Gsm Gprs Edge

7/27/2019 Gsm Gprs Edge

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, ,

Prof. Kwang-Cheng Chen

Institute of Communications En ineerin

National Taiwan University

email: [email protected]

NTUEE Mobile Communications KC Chen 1


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u nes

GSM Architecture and Principles Physical Layer

Network Layer

Testing



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GSM Phase 1 Services

Tele honTeleservices Full-rate 13 kb s

Category Services Comments

Emergency calls

Short-message: point-to-

Alphanumericalpoint and cell broadcast

Telefax

information

Group 3

Synchronous data

As nchronous PAD

services

- .

access (packet switched)

Alternate speech/data

a orwar ng

Call barring

upp ement-

ary services



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GSM Phase 2 Services

TelephonyTeleservices Half-rate 6.5 kbps

Category Services Comments

Short-message services

Synchronous dedicatedBearer 2.4-9.6 kbps

Calling/connected lineSupplement-

Calling/connection lineidentity restriction

Call waiting

Call hold .

Closed user group

Advice of char e

On-line information


Operator barring


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.

GSM (group special mobile) was first developed.

GSM services follow ISDN and are classified as

tele-services and data services.

Subscriber Identity Module (SIM) is a memory

device storing ID, networks or countries for

services, privacy keys, etc.

GSM is still most widely used cellular technologytoday.



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ur er an ar za on-

improvements

- -

14.4 kbps (single-slot) data

EDGE (enhanced data rates for global evolution)

peec -re a e

EFR (enhanced full-rate) speech codec

AMR (adaptive multi-rate) codec

TFO (tandem free operation)



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ur er an ar za on Mobile station MS ositionin relatedCell identity

Uplink time of arrival (TOA) and enhancedo serve me erence -

GPS and A-GPS

-GSM-400/700/850

, ,

Service platforms

SIM a lication toolkitCustomized applications for mobile network

enhanced logic (CAMEL)



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ys em rc ec ure

BTSBSC HLR VLR AUC

s

BTS

BTSPSTNISDNSS7

A

BTSBSC MSC a a

net.

Base Station

Subsystem Network Switching Subsystem



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eg s ra on en a mo e s a on s on, a scann ng

algorithm scans the whole GSM frequencyan .

If a network is detected, mobile station reads

system information from (forward) basechannel.

If current location is not the same as it was

when the mobile station off, registrationprocedure starts.



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Registration in Network

MS BTS BSC (G)MSC VLR HLR Action

channel request

channel activation

activation knowledge

location update

authetication responsecomparison of authet.

assignment of new

area and TMSI

.

entry area & ID into

VLR & HLR


channel release


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MS BTS Action Mobile

channel requestchannel assignment

r g na eCall Establishment

authentication request

authentication res onse

ciphering command

ciphering complete and in function

setup messagecall proceeding

assignment complete & all messages on channel

alertin rin inconnect (call party accepted the call)

connect ack. (two-way call)


speech data


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MS BTS Actiona in mobile station

Mobile

channel requestchannel assignment

Establishment

answer o pag ng on e ass gne c anne

authentication request

request to transmit in the ciphered mode

ack. of ciphered mode

setup msg. for the incoming callconfirmation

ass gnmen o a ra c c anne

ack. of traffic channel

connect when mobile off-hook

acceptance of connected msg.

NTUEE Mobile Communications KC Chen 12exchange of speech data


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an o n na og ys ems

between a mobile station and itself. Ife qua y egra e , reques s

adjancent cells to report power level for

the mobile. Network decides thefre uenc to use in the new cell and

eventually command change.

o e s a on s pass ve an ce s es

are equipped with measuring receiver.



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an over n

The mobile station monitors the perceived

ower levels of nei hborin cells that areprovided by the base station. Measurement

re ort is eriodicall sent back to the base

station that might conduct measurements too.In case necessit of a handover it can be

performed without delay.

handovers.



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ypes o an over

In case a handover is performed within the

,

handover and MSC is just informed.

,

MSC has to control the handover.

or a an over e ween s, e rs

MSC still has to maintain control of callmanagmen , oug n w an e

evantually.



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u en ca on

KEY (in SIM) RAND (generated

random number)authentication

algorithm (SRES)

= ?SRES

Umo e tat on Interface etwor

A set of (RAND,SRES) are stored in the HLR & VLR for the


use o au en ca on cen er.


