Copy Of Rttc Training

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Global System for Mobile communications (1984 )

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Globally accepted standard for digital cellular communication.

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Use narrowband TDMA (time division multiple access) technique for transmitting signal

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GSM makes use of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA).

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It provides fundamental recommendation and requirement for mobile set, network system. So, there is open interface.

Imp ro ved s pec tr um effi cienc y. In ter nat ional roaming. Lo w- cos t mobile set s and bas e stat ions (B Ss ) Hig h- qualit y s pe ec h Co mpati bility w ith Int egr at ed S erv ic es Dig ital Net wor k (IS DN) an d ot her t eleph one c ompany ser vic es . Supp or t f or n ew s erv ic es . Standar di za tion of the air an d t he net wor k in ter fac es . Sec urit y

3G

2.75G Intermediate Multimedia

2.5G 2G

Multimedia

Packet Data

Digital Voice

1G Analog Voice

GPRS

GSM

EDGE

W-CDMA (UMTS)

384 Kbps

Up to 2 Mbps

115 Kbps

NMT

9.6 Kbps

GSM/ GPRS

TD-SCDMA

(Overlay) 115 Kbps

2 Mbps?

TDMA TACS

9.6 Kbps

iDEN 9.6 Kbps

iDEN PDC

(Overlay)

9.6 Kbps

AMPS

CDMA 1xRTT

CDMA

PHS

1984 - 1996+

14.4 Kbps / 64 Kbps

1992 - 2000+

PHS (IP-Based)

144 Kbps

64 Kbps

2001+

2003+

cdma2000 1X-EV-DV Over 2.4 Mbps

2003 - 2004+ Source: U.S. Bancorp Piper Jaffray

GSM Network Structure GSM

service area PLMN service area MSC service area Location area Cell

Functions Particular to GSM Frequ

ency B and 89 0-915M Hz – u pli nk 93 5-960M Hz – d ownlink Han dover Power Con trol – 30dB d yna mic range, step s of 2dB Disc on tinuous Transm is sion (DTX ) Synchron ization

Cellular concept 

In terference problem

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In terference and syst em ca paci ty

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Fre quency reuse p att ern

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Trunki ng effici ency

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Ce llular envi ronme nt

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Ca paci ty co nsi derations

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Future t rends

CELLULAR COMMUNICATION     

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Cel lu lar co mmu ni cation mea ns co mmun icatio n b\w ce lls. Whole geo gra phi cal area is con verted into smal l cel l and se rved by on e BT S. Cel lu lar network comp rise s nu mber of he xag ona l cel ls Clu ster : Col le ct ion of cell Advan tage s of cel l st ru ct ures:  hig he r ca paci ty , hi ghe r numb er of users  less transm issio n po wer ne ede d  more rob ust, decen tra lize d  base statio n de al s wit h interfere nce , t ra nsmissi on area etc. lo call y Probl ems:  fixed net work ne ede d for the base statio ns  han do ver (chan gi ng from one ce ll to an othe r) ne cessa ry  inte rf ere nce with other ce lls

TYPES OF CELL 

Macro cells(3 to 35 km): Lar ge c ell s which se rv es rem ote a nd seg re ga ted a re as.

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Microcells(0,1 to 1 km): - Pi co c ells (0 ,0 1 t o 1km ) - Nano cell s(1m to 10 m)

{T HESE CELL AR E USED AT D ENSE POPU LA TED AR EA}

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Se lectiv e c ells : Cells having particular coverage.

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Um brella cell : Cell that is

located very high off the ground. Mainly used between mountains and high buildings. It support all same BTS service when they fail to support mobile station. So, MS get proper signal.

LIMITED FREQUNCY BAND FOR COMMUNICATION LEADS TO LESS CAPACITY AND POOR QUALITY DUE TO INTERFARANCE

The need: Optimum spectrum usage More capacity High quality of service Low cost

SOLUTION ACHIEVED BY

Network capacity at required QoS with conventional frequency plan Out of Capacity!!! Subscriber growth Time

increase capacity without adding NEW BTS!

I wish I could

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Frequency Re-Use Distance

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The K factor or the cluster size

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Cellular coverage or Signal to interference ratio

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Sectoring

What can I do?

The K factor and Frequency Re-Use Distance 7 6 K = i + ij + j 2

1

K = 22 + 2*1 + 12

5

K=4+2+1 K=7

2

2

7 6

j

R

2 i

1

5

3

3

D

4 D = √3K * R D = 4.58R

Frequency re-use distance is based on the cluster size K The cluster size is specified in terms of the offset of the center of a cluster from the center of the adjacent cluster

Uplink and downlink 

Up Link (Trans) : travel from MS to BTS.

