3gpp GSM Principles - Basics

8/3/2019 3gpp GSM Principles - Basics

http://slidepdf.com/reader/full/3gpp-gsm-principles-basics 1/236

31 January 2008 3GPP CE at UP 1

Radio Network Planning andOptimisation

Magdaleen Snyman




References

GSM, GPRS and EDGE Performance:evolution towards 3G/UMTS

o T.Halonen, J. Romero, J. Meleroo Second Edition

o John Wiley & Sons

o ISBN 0-470-86694-2Principles & Applications of GSM

o V.K.Garg & J.E.Wilkes

o Prentice Hall PTR

o ISBN 0-13-949124-4




3GPP

ITU

IMT2000

3GPP

GSM GPRS EDGE UMTS

FDD TDD




3GPP

Project Coordination Group (PCG)

TSG SA

TSG GERAN TSG RAN TSG CN TSG T

WG1 – Radio Aspects

WG2 – Protocol Aspects

WG3 – BTS Testing

WG4 – Terminal Testing: Radio Part

WG5 – Terminal Testing: Protocol Part




3GPP

TSG – Technical Specification Group

GERAN – Gsm/Edge Radio Access NetworkRAN - UMTS (WCDMA) Radio Access Network

CN – UMTS/GSM Core Network

T - Terminals

SA – Service and System Aspects

http://www.3gpp.org/

UTRAN – UMTS Terrestrial Radio Access Network




3GPP

See Numbering Scheme

and list of abbreviations




PROTOCOLS

LAYER 3

LAYER 2LINK CONTROL

PROTOCOLS

LAYER 1

PROTOCOLS

CHANNEL

CODER/DECODER

INTERLEAVING

ENCRYPTION

MULTIPLEXING

& MULTIPLE

ACCESS DEMODULATOR

AND

MODULATOR TRANSMITTER

AND

RECEIVER

SPEECH

CODER/DECODERto all blocks

Relationsbetween specifications

(HAND-OVER, POWER CONTROL)

SYNCHRONIZATION

45.002 45.004 45.00545.003

TS 45.010

44.005 & 44.006

43.020 & 23.221

44.004

46 series

24.007 & 44.018

23.009 & 45.008 & 43.022

3GPP - specifications




GSM System

BSCBTS

BTS

MobileStation

Access Network:Base Station Subsystem

HLR VLR EIR AuC

MSCPSTN

Um Abis A

Core Network:GSM CS network

SS7




GSM & GPRS network

Traffic and signaling

Signaling

TE Terminal EquipmentMT Mobile TerminalMS Mobile StationBSS Base Station SystemBTS Base Transceiver StationBSC Base Station ControllerGMSC Gateway Mobile Services Switching

Center

MSC Mobile services Switching CenterVLR Visitor Location RegisterHLR Home Location RegisterAUC Authentication CenterEIR Equipment Identity RegisterSGSN Serving GPRS Support NodeGGSN Gateway GPRS Support NodeUm Air InterfaceA, Abis Interfaces (GSM)

Gx Interfaces (GPRS)

ExternalIP Network(Corporate

LAN)

Gi

TE MT

MS

BSC

GMSC

MSC/VLR

SGSN

EIR

HLR

AUC

GGSNIP-BackboneNetwork

External

IP Network(Internet)

ExternalX.25 Network

GsGf

Gr

BTS

Gb

UmISDN/PSTN

Gn

A

OtherPLMN

Gp

BSS Abis




Frequency Bands - GSM

8 7 6 M H z

8 8 0 M H z

8 9 0 M H z

9 1 5 M H zE-GSM

MTX

GSM MTX

T E T R A / G S M - R

M T X

GSM BTX

9 6 0 M H z

9 2 5 M H z E-GSM

BTX

9 3 5 M H z

9 2 1 M H z

T E T R A / G S M - R

B T X

RF ID

System P-GSM 900 E-GSM 900 GSM 1800 GSM 1900Frequencies:

• Uplink

• Downlink

890-915 MHz935-960 MHz

880-915 MHz925-960 MHz

1710-1785 MHz1805-1880 MHz

1850-1910 MHz1930-1990 MHz

Wavelength ~33cm ~33cm ~17cm ~16cm

Bandwidth 25 MHz 35 MHz 75 MHz 60 MHz

Duplex Distance 45 MHz 45 MHz 95 MHz 80 MHz

Carrier Separation 200 kHz 200 kHz 200 kHz 200 kHz

Radio Channels 125 175 375 300

Transmission Rate 270 kbits/s 270 kbits/s 270 kbits/s 270 kbits/s




Mapping Channel numbers

to Frequencies

P-GSM 900 Fl(n) = 890 + 0.2*n 1 ≤ n ≤ 124 Fu(n) = Fl(n) + 45E-GSM 900 Fl(n) = 890 + 0.2*n 0 ≤ n ≤ 124 Fu(n) = Fl(n) + 45

Fl(n) = 890 + 0.2*(n-1024) 975 ≤ n ≤ 1 023

R-GSM 900 Fl(n) = 890 + 0.2*n 0 ≤ n ≤ 124 Fu(n) = Fl(n) + 45

Fl(n) = 890 + 0.2*(n-1024) 955 ≤ n ≤ 1023DCS 1 800 Fl(n) = 1710.2 + 0.2*(n-512) 512 ≤ n ≤ 885 Fu(n) = Fl(n) + 95

PCS 1 900 FI(n) = 1850.2 + 0.2*(n-512) 512 ≤ n ≤ 810 Fu(n) = FI(n) + 80

GSM 450 Fl(n) = 450.6 + 0.2*(n-259) 259 ≤ n ≤ 293 Fu(n) = Fl(n) + 10

GSM 480 Fl(n) = 479 + 0.2*(n-306) 306 ≤ n ≤ 340 Fu(n) = Fl(n) + 10GSM 850 Fl(n) = 824.2 + 0.2*(n-128) 128 ≤ n ≤ 251 Fu(n) = Fl(n) + 45

GSM 750 Fl(n) = 747.2 + 0.2*(n-438) 438 ≤ n ≤ 511 Fu(n) = Fl(n) + 30




Frequency Bands - UTRA

UL Frequencies DL frequencies

UE transmit,Node B receive

UE receive,Node B transmit

I 1920 – 1980 MHz 2110 –2170 MHz

II 1850 –1910 MHz 1930 –1990 MHzIII 1710-1785 MHz 1805-1880 MHz

IV 1710-1755 MHz 2110-2155 MHz

V 824 – 849 MHz 869-894 MHzVI 830-840 MHz 875-885 MHz

Operating

Band

UMTS - FDD - Uses 5MHz spacing




UMTS channels

9612 to 9888 - 10562 to 10838

UE transmit, Node B receive

I

Additional

Downlink (DL)