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p er ng The ciphering algorithms are usually based

on certain one-way function. If a ciphering algorithm A5 is used to encipher

a data stream in GSM system, the same

algorithm is used to decipher. In current s stem onl A5/1 al orithm is

used. But for non-COCOM countries, a

sim ler A5/2 is used. Both al orithms cancoexist in western European countries.



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ynam c p er ngm etwor

KiRAND

A8Ciphering

Command

A5 A5p ere

Data



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an seIrDA

Power/Battery Management Bluetooth

WLAN

Baseband

Processor

Multimedia

Co-ProcessorUWB

FM

DVB/DAB-TDVB-H

RF PA MemoryDSC

SD/MS

MPEG, H.264

LCD Driver


n enna

LCD Controller


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an se

Power/Battery Management IrDA

Bluetooth

Baseband

Processor

Multimedia

Co-ProcessorWiMAX

UWBLayer 1/2/3

, r vers,

Middleware,

FMDVB/DAB-T

.

RF PA MemoryDVB-H

DSC

MP3

LCD Driver


n enna

LCD Controller


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- La er 1



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rame ruc ure...

6.12 sec

... 26 Frames120 msec

8 Time Slots4.615 msec 0 7

Coded Data Midamble.

156.25 bits 3 57 1 1 326 57 8.25



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ra c anne s

full rate speech at 13 kbps with channel

.

full rate data for 9600/4800/2400 bps.

With FEC, data is sent at 22.8 kbps.- .

carry up to 11.4 kbps

a -ra e a a a ps.



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requenc es: r mary

Mobile station transmits in 890-915 MHz.

Base station transmits in 935-960 MHz. 125channels are numbered from 0 to 124.

,

frequency channel number (ARFCN) is used.

Channel 0 is used as the guard band for GSM

.



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requenc es: -

Additional 10 MHz bandwidth has been

added to the bottom end of the du lexbands.

numbers from 974 to 1023.

anne num er s re urne or use n

extended GSM and channel 974 servesas e guar an .



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- or

techniques as GSM.Also known as GSM-1800

1710-1785 MHz for u link and 1805-

1880 MHz for downlink. Duplex spacing.

Channel numbers are 512 to 885.



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- --

America PCS.Also known as GSM-1900

Lower fre uenc starts from 1850 MHz

with 80 MHz duplex spacing.

anne num ers range rom o

810.



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ower eve s nPower

Class

Max. Power of a

Mobile Station (dBm)

Max. Power of a

Base Station (dBm)

1 20W(43) 320W(55)

2 8W(39) 160W(52)

3 5W(37) 80W(49)4 2W(33) 40W(46)

.

6 10W(40)

8 2.5W(34)



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Power Levels in DCS-1800

and Phase II GSM

Max. Power Max. Power Max. Power Max. PowerPower

Classof DCS-1800

MS (dBm)

of DCS-1900

MS (dBm)

of DCS-1800

BTS (dBm)

of DCS-1900

BTS (dBm)

1 1W(30) 1W(30) 20W(43) 20-40W2 0.25W(24) 0.25W(24) 10W(40) 10-20W

-

4 2.5W(34) 2.5-5W



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acro-ce an cro-ce

hot spot



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acro-ce an cro-ce

hot spot



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ower eve s or cro-

Max. Power Max. Power Max. Power

Class

Micro-BTS

-

Micro-BTS

-

Micro-BTS

. . . - .

M2 0.08W 0.5W 0.16-0.5WM3 0.03W 0.16W 0.05-0.16W



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u se ower ro edB+4

+1-

-6

-30

-70

147 bits10us10us

NTUEE Mobile Communications KC Chen 370.5428 msec


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Time Division Du lex TDD

in GSM

BTS transmits

0 1 2 3 4 5 6 7 0 1 2 3

5 6 7 0 1 2 3 4 5 6 7 0

MS transmts

.around 216.6 Hz effect



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(duplexer); only requiring fast-switching

syn es zer, er pa s, as

antenna switching

increased battery life or lighter battery



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orma urs

T Coded Data S Training

Se uence 26S Coded Data T GP

.

= .



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a s

uncertainty during power ramping up

an ramp ng own.