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When signal

Down Link (Receive)

:

When signal travel from BTS to MS. 

For frequency band (900MHz) UPLINK – 890-915MHz DOWNLINK – 935-960MHz

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Duplex pacing – 45MHz

Co channel interference

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Interference between same frequency transmitted by two different BTS.

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Occurs when the same carrier frequency reaches the single receiver. Plan the cell structure in such a way that two or more BTS having same frequency doesn’t interfere with each other. Hence there is no co-channel interference.

b2 b1 b3 a2 OMNI CELL 1 ANTENNA

a1

a3

a6

a4 a5

60O CELLS

6 ANTENNAS

120O CELLS 3 ANTENNAS

Principal Of Sectorization 

Omni Directional Cells

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120 degree Sectors

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60 Degree sectors  Each Sector in a Site has its own allocation of Radio Carriers.

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Advantage  By frequent reuse of frequency more capacity can be achieved.

Typical 2G Architecture

PSDN BSC BTS BSC

HLR

SMS-SC

PLMN

BSC

MSC/VLR

MSC/VLR BSC

BT S — Base T ransc ei ver St atio n BSC — Base Station Con trol ler GMSC

Tandem CO

PSTN

Tandem CO

CO

MSC — Mo bi le Swi tc hi ng Cen ter VL R — Vi sitor Locat ion Reg ister HL R — Home Locatio n Reg ister

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Mobile Station: SIM + Mobile set

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Base Station Subsystem :BTS+BSC

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Network Subsystem : MSC,AuC ,EIR,VLR,HLR

MOBILE SET – Fix ed – Por tabl e • Int er natio nal Mo bile Equipment Id ent ity ( IM EI ) numb er ----- ----- ----- ----- ----- ----- ----- ----- ----- -------- ----- -oic e and dat a t ran smis sion reque nc y an d t ime s ync hro nis ation on itoring of po wer an d s ign al qu ality for

han dov er rov is ion of loc ati on up dat es qua li sation of mult ipath dis to rtion

SIM • Enables ac ces s t o s ubs cribed ser vic es • Sma rt c ard -------a---------trat ------------• For dminis ion----in G SM----netw or---k ----- l Id entif ic atio n N umber – ----Per sona (PIN ) – In ter nat ional Mobile Subs criber Id entit y ( IMS I) – Tempo rary Mobile S ubs cribe r Id entit y ( TMSI) – Mobile S tati on I nte rn ation al I SDN Nu mber ( MS IS DN) – Mobile S tati on R oaming Nu mber (MS RN)

Permanent SIM Card Data IM card t ype C card ident ifi cat ion - serial number of card IM serv ice t able - lis t of servic es s ubsc ribed to MSI IN

Dynamic SIM Data UK - pers onal unbloc king Card key cation Inon forkmat ut•Lo henticati ey ion Ki and A3, A5, and A8 al gorithm s

– TMS I, L AI, LA u pdat e t imer , u pdat e s tatu s • Ciphe ri ng k ey Kc an d s eq uenc e numb er • BCC H in for matio n – Lis t of c ar rier f re quen ci es f or c ell selec tio n du ring ha ndov er and c all set up •Lis t o f bl oc ked P LMNs •HPLMN sear ch – per iod of time in w hic h MS s ear che rs for home netw or k bef or e it chec ks fo r othe r net wor ks

MS Services • Full rate voice service - 13kb/s • Enhanced full rate voice service - 12.5kb/s • Half rate speech service - 6.5kb/s • Transparent data rate service – 14.4kb/s, 9.6kb/s, 4.8kb/s, 2.4kb/s • Short Message Service (SMS) – Maximum of 160 characters

BASE TRANSCEIVER STATION

Functions of BTS • Enc oding , en cry ption , mu ltiplex in g, modulat ion, and radio signal tr ans mis sio n • Dec od ing, dec rypti on, demult iplex ing and demodul ation of r ec eiv ed r adio signa ls • Eac h B TS s erv es a single ce ll • Suppor t fo r full- and half- rat e s pe ec h c odec • Cont rol of f re quenc y hopp ing • Rand om ac cess det ec tion • Timing adv anc e • Uplink ra dio c hannel meas ure ments

Functions of the BSC • RR manag ement for BTS s unde r cont ro l • Int erc ell ha ndov er •Alloc ates a c ha nnel for t he dur ation of a call • Reallo cation of fr eq uenc ies among B TSs • Power m anage ment • Time and fr equ enc y s ync s igna l for BTS s • Time delay meas ur emen ts of re ceiv ed signal fr om MS • Per for ms t runk ing to reduc e line c apac ity bet wee n BSS an d MS C • Pro vides in ter fac e t o O MC

