1. GSM GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile) -is a standard developed by the European Telecommunications Standards Institute (ETSI) - to describe protocols for second-generation (2G) digital cellular networks used by mobile phones. -As of 2014 it has become the default global standard for mobile communications - with over 90% market share, operating in over 219 countries and territories.

2. GSM phones make use of a SIM card to identify the user's account. The use of the SIM card allows GSM network users to quickly move their phone number from one GSM phone to another by simply moving the SIM card. Currently GSM networks operate on the 850MHz, 900MHz, 1800MHz, and 1900MHz frequency bands. Devices that support all four bands are called quad- band, with those that support 3 or 2 bands called tri- band and dual-band, respectively.

3. 3 Network Structure Cell A cell is the basic unit of a cellular system and is defined as the radio coverage given by one BTS.

4. 4 LOCATION AREA A LA is defined as a group of cells.Within the network, a subsriber’s location is known by the LA which they are in. The identity of the LA in which an MS is currently located is stored in the VLR. (LAI) Network Structure

5. 5 MSC Service Area An MSC Service Area is made up of LAs and represents the geographical part of the network controlled by one MSC.

6. 6 Network Structure PLMN SERVICE AREA A PLMN service area is the entire set of cells served by one network operator and is defined as the area in which an operator offers radio coverage and access to its network.

7. 7 Network Structure GSM SERVICE AREA The GSM service area is the entire geographical area in which a subscriber can gain access to a GSM network.

8. 8 Relation between areas in GSM Location Area Cell Location Area MSC Service Area PLMN Service Area GSM Service Area

9. 9 Mobile Station GSM MSs consist of: Mobile Equipment Subscriber Identity Module

10. 10 Functions of Mobile Station Voice and data transmission & receipt Frequency and time synchronization Monitoring of power and signal quality of the surrounding cells Provision of location updates even during inactive state

11. 11 Mobile Station Can receive, store, send SMS up to 160 characters. MS identified by unique IMEI shown on pressing *#06#. Power levels of 20W, 8W, 5W, 2W and.8W

12. 12 SIM(Subscriber Identity Module ) SIM has microprocessor and memory. Fixed data stored for the subscription: IMSI, Authentication Key, Ki Security Algorithms:kc,A3,A8 PIN & PUK

13. 13 Network Identities IMEI MSISDN IMSI TMSI MSRN

14. 14 IMEI International Mobile Equipment Identity The IMEI is an unique code allocated to each mobile equipment. It is checked in the EIR. IMEI check List  White List  Grey List  Black List

15. 15 MSISDN Mobile Station ISDN Number The MSISDN is registered in the telephone directory and used by the calling party for dialing. MSISDN shall not exceed 15 digits. NDC--National Destination Code SN--Subscriber Number CCNDCSN 1 to 3 digitsVariable

16. 16 IMSI International mobile subscriber Identity The IMSI is an unique identity which is used internationally and used within the network to identify the mobile subscribers. The IMSI is stored in the subscriber identity module (SIM), the HLR, VLR database.

17. 17 Temporary Mobile subscriber Identity TMSI is a temporary IMSI no. made known to an MS at registration. The VLR assigns a TMSI to each mobile subscribers entering the VLR area. Assigned only after successful authentication.

18. 18 MSRN Mobile Station Roaming Number The MSRN is used in the GMSC to set up a connection to the visited MSC/VLR. MSRN--is a temporary identity which is assigned during the establishment of a call to a roaming subs.

19. 19 BASE STATION SYSTEM (BSS) n BTS BSC MSC/VLR BSS

20. 20 FUNCTIONS OF BTS (Base Transceiver Station)Base Transceiver Station Radio resources Signal Processing Signaling link management Synchronization Local maintenance handling Functional supervision and Testing

21. 21 FUNCTIONS OF BSC Radio Resource management Internal BSC O&M Handling of MS connections

22. 22 MSC-BSS Configurations BTS A-bis BSC BSS MSC A A-bis

23. Transcoder Is a device that takes 13 KBPS speech data and multiplexes four of them into standard 64 Kbps data. 23

24. 24 Switching System (SS) MSC (PSTN) VLR HLRAUC EIR D C SS7 Signalling Traffic Path F (BSS) A E Other MSC

25. 25 MSC Functions Switcing and call routing Charging Service provisioning Communication with HLR Communication with VLR Communication with other MSCs Control of connected BSCs

26. 26 MSC Functions Echo canceller operation control Signaling interface to databases like HLR, VLR. Gateway to SMS between SMS centers and subscribers Handle interworking function while working as G -MSC

27. 27 VISITOR LOCATION REGISTER (VLR) It contains data of all mobiles roaming in its area. One VLR may be incharge of one or more LA. VLR is updated by HLR on entry of MS its area. VLR assigns TMSI which keeps on changing.