UE receive, Node B transmit

GeneralBand Additional

Uplink (UL)

General

-

II

9262 to 9538 12, 37, 62,

87, 112, 137,

162, 187, 212,

237, 262, 287

9662 to 9938 412, 437, 462,

487, 512, 537,

562, 587, 612,

637, 662, 687

III 8562 to 8913 - 9037 to 9388 -IV 8562 to 8763 1162, 1187, 1212,

1237, 1262, 1287,

1312, 1337, 1362

10562 to 10763 1462, 1487, 1512,

1537, 1562, 1587,

1612, 1637, 1662

782, 787, 807,

812, 837, 862

4357 to 4458 1007, 1012, 1035,

1037, 1062, 1087

1037, 1062VI 4162 to 4188 812, 837 4387 to 4413

V 4132 to 4233




GSM Areas

BTS

BTS

BTS

BTS

BTS

BTS

BTS

BSC BSC

MSC

Cell

Location AreaMSC/VLR Area




"Hardware" view of a Sample Network

HLR

EIR

AUC

GMSC

ILR

MSC/VLR 1PSTN

MSC Service Area 2

MSC Service Area 1

LEGEND

MSC Boundary

BSC Boundary

PCM Links

Base Station

MSC/VLR 2

BSC 1B

BSC 1C

BSC 2B

BSC 1A

BSC 2A

BSC 2C




"Software" view of a Sample Network

LA 1-B

LA 1-A

LA 2-D

LA 2-ACell 2-A-25

LA 2-B

HLR

EIR

AUC

GMSC

ILR

MSC/VLR 1PSTN

MSC Service Area 2

MSC Service Area 1

LEGEND

MSC Boundary

BSC Boundary

PCM Links

Base Station

MSC/VLR 2

LA 2-C




Quantisation

q7

q6

q5

q4

q3

q2

q1

q0

Ts 2Ts 3Ts 4Ts 5Ts 6Ts 7Ts 8Tstime

}}}}

Sampledvalue

Quantisationvalue

D = Quantisation error




Speech Coding

Sampling rate: 8000 samples per second

Quantisation: 8192 -> 2

13

, 13bits/sampleRequired bit rate: 104kb/s

RPE-LTP Speech Coder Compress speech

to 13kb/s

20ms of speech is processed at a time – 260bits (at 13kb/s)




Different Speech Coders

Excellent

Good

Average

Bad

Speechquality

2 4 8 16 32 64

Bitrate(kbit/s)

Hybrid coders

Increasing complexity

Waveform coders

Vocoders




RPE-LTP Speech Coder

SourceAnalysisRegular

Pulse

VocalTract

Analysis8 Taps

LongTerm

Predictor

S p e e c h

S y n t h e s i s

Error

20msspeech

36 bits

36 bits

188 bits




RPE-LTP Speech Coder

LPC Filter 8 Parameters 36 bits

Delay Parameter 28 bits

Gain Parameter 8 bits

Subsampling Phase 8 bits

Maximum Amplitude 24 bits

13 Samples 156 bits

Total 260 bits

LTP Filter

Excitation Signal




Channel Coding

BlockBlockBlockBlockcoder coder coder coder

50 Very important bits

132 Important bits

78 Not so important bits

1:21:21:21:2

ConvolutionalConvolutionalConvolutionalConvolutional

Coder Coder Coder Coder

456

4 Tail bits

53 bits 378 bits




Coding Schemes

# Info

bits

# Coding

bits

Code

Rate

Max data rate

(kbs) /TSRequired C/I (dB)

(BLER <10%; TU3 FH)

Modul

ation

GSM 260 196 0.5 13.3 9 GMSK

CS-1 181 275 0.45 9.05 9 GMSK

CS-2 268 188 0.65 13.4 13 GMSK

CS-3 312 144 0.75 15.6 15 GMSK

CS-4 428 28 21.4 23 GMSK

MCS-1 176 0.53 8.4 9 GMSKMCS-2 224 0.69 11.2 13 GMSK

MCS-3 296 0.89 14.8 15 GMSK

MCS-4 352 1 16.8 23 GMSK

MCS-5 448 0.38 22.4 14.5 8PSKMCS-6 592 0.5 29.6 17 8PSK

MCS-7 896 0.78 44.8 23.5 8PSK

MCS-8 1088 0.92 54.4 29 8PSK

MCS-9 1184 1 59.2 32 8PSK




Bit-interleaving

HalfBurst#1 HalfBurst#2 HalfBurst#3 HalfBurst#4 HalfBurst#5 HalfBurst#6 HalfBurst#7 HalfBurst#8

0 1 2 3 4 5 6 7

8 9 10 11 12 13 14 15

16 17 18 19 20 21 22 2324 25 26 27 28 29 30 31

32 33 34 35 36 37 38 39

40 41 42 43 44 45 46 47

48 49 50 51 52 53 54 5556 57 58 59 60 61 62 63

64 65 66 67 68 69 70 71

72 73 74 75 76 77 78 79

80 81 82 83 84 85 86 87

. . . . . . . .

. . . . . . . .

440 441 442 443 444 445 446 447

448 449 450 451 452 453 454 455




Interleaving in GPRS and EDGE

EDGE MSC 7-9 interleave over half thetimeslots




“Burst” Interleaving

57 1 26 1 573 3

Normal Burst




“Burst” Interleaving A/8

A/8

A/8

A/8

B/8B/8B/8B/8 A/8

B/8B/8B/8B/8 A/8

B/8B/8B/8B/8 A/8

B/8B/8B/8B/8A/8

C/8C/8C/8C/8 B/8B/8B/8B/8

C/8C/8C/8C/8 B/8B/8B/8B/8

C/8C/8C/8C/8 B/8B/8B/8B/8

C/8C/8C/8C/8 B/8B/8B/8B/8

D/8 C/8

D/8 C/8

D/8 C/8




Equalisation

Data S’ Data

? S ?

Correlator

Channelmodel

“diff.”

Choose“?”

so that“diff.”

isminimized

Received burst

Probable transmittedbit pattern:

VITERBI

}

}

Can compensate for Delay Spread of up to 16µs




Modulation

I

Q

“1”

“0”

“1 bit per symbol”

GMSK – Gaussian Minimum Shift Keying




Modulation Schemes

I

Q

(0,1,1)

(1,1,0)(1,0,1)

(0,0,0)

(0,0,1) (1,1,1)

(1,0,0)

(0,1,0)

I

Q

“1”

“0”

“1 bit per symbol” “3 bits per symbol”

GMSK 8PSK




0

Frequency 1

1 2 3 4 5 6 7

User 1

User 2




TDMA Frame Structure

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

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

Downlink C1

Uplink C1

N N + 1

TDMA frame no.