The tail bits are alwa s set to be zero

while the demodulation process.



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ea ng ag

receiver whether the incoming burst is

carry ng s gna ng a a o ma n a n e

link) or user data (traffic).

Indicating flag is needed since signaling

different places.



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ra n ng equence

with burst, e.g. equalizer for multipath

a ng.

8 se uences are defined in GSM. All

radios in a particular cell share the.

An equalizer in GSM can compensate

up to 16 micro-sec path delay.



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uar er o

considered as guard time, to avoid

poss e over ap o ra a on power o

two bursts.



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an om ccess urs

T TSynchronizationCoded Data Guard Period

.

88 bits = 0.32472 msec

68.25 bits = 0.252 msec which is equivalent to 75.5 km

.

and BTS is 37.75 km. Based on other system parameters,

the max. cell size is 35 km in GSM.



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requency- orrec on urs

T T GPfixed bit sequence

.

=

correction due to the nature of GMSK.



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ync ron a on ursT

3

T

3

Coded Data

39

Coded Data

39

Synchronization

Seq. 64

GP

8.25

148 bits

At beginning of mobile communicating to network, it only detectsthe frequency of base channel and needs to know the training seq.

an sys em parame ers. s s one y e sync ron za on urs .

In this kind of burst, in addition to a longer synchronization seq.,

including BCC (BS color code) and NCC (national color code),

and shortened TDMA frame number.



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og ca anne s A lo ical channel carries si nalin data or

user data. It can be mapped into any physical

channel (frequency and time slot). Once a physical channel is assigned to carry

the content of a logical channel, the

assignment shall not change. 7 combinations of logical channels.

GSM distinguishes between traffic channels

and control channels.



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roa cas anne sBCHs are only transmitted by the base

to synchronize with the network. Three

ypes o :

broadcast control channel BCCH

frequency-correction channel (FCCH)

sync ron za on c anne


Common Control Channels


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(CCCH)

dedicated link between a mobile and a

. prov es oo s or ca

setups and can originate from the

network or mobiles..




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(CCCH): continued

random access channel (RACH): to request a

. paging channel (PCH): BTS calls individual

.

access grant channel (AGCH): where MS

ge s n orma on rom on w c

dedicated channel for its immediate needs.


Dedicated Control Channels


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Dedicated Control Channels

(DCCH)used for message transfers between network

-, ,level signaling messages among radios.

(SDCCH)

s ow assoc a e con ro c anne :

carrying control and measurement

parame ers rou ne a a o ma n a n a n .


Fast Associated Control


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Fast Associated Control

Channel (FACCH) ,

set of system parameters to keep

mo e up o a e on e a es c anges

in the system. In uplink, MS reports the

measurement results.

as SDCCH but FACCH replaces all/part

o a ra c c anne .


Lo ical Channels and


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Lo ical Channels and

DirectionsLogical Channel MS BTS

TCH FACCH

BCCH


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anne om na ons1. TCH/FS+FACCH/FS+SACCH/FS

2. TCH/HS(0,1)+FACCH/HS(0,1)+SACCH/HS(0,1)

3. TCH/HS(0)+FACCH/HS(0)+SACCH/HS(0)

+TCH/HS(1)+FACCH/HS(1)+SACCH/HS(1)

4. FCCH+SCH+CCCH+BCCH

5. FCCH+SCH+CCCH+BCCH+SDCCH/4

+SACCH/4

6. CCCH+BCCH

7. SDCCH/8+SACCH/8



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u rame ruc ure Each channel combination re uires one

single physical channel. Multiframe structure

made of a fied number of TDMA fames allowslogial channels to be ordered into time slots.

-

channel combinations and 51-multiframe.


Traffic Channel Frame


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Structure (26-Multiframe),

fames for traffic data (speech & data),

r rame or , ano er

frames for traffic, and the last frame idle

for MS to measure etc..




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ruc ure-

For combination II or III (TCH/HS), 2 half-ratespeech channels are packed onto one 26-

multiframe structure. One logical channel

uses every other TDMA frame. Frame 13 for

SACCH1 and 26 for SACCH2.

Combination II for one half-rate channel and

III for two half-rate channels. FACCH may take a position of traffic channel


.

Si nalin Frame Structure


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Si nalin Frame Structure

(51 Multiframe).

more complex as incorporating 4different channel combinations and

structures.