28. 28 Data in VLR IMSI & TMSI(Tem.Mob. Subscriber Id) MSISDN (Mob.Sta. ISDN) MSRN.(Mob.Stat.Roaming Num.) Location Area Supplementary service parameters MS category Authentication Key

29. 29 Home Location Register(HLR) Reference store for subscriber’s parameters, numbers, authentication & Encryption values. Current subscriber status and associated VLR. Both VLR and HLR can be implemented in the same equipment in an MSC. one PLMN may contain one or several HLR.

30. 30 Home Location Register(HLR) Permanent data in HLR Data stored is changed only by commands. IMSI, MS-ISDN number. Category of MS ( whether pay phone or not ) Roaming restriction ( allowed or not ). Supplementary services like call forwarding

31. 31 Home Location Register(HLR) Temporary data in HLR The data changes from call to call & is dynamic MSRN VLR address, MSC address. Messages waiting data used for SMS

32. 32 EQUIPMENT IDENTITY REGISTER ( EIR ) This data base stores IMEI for all registered mobile equipments and is unique to every ME. Only one EIR per PLMN. White list : IMEI, assigned to valid ME. Black list : IMEI reported stolen Gray list : IMEI having problems like faulty software, wrong make of equipment etc.

33. 33 AUthentication Center (AUC) To authenticate the subs. attempting to use a network. AUC is connected to HLR which provides it with authentication parameters and ciphering keys used to ensure network security.

34. 34 AUC Functions To perform subscriber authentication and to establish ciphering procedures on the radio link between the network and MS.

35. 35 Information provided is called a TRIPLET consists of: 1.RAND (non predictable random number) 2.SRES (Signed response ) 3.Kc (ciphering key ) AUC Functions

36. 36 The centralized operation of the various units in the system and functions needed to maintain the subsystems. Dynamic monitoring and controlling of the network Operations and Maintenance Centre OMC Operations and Maintenance Centre OMC

37. 37 - O&M data function -Configuration management --Fault report and alarm handling -Performance supervision/management -Storage of system software and data Functions Of OMC Functions Of OMC

38. 38 Basic radio Transmission Parameters of GSM System GSM network consist of different cells. -each cell transmit signals to and receive signals from the mobile station. - for proper working of base station many parameters are defined before functioning the base station. -E.g. the coverage area of a cell depends on different factors including - the transmitting power of the base station -obstructing buildings in cells -height of the base station - location of base station.

39. 39 GSM Parameters: Paging Success Rate Immediate Assignment Success Rate Random Access Success Rate SDCCH Drop Rate TCH Assignment Success Rate Call Drop Rate Handover Success Rate

40. 40 Paging Success Rate Paging Success Rate is the to deal with as the process of paging touches almost all the nodes in GSM system. -In response to an incoming call, the MSC initiates the paging process. -by broadcasting a "paging request" message on the paging sub channel (IMSI or TMSI of the MS and its Paging Group) and starts timer T3113. - A "paging message" consists of the mobile identity (IMSI or TMSI) of the MS being paged and its "paging group number".

41. 41 -A Paging Request Message may include more than one MS identification. -The maximum number of paged MS per message is 4 when using "TMSI" for identification of the MS (maximum number of paged MS per message is 2 when using IMSI). -The BSC receives this page. -processes the paging request. - schedules it for transmission at appropriate time.

42. 42 - The MS on its part will analyze the paging messages (and immediate assignment messages) sent on the paging sub channel corresponding to its paging group. Upon receipt of a "paging request" message, MS will initiate within 0.7s an immediate assignment procedure. -Upon receipt of a page at the MS, the MS responds by transmitting a channel request.

43. 43 BSS in response to the received "channel request“. -It will process it. -immediately assign the MS a SDCCH (Stand alone Dedicated Control Channel). -MS Paging response- After receiving the immediate assignment command, MS switches to the assigned "SDCCH" and transmits a "Paging Response". -The establishment of the main signalling link is then initiated with information field containing the "PAGING RESPONSE" message and the "paging response" is sent to the MSC.

44. 44 -Upon receipt of the "Paging Response" MSC stops the timer T3113. -If the timer T3113 expires and a "Paging Response"message has not been received, the MSC may repeat the "Paging Request" message and start T3113 all over again. -The number of successive paging attempt is a network dependent choice.

45. 45 Random Access Success Rate -Random Access Channel (RACH) is used by the MS on the "uplink" to request for allocation of an SDCCH. -This request from the MS on the uplink could either be as a page response (MS being paged by the BSS in response to an incoming call) or due to user trying to access the network to establish a call. -Availability of SDCCH at the BTS will not have any impact on the Random Access Success.