Mapping of Logical Channels on




Mapping of Logical Channels on

Physical Channels

0 1 2 3 4 5 6 7TDMA Frame n+x

TDMA Frame n+1TDMA Frame n

0 1 2 3 4 5 6 7

Physical Channel 5

890 915MHz

TDMA Frame n+2

5 5 5 5 5 5 5TDMA Frame n n+1 n+2 n+x

Physical Channel 5:

Logical Channel: TCHTCH FACCH TCH




Logical Channels

SCH AGCH

PCHBCCHFCCH FACCH

SACCH

SDCCH

RACH

FRHR

BCH DCCHCCCH

Control Channels Traffic Channels

Logical Channels

FrequencyCorrectionBurst

AccessBurst

DummyBurst

Synchro=nisationBurst

NormalBurst




TCH (Traffic Channels)

Used to carry speech and data

Types of TCH

o Full-rate (TCH/F)o Half-rate (TCH/H)

26 TDMA frames

o 24 TCH

o 1 SACCH (Slow Associated Control Channels)o 1 unused channel

C C




Control Channels

Accessed by:o Idle mode mobiles to exchange signaling

information required to change to dedicatedmode

o Dedicated mode mobiles to monitor surroundingbase stations for handover and other

information51 TDMA frame format

Broadcast Control Channel (BCCH)o Broadcasts on the downlink information such as

base station identity, frequency allocation,frequency-hopping sequences

C l Ch l (2)




Control Channels (2)

Frequency Correction Channel (FCCH) andSynchronization Channel (SCH)o Synchronize mobile to time slot structure of cell

Random Access Channel (RACH)o Used by mobile to request access to GSM

networkPaging Channel (PCH)

o Alerts mobile to incoming call

Access Grant Channel (AGCH)o Allocates an SDCCH to mobile for signaling

following a request on the RACH

L i l Ch l




Logical Channels∗Downlink

–FCCH info about frequency

–SCH info about TDMA structure & BSIC

–BCCH general cell info (LA, Power)

–PCH tells MS its being paged

–AGCH tells MS which signalling channel to use

–SDCCH info about call set-up sent to MS –SACCH info about power and timing advance

–FACCH used for handover

–TCH speech

L i l Ch l




Logical Channels

∗ Uplink

– RACH MS asks BTS for Signaling channel

– SDCCH info about call set-up to BTS

– SACCH info about signal strength and quality

– FACCH handover info

–TCH speech

F St t




Frame Structure

0 1 2 3 4 5 6

1 hyperframe = 2048 superframes = 2,715,648 TDMA frames (3 hours 28 minutes 53 seconds 760 milliseconds)

0 1

(= 51 (26 - frame) multiframes or 26 (51 - frame) mulitframes )

1 superframe = 1326 TDMA frames ( 6.12 seconds )

0 1 2 3 22 23 24 25 0 1 2 3 47 48 49 50

1 (51 - frame) multiframe = 51 TDMA frames (235 ms)1 (26- frame) multiframe = 26 TDMA frames (120 ms)

0 1 2 3 4 5 6 7

1 TDMA frame =8 timeslots (120/26 ~4.615 ms)

1 timeslot = 156.25 bit durations (15/26 ~ 0.577 ms)

( 1 bit duration 48/13 ~ 3.69 micro sec )

TB3

Encrypted bits57

flag1

Training sequence26

flag1

Encrypted bits57

TB3

GP8.25

TB3

TB3

GP8.25

TB3

Encrypted bits39

Synchronization sequence64

Encrypted bits39

TB3

GP8.25

TB8

Synchronization sequence41

Encrypted bits36

GP68.25

TB3

Mixed bits58

Training sequence26

Mixed bits58

TB3

GP8.25

Fixed bits142

TB3

TB: Tail bitsGP: Guard period

Normal burst (NB)(Flag is relevant forTCH only)

Frequecy correctionburst (FB)

Synchronizationburst (SB)

Access burst (AB)

Dummy burst (DB)

2042 2043 2044 2045 2046 2047

0 1 2 3

24 25

47 48 49 50

M lti f t t




Multi-frame structure

C TS




C0 TS0

0 4 9 14 19

F S B B B B C0 C0 C0 C0 F S C1 C1 C1 C1 C2 C2 C2 C2

20 24 29 34 39

F S C3 C3 C3 C3 C4 C4 C4 C4 F S C5 C5 C5 C5 C6 C6 C6 C6

40 44 49

F S C7 C7 C7 C7 C8 C8 C8 C8 I

Dedicated Control Channel




Dedicated Control Channel

0 4 9 14 19

D5 D5 D5 D5 D6 D6 D6 D6 D7 D7 D7 D7 A0 A0 A0 A0 A1 A1 A1 A1

20 24 29 34 39

40 44 49

A2 A2 A2 A2 A3 A3 A3 A3 I I I

D0 D0 D0 D0 D1 D1 D1 D1 D2 D2 D2 D2 D3 D3 D3 D3 D4 D4 D4 D4

Mapping of Logical Channels




Mapping of Logical Channels

on Air Interface

Time slot

Carrier Frequency0

0

1

2

1 2 3 4 5 6 7

B,C DT T T T T T

T T D T T T T T

T T T T T T T T

3 T T T T T T T T

Legend:

B: BCH

C: CCCH

D: DCCHT: TCH

Call to an MS




Call to an MS

9805024

BSC

MSC/VLR

TRC

BTS

BTS

1

2

4

52

2

2

3

1

4

3

5

6

PCH

PCH

PCH

RACH

AGCH

SDCCH/SACCH

TCH

MSC knows the LAI

SDCCH isassigned

using AGCH

SDCCH isassigned

using AGCH

SDCCH/SACCH

are used for callset up. SDCCH

Used to allocateTCH

MS and BTS switchtothe identified TCH

frequency and

Time slot

MS and BTS switchtothe identified TCH

frequency andTime slot

PCHRACH is used to request

Access to the networkRACH is used to request

Access to the network

MSISDN




MSISDN

National mobile number

International Mobile Station

ISDN number

MSISDN = CC + NDC + SN

CC NDC SN

IMSI




IMSI

Maximum 15 digits

3 digits 2-3 digits

National MSI

IMSI

IMSI = MCC + MNC + MSIN

MCC MNC MSIN

IMEI




IMEI

6 digits 2 digits 6 digits 1 digit

IMEI

IMEI = TAC + FAC + SNR + spare

TAC FAC SNR spare

LAI




LAI

3 digits 2-3 digits Max. 16 bits

LAI

LAI = MCC + MNC + LAC

MCC MNC LAC

CGI




CGI

3 digits 2-3 digits Max. 16 bits Max. 16 bits

Location Area IdentityCell Global Identity

CGI = MCC + MNC + LAC + CI

MCC MNC LAC CI

BSIC




BSIC

BSICBSIC = NCC + BCC

NCC BCC




TrafficCasesWhen

MS is inIdle

Mode

9600870

MSC/VLR-A(LA1 + LA2)

MSC/VLR-B(LA3)

LA1

LA2

LA3

1. 2.

