DE1.1 6th Sem.08 Wireless

7/25/2019 DE1.1 6th Sem.08 Wireless

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Introduction to GSM(Global system for MobileCommunications)


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Architecture for GSM


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HLR

VLR1 VLR2

LA1 LA2

Registration Message Flow

Inter!"R Mo#ement

1 6

78

32

45

MSC2MSC1


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M bil t i t d ll i th i iti


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Mobile terminated call in the #isitingnetwor$


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%asic Features &ro#ided by GSM

Call 'aiting

otification of an incoming call while on the handset

Call old

&ut a caller on hold to ta$e another call Call %arring

All calls* outgoing calls* or incoming calls

Call Forwarding

Calls can be sent to #arious numbers defined by the user

Multi &arty Call Conferencing

"in$ multi+le calls together

Ad d F t & id d b


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Ad#anced Features &ro#ided byGSM

Calling "ine I, incoming tele+hone number dis+layed

Alternate "ine Ser#ice one for +ersonal calls

one for business calls

Closed -ser Grou+ call by dialing last for numbers

Ad#ice of Charge tally of actual costs of +hone calls

Fa. / ,ata !irtual 0ffice 1 &rofessional 0ffice

Roaming ser#ices and features can follow customer from mar$et to mar$et


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Ad#antages of GSM

Cris+er* cleaner 2uieter calls

Security against fraud and ea#esdro++ing

International roaming ca+ability in o#er 344 countries

Im+ro#ed battery life

5fficient networ$ design for less e.+ensi#e system e.+ansion 5fficient use of s+ectrum

Ad#anced features such as short messaging and caller I,

A wide #ariety of handsets and accessories

igh stability mobile fa. and data at u+ to 6744 baud 5ase of use with o#er the air acti#ation* and all accountinformation is held in a smart card which can be mo#ed fromhandset to handset


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Air Interface


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Air Interface

Radio 8ransmission 8echni2ues

9 F,MA

9 8,MA

9 C,MA

Channels

9 &hysical channels

9 "ogical channels


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F,MA

Time

Frequency

Channel


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8,MA

Time

Frequency

0 1 2 3 4 5 6 7

Channel

Time Slot


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,i#ison of s+ectrum into GSM


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,i#ison of s+ectrum into GSMcarrier


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Channels

&hysical Channels9Associated with fre2uency bands* time slots* codes

9 &hysical channels transfer bits from one networ$

element to another "ogical Channels

9 ,istinguished by the nature of carried informationand the way to assemble bits into data units

9 8hree ty+es onetoone: traffic channels between a %8S and a MS onetomany: synchroni;ation signals from %8S to MSs in a

cell manytoone: from MSs to the same %8S


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Air Interface "ayers

RadioTransmission

Logical

Channels

essages

RadioTransmission

Logical

Channels

essages

Terminal !ase"#a#ion

Layer 1!i#s

Layer 2

$ac%e#s

Layer 3

essages


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GSM Frame Structure

3 57 26 57 8&251 1 3

0 7

&&&

&&&"u'er(rame6&12 sec

120 msec

4&615 msec

0&576)2 msec

156&25 *i#s

51 ul#i(rame

26 Frames

8 ul#i(rame

Coded da#a idam*le

Tail *i# "#ealing Flag +uard 'eriod


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8here are two ty+es of multiframe

9 26 TDMA-frame multiframeis used tocarry 8C* SACC and FACC

9 51 TDMA-frame multiframeis used tocarry %CC* CC* S,CC and SACC

Frame 8y+es


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Trafficchannels(TCH)

Signaling

channel

TCH/F: Fll!rate Traffic Channel

TCH/H: Half!rate Traffic Channel

FCC,- Frequency correc#ion

"C,- "ynchroni.a#ion

!CC,- !roadcas# con#rol

$C,- $aging

/+C,- /ccess gran#

R/C,- Random access"CC,- "#andalone dedica#ed con#rol

"/CC,- "lo associa#ed con#rol

F/CC,- Fas# associa#ed con#rol

Toay

!ase#o

mo*ile

Toay

"ogical Channel "ist

"CH

CCCH

#CCH


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"ogical Channels

Control Channels

9 %roadcast Channels (%C)

9 Common Control Channels (CCC)9 ,edicated Control Channels (,CC)

8raffic Channels (8C)

9 Full Rate (8C1F)9 alf Rate (8C1)


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-& 1 ,own"in$

,ownlin$: the transmission +ath from%ase Station to Mobile Station

-+lin$: the transmission +ath from Mobile

Station to %ase Station

C l Ch l


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Control Channels

%roadcast Channels (%C)9 Fre2uency Correction Channel (FCC)9 Synchroni;ation Channel (SC)9 %roadcast Control Channel (%CC)

Common Control Channels (CCC)9 &aging Channel (&C)9 Random Access Channel (RAC)9 Access Grant Channel (AGC)

,edicated Control Channels (,CC)9 Stand alone ,edicated Control Channel (S,CC)9 Cell %roadcast Channel (C%C)9 Slow Associated Control Channel (SACC)9 Fast Associated Control Channel (FACC)


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G&RS

(General +ac$et radio ser#ice)