46. 46 Random Access Success Rate In the transceiver, the timeslot handler in charge of the RACH channel listens for access burst from mobiles. - These bursts contain a check sequence (8 bits) that is used to determine if the message is valid.

47. 47 -Immediate Assignment Success Rate -SDCCH Drop Rate

48. 48 TCH(Traffic Channel) Assignment Success Rate -TCH assignment failure is a phenomenon where the MS is not able to use the TCH which is assigned to it for voice call. -This could happen due to uplink /downlink interference, faulty radio or faulty antenna system.

49. 49 Call Drop Rate TCH drop Rate (or a dropped call) could be broadly classified into 3 sub classes: -Degradation of the links (Uplink and Downlink): either degradation of Signal Strength which falls near or lower than the sensitivity of the base station. or that of the mobile or degradation of quality of the links (Uplink and Downlink) often due to interference. Excess TA (TA higher or excess path imbalance due to high TA). Other Reasons.

50. 50 Handover Success Rate Handover in BSS system is controlled an algorithm in the BSC. -This algorithm operates on the basis of Measurement Reports (MR) sent in by the MS on SACCH.

51. 51 Handover Success Rate -The inputs that the BSC uses for making a handover decision are. - from the received MRs from the MS is the DL signal strength - DL quality - the signal strength of the six best reported neighbours. -From the serving BTS, for the same MS the BSC will use UL signal strength - UL quality and TA.

52. 52 GSM Burst: It is defined as the information present in a particular time slot Each GSM RF carrier supports eight times lots and the data are transmitted in the form of bursts that are designed to fit within these slots.

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55. In GSM frequency band of 25 MHz is divided into 200 KHz of smaller bands,. -each carry one RF carrier, this gives 125 carriers. -As one carrier is used as guard channel between GSM and other frequency bands 124 carriers are useful RF channels. -This division of frequency pool is called FDMA. -Now each RF carrier will have eight time slots. -This division time is called TDMA.

56. Here each RF carrier frequency is shared between 8 users. -Hence in GSM system, the basic radio resource is a time slot with duration of about 577 microsec. As mentioned each time slot has 15/26 or 0.577ms of time duration. This time slot carries 156.25 bits which leads to bit rate of 270.833 kbps. This is explained below in TDMA gsm frame structure.

57. The GSM frame structure is designated as - hyperframe, -superframe, -multiframe -frame. -The minimum unit being frame (or TDMA frame) is made of 8 time slots.

58. -One GSM hyperframe composed of 2048 superframes. -Each GSM superframe composed of multiframes (either 26 or 51 as described below). -Each GSM multiframe composed of frames (either 51 or 26 based on multiframe type). Each frame composed of 8 time slots. -Hence there will be total of 2715648 TDMA frames available in GSM and the same cycle continues.

59. there are two types multiframe structure. 1.26 frame multiframe -It is Called traffic multiframe -composed of 26 bursts in a duration of 120ms -out of these 24 are used for traffic -one for SACCH and one is not used. 51 frame multiframe- -Called control multiframe -composed of 51 bursts in a duration of 235.4 ms.

62. each ARFCN or each channel in GSM will have 8 time slots TS0 to TS7. During network entry each GSM mobile phone is allocated one slot in downlink and one slot in uplink. In the figure GSM Mobile is allocated 890.2 MHz in the uplink and 935.2 MHz in the downlink.

63. As mentioned,TS0 is allocated which follows either 51 or 26 frame multiframe structure. Hence if at start 'F' is depicted which is FCCH after 4.615 ms ( which is 7 time slot duration), S(SCH) will appear. -Then after another 7 slots B(BCCH) will appear and so on till end of 51 frame Multiframe structure is completed. -cycle continues as long as connection between Mobile and base station is active.

64. -Similarly in the uplink, 26 frame multiframe structure follow, where T is TCH/FS (Traffic channel for full rate speech), and S is SACCH.(slow associated control channel).

65. Frequencies in the uplink = 890.2 + 0.2 (N-1) MHz Frequencies in the downlink = 935.2 + 0.2 (N-1) MHz where, N is from 1 to 124 called ARFCN. As same antenna is used for transmit as well as receive, there is 3 time slots delay introduced between TS0 of uplink and TSO of downlink frequency. It avoid need of simultaneous transmission and reception by GSM mobile phone.

66. This 3 slot time period is used by the Mobile subscriber to perform various functions e.g. processing data, measuring signal quality of neighbour cells etc.