Combination IV downlink :


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Combination IV downlink :

FCCH+SCH+CCCH+BCCCH

F SBCCHCCCH CCCH CCCH CCCH

235.38 ms

0 1 2-5 6-9 12-19 22-29 32-39

42-49 50

FCCH

idle

CCCH includes PCH and AGCH



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om na on up n :

R RBCCHCCCH CCCH CCCH CCCH0 1 2-5 6-9 12-19 22-29 32-39

42-49 50RACH

This combination is normally used for cells with several

carriers and a large amount of traffic on CCCH.

slot 0. The frequency here is a reference for neighboring

cells.



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om na onscells with only one or two transceivers. It may

assi n u to 4 DCCHs. Combination VI is similar to IV but without

FCCHs and SCHs for cases with a hu e

number of transceivers. Combination VII is to rovide routine

signaling. 8 DCCHs may be used to servce 8parallel signaling links on one physicalchannel.


Cell Broadcast Channel


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(CBCH) suppor s a par o e group o

short message services (point-to-omnipoint). An operator is thus able totransmit messages to its subscribers.

CBCH is always mapped on the 2ndsubslot of SDCCH inde endentl forchannel combination V and VII.

.



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Coding of Full-Rate Speech

Class Ia Class Ib Class IIblock coding

with

3 CRC bits

of zeros toreset codec

convolutional code r=1/2 K=5

378 coded bits 78 bits



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o ng or . ps a a.

bits (at 3.6 kbps)

By adding 0000, 76 bits

= = ,

coded bits.



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o ng or gna ng anne

signaling information

Fire Code

parity40 bits 0000

convolutional code r=1/2 K=5

456 coded bits



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Communications



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ave orm o ers ource o ers

me oma n requency oma nLPC

VocodersSBC

ATCDELTA

CVSDM

ADPCM



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Channel Vocoder: S eech


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Generation ModelAnaylzer Transmissionspeech

secondary source

Noise

Vocal

Tractspeech

output

u seSource



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o ng ys em

LPC Encoder Decoder

S

Y

Voiced/H T

Buffer Unvoiced

DecisionEncoder

NN Decoder ES

PitchEncoder

E

L Decoder

I

Z

R


xc a on


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o e- xc ecode book of stochastic (zero-meam white

. Transmitter searches its codebook for best

index is transmitted. e rece ver uses t e n ex or synt es zer.

CELP coders are extremely complicated.


peec o ers se n ar ous o e a o ys ems


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GSM cellular RPE-LTP 13

-IS-54 cellular VSELP 8

IS-95 cellular CELP 8

IS-95 PCS PCS CELP 14.4

PDC cellular VSELP 4.5/6.7/11.2

- cor ess

DECT cordless ADPCM 32

DCS-1800 PCS RPE-LTP 13

PACS PCS ADPCM 32



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o ec

prediction (RPE-LTP)

combination of RELP (France) and

MPE-LTP German

13 kbps complicated and power hungry



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peec nco er Hamming

Window

LPC

Inverse + LPFGrid

SelectionM

Filter U

X

-

STP

Analysis

LTP

Analysis

-



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peec eco er

E

M

Position/

RPESynthesis

Filter

Synthesis

Filter

os -Processing

U

X

Decoding



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ransm ss on Speech coder issues 260 bits every 20 msec.

50 bits out of 260 bits describe filter coef.block amplitude, LTP parameters and are

class Ia under channel codin rotection.

132 bits describe RPE pointers, RPE pulses,.

78 bits contain RPE pulse and filter

.


Discontinuous Transmission


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(DTX) When a pause is detected by speech

, .for the duration of pause, 50% duty cycle.

presence/absence of speech, even under.

Every 480 ms, a silence descriptor (SID)

rame s ransm e o y e presence.



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ap ve u -ra e o ec,

Ericsson, Nokia, Siemens.

AMR contains a set of fixed-rate speech, channel

-, , .

Operating at full-rate (22.8K bps) and half-rate (11.4Kbps)

Ability to adapt to radio channel and traffic load

conditions, to select optimal channel mode (HR/FR) and

codec mode

Tradeoff between speech and channel coding to deliver

best possible combination of speech quality and system



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peec anne o ng

excitation linear prediction (ACELP)

12.2, 10.2, 7.95, 7.4, 6.7, 5.9, 5.15, 4.75 kbps

or u -ra e co ec

Lower 6 rates for half-rate codec

Error correction is based on recursive systematic

6-bit CRC is used for detecting bad frames


-


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Both MS and BS perform channel quality

Codec mode command (up link) or codec moderequest (down link) is sent over radio interface inin-band messages

The receiving end uses information to select

conditionCodec mode indicator is sent over radioCodec mode might be different in up/down links

but the channel mode (FR/HR) must be the same

e wor con ro s co ec c anne mo e, anfollows

AMR contains voice activit detection VAD and

NTUEE Mobile Communications KC Chen 85DTX


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(Kb ) LPC LTP FCB G i T t l


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(Kbps) LPC LTP FCB Gains Total

12.2 38 30 140 36 244

10.2 26 26 124 28 204

7.95 27 28 68 36 159

7.4 26 26 68 28 148

6.7 26 24 56 28 134

5.9 26 24 44 24 118

5.15 23 20 36 24 103

.1.75 29 0 0 6 35


: xe co e oo : a ap ve co e oo


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ayer gna ngbetween a MS and a BTS is link access

proce ure or e m-c anne(LAPDm).

It is adapted from link access protocol.

LAPD is used in GSM on Abis interface

between BTS and BSC.


r nc p e o n on ro


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Stop-and-wait

Low efficiency

Resend only those with errors

Go-back-N

acknowledgement

Widel used in link control rotocols



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as s o a a n ayer The data link la er is res onsible for the correct and com letetransfer of information blocks between layer 3 entities over GSM

air interface. The protocol have the following functions:

organization of layer 3 information into frames

- -

recognition of frame formats establishment, maintainance/su ervision, termination of one or

parallel data links on signaling channels

acknowledgement of transmission and reception of numbered

n ormat on rames - rames unacknowledged transmission and reception of unnumbered


-


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rame orma

field fieldfield

s

1 octet

variable length



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rame orma

field fieldfield

& fill bits

1 octetvariable length


rame orma s Frame format A is used when no signaling but


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Frame format A is used when no signaling butwant ng to eep t e s gna ng c anne .

When signaling is ready for transmission,

frame format B is used, which contains an

information field. Such a frame is called an I-

frame.

When numbered I-frames are transmitted it is

referred as the acknowledged mode and the

rocedure called multi-frame o eration.


rame orma s s an s


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rame orma s s an s

Length Indicator

Field

Length Indicator

Field

Information Field

& Fill BitsBbis

Formats Abis and Bbis are equivalent to formats A and B

u ey are on y use n e unac now e ge mo e osignaling data transfer.


ress e


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ress e In GSM control channels, the address field is

fixed at one octet.

It is primarily used to addressed the service

access point (SAP), a defined interaface

which provides services to a layer 3 entity.

GSM rovides two SAPs on radio interface:

for signaling and for short message.


ress e : con nue


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ress e : con nue8 7 6 5 4 3 2 1

=

SAPI=000 for layer 3 signaling

011 for short messages

C/R=0 for mobile sending a command

1 for mobile sending a response

E/A=1 for GSM control channels


on ro eIt consists of only one octet and is only in


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It consists of only one octet and is only inrame orma s . ypes:

I-frame: numbered and carrying numbered

S-frame: control functions like I-frame ack.,,

suspension of numbered informationtransfers.

U-frame: unnumbered type frames offeringadditional data link functions.


on ro e : con nue


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8 7 6 5 4 3 2 1

N R P N S 0I-frame

N(R) P/F 1S S 0

S-frame

8 7 6 5 4 3 2 1

P/FU U U U U 1 1-


I-frame: This type of frames are numbered and carry

numbered Layer 3 information.


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numbered Layer 3 information.

S-frame: Supervisor frames are control function like

- .(b) request for repetitors

(c) intermittent suspension of numbered information

transfers

- rame: e unnum ere rames o er a ona a a

link functions for Layer 2 and allow for the transfer of

.

channels.


on ro e arame ers


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Number: modulo-8 counter

ransm er ece ve equenceNumber: also a modulo-8 counter

Poll/Final Bit: Poll bit is set when ares onse is re uested; final bit is setwhen a response to a command is sentback.


Control Field Parameters:

uperv sor an nnum ere


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Receive Ready RR frame, SS=00, has 3

an I frame; ack. reception up to N(R)-1

Receive Not Ready, RNR frame, SS=01: canno rece ve - rame

Reject, REJ frame, SS=10: reception of one

or more frames is required.



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eng n ca or e


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8 7 6 5 4 3 2 1

One octet is sufficient for GSM signaling.

L stands for the length of Information Field.

M=0 either an entire layer 3 message included

or the last art of se mented messa e

M=1 another part of message followingEL=1 the last octet in the length indicator field


EL=0 not the last octet


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Network Layer - Layer 3


ayer


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,

as signaling layer, uses a protocol to

es a s , ma n a n, erm na e mo econnections.

Three sublayer defined for Layer 3

management (RR), mobility

managemen , connec onmanagement (CM).


u ayer


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frequency spectrum, system reaction to

ra o env ronmen c anges, ma n a n ngof a clear channel between PLMN and

MS.

,

control, time alignment, handover, etc.


u ayer roce ures


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channel release

c anne c ange an an over proce ures change of frequencies, hopping sequences or

a gor ms, requency a es

measurement report from mobiles power control and timing advance

modification of channel modes

cipher mode setting


u ayer


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, ,management of mobile data

checking allowed services for users

support of confidentiality (e.g. TMSI)

provision of MM connection, based on

,



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u ayer mana in all functions necessar for


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circuit switching call control in GSMPLMN

call control responsibilities, which are,

call control entity in GSM establishing,ma n a n ng,an re eas ng caconnection for communication links.


u ayer roce ures


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mo e-or g na e ca es a s men

mobile-terminated call establishment

changes of transmission mode during

call re-establishment after interruption of

dual-tone multi-frequency (DTMF)

control for DTMF transmissions


ruc ure o ayer essage


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8 7 6 5 4 3 2 1

Discriminatorflag

Information Elementsman atory

optional


ransac on en er


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parallel CM connections and various

. For RR & MM, TI is not relevant,

.

TI flag indicates originator of a CMconnection. It is set 0 by the originatorand 1 when sent back.


ro oco scr m na or


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addressed entity and identifies 6

(0110), mobility management (0101),

ca con ro , s or message

services (1001), supplementary service(1011), test procedure (1111).


n orma on emen s Mandator IEs have a reserved lace in


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structure of message; optional IEs carry

information element identifier IEI tellin

receiver the purpose of information

contained.

4 possible IE types: mandatory fixed length

, ,

optional fixed length (OF), optional variable

.



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Testing GSM



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ransm er easuremen s

power


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power

frequency error and phase error

special transmitter power measurements:peak power, power-time template, burstm ng

measurements in spectrum: due tomo u a on, ue o sw c ng rans en s,spurious emissions, intermodulation


Measurements on Di ital

Receivers, ,


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, ,

sensitivity

cochannel rejection

intermodulation rejection blocking & spurious response rejection


es o ayer


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power control

radio channel management


a ng nv ronmen s


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hilly terrain (HT)

typical urban (TU)


es o ayer

establishment of an acknowledged data link


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establishment of an acknowledged data link

error control durin data link establishment

seq. counting during ack. block transfer

loss of I-frame reaction to erroneous C/R in address field

reaction to erroneous values in control field

reaction to invalid frames



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ona es s on a

-


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intermodulation rejection

transceiver test for spurious emission

.


gna ng es o ayer


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correction of burst timing

report of actual timing advance & power

measurement report


equalizer s eech 64 kbpsrece v ng

A/Demo u a or

codec


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circuitsA/D

demultiplexercodec

A-law

VCO &

s nthesizer

controlsignaling

channel

codecsignaling

64 kbps

unit

transmittin 16 kbpsspeech

codeccircuits

multiplexer

modulator

64 kbps

Abis

3 kbps in-bandsignaling

BTS BSC



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Satellite Mobile Usin GSM


r e ng 66 LEO low-earth-orbit satellites in 6 olar

orbital planes which 780 km above sea-


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orbital planes which 780 km above sea

surface. Each has 48 L band beams for

subscriber coverage.

system control segment (SCS). SCS also

information.

.


Iridium System Overview

K-band


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- --

a ewaySystem

Control

switchingSegmentISU

PSTN


r um a eway

MOC GMS


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MOC GMS

MHLR

CEIR

International

Switch &PSTN

: message or g na on con ro er

GMS: gateway management system

ETC: earth station controller


EIR: equipment identity register

communication system


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communication system

3 geo-stationary satellites over Pacific,Indian, Atlantic oceans

Supporting speech, data, video traffic

Originally for marine-time applications



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What Is GPRS?Conventional Way: Circuit Switched Data

PSTN


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HLR

HED

MSC/

VLR

A

SW

IT

Data overRCUIT

C

I

GSM


What Is GPRS?Packet Switched Technology on GSM

PSTN


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InternetPSDNPSTN

HLR

MSC/ ET

CHED

GGSN

GAP

AC

S

WIT

SGSN

BSC

GGSN: Gatewa GPRS

DataSupport Node

SGSN: Serving GPRS

NTUEE Mobile Communications KC Chen 135BTS

GPRS VS Circuit Switched DataTimeTime


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TS1TS1

TS2TS2

TS3TS3

GPRSGPRS

Stochastic Multiplexing

TS1TS1


GPRS Multi-slot Capabilities0 1 2 3 4 5 6 7 0 1

5 6 7 0 1 2 3 4 5 6

Downlink

Uplink-

Monitor


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0 1 2 3 4 5 6 7 0 1Downlink

5 6 7 0 1 2 3 4 5 6Uplink

Monitor

2-slot

0 1 2 3 4 5 6 7 0 1Downlink

5 6 7 0 1 2 3 4 5 6Uplink

Monitor

3-8-slot


3 slots: 4th slot: 5th slot:

GPRS Network Seen by IP NetworkHost

155.222.33.55


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191.200.44.xxx

NTUEE Mobile Communications KC Chen 138Source: Nokia


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Users View

A global and wireless access to the Internet !


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A global and wireless access to the Internet !

ex s ng app ca ons can e use . New and attractive services.

Users stay on the line long but only pay for the

capacity used. Data rate from 9.05 kbps up to 171.2 kbps.

9.05 kbps per channel by CS-1 (Channel Coding Scheme 1).

. ps y - , . ps y - , an . ps y -

4.

Maximum date rate: 21.4 x 8 = 171.2 kb s.


GPRS is only a bearer! E-mail

File transfer


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File transfer

Shopping and ticket sales Bankin and finance mana ement

News

Traffic information

And many others...


GPRS Lo ical Architecture

SGSN: Serving GPRS Support Node

GGSN: Gateway GPRS Support Node


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y pp

SGSN GGSN

SGSN

New Interface ( IP/X.25 )

New Interface ( FR )

New Interface ( SS7 )

Same level as the MSC/VLR.


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.

Detects new GPRS MSs in its service area.

.

Sends/Receives data packets to/from the MSs.

Provides interworking with the PDN (e.g., the

.

Looks like a router, when seen by the Internet.


onnec e o e v a an - ase ac one.

Enhanced Elements for GPRS

HLRHLRn ance w su scr er a a an

routing information.


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Enhanced for co-ordination of GPRS and CircuitSwitched services e. . combined location u datepaging for circuit-switched calls via the SGSN ).

BSSBSSSupports flexible radio channel allocation, and

supports a new interface to the SGSN.

SMSSMS--GMSC and SMSGMSC and SMS--IWMSCIWMSCSupports SMS transmission via the SGSN.


-

Internet

HLR


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HLR

IP based

GGSN GGSN

backbone

SGSN

SGSN

BSSBSS

Attach


Illustration - Activate an IPress

Internet

HLR


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HLR

IP based

GGSN GGSN

backbone

SGSN

SGSN

BSSBSS

Activate


Illustration-

UpdateInternet

HLR


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HLR

IP based

GGSN GGSN

backbone

SGSN

SGSN

BSSBSS


Illustration - Inter SGSN RAp a e

Internet

HLR


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HLR

IP based

GGSNGGSN

backbone

SGSN

SGSN

BSSBSS


Illustration-

the MSInternet

HLR


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HLR

IP based

GGSNGGSN

backbone

SGSN

SGSN

BSSBSS


Illustration-

InternetInternet

HLR


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HLR

IP based

GGSNGGSN

backbone

SGSN

SGSN

BSSBSS



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GPRS Tunnelin ProtocolBy GTP, many packet data protocol ( e.g., IP, X.25

) can be supported, even if the protocol is not


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supported by all SGSNs.GTP header contains an IMSI (International Mobile

Subscriber Identifier) and an NSAPI (Network Service

Access Point Identifier) .

e ow , or s use as a ac one

network protocol. Ethernet, ISDN, or ATM may be

.

TCP carries GTP protocol data unit for X.25, UDP


Subnetwork Dependent Convergencero oco

Multilplexing, segmentation, and compression.


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TLLI: Temporary Logical Link Identifier


RLC/MAC


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RLC/MAC (uplink)

The access to the uplink uses a Slotted-Aloha


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based reservation protocol.


RLC/MAC (uplink)A selective ARQ protocol that provides

retransmission of erroneous RLC data blocks.


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own n

The network initiates packet to an MS that is in

an y s a e y sen ng a ac e ag ng


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an y s a e y sen ng a ac e ag ng

Request.



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LLC

Provides a reliable logical link between the MS


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and its SGSN.Acknowledged mode for Packet Data Unit.

Unacknowledged mode for signaling and SMS.

BSS GPRS ProtocolConveys routing information between SGSN and

BSS.

Network ServiceFrame Relay.



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-


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: w en ancemen or


Signaling plane: SGSN-


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BSSAP+: A subset of Base Station S stemApplication Part ( BSSAP ) . It supports signaling forMobility Management Functionality ( e.g. combined



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--based on MAP


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-

PDP ( Packet Data Protocol ) Context ActivationProcedure


-based on GTP and MAP


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Interworking: between GTP and MAP


e erences CHT Labs. Presentation

GSM 03.60 Version 6.3.2 ( 1999-07 )

GSM 03 64 V i 6 2 0 ( 1999 05 )


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GSM 03.64 Version 6.2.0 ( 1999-05 ) Nokias White Paper on GPRS

http://www.nokia.com

http://www.ericsson.com http://www.motorola.com

http://www.alcatel.com

http://www.nortelnetworks.com


EDGE


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EDGE

EDGE: Enhanced data rate for GSM evolutionECSD: Enhancement of HSCSD

EGPRS: Enhancement of GPRS for throu h

per time slot


Logical architecture


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.

Network architecture for

supporting HSCSD (High Speed

-


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Pocket data

u p ex ng o ne wor pro oco s

protocol

N-PDU

SNDCP

NSAPI


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SNDCP

NSAPI + control Data

SAPI LCC

LCC header LCC information

RLC or BSSGP

control Data


EGPRS is built on top of GPRS with majormpac s onRF

RLC/MAC with inclusion of type II hybrid ARQ


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RLC/MAC with inclusion of type II hybrid ARQ . .

1/3 punctured with PS 1 of selected MCS). If RLC datablock is received in error, additional coded bits (i.e.

2 of prevailing MCS) are sent and decoded together withalready received code words until successful decoding.

MSC-5-7 or MCS-6-9.

With higher coding schemes, RLC window size is


.


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MCS Code Rate Modulation Data Rate / time Family

slot (kbps)

9 1.0 8-PSK 59.2 A

. .

7 0 76 44 8 B


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7 0.76 44.8 B

6 0.49 29. A

5 0.37 22.4 B

4 1.0 GMSK 17.6 C

3 0.8 14.8 A

2 0.66 11.2 B

1 0.53 8.8 C


EGPRS codin and uncturin

example

3 bits 45 bits 612 bits 612 bits

(MCS-9: uncoded 8-PSK, two RLC blocks per 20ms)

USFRLC/MAC

Hdr. HCS E FBI Data=592 bits BCS TB E FBI Data=592 bits BCS TB


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Rate 1/3 convolutional coding Rate 1/3 convolutional coding

36 bits 135 bits 1836 bits 1836 bits

Puncturing PuncturingPuncturing

36 bits 124 bits 612 bitsSB=8 612 bits 612 bits 612 bits 612 bits 612 bits

P1 P2 P3 P1 P2 P3


1392 bits


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(a) 57.6 kbps non-transparent service


(b) 56.0 / 64.0 kbps transparent service

Documents

Gsm Gprs Edge