Network and Switching Subsystem • Contains switching and network oriented functions • Forms gateway between radio network and other public networks • NSS comprises of Mobile Services Switching Centre (MSC) Visitors Location Register (VLR) Home Location Register (HLR) Authentication Center (AuC) Equipment Identity Register (EIR)

Functions of MSC • Paging • Call management • Dynamic resource allocation • Location registration • IWF with different networks • Handover management • Billing • Encryption • Gateway to SMS centre •Switching call, controlling call, and logging calls

Data Stored in VLR • IMSI • MSISDN • MSRN • TMSI • LA where MS is located • Supplementary service parameters • Authentication key, query and response from AuC • ID of current MSC

Data Stored in HLR • Permanent – IMSI – MSISDN – MS category - payphone or not – Roaming restrictions – Supplementary services parameters – Closed User Group (CUG) membership – Authentication key Ki Data • Temporary – LMSI (Local MS ID) – RAND/SRES and Kc – MSRN – VLR address – MSC address – Roaming restrictions – SMS messages waiting

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Authentication Center (AUC) -

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Protects against intruders in air interface Maintains authentication keys and algorithms and provides security triplets ( RAND,SRES,Kc) Generally associated with HLR

Equipment Identity Register (EIR) -

Database that is used to track handsets using the IMEI (International Mobile Equipment Identity) Made up of three sub-classes: The White List, The Black List and the Gray List Only one EIR per PLMN

Operation subsystem Function • Three areas of responsibility – Subscription management – Network operation and maintenance – Mobile equipment management • Network elements of OSS – Operations and Maintenance Centre (OMC) – Authentication Centre (AuC) – Equipment Identity Register (EIR) OM C F un ctio ns • Alarm Handling • Fault Management • Performance Management • Configuration Management • Software Version Management • Network Statistics Data Collection • Network Status Control

Network Management Centre • Single NMC per network • Traffic management for whole network • High-level alarm handling • Manages unstaffed OMC • Provide network planners with network interface and data collection tool

Channels On Air Interface 

Physical Channel

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Logical Channel

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Physical Channel 

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Physical channel is the medium over which the information is carried.

Logical Channel 

Logical channels consists of the information carried over the Physical Channel.

LOGICAL CHANNELS

de SIGNALLIN G

TRAFFIC

FULL RATE Bm 22.8 Kb/S

HALF RATE Lm 11.4 Kb/S

FCCH

SCH

BROADCAST

COMMON CONTROL

DEDICATED

BCCH PCH

CCH -- FREQUENCY CORRECTION CHANNEL CH -- SYNCHRONISATION CHANNEL CCH -- BROADCAST CONTROL CHANNEL CH -- PAGING CHANNEL ACH -- RANDOM ACCESS CHANNEL GCH -- ACCESS GRANTED CHANNEL DCCH -- STAND ALONE DEDICATED CONTROL CHANNEL ACCH -- SLOW ASSOCIATED CONTROL CHANNEL ACCH -- FAST ASSOCIATED CONTROL CHANNEL

RACH

AGCH

SDCCH

SACCH

DOWN LINK ONLY UPLINK ONLY

FACCH

Location update from the mobile RACH send channel request AGCH receive SDCCH SDCCH request for location updating SDCCH authenticate SDCCH authenticate response SDCCH switch to cipher mode SDCCH cipher mode acknowledge SDCCH allocate TMSI SDCCH acknowledge new TMSI SDCCH switch idle update mode

Call establishment from a mobile RACH send channel request AGCH receive SDCCH SDCCH send call establishment request SDCCH do the authentication and TMSI allocation SDCCH send the setup message and desired number SDCCH require traffic channel assignment FACCH switch to traffic channel and send ack (steal bits) FACCH receive alert signal ringing sound FACCH receive connect message FACCH acknowledge connect message and use TCH TCH conversation continues

Call establishment to a mobile Mobile looks for BCCH after switching on Mobile receives paging message on PCH Generate Channel Request on RACH Receive signaling channel SDCCH on AGCH Answer paging message on SDCCH Receive authentication request on SDCCH Authenticate on SDCCH Receive setup message on SDCCH Receive traffic channel assignment on SDCCH FACCH switch to traffic channel and send ack (steal bits) Receive alert signal and generate ringing on FACCH Receive connect message on FACCH FACCH acknowledge connect message and switch to TCH

Authentication in GSM

Key generation and Encryption