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69. 69 Burst types The information contained in one time slot is a burst. 5 types of bursts are available Normal burst Used to send all other logical channel information. Frequency correction burst Used to transmit the FCCH channel. Synchronisation burst Used to transmit synchronization information.

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72. 72 Access burst Used to send RACH information.It has a long guard period to allow the BTS to calculate the MS distance from the BTS and to provide timing advance information to the MS. Dummy burst Used to fill up unused timeslots, which transmits the BCCH channel. No real information.

73. Location Update

74. Procedure of Location Update

75. SET UP CALLS IN GSM NETWORK +90 400 398 0102 MSISDN = CC + NDC + SN CC : Country Code NDC : National Destination Code SN : Subscriber Number GMSC : Gateway Mobile Services Switching Center

76. REACH CALLS FROM PSTN TO GSM NETWORK

77. GUİDE CALL TO GSM NETWORK

78. CONTENT OF HLR MSISDN IMSI They provide the right call, right service IMSI = MCC+MNC+MSIN MCC = Mobile Country Code MNC = Mobile Network Code MSIN = Mobile Sucscriber Identification Number

79. MSRN (Mobile Station Roaming Number) MSRN = CC + NDC + SN CC : Country Code NDC : National Destination Code SN : Subscriber Number 2.MSC wants to MSRN FROM HLR(Left Photo) HLR gives MSRN to MSC for startin call(Right Photo)

80. PROCEDURE OF CALL SET UP

81. Procedure The number is MSISDN PSTN central analyse the MSISDN and connect to GMSC GMSC analyse the MSISDN and send message HLR HLR control databases and thrust into the user’s location HLR query MSC/VLR

82. MSC/VLR produce MSRN MSC/VLR send MSRN to HLR, HLR send it to GMSC GMSC realise MSC/VLR for forwarding call MSC/VLR gets MSRN and starts to call MSC/VLR starts to paging process in location area.The user is found with paging signal and call set up

83. PROCEDURE OF CALL SET UP FROM MOBİLE USER

84. HANDOVER TWO REASON When The Radio Signal’s quality and power decreases to necessary scores, the connection deliver to more powerful cell When The Trraffic Capacity approaches to maximum, the connection deliver to less density of traffic cell

85. SIGNALS AND PROTOCOLS STANDART MESSAGES SENDER WANTS TO SERVICE OPERATOR ASK THAT YOU WANTS TO TALK,BUT WHICH USER OPERATOR CONNECT TO RECEIVER WHEN THE RECEIVER REPLIES TO CALL,THE CALL STARTS WHEN THE RECEIVER OR SENDER CLOSE THE PHONE, THE OPERATOR FINISH CONNECTION TO EACH OTHER

86. PROCEDURE OF SIGNALS

87. COMMON CHANNEL SIGNALLING SYSTEM MTP(MASSAGE TRANSFER PART) TUP(TELEPHONE USER PART) SSCP(SIGNALLING CONNECTION AND CONTROL PART)

88. MTP(MASSAGE TRANSFER PART)

89. PHYSICAL CONNECTION It includes data links and their propertie DATA LINK CONTROL It helps to transfer messages between component of network perfectly NETWORK LAYER It provides to transfer messages between component of network

90. TUP(TELEPHONE USER PART)

91. User’s identification Who get this messages or signals Who make a process this signal TUP,NUD,ISUP help to set up calls and they make same task

92. SIGNALLING CONNECTION AND CONTROL PART

93. It provides virtual connections It guarentee to transfer messages from every signals point to every signals point secure It provides multi-point communication

94. Briefly MTP transmit messages TUP use this messages.It sets up calls,manages calls and finishes calls SCCP create virtual connections and multi- point communication

95. OTHER SS7 APPLICATION IN GSM NETWORK BSSAP(Base Station Subsystem Application Part) MAP (Mobile Application Part) TCAP (Transaction Capabilities Application Part)

96. BASE STATION SUBSYSTEM APPLICATION PART It provide MSC-BSC and MSC-MS communication SCCP service is required

97. MOBILE APPLICATION PART Before the call is guided to HLR, MSRN is wanted from HLR, so the another protocol is added SS7 which is called MAP It provides to communicate between Component of Network Switching Subsystem MAP only uses for non-call-related messaging in MSC-MSC communication

98. TCAP (Transaction Capabilities Application Part) It manages to communication in MAP It likes a secretary

99. SS7 LAYER IN COMPONENT OF GSM SET OF PROTOCOL IN MSC SET OF PROTOCOL IN HLR SET OF PROTOCOL IN BSC

100. SET OF PROTOCOL IN MSC

101. MSC control calls MTP is required for all components which works with SS7 TUP/ISUP is reuired for calls It has all components of layers in SS7