systemscombined with GPRS are oftendescribed as "2.5G", that is, atechnology between the second (2G)and third (3G) generations of mobiletelephony.
EDGE – Enhanced Data rates forGSM Evolution (EDGE) is a digitalmobile phone technology thatallows increased data transmissionrates and improved datatransmission reliability. EDGE isgenerally classified as 2.75G,although it is part of the 3Gdefinition.
3-G the third generation of telecommunication3G is hardware standards and general technology for mobile networking.3G networks enable network operators to offerusers a wider range of more advancedservices while achieving greater networkcapacity through improved spectral efficiency.Services include wide-area wireless voicetelephone, video calls, and broadband wirelessdata, all in a mobile environment.
Additional features also include HSPA datatransmission capabilities, which providesusers with data rates up to 14.4 Mbit/s onthe downlink and 5.8 Mbit/s on the uplink.HSPA:High-Speed Packet Access (HSPA)is a 3G mobile telephony communicationsprotocol in the HSPA family, which allowsnetworks based on Universal MobileTelecommunications System (UMTS) toincrease data capacity and speed uptransfer rates.
HSPA+ - HSPA+, also known as EvolvedHSPA is a wireless broadband standardthat provides HSPA data rates up to 42Mbit/s on the downlink and 22 Mbit/s on theuplink .UMTS – Universal MobileTelecommunications System (UMTS) is oneof the third-generation (3G) cell phonetechnologies, which is also being developedinto a 4G technology. It is closely related toGSM/EDGE as it borrows and builds uponconcepts from GSM
4-G 4G working group has defined the following as objectives of the 4G wireless communication standard: A spectrally efficient system . High network capacity: more simultaneous users per cell.
A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions as defined by the ITU-R. A data rate of at least 100 Mbit/s between any two points in the world. Smooth handoff across heterogeneous networks.
Seamless connectivity and global roaming across multiple networks. High quality of service for next generation multimedia support (real time audio, high speed data, HDTV video content, mobile TV, etc). Interoperability with existing wireless standards. IP, packet switched network.
LTE – Long Term Evolution (LTE) is thename given to a project to improve theUMTS mobile phone standard to copewith future technology evolutions. Goalsinclude improving spectral efficiency,lowering costs, improving services,making use of new spectrum andreframed spectrum opportunities, andbetter integration with other openstandards.
CDMA analog-to-digital conversionCDMA employs (ADC) in combination with spread spectrum technology. Audio input is first digitized into binary elements. The frequency of the transmitted signal is then made to vary according to a defined pattern (code), so it can be intercepted only by a receiver whose frequency response is programmed with the same code, so it follows exactly along with the transmitter frequency. There are trillions of possible frequency-sequencing codes, which enhances privacy and makes cloning difficult.