GSM      www.awesomebackgrounds.com
Introduction to GSM
• Problem: Beginning of 1980s - European  countries were using many and different  incompatible mobile phone systems.  Inc...
• Advantage of GSM:• Digital Radio Path = system tolerates more  inter-cell interference, thus efficient use of RF• Better...
Three Subsystems in GSMNetwork• Network Switching Subsystem (NSS)• Base Station Subsystem (BSS)• Network Management System
Base Station Controller (BSC ) handles allocation of radio channels, receivesmeasurements from the mobile phones, control...
• How does the network keep track of  the subscribers?   – Through LOCATION UPDATE   – Through the help of various DATABASES
The First Database•   The Subscriber Identity Module (SIM)     – a small memory device mounted on a card that contains use...
The Second•                Database    The Visitor Location Register (VLR)    – database which temporarily keeps record of...
The Third Database• The Home Location Register (HLR)   – The HLR is a database used for storage and     management of subs...
SECURITY ANDAUTHENTICATION
SIM CARDS•   SIM cards store network specific information used to authenticate    and identify subscribers on the Network....
•   IMSI        International Mobile Subscriber Identity is a unique number    stored in the Subscriber Identity Module (S...
•   AUTHENTICATION CENTER (AUC) —         authentication and encryption parameters that verify the    users identity•     ...
•   AUTHENTICATION PROCESS:•     Ki is a 128-bit value securely burned into the SIM during manufacture    and is also secu...
• TRIPLET NUMBER:• The triplets are RAND,SRES,KC. they are stored         in the    AUC. They are sent to the mobile switc...
GSM Security Management      AC             VLR               BTS      Air Interface          ME         SIMRAND          ...
•   International Mobile Equipment Identity :            The International Mobile Equipment Identity or    IMEI is a numbe...
•    The model and origin comprise the initial 8-digit portion of the    IMEI/SV, known as the Type Allocation Code (TAC)•...
•   Retrieving IMEI information from a GSM device•      On many devices the IMEI number can be retrieved by entering    *#...
• Blacklisted or Barred Handsets                 If your phone is lost , report it to your service provider    (your netwo...
Location Update  • Location Registration (power on) -                          IMSI Attach.  • Generic - every time MS det...
First time Location Update (1)              HLR DB              MSISDN         IMSI              VLR Address   Sub. Data  ...
Generic Location Update                                    HLR DB                                    MSISDN         IMSI  ...
Call Establishment (PSTNO-MT)                                HLR DB                                MSISDN         IMSI    ...
Paging• What the network does to locate the called  subscriber.• Service Area of VLR is divided into smaller  areas called...
Call Establishment (MO-PSTNT)                                          MSISDN (A)                                         ...
Call Establishment (MO-MT)                                       HLR DB                                       MSISDN      ...
Handover • The process by which an ongoing call   handled by one cell is transferred to another   cell. • Two reasons for ...
Handover (1)                                    HLR          PSTN         MSC/VLR 1                 MSC/VLR 2             ...
Handover (2)                             HLR     PSTN       MSC/VLR 1                 MSC/VLR 2               BSC1        ...
Handover (3)                             HLR     PSTN       MSC/VLR 1                 MSC/VLR 2               BSC1        ...
Handover (4)                             HLR     PSTN       MSC/VLR 1                 MSC/VLR 2               BSC1        ...
Handover (5)                             HLR     PSTN       MSC/VLR 1                   MSC/VLR 2               BSC1      ...
Handover (6)                             HLR     PSTN       MSC/VLR 1                 MSC/VLR 2               BSC1        ...
Handover (7)                             HLR     PSTN       MSC/VLR 1                 MSC/VLR 2               BSC1        ...
Transmission
AIR INTERFACE            Frequency Allocation                              Radio Channel                              DOWN...
Terminologies • Uplink - signal flow from MS to BTS • Downlink - signal flow from BTS to MS • Transceivers (TRX) - devices...
LOGICAL CHANNELS• Common Channels - used for  broadcasting different info to MS and  setting up of signaling channels betw...