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Circuit switching

9 ,edicated communications +ath between twostations

9 5


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ow &ac$et Switching 'or$s

,ata is transmitted in bloc$s* called +ac$ets

%efore sending* the message is bro$en into aseries of +ac$ets

9 8y+ical +ac$et length is 3444 octets (bytes)9 &ac$ets consists of a +ortion of data +lus a +ac$et

header that includes control information

At each node en route* +ac$et is recei#ed*

stored briefly and +assed to the ne.t node


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"ine efficiency is greater


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"ine efficiency is greater

9 Many +ac$ets o#er time can dynamically share the samenode to node lin$

&ac$etswitching networ$s can carry out dataratecon#ersion9 8wo stations with different data rates can e.change

information

-nli$e circuitswitching networ$s that bloc$ calls whentraffic is hea#y* +ac$etswitching still acce+ts +ac$ets*but with increased deli#ery delay

&riorities can be used

,i d f & $ S i hi


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,isad#antages of &ac$et Switching

5ach +ac$et switching node introduces a delay 0#erall +ac$et delay can #ary substantially

9 8his is referred to as =itter

9 Caused by differing +ac$et si;es* routes ta$en and#arying delay in the switches

5ach +ac$et re2uires o#erhead information9 Includes destination and se2uencing information

9Reduces communication ca+acity More +rocessing re2uired at each node

&ac$etr Switching networ$


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&ac$etr Switching networ$,atagram

5ach +ac$et treated inde+endently* withoutreference to +re#ious +ac$ets

5ach node chooses ne.t node on +ac$et>s +ath

&ac$ets don>t necessarily follow same route andmay arri#e out of se2uence

5.it node restores +ac$ets to original order

Res+onsibility of e.it node or destination to

detect loss of +ac$et and how to reco#er


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Ad#antages:9 Call setu+ +hase is a#oided

9 %ecause it>s more +rimiti#e* it>s more fle.ible

9 ,atagram deli#ery is more reliable

&ac$et Switching etwor$s!irtual


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&ac$et Switching etwor$s !irtualCircuits

&re+lanned route established before+ac$ets sent

All +ac$ets between source and

destination follow this route Routing decision not re2uired by nodes foreach +ac$et

5mulates a circuit in a circuit switching

networ$ but is not a dedicated +ath9 &ac$ets still buffered at each node and

2ueued for out+ut o#er a line


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Ad#antages:9 &ac$ets arri#e in original order

9 &ac$ets arri#e correctly

9 &ac$ets transmitted more ra+idly withoutrouting decisions made at each node


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USER FEATURES 3 TO 10 TIMES THE SPEED 8he ma.imum s+eed of 3?3


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INSTANT CONNECTIONS IMMEDIATE TRANSFER OF DATA G&RS will allow for instant* continuous connections that will allow information and data to be

sent whene#er and where#er it is needed


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5,G5


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5,G5

(5nchanced ,ata Rates for Global5#aluation)


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5,G5 : 5nhanced ,ata forGSM 5#olution


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GSM 5#olution

GPRS EDGEModulation GMSK 8-PSK/GMSK

Symbol rate 270ksym/s 270ksym/s

Modulation bit rate 270kbs 810kbs

Radio data rate per time slot 22.8kbs 69.2kbs

User data rate per time slot 20kbs (CS4) 59.2kbs (MCS9)User data rate (8 time slots) 160kbs 473.6kbs


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etwor$ im+lementation of 5,G58echnology


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8echnology

Radio &erformances


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Continuity of Ser#ice


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5,G5 status wordwide


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9 -M8S9 (uni#ersal mobile telecommunication systems)

-M8S : -ni#ersal Mobile8elecommunication System


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8elecommunication System8hird Generation mobile telecoms 9 BGto co+e with increasing #olumes of traffic

9and new ca+acitydemanding a++s such as #ideo streaming / musicdownload

de#elo+ed as a global standard to assure international roaming9though now unli$ely to be uni#ersal e


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BG


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8hird Generation (BG)9 'e ha#e loo$ed at current and older technologies o#er

the last few wee$s

8ACS GSM

G&RS

5,G5

9 BG is the currently widely a#ailable state of the art

technology In terms of high s+eed data access o#er a cellular en#ironment

8he user can get access anywhere any time

BG -M8S


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8he ,ream (intention)9 @G and @


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8he ,ream (continued)9 'orldwide +ositioning a#ailable

Able to +in+oint a de#ice and direct ser#ices to its to re2uestaccess to the networ$

9 8his is to +re#ent too many de#ices communicating at once

9 Although C,MA will theoretically allow a #ery large numberof user to communicate at once

N 'hat actually ha++ens is the 2uality of the calls isreduced considerably

N 8his is a issue for #oice but is a disaster for data calls


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BG -M8S 'C,MA 8he technology which -M8S is based u+on ('C,MA)


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gy + ( )

has some +atented content9 0n this basis any manufacturer who builds a handset needsto +ay royalties to Oualcomm

9 0n the 3stof 0ctober @44? the 5uro+ean Community startedloo$ing into this to in#estigate if Oualcomm was o#ercharging

htt+:11www


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BG -M8S was tested in the Isle of Man for 5uro+e 8he e2ui+ment was run and o+erated by 0@

8he license s+ectrum used on this island was gi#en free by the go#ernment

8he actual de#ices used were gi#en to some of the islanders9 8he idea was to trial the e2ui+ment in a limited manner

9 Also they wanted to see if there was a +attern of usage for the technology i


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Rules for 5fficient Multi+le Access


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8hree laws9 Enow the channel

9 Minimi;e interference to others

9 Mitigate interference recei#ed from others Re2uirements of wireless multi+le access9 Channel measurement

9 Channel control and modification

9 Multi+le user channel isolation

'hat is 8hird GenerationU 3 Fle.ible su++ort of multi+le ser#ices


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Fle.ible su++ort of multi+le ser#ices9 !oice

9 Messaging 9 email* fa.* etc

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DE1.1 6th Sem.08 Wireless

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