5.

3.6.

8.

4.

1. IMSI attach

2. Location updating, type IMSI attach3. Changing cells within an LA

4. Location updating, same MSC/VLR5. Location updating, new MSC/VLR

6. Location updating type periodic registration

7. IMSI detach

8. Implicit detach

7.

IMSI Attach




IMSI Attach

9600873

MSC/VLRBSC/TRC

BTS

2.

1.

3.

4.

4.

RACH is used toaccess the network

AGCH assigns a SDCCH

SDCCH is used to send

IMSI attach message toThe network

IMSIAttach

VLR checks forSubscriber record

VLR updates MSstatus to idle

Acknowledgement sent to MS

IMSI Detach is a complementto this procedure

•Remove the SIM•Power Off

•HLR is not informed•No Acknowledgement sent to MS

Location Updating,




p g,

same MSC/VLR

BSC/TRC MSC

4.

3.

2

.

1.2.

3.

4.

HLRVLR

Authenticationperformed

Using SDCCH

Authenticationperformed

Using SDCCH

BCCH is checked

Location update Request

System acknowledges

the location updaterequest. Informs MS and

BTS to release SDCCH

Location Updating,




p g,

new MSC/VLR

9805058

BSC/TRC MSC

4.4.

HLR

VLR

2.

3.

3.

1.

MSC/VLR-B GMSC




Caseswhich

Activate aMS and

Caseswhen MS

is inActiveMode

1. Call from MS (speech, fax, data, short message)2. Call to MS (speech, fax, data, short message, cell broadcast)3. Handover - intra - BSC4. Handover - inter - BSC, intra - MSC5. Handover - inter - MSC

1.

2.

3.

4.

5.

BSC/TRC

MSC/VLR-A

BSC/TRC

BSC/TRC

Call set-up MS to PSTN




p

9600875

BSC/TRC

4.

3.2.

1.

4.

1.

2.3.

4.

GSM/PLMN

5.MSC/VLR TE

PSTN

RACH AGCHCall request using SDCCH

Allocate idle TCH

B-number

SDCCH used for•Marking the MSM active in VLR

•Authentication/Ciphering•Equipment Identity register

•sending B-number to the Network

Call to MS from PSTN




HLR

GSM/PLMN PSTN

MSC/VLR

GMSCLocal

exchange

11.

10.

9.

8.

8.9.

10.

11.

7. 11.

8.

8.

5.

4.

3.

2.

5.1.

6.

1.

BSC/TRC

PCH

PCH

PCH

RACH

AGCH

SDCCH

12

Allocate TCH

and inform MS

and RBS of this

TCH

Measurements sent to BSC




Evaluation

and decisionabout handover

Measurements from RBS and MS

RBS measures:

Signal strength andtransmission quality

on TCH, uplink

MS measures:

Signal strength andtransmission qualityon TCH, downlink

Signal strengthfrom neighboringBTS

Measurementreports from MSare sent to RBS

BSC/TRC

MSC/TRC

Handover




Four types of handovers:

o Channels (time slots) in same cell

o Between cells within same BSCo Between BSCs, within same MSC

o Between MSCs

Handover: Cells Controlled




by the Same BSC

9600878

old

new

BSC

2.

6.

1.

5.

3.

4.5.

2.

Activate a new TCH

Info on new frequency, TS and output power

Handover access burst

TA infoHandovercomplete

Release old TCH

Handover: Different BSCs




but the same MSC/VLR

9600879

OldBSC/TRC

4.

9.

3.

7.

5.

6.7.

4.

new

BSC/TRC

MSC

1.

4.

8.

4.7.

2.

HO required message with CGI

HO request

Activate a TCH

Info on freq, TS and Tx Power

HO burst

TA

HO completemessage to MSC

Release TCH

Release TCH

Handover: Cells Controlled




by Different MSCs

9600880

oldBSC/TRC

4.

5.

8.

9.

10.

7.

newBSC/TRC

MSC-A

1.

7.

3.

MSC-B10.

2. 5. 10.

GSM PLM PSTN

11.

6.

HO required message with

CGI

Requests help

HO requestActivate a TCH

Info & HO number

Link set up to target

mscHO command

Freq, ts,

output power

HO burst

TA

HO complete

HO complete

New path set up in GS

SS Overview




HLR VLR EIR AuC

MSC

PSTN

SS7

MSC – Mobile Switching Center




It is Switch

ALL calls are routed through at least one MSC

Generates CDRs (Call Data Records) that are

used for Billing

Service Provisioning – SMS and Supplementaryservices are switched through MSC

DTI (Data Transmission Interface) handles

(HS)CSD ((High Speed) Circuit Switch Data)Call

MSC – Mobile Switching Center




RPRP

MSC/VLR TRC

ETC

ETC

ETC

ETC

RP

CPSP

RPD

ST7

GS

SMS-C




MSC/VLR SMS-C2.

1.

2.

RACHAGCH

SMS on SDCCH

HLR

SMS - GMSCSMS - C MSC/VLR

1.

2.

8.

4. 3.

5.

6.

7.