LOGICAL CHANNELS11 Logical Channels in the GSM system:    2 are used for Traffic    9 are used for Control Signaling
LOGICAL CHANNELSTRAFFIC CHANNELS (TCH)          Full Rate Channel          Half Rate ChannelCONTROL CHANNELS    Broadcast ...
BROADCAST CHANNELSFCCH = FREQUENCY CORRECTION CHANNEL=> To tell the Mobile that this is the BCCH carrier=> To able the Mob...
BROADCAST CHANNELSall downlink! Hey. I’m a                GSM?                     GSM emitter!                 FCCH      ...
COMMON CONTROL CHANNELSPCH = PAGING CHANNEL=> Used for paging the Mobile. (Downlink only)   Reason could be an incoming ca...
COMMON CONTROL CHANNELS      Hello! You have a call.                                Hello! I have to set           PCH dow...
DEDICATED CONTROL CHANNELSSDCCH = STAND ALONE DEDICATED CONTROL CHANNEL=> Used for allocating voice channel (TCH) to the m...
DEDICATED CONTROL CHANNELSuplink and downlink    On SDCCH:                         -call set up signaling                 ...
CBCH = CELL BROADCAST CHANNEL=> Used for sending short messages to all the mobiles within a geographic area.  Up to 93 cha...
FUTURE OF GSM•    UMTS    Universal Mobile Telecommunications System (UMTS) is one of the    third-generation (3G) cell ph...
CONCLUSION •   What is GSM? •   Advantages of GSM •   Security and authentication •   Location updates •   Handover •   Ch...
Queries?       www.awesomebackgrounds.com
Final gsm1
Final gsm1
Final gsm1
Upcoming SlideShare
Loading in …5
×

Final gsm1

2,446 views

Published on

College Tech Ppt2

Published in: Education
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
2,446
On SlideShare
0
From Embeds
0
Number of Embeds
4
Actions
Shares
0
Downloads
68
Comments
0
Likes
2
Embeds 0
No embeds

No notes for slide
  • 1. Mobile Station monitors the information broadcast by the network. includes ID of the VLR area. 2. Mobile station stores the current ID (LAI) in the SIM card...compares it with the incoming ID. If different, MS requests for Location Update request.
  • 1. Mobile continues to monitor the broadcast information. 2. If the LAC broadcasted by the network is different from what is stored in the SIM, the MS starts Location Update procedure ( channel request ). 3. New VLR reads TMSI and old LAI. 4. New MSC gets IMSI from old MSC. 5. New MSC asks info from HLR via IMSI and updates both VLR and HLR after successful authentication.
  • How do we maintain connection when we are mobile? 1. Handover due to measurements ( BSC decides ) 2. Handover due to traffic reasons. ( MSC decides )
  • 02/02/99 14 OD and Training Smart Communications, Inc.
  • 02/02/99 11 OD and Training Smart Communications, Inc. Traffic Channels (TCH) Two types of TCH are used:  Full rate channel This channel can be used for full rate or enhanced full rate speech (13 kbps after speech coder) or data up to 9.6 kbps.  Half rate channel This channel can be used for half rate speech (6.5 kbps after speech coder) or data up to 4.8 kbps. Control Channels Nine different types of control channels are used.  Broadcast Channels (BCH)  FCCH is used for frequency correction of the MS, downlink only.  SCH carries information about TDMA frame number and BSIC of the BTS, downlink only.  BCCH broadcasts cell specific information to the MS, downlink only.
  • 02/02/99 11 OD and Training Smart Communications, Inc. Traffic Channels (TCH) Two types of TCH are used:  Full rate channel This channel can be used for full rate or enhanced full rate speech (13 kbps after speech coder) or data up to 9.6 kbps.  Half rate channel This channel can be used for half rate speech (6.5 kbps after speech coder) or data up to 4.8 kbps. Control Channels Nine different types of control channels are used.  Broadcast Channels (BCH)  FCCH is used for frequency correction of the MS, downlink only.  SCH carries information about TDMA frame number and BSIC of the BTS, downlink only.  BCCH broadcasts cell specific information to the MS, downlink only.
  • 02/02/99 12 OD and Training Smart Communications, Inc.  Common Control Channels (CCCH)  PCH is used to page the MS, downlink only.  RACH is used by the MS to request allocation of a SDCCH, either as a page response or an access at MS call origination/registration, location updating, etc., uplink only.  AGCH is used to allocate SDCCH to a MS, downlink only.  Dedicated Control Channels (DCCH)  SDCCH is used for signaling during call set-up or registration, up and downlink.  SACCH - control channel associated with a TCH or a SDCCH, up and downlink. On this channel the measurement reports are sent on uplink, and timing advance and power orders on downlink.  FACCH - control channel associated with a TCH, up and downlink. FACCH works on stealing mode, such as 20 ms of speech is replaced by a control message. It is used during handover when the SACCH signaling is not fast enough. Several logical channels can share the same physical channel, or Time Slots (TS). On TS zero, the BCCH and the CCCH are multiplexed.
  • 02/02/99 12 OD and Training Smart Communications, Inc.  Common Control Channels (CCCH)  PCH is used to page the MS, downlink only.  RACH is used by the MS to request allocation of a SDCCH, either as a page response or an access at MS call origination/registration, location updating, etc., uplink only.  AGCH is used to allocate SDCCH to a MS, downlink only.  Dedicated Control Channels (DCCH)  SDCCH is used for signaling during call set-up or registration, up and downlink.  SACCH - control channel associated with a TCH or a SDCCH, up and downlink. On this channel the measurement reports are sent on uplink, and timing advance and power orders on downlink.  FACCH - control channel associated with a TCH, up and downlink. FACCH works on stealing mode, such as 20 ms of speech is replaced by a control message. It is used during handover when the SACCH signaling is not fast enough. Several logical channels can share the same physical channel, or Time Slots (TS). On TS zero, the BCCH and the CCCH are multiplexed.
  • 02/02/99 15 OD and Training Smart Communications, Inc.
  • 02/02/99 12 OD and Training Smart Communications, Inc.  Common Control Channels (CCCH)  PCH is used to page the MS, downlink only.  RACH is used by the MS to request allocation of a SDCCH, either as a page response or an access at MS call origination/registration, location updating, etc., uplink only.  AGCH is used to allocate SDCCH to a MS, downlink only.  Dedicated Control Channels (DCCH)  SDCCH is used for signaling during call set-up or registration, up and downlink.  SACCH - control channel associated with a TCH or a SDCCH, up and downlink. On this channel the measurement reports are sent on uplink, and timing advance and power orders on downlink.  FACCH - control channel associated with a TCH, up and downlink. FACCH works on stealing mode, such as 20 ms of speech is replaced by a control message. It is used during handover when the SACCH signaling is not fast enough. Several logical channels can share the same physical channel, or Time Slots (TS). On TS zero, the BCCH and the CCCH are multiplexed.
  • 02/02/99 16 OD and Training Smart Communications, Inc.
  • 02/02/99 12 OD and Training Smart Communications, Inc.  Common Control Channels (CCCH)  PCH is used to page the MS, downlink only.  RACH is used by the MS to request allocation of a SDCCH, either as a page response or an access at MS call origination/registration, location updating, etc., uplink only.  AGCH is used to allocate SDCCH to a MS, downlink only.  Dedicated Control Channels (DCCH)  SDCCH is used for signaling during call set-up or registration, up and downlink.  SACCH - control channel associated with a TCH or a SDCCH, up and downlink. On this channel the measurement reports are sent on uplink, and timing advance and power orders on downlink.  FACCH - control channel associated with a TCH, up and downlink. FACCH works on stealing mode, such as 20 ms of speech is replaced by a control message. It is used during handover when the SACCH signaling is not fast enough. Several logical channels can share the same physical channel, or Time Slots (TS). On TS zero, the BCCH and the CCCH are multiplexed.
  • 02/02/99 17 OD and Training Smart Communications, Inc.
  • 02/02/99 12 OD and Training Smart Communications, Inc.  Common Control Channels (CCCH)  PCH is used to page the MS, downlink only.  RACH is used by the MS to request allocation of a SDCCH, either as a page response or an access at MS call origination/registration, location updating, etc., uplink only.  AGCH is used to allocate SDCCH to a MS, downlink only.  Dedicated Control Channels (DCCH)  SDCCH is used for signaling during call set-up or registration, up and downlink.  SACCH - control channel associated with a TCH or a SDCCH, up and downlink. On this channel the measurement reports are sent on uplink, and timing advance and power orders on downlink.  FACCH - control channel associated with a TCH, up and downlink. FACCH works on stealing mode, such as 20 ms of speech is replaced by a control message. It is used during handover when the SACCH signaling is not fast enough. Several logical channels can share the same physical channel, or Time Slots (TS). On TS zero, the BCCH and the CCCH are multiplexed.
  • Final gsm1

    1. 1. GSM www.awesomebackgrounds.com
    2. 2. Introduction to GSM
    3. 3. • Problem: Beginning of 1980s - European countries were using many and different incompatible mobile phone systems. Increased needs for telecommunication services• Action by CEPT: founded a group to CEPT specify a common mobile system for WESTERN EUROPE• Name of the Group and System: GSM – “Groupe Speciale Mobile” – Global System for Mobile Communications
    4. 4. • Advantage of GSM:• Digital Radio Path = system tolerates more inter-cell interference, thus efficient use of RF• Better Quality of speech• Data transmission is supported• New services offered due to ISDN compatibility• International Roaming possible• Large market = increased competition and lower investment for operators and rates for users.
    5. 5. Three Subsystems in GSMNetwork• Network Switching Subsystem (NSS)• Base Station Subsystem (BSS)• Network Management System
    6. 6. Base Station Controller (BSC ) handles allocation of radio channels, receivesmeasurements from the mobile phones, controls handovers from BTS to BTS . Akey function of the BSC is to act as a concentrator where many different lowcapacity connections to BTSs (with relatively low utilisation) become reduced toa smaller number of connections towards the Mobile Switching Center (MSC)The Base Transceiver Station, or BTS, contains the equipment for transmittingand receiving of radio signals (transceivers), antennas, and equipment forencrypting and decrypting communications with the Base Station Controller(BSC).TRAU (Transcoder and Rate Adaptation Unit). The transcoding functionconverts the voice channel coding between the GSM . compress voice channelsfrom the 64 kbit/s PCM standard to the 13 kbit/s rate used on the air interface.Packet Control UnitIt performs some of the processing tasks of the BSC, but for packet data. Theallocation of channels between voice and data is controlled by the base station,but once a channel is allocated to the PCU, the PCU takes full control over thatchannel.
    7. 7. • How does the network keep track of the subscribers? – Through LOCATION UPDATE – Through the help of various DATABASES
    8. 8. The First Database• The Subscriber Identity Module (SIM) – a small memory device mounted on a card that contains user specific identification – The SIM is a detachable smart card containing the users subscription information and phonebook – the SIM + mobile equipment = mobile station (MS), a device able to access services in a GSM network via the Air interface. + = Air Interface Subscriber Identity Mobile Module Mobile GSMEquipment Station Network
    9. 9. The Second• Database The Visitor Location Register (VLR) – database which temporarily keeps record of subscribers currently located in the service area of the MSC – to inform the HLR that a subscriber has arrived in the particular area covered by the VLR – to track where the subscriber is within the VLR area (location area) when no call is ongoing – to allocate roaming numbers during the processing of incoming calls Visitor Location Register Mobile Switching Center
    10. 10. The Third Database• The Home Location Register (HLR) – The HLR is a database used for storage and management of subscriptions. – stores permanent data about subscribers, including a subscribers service profile, location information, and activity status. – When an individual buys a subscription he or she is registered in the HLR of that operator. Home Location Register
    11. 11. SECURITY ANDAUTHENTICATION
    12. 12. SIM CARDS• SIM cards store network specific information used to authenticate and identify subscribers on the Network. ICCID IMSI Authentication Key (Ki) Local Area Identity (LAI) Operator-Specific Emergency Number SMSC (Short Message Service Center) number Service Provider Name (SPN) Service Dialing Numbers (SDN) Value Added Service (VAS) applications
    13. 13. • IMSI International Mobile Subscriber Identity is a unique number stored in the Subscriber Identity Module (SIM) inside the phone and is sent by the phone to the network. MCC 284 Bulgaria IMSI: 284011234567890 MNC 01 MobilTel MSIN 1234567890 IMSI analysis is the process of examining a subscribers IMSI to identify which network the IMSI belongs to and whether subscribers from that network are allowed to use a given network . If they are not local subscribers, this will require a roaming agreement.
    14. 14. • AUTHENTICATION CENTER (AUC) — authentication and encryption parameters that verify the users identity• ensure the confidentiality of each call.• FUNCTION OF AUC: AUC generates data known as triplets for the MSC to use during the procedure. The security of the process depends upon a shared secret between the AUC and the SIM called the Ki. The AUC stores the following data for each IMSI:• the Ki• Algorithm id (the standard algorithms are called A3 or A8, but an operator may choose a proprietary one).
    15. 15. • AUTHENTICATION PROCESS:• Ki is a 128-bit value securely burned into the SIM during manufacture and is also securely replicated onto the AUC.• This Ki is never transmitted between the AUC and SIM• Each SIM holds a unique Ki assigned to it by the operator during the personalization process.• When the MSC asks the AUC for a new set of triplets for a particular IMSI, the AUC first generates a random number known as RAND. This RAND is then combined with the Ki to produce two numbers as follows: The Ki and RAND are fed into the A3 algorithm and a number known as Signed RESponse or SRES is calculated. The Ki and RAND are fed into the A8 algorithm and a session key called Kc is calculated.
    16. 16. • TRIPLET NUMBER:• The triplets are RAND,SRES,KC. they are stored in the AUC. They are sent to the mobile switching centre.• MSC sends the RAND part of the triplet to the SIM. The SIM then feeds this number and the Ki (which is burned onto the SIM) into the A3 algorithm as appropriate and an SRES is calculated and sent back to the MSC .• If this SRES matches with the SRES in the triplet generated from the authentication center.• The SIM card is made valid and authenticated.
    17. 17. GSM Security Management AC VLR BTS Air Interface ME SIMRAND SRES Authentication SRES KiKi A3 COMPARING A3 Request of IMEI EIR IMEI Checking ME Provide IMEI Traffic Traffic Ciphering Kc Kc A8 A5 Encrypted Data Encrypted Data A5 A8
    18. 18. • International Mobile Equipment Identity : The International Mobile Equipment Identity or IMEI is a number unique to every GSM and UMTS mobile phone• The IMEI number is used by the GSM network to identify valid devices .• The IMEI (14 digits plus check digit) or IMEISV (16 digits) includes information on the origin, model, and serial number of the device AA BBBBBB CCCCCC D EE Reporting The remainder Serial sequence Luhn check Software Body of the TAC of the model digit of the Version Identifier, entire number Number indicating the (or zero) (SVN). GSMA- approved group that allocated the model TAC
    19. 19. • The model and origin comprise the initial 8-digit portion of the IMEI/SV, known as the Type Allocation Code (TAC)• The remainder of the IMEI is manufacturer-defined, with a Luhn check digit at the end (which is never transmitted).• The IMEISV drops the Luhn check digit in favour of an additional 2 digits for the Software Version Number (SVN) in the format AA- BBBBBB-CCCCCC-EE• For example• IMEI code 35-209900-176148-1 IMEISV code 35-209900-176148-23 tells us the following: TAC: 352099 so it was issued by the BABT and has the allocation number 2099 FAC: 00 so it was numbered during the transition phase from the old format to the new format (described below) SNR: 176148 - uniquely identifying a unit of this model CD: 1 so it is a GSM Phase 2 or higher SVN: 23 - The software version number identifying the revision of the software installed on the phone.
    20. 20. • Retrieving IMEI information from a GSM device• On many devices the IMEI number can be retrieved by entering *#06#.• The IMEI can frequently be displayed through phone menus, under a section titled System Information, Device, Phone Info or similar. Many phones also have the IMEI listed on a label in the battery compartment.• Retrieving IMEI Information from a Sony or Sony Ericsson handset can be done by entering these keys: Right * Left Left * Left * (Other service menu items will be presented with this key combination).• The IMEI information can be retrieved from most Nokia mobile phones by pressing *#92702689# (*#WAR0ANTY#), this opens the warranty menu in which the first item is the serial number (the IMEI). The warranty menu also shows other information such as the date the phone was made and the life timer of the phone.
    21. 21. • Blacklisted or Barred Handsets If your phone is lost , report it to your service provider (your network) immediately.• Add your phones serial number onto a national blacklist database CENTRAL EQUIPMENT IDENTITY REGISTER(CEIR).• At this point the IMEI number of your handset is cross referenced with the Central Equipment Identity Register. If the IMEI number of your handset• 1) Refuse to send a signal to your phone (No signal strength at all) 2) OR WILL supply a signal but will not allow any outgoing or      incoming calls• Changing the IMEI number is illegal.
    22. 22. Location Update • Location Registration (power on) - IMSI Attach. • Generic - every time MS detects a change in Location Area • Periodic - location updates at regular intervals set by the operator. (default 7 hours)
    23. 23. First time Location Update (1) HLR DB MSISDN IMSI VLR Address Sub. Data 63+918+9499247 310+02+1234567890 vlr 2 services HLR Loc Up IMSI Request IMSIMSC MSC BTS MS B BSC VLR2 1 VLR1 Authen 1 Loc Up + TMSI LAI 1 VLR DB IMSI MSRN LAI DATA 310+02+1234567890 1
    24. 24. Generic Location Update HLR DB MSISDN IMSI VLR Address Sub. Data 63+918+9499247 310+02+1234567890 vlr12 vlr services HLR Subscriber Info TMSI + LAI Del old Update data TMSI MSC MSC BTS MS B BSC 1 VLR1 VLR2 Authentication 1 IMSI Loc Up + new TMSI Security Info LAI 1VLR 1DBIMSI MSRN LAI VLR2 DB IMSI MSRN LAI DATA310+02+1234567890 x 310+02+1234567890 1 services
    25. 25. Call Establishment (PSTNO-MT) HLR DB MSISDN IMSI VLR Address Sub. Data 63+918+9499247 310+02+1234567890 vlr2 services HLR Enquiry HLR MSISDN IMSI = MCC+MNC+MSIN IMSI MSC 1 MSC 2 BTS B B BSC1 MS PSTN 1 VLR1 VLR2 MSISDN VLR DB IMSI MSRN LAI LAI 1 DATA 310+02+1234567890 1 MSRN A services POOL MSRN = CC+NDC+SNMSISDN (B)CC+ NDC + SN63 9189499247
    26. 26. Paging• What the network does to locate the called subscriber.• Service Area of VLR is divided into smaller areas called Location Areas (LA)• LAI - Location Area Identity – LAI = MCC + MNC +LAC• VLR knows the LA of the subscriber• VLR2 DB• IMSI MSRN LAI DATA• 310+02+1234567890 1 services• All the BTSs within that LA is paged for the subscriber.
    27. 27. Call Establishment (MO-PSTNT) MSISDN (A) CC+ NDC + SN HLR 63 2 5113580 MSISDN MSC MSC BTS B PSTN BSC MS 1 VLR1 VLR2 1 LAI 1A
    28. 28. Call Establishment (MO-MT) HLR DB MSISDN IMSI VLR Address Sub. Data 63+918+9499247 310+02+1234567890 vlr1 services HLR HLR Enquiry IMSI = MCC+MNC+MSIN MSISDN MSISDN IMSI MSC MSC BTS B B MS BSC 1 VLR1 VLR2 1VLR DBIMSI MSRN LAI Services 2 Speech LAI 1 MSISDN (C) CC+ NDC + SNMSRN 63 918 9499247 BTS MS C MSRN = CC+NDC+SN BSC 2 2 LAI2
    29. 29. Handover • The process by which an ongoing call handled by one cell is transferred to another cell. • Two reasons for Handover: – Handover due to Measurements – Handover due to Traffic Reasons • Four Types of Handover: – Intra cell - Intra BSC Handover – Inter cell - Intra BSC Handover – Inter cell - Inter BSC Handover – Inter MSC Handover
    30. 30. Handover (1) HLR PSTN MSC/VLR 1 MSC/VLR 2 BSC1 BSC2 BSC3 A BTS1 BTS2 BTS3 BTS4Measurement Report B
    31. 31. Handover (2) HLR PSTN MSC/VLR 1 MSC/VLR 2 BSC1 BSC2 BSC3A BTS1 BTS2 BTS3 BTS4 BI am OK
    32. 32. Handover (3) HLR PSTN MSC/VLR 1 MSC/VLR 2 BSC1 BSC2 BSC3A BTS1 BTS2 BTS3 BTS4 Measurement Report B
    33. 33. Handover (4) HLR PSTN MSC/VLR 1 MSC/VLR 2 BSC1 BSC2 BSC3A BTS1 BTS2 BTS3 BTS4 BI am OK
    34. 34. Handover (5) HLR PSTN MSC/VLR 1 MSC/VLR 2 BSC1 BSC2 BSC3A BTS1 BTS2 BTS3 BTS4 Measurement Report B
    35. 35. Handover (6) HLR PSTN MSC/VLR 1 MSC/VLR 2 BSC1 BSC2 BSC3A BTS1 BTS2 BTS3 BTS4 I am OK B
    36. 36. Handover (7) HLR PSTN MSC/VLR 1 MSC/VLR 2 BSC1 BSC2 BSC3A BTS1 BTS2 BTS3 BTS4 B
    37. 37. Transmission
    38. 38. AIR INTERFACE Frequency Allocation Radio Channel DOWNLINK 935 - 960 MHz 1805-1880 MHz UPLINK 890-915 MHz 1710-1785 MHz MobileCell Site Air Interface
    39. 39. Terminologies • Uplink - signal flow from MS to BTS • Downlink - signal flow from BTS to MS • Transceivers (TRX) - devices in the BTS that transmit and receive radio signals in each of the GSM channels. • Implementation of Digital Radio Transmission in GSM: – FDMA (Frequency Division Multiple Access) – TDMA (Time Division Multiple Access)
    40. 40. LOGICAL CHANNELS• Common Channels - used for broadcasting different info to MS and setting up of signaling channels between MSC/VLR and the MS• Dedicated Channels - used to facilitate the discussions between the MS and the BTS, BSC and MSC/VLR.
    41. 41. LOGICAL CHANNELS11 Logical Channels in the GSM system: 2 are used for Traffic 9 are used for Control Signaling
    42. 42. LOGICAL CHANNELSTRAFFIC CHANNELS (TCH) Full Rate Channel Half Rate ChannelCONTROL CHANNELS Broadcast Channels (BCH) Frequency Correction Channel (FCCH) Synchronization Channel (SCH) Broadcast Control Channel (BCCH) Common Control Channels (CCCH) Paging Channel (PCH) Random Access Channel (RACH) Access Grant Channel (AGCH) Dedicated Control Channels (DCCH) Stand alone Dedicated Control Channel (SDCCH) Slow Associated Control Channel (SACCH) Fast Associated Control Channel (FACCH)
    43. 43. BROADCAST CHANNELSFCCH = FREQUENCY CORRECTION CHANNEL=> To tell the Mobile that this is the BCCH carrier=> To able the Mobile to synchronize to the frequency (Downlink only)SCH = SYNCHRONISATION CHANNEL=> Used for sending BSIC (Base station Identity Code)=> Give TDMA frame number to the Mobile. (Downlink only)BCCH = BROADCAST CONTROL CHANNEL=> Used for sending information to the mobile like CGI (Cell Global identity), LAI (Location Area Identity), BCCH carriers of the neighboring cells, maximum output power allowed in the cell. (Downlink only)
    44. 44. BROADCAST CHANNELSall downlink! Hey. I’m a GSM? GSM emitter! FCCH GSM!!! SCH TDMA…BSIC... BCCH LA…neighbors…cell info…max power... Hey! Don’t shout at me, lower your power... Ok…ok
    45. 45. COMMON CONTROL CHANNELSPCH = PAGING CHANNEL=> Used for paging the Mobile. (Downlink only) Reason could be an incoming call or an incoming Short Message.RACH = RANDOM ACCESS CHANNEL=> Used for responding to the paging (terminating), Location updating or to make call access (originating) by asking for a signaling channel. (Uplink only)AGCH = ACCESS GRANT CHANNEL=> Used to allocate SDCCH to the mobile. (Downlink only)
    46. 46. COMMON CONTROL CHANNELS Hello! You have a call. Hello! I have to set PCH downlink only up a call. I need SDCCH. RACH uplink only AGCH downlink only Ok. Use SDCCH.
    47. 47. DEDICATED CONTROL CHANNELSSDCCH = STAND ALONE DEDICATED CONTROL CHANNEL=> Used for allocating voice channel (TCH) to the mobile (call setup) and Location updating.=> Send Short Text message to Idle Mobile (Uplink & Downlink)SACCH = SLOW ASSOCIATED CONTROL CHANNEL=> Used for sending information to the mobile like CGI (Cell Global identity), LAI (Location Area Identity), BCCH of all the neighbors cells.=> Send Short Text message to Busy Mobile (Downlink)=> Used for sending signal strength & bit error rate measurement of the serving cell and signal strength of the BCCHs of the neighboring cells. (Uplink)FACCH = FAST ASSOCIATED CONTROL CHANNEL=> Used for handover. (Uplink & Downlink)
    48. 48. DEDICATED CONTROL CHANNELSuplink and downlink On SDCCH: -call set up signaling -location updating -periodic registration -SMS SDCCH etc….. SACCH On SACCH -used to send signal strength & bit error rate measurement of the serving cell FACCH handover
    49. 49. CBCH = CELL BROADCAST CHANNEL=> Used for sending short messages to all the mobiles within a geographic area. Up to 93 characters can be sent.=> If the mobile is in the Idle mode then the short message will be send through the CBCH. If the mobile is Busy, it will not be sent. SMS(SHORT MESSAGE SERVICE)=> SMS messages are short TEXT messages up to 160 characters in length that you can send or receive. The messages are not sent straight to the other mobile but is sent to message centre operated by the Network provider.=> If the mobile was switched off or is at outside of the coverage area, the message is stored in the Message Service Center. The message will be offered to the subscriber when the mobile is switched on again or has reentered the coverage area again.=> If the mobile is in the Idle mode the short message will be send through the SDCCH. If the mobile is Busy the short message will send through the SACCH.
    50. 50. FUTURE OF GSM• UMTS Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) cell phone technologies It uses WCDMA access method It is also called as 3GSM 1GB SIM CARD The new 1 GB S-SIM card utilizes System-in-Package (SiP) technology that enables it to carry the high-capacity NAND flash memory module without increasing the size of the standard SIM card.
    51. 51. CONCLUSION • What is GSM? • Advantages of GSM • Security and authentication • Location updates • Handover • Channels • Future of GSM REFERENCES • Google.com • Wikipedia.org • Howstuffworks.com
    52. 52. Queries? www.awesomebackgrounds.com

    ×