VLR – Visitor Location Register




Keeps record of all IMSI in MSC/VLR area

Info on each subscriber:

o Subscribed Supplementary Services

o Activity of MS (Active / Idle)

o LA (Location Area) of MSo MSISDN

o TMSI

o IMSI

HLR

U p d a t e D

e l e t

e

MSC/VLR MSC/VLR

HLR – Home Location Register




Is a database that stores information on allsubscribers on the network:

o IMSIo MSISDN

o Subscribed Supplementary Services

o MSC/VLR area

o Authentication information

Interacts with AUC (Authentication Center)Coordinate info in VLR’s

EIR – Equipment Identity Register




Database containing three lists of IMEI:

o White listed

o Black list of all IMEI that has been barredo Gray list – faulty or non-approved phones

AUC – Authentication Center




Subscriber Authentication

Provides ciphering keys

AUC

RANDgenerator

Database

IMSIKi

A3Authentication

Algorithm

A8

CipheringAlgorithm

Ki

RAND

SRES

Kc

Request for tripletsfrom HLR (IMSI)

Triplets(or many per request)

RAND Random numberSRES Signed Response

Kc Ciphering keyKi Subscriber authentication keyIMSI International Mobile Subscriber Identity

Information stored on SIM




Security information

o Subscriber authentication key, Ki

o Ciphering key, Kco Supports Authentication Algorithm, A3

o Supports Ciphering key generation algorithm, A8

Othero IMSI (International Mobile Subscriber Identity)

o LAI (Location Area Identity)

o List of frequencies to be used for cell selection

o Forbidden PLMN

Authentication Procedure




MSC/VLR

1. RAND

3. SRES

MS

2. MS calculates SRES using RAND + Ki

(SIM-card) through A3 and Kc using RAND+Ki

through A8.

4. Compare SRES received fromMS with SRES in triplet. If they

are equal access is granted.

MSC/VLRMobile service Switching CenterMS Mobile StationRAND Random numberSRES Signed Response

Ciphering Procedure2 M




VLR

MSC

MS

1. M + Kc2. M

Decryption

process using

A5

Encryption

process

using

A5

TDMA

frame no.Kc

4. Encrypted

M’ c

M’

Kc

TDMA

frame

no.3. Encrypt M5. Decryption of M’

successful?

If yes

6. Ciphering

mode complete

A5 Encryption and decryption algorithm

M Ciphering Mode Command

M’ Ciphering Mode CompleteM’ c Ciphering Mode Complete, ciphered

Kc Ciphering key

MSC Mobile services Switching Center

VLR Visitor Location Register

BSS Overview: BSC/TRC




RPRP

GroupSwitch

MSC/VLR

SRS

RBS

ETC

ETC

ETC

ETC

RP

CPSP

TRAU

RPRPG

TRH

RPD

ST7

Remote BSCs




MSC BSC/TRC

TRC

(Remote) BSC

Abis

Abis

Abis3 E1 TS per TRX;16kb/s per TCH

Ater16kb/s per TCH“multiplexed”

A64kb/s per TCH“multiplexed”A

Usage of E1




TCH TCH TCH TCH

TCH TCH TCH TCH

LAPD

TCH TCH TCH TCH

TCH TCH TCH TCH

LAPD

Synch

T R X 1

T R X 2

T R X 3

T R X 4

T R X 9

T R X 1 0

T

R X 5

T R X 6

T R X 7

T R X 8

AbisTCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

LAPD LAPD

TCH TCH TCH TCHTCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

Synch

LAP-DConcentrationTCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCHTCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

TCH TCH TCH TCH

SynchAter

TCH

TCH

TCH

Synch

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

SignallingTCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

A

Radio Link Features




DTX (Discontinuous Transmission)

Dynamic Power ControlFrequency Hopping

Radio Link Measurements

Handovers

DTX- Discontinuous




TransmissionAverage Voice activity is around 50%

DTX is a feature that allows to betransmitted only when there is something tobe transmitted

o Uses VAD (Voice Activity Detector)

Battery power

Improves the overall network quality byreducing unnecessary interference

Dynamic Power Control




This enable the BTS and the Mobile totransmit only the power necessary foreffective communications

Power Control Commands are via theSACCH

This improves the battery life of MobilePhones

And it improve the overall network qualityby reducing unnecessary interference

MS power output levelsFor GMSK modulation




For GMSK modulationGSM 400 &

GSM 900 & GSM

850 & GSM 700

DCS 1 800 PCS 1 900

normal extreme

1 1 W (30 dBm) 1 W (30 dBm) ±2 ±2,5

2 8 W (39 dBm) 0,25 W (24 dBm) 0,25 W

(24 dBm)

±2 ±2,5

3 5 W (37 dBm) 4 W (36 dBm) 2 W (33 dBm) ±2 ±2,5

4 2 W (33 dBm) ±2 ±2,5

5 0,8 W (29 dBm) ±2 ±2,5

For 8-PSK modulationGSM 400 &

GSM 900 & GSM

850 & GSM 700

DCS 1 800 PCS 1 900

normal extreme normal extreme

E1 33 dBm 30 dBm 30 dBm ±2 ±2,5 ±2 ±2,5

E2 27 dBm 26 dBm 26 dBm ±3 ±4 -1.33 -4,5/+4

E3 23 dBm 22 dBm 22 dBm ±3 ±4 ±3 ±4

DCS 1 800 &

PCS 1 900

Power

class

Tolerance (dB)

for conditions

GSM 400 and

GSM 900 & GSM

850 & GSM 700

NominalMaximum

output Power

NominalMaximum

output Power

Tolerance (dB)for conditions

NominalMaximum

output Power

Tolerance (dB)for conditions

Power

class

Nominal

Maximum

Nominal

Maximum

Nominal

Maximum

MS Power Control levelsGSM 900 DCS 1 800




norma

l

extrem

e

norma

l

extrem

e

0-2 39 ±2 ±2,5 29 36 ±2 ±2,5

3 37 ±3 ±4 30 34 ±3 ±44 35 ±3 ±4 31 32 ±3 ±4

5 33 ±3 ±4 0 30 ±3 ±4

6 31 ±3 ±4 1 28 ±3 ±4

7 29 ±3 ±4 2 26 ±3 ±4

8 27 ±3 ±4 3 24 ±3 ±4

9 25 ±3 ±4 4 22 ±3 ±410 23 ±3 ±4 5 20 ±3 ±4

11 21 ±3 ±4 6 18 ±3 ±4

12 19 ±3 ±4 7 16 ±3 ±4

13 17 ±3 ±4 8 14 ±3 ±4

14 15 ±3 ±4 9 12 ±4 ±5

15 13 ±3 ±4 10 10 ±4 ±516 11 ±5 ±6 11 8 ±4 ±5

17 9 ±5 ±6 12 6 ±4 ±5

18 7 ±5 ±6 13 4 ±4 ±5

19-31 5 ±5 ±6 14 2 ±5 ±6

15-28 0 ±5 ±6

Tolerance (dB)

for conditions

Power

control

level

Nominal

Output

power

(dBm)

Tolerance (dB)

for conditions

Power

control

level

Nominal

Output

power

(dBm)

BTS Power Control Levels




BTS actual power level is

Max. power (dBm) – 2*N (i.e. 2dB at a time)

TRX

powerclass

Maximum

output power

TRX

powerclass

Maximum

output power

Micro Micro

1 320 - (< 640) W 1 20 - (< 40) W M1 (> 19) - 24 dBm M1 (> 27) - 32 dBm

2 160 - (< 320) W 2 10 - (< 20) W M2 (> 14) - 19 dBm M2 (> 22) - 27 dBm

3 80 - (< 160) W 3 5 - (< 10) W M3 (> 9) - 14 dBm M3 (> 17) - 22 dBm

4 40 - (< 80) W 4 2,5 - (< 5) W Pico Pico

5 20 - (< 40) W P1 (> 13) - 20 dBm P1 (> 16) - 23 dBm

6 10 - (< 20) W

7 5 - (< 10) W

8 2,5 - (< 5) W

Maximum

output power

Maximum

output power

TRX

powerclass

TRX

powerclass

For a normal BTS, the maximum output power

measured at the input of the BSS Tx combiner

For a micro-BTS or a pico-BTS, the maximum outputpower per carrier measured at the antenna connector

after all stages of combining

GSM 900 & GSM 850 &

MXM 850 and GSM 700

DCS 1 800 & PCS 1 900

& MXM 1900 micro and

GSM 400 & GSM 900 &

GSM 850 & MXM 850

DCS 1 800 & PCS 1 900

& MXM 1900




Effect of DTX and PC on Quality

2.00%

3.00%

4.00%

5.00%

6.00%

7.00%

8.00%

9.00%

10.00%

0 10 20 30 40Time (hours)

P e r c e n t a g e

%HOIU

%HOID

DTX + PC Off

PC Off


R L (i GSM i i l h




RxLev (in GSM units: reports signal strengthabove –110dBm – maximum 63 i.e. –47dBm

RxQualRxQual BER (%)

0 <0.2%

1 0.2% -0.4%

2 0.4%-0.8%3 0.8%-1.6%

4 1.6%-3.2%

5 3.2%-6.4%6 6.4%-12.8%

7 >12.8%


Th M bil t t th BSC ( i th BTS)




The Mobile reports to the BSC (via the BTS) everySACCH period (480ms):

o Serving Cell Signal Strength (on allocated TCH)

o Serving Cell Signal Quality

o BCCH, BSIC and RxLev of the 6 strongest neighbours

The BTS reports to the BSC

o The Signal Strength from the Mobile

o The Signal Quality from the Mobile

o The BTS power control level

o The MS power control level

o The TA (timing Advance)

Handovers

A h d i i iti t d h




A handover is initiated wheno A Neighbour Cell exceeds the signal strength of

the serving Cell with CRH for more than the

specified period (e.g. 5 Seconds)

o Excessive Timing Advance occurs

o The Signal Strength (uplink or downlink) dropsbelow a said minimum

o The signal quality (uplink or downlink) drops

below a said minimum

Handover

Th BSC t i th f ll i i f




The BSC contains the following infoo Traffic Measurements for each Cell

o Cell list with CGI, BCCH frequency, BSIC &TxPower

o Neighbour list for each Cell with

CGI, BCCH & BSIC and “CRH” (Cell ReselectionHysteresis) and other handover parameters

Frequency Hopping




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

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

Downlink C1

Uplink C1

N N + 1TDMA frame no.

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

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

Downlink C2

Uplink C2

N N + 1TDMA frame no.

Frequency Diversity




Raleigh fading is frequency dependant

f0

f1

Position

S i g n a l l e v e l

Frequency Diversity




Diversity: combining two or moreuncorrelated versions of the same signal

For “conventional” frequency diversity the infois sent on two different frequencies at thesame time.

To be uncorrelated the two frequencies

should be more than 1/(multi-path spread ),where the multi-path spread is dependant onthe environment.

For urban areas the frequencies should bemore than 600kHz apart

Base Band Frequency Hopping




ControllerCALL 2 Tx and Rx on f1

ControllerCALL 3

ControllerCALL 4

Controller

CALL 1

Tx and Rx on f2

Tx and Rx on f3

Tx and Rx on f0

“Baseband Bus”

for routing bursts

C o m

b i n

e r f1 f2 f3 f0

f0 f1 f2 f3

f2 f3 f0 f1

f3 f0 f1 f2

Number of frequencies equal to number of transceiversNumber of frequencies equal to number of transceivers

Synthesised Hopping




Controller

CALL 2

Tx and Rx hopping

ControllerCALL 3

ControllerCALL 4

ControllerCALL 1

Tx and Rx hopping

Tx and Rx hopping

Tx and Rx hopping

f1 f2 f3 f0

f0 f1 f2 f3

f2 f3 f0 f1

f3 f0 f1 f2

Number of frequencies more or equalNumber of frequencies more or equal

to number of transceiversto number of transceivers

Why does hopping work?




Review interleaving

If one timeslot gets completely lost during

transmission 1/8 of two speech frames are lost.At the receiver the speech frames are de-interleaved

The channel coding can recover from the 12.5%

BER.

Interleaving and Channel Coding is part and parcel

of the GSM standard - it works even without hopping.

Interleaving and ChannelCoding work always




FER and SQI vs.RxQual

-10

0

10

20

30

0 1 2 3 4 5 6 7

RxQual

S Q I / %

F E

Non-Hopping (calls on BCCH-carrier)

Non-Hopping (calls on BCCH-carrier)

Hopping w ith 20% load

Hopping w ith 20% load

FER

SQI

Synthesized hopping

S th i d h i id




Synthesised hopping provides:o Higher capacity for the same quality.

o Simplified frequency planning.

o Can implement new transceivers without newfrequency plans

But

o It costs moreo Can not be implemented with filter combiners - might

impose limit on #TRX/cell

o Complications with implementation combined withBase Band hopping

Base-band hopping




Base band hopping provides:

o Lower cost

o Some frequency diversity gain

o Can be implemented on all equipment

o Hence no limit on number of TRX’sBut

o Require frequency plan with upgrade

o More complex planning

Frequency Diversity Gain

Frequency Diversity Gain vs Number of Hopping Channels




0

1

2

3

4

5

6

7

8

1 2 3 4 5 6 7 8

Number of Carriers

G

a i n ( d B )

Cyclic Random Poly. (Cyclic) Poly. (Random)

Interference Diversity

Extent of Interference diversity depends on:




Extent of Interference diversity depends on:o Interference load (DTX and Power Control)

o Frequency reuse: low re-use -> low gain;Dependant on area type.

o Number of Frequencies (less -> less gain)

o Cyclic or Random

Interference diversity gain reached with 25%

load, 12 frequencies in Urban area withrandom hopping is 2.5dB - mostly it is less.

Co-channel interference

The total co-channel




D

interference experienced atthe yellow spot is the sum ofinterference of all six cellswith the same frequency

The interference from one

co-channel interferer can bewritten asI =KD-γ

The carrier level isC= KR-γ

C/I = (D/R)γ /6

R

Re-use distance




v

30°

u

D

D = (i2 + ij + j2)½2Rcos 30°D = (i2 + ij + j2)½ (3) ½ R

Number of cells in the

re-use pattern

N = i2 + ij + j2i (1,2,3,4 …..)

j (0,1,2,3,4 …..)

D/R = (3N)½

i

j

The Hexagon




Area of a hexagon:A = ½. 3 (3)½R2

Distance between centers

of two adjacent cells:d = (3)½R

R

d

Traffic calculations revision

An Erlang




a g

Erlang B Table

Examples of Traffic channels

Problem

The average traffic generated by one user is10 illiE l /S b ib




g g y10milliErlang/Subscriber

The population density is 50 people/km2

Assume a phone penetration of 80%

You are implementing a CS-2 system.

You have 48 (1-48)channels available

Assume free-space propagation … i.e. γ = 2

Draw the re-use pattern and assign frequencies to

the cells.Calculate the site to site distance that you will

need to implement.




Sectorisation




C/I = (D/R)γ γγ γ /2

4/12 Cell Pattern

FrequencyGroups

A1 B1 C1 D1 A2 B2 C2 D2 A3 B3 C3 D3

Channels 1 2 3 4 5 6 7 8 9 10 11 12




Channels 1 2 3 413 14 15 16

5 6 7 817 18 19 20

9 10 11 1221 22 23 24

A3 A2

D3

D1 D2 C1

C3C2

B1

B3 B2

1721

13

9

10

5

22

16

12

24

8

20

3

15

711

1923

2

14

6

18

A1

1

4

Adjacent Channel interference

for co channel interference C/Ic 9 dB




for co-channel interference C/Ic=9 dB

for adjacent (200 kHz) interference C/Ia1=-9 dB



Adjacent channel interferenceRelativepower(dB)

00

Relative

power

(dB)




-10

-20

-30

-50

-40

-60

-70

-80

0 200 400 600Frequency from the carrier (kHz)

measurement bandwidth 30 kHz measurement bandwidth 100k Hz

1200 1800 60003000

-10

-20

-30

-40

-50

-60

-70

-80

0 200 400 600 1200 1800 6000

Frequency from the carrier (kHz)

measurement bandwidth 30 kHz

measurement bandwidth 100 kHz

Edge of TX

band + 2 MHz3000

Co-channel interference

# Info

bits

# Coding

bits

Code

Rate

Max data rate


(BLER 10%; TU3 FH)

Modul

ation




bits bits Rate (kbs) /TS (BLER <10%; TU3 FH) ation

GSM 260 196 0.5 13.3 9 GMSK

CS-1 181 275 0.45 9.05 9 GMSK

CS-2 268 188 0.65 13.4 13 GMSKCS-3 312 144 0.75 15.6 15 GMSK

CS-4 428 28 21.4 23 GMSK

MCS-1 176 0.53 8.4 9 GMSK

MCS-2 224 0.69 11.2 13 GMSKMCS-3 296 0.89 14.8 15 GMSK

MCS-4 352 1 16.8 23 GMSK

MCS-5 448 0.38 22.4 14.5 8PSK

MCS-6 592 0.5 29.6 17 8PSKMCS-7 896 0.78 44.8 23.5 8PSK

MCS-8 1088 0.92 54.4 29 8PSK

MCS-9 1184 1 59.2 32 8PSK

Effect of γ and C/I

C/I (dBMinimum

f iAssuming 3 sectored sites




gamma 9 12 13 17 362 18 33 42 102 7965

2.5 12 18 21 42 13233 9 12 12 24 399

3.5 6 9 9 15 1714 6 6 9 12 90

C/I (dBfrequencies

Spectral Efficiency

Erlang/Hz/km2




Using the previous problem as starting point

– calculate the spectrum density that couldbe achieved if the sites were sectorised.Compare with the omni-cells

Benefits of sectorisation

Higher gain antennas are available – betterpenetration




penetration

Less cost for same traffic density

Underlay / Overlay - MRP




Cell Splitting




Hierarchical Cells

Umbrella Cell:Macro Cell: Antenna above average rooftop height




g p gMicro Cell: Antenna below average rooftop height

Pico Cell: Indoors

C/I reduction from DTX

C/I values




0

0.02

0.04

0.06

0.08

0.1

0.12

-50 -40 -30 -20 -10 0 10 20 30 40 50

Signal Level

P r o b a b i l i t y D i s t r i b u t i o n

C/IC/I DTX

Interference reduction fromPower Control

The level of the transmitted signal is reducedto what is required for the specified Receive




to what is required for the specified ReceiveSignal and Quality levels.o Assume Urban Environment where 90% of the traffic is in

the regulation area

o The average in building expected received signal is -60dBm

o Assume a desired signal level of -92dBm

o For affective power control the average interferencelevel, and the average signal level will be down by 32dB.

The effect on the C/I is difficult to determine.

Interference Reduction from PC

Interference Levels




0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

-140 -120 -100 -80 -60 -40 -20 0

Signal Level


Interference

Int. DTX

Int. PC +DTX

Carrier Reduction from PC

Carrier Levels




0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

-140 -120 -100 -80 -60 -40 -20 0

Signal Level

P r o b a b i l

i t y D i s t r i b u t i o n

Carrier

Car. DTXCar. PC + DTX

Impact of PC on the C/I ?

C/I values

0 16




0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

-50 -40 -30 -20 -10 0 10 20 30 40 50

Signal Level


C/I

C/I DTXC/I PC + DTX

Frequency Hopping

with DTX and PC




• Power control: 0• DTX: 0

• TS active: 1

• No call: 0

Hopping with DTX and PC

C/I values

0 25




0

0.05

0.1

0.15

0.2

0.25

-50 -40 -30 -20 -10 0 10 20 30 40 50

Signal Level


C/I

C/I DTX

C/I PC + DTX

Hopping

Effect of DTX and PC on Quality

10 00%




2.00%

3.00%

4.00%

5.00%

6.00%

7.00%

8.00%

9.00%

10.00%

0 10 20 30 40Time (hours)

P e r

c e n t a g e

%HOIU

%HOID

DTX + PC Off

PC Off

Planning for FH network

Use separate frequency blocks for TCH andBCCH




o BCCH frequency channel must be Always On

o No hopping over BCCH.

Plan TCH layer:

o MAL : Mobile radio frequency channelAllocation List

o HSN: Hopping sequence number

o MAIO: Mobile Allocation Index Offseto MAI: Mobile Allocation Index

Selecting a BCCH block

Why a BCCH block?o Identifying the source of interference




y g

o Re-evaluation of the neighbour list

o For collecting data for a measurement based

plan

Optimum size?

o Where a change in a BCCH carrier will on

average make the same difference as a changein a TCH carrier in the optimised plan

Selecting a BCCH block

BlockSize

Total Number of Carriers Available

BCCH =




Total Number of Carriers Available

AverageTraffic TCHlayer Scaling perCell DTX PC on × +

_ _ _ _

( / ) ( , )8 1

Frequency Hopping

MAI 0 2 1A 2A 3A 1B 2B 3B 1C 2C 3C

MAMAIO




MAI 0 2 1A 2A 3A 1B 2B 3B 1C 2C 3C

1 1 3 1 2 3 4 5 6 7 8 92 2 4 10 11 12 13 14 15 16 17 18

3 3 1 19 20 21 22 23 24 25 26 27

4 4 2 28 29 30 31 32 33 34 35 36

4 1 2 3 2 4 3 1

28 1 10 19 10 28 19 110 19 28 1 28 10 1 19

HSN =x

TRX1 on 1A has MAIO = 0

TRX2 on 1A has MAIO = 2

Automatic FrequencyPlanning Tools

TRXR i t

AFP Tool




Coverage

Analysis

Interference

Matrix

Propagation

Predictions

SeparationConstraints,

etc

Frequency

Plan

Requirements

etc

Automatic Frequency Planning

Model of NetworkCost Function:Sum of remaining




Model effect of particularassignment on quality

Propagation PredictionsDrive Test DataHandover StatisticsLive Measurements

Sum of remaininginterference and

other penalties.Quality

Change:Frequency

BSICHSN, MAIO

Interference Matrix

The “conventional” interference matrixrepresent:o The Traffic that ill be interfered on if t o




o The Traffic that will be interfered on if two

“radios” were assigned the same frequency;o The area that will be interfered on if two “radios”

were assigned the same frequency –

o pixel by pixel.

o Need ACCURATE propagation predictions andtraffic distribution maps.

o What is the cost of accurate enoughpredictions?

Generating theInterference Matrix

2 m Resolution50 m Resolution




2.5 km

2.0 km

2.5 km

2.0 km

Microcell Service Area ≈ 1 pixel

Probability of C/I>9dB

Cummulative Probability Distribution

for C/I exceeding 9dB

0.9

1

B




0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

-20 -15 -10 -5 0 5 10 15 20 25 30

Calculated C/I (dB)

P r o b a b i l i t y t h

a t C / I w i l l b e b e l o w 9 d B

AFP

Implements a mathematical optimisationmethod or Artificial Intelligence method to

i i i




minimise

Cost = Cijδij + Aijδij

o δij = 1 if radios i and j are assigned the same(adjacent)frequency,

o δij = 0 else

By changing the frequency assignments tothe different cells

What are the true aims inCell and Frequency Planning




What will really give optimum quality?

The inputs to Cell PlanningT r a f f i c : ( T b l

eG S




(Tr a f f i c d i s t r i b

u t i o n m a p s

)

S p e

c t r u m

A v a i l a

b

Cost / Money

GoS

QoSQuality

CoverageSpeech Quality

System Choice - C/I

Quality

Voice Qualityo Impacted by the FER (Frame Erasure Rate /

Probability




Probability

o And to some extent by the BER (Bit Error Rate / probability)

Dropped Calls

o Radio Link Timeout based on unsuccessful

SACCH frame - FER

C/I to FER

Frame Erasure Rate0




-30

-25

-20

-15

-10

-5

-5 0 5 10 15 20C/I(dB)

1

0 l o g ( F E R )

Frequency Hopping

on 8 freqquencies,

Random Hopping

Non-Hopping

Measurement BasedFrequency Planning

Using Mobile Measurement Reports howwill you go about generating the optimal




y g g g p

Interference Matrix?

The first MeasurementBased Plan

Johannesburg’s Central Business District

12km×12km




65 sites (≈350 cells)477 carriers

Despite questioned cluttered data and propagationprediction models

very low dropped call rate of about 1.4% was very

often achieved

partly due to dedicated optimisation

Cell Traffic Recordings was used to collect MobileMeasurement Reports on all the cells

Measurement BasedFrequency Planning




With the mobiles measuring on all BCCH channels

The process took about a month.

The signal strength of the serving cell and the

reported neighbours was used to calculated theC/I and eventually the FER.

The average FER for each server-interferer

relation was calculated.and multiplied with the traffic on the serving cell




TheSanity

Check

Using

Dropped Call Rate

1 90%

2.10%

2.30%

n t e d




Using

MMRs inFrequencyPlanning

0.90%

1.10%

1.30%

1.50%

1.70%

1.90%

0 10 20 30 40

Time

P e r c e n t a g e

Traffic

1.29%

%Drop

DayAvg

P l a n I m p l e m e n

Measurement Based Frequency Plan

Dropped Call Rate

2.30%

n r u n i n

e T e s t s




0.90%

1.10%

1.30%

1.50%

1.70%

1.90%

2.10%

0 10 20 30 40 50 60

Time

P e r c e n t a g e

( 0 . 1

% p e r d e v i s i o n )

Traffic

Previous Minimum

%Drop

DayAvg

M

e a s u r e m e n t B a s e

d P l a

P r e d i c t i o n s a n d

D r i v e

The

Intra-cell Hand-over and TCH Dropped

due to Bad Quality

7.00%

8.00%

c a s s a l f o r T ) %HoBUQ

%HoBDQ

Traffic

%TBQDis*50n

I m p l e m e n t e d




TheResults:Quality

2.00%

3.00%

4.00%

5.00%

6.00%

0 10 20 30 40

Time

P e r c e n t a g e ( o f t c a l l s f o r H a n

d t c

P l a n

Data Sources for theInterference Matrix (1)

Propagation Predictionso Well established conventional method




o Based on Predicted Carrier to Interferenceratios that is often translated with a “C/I weights”curve

o Integration with AFP tools eases useo Suited for new networks with many new cells

o Dependant on elevation and clutter data thatoften has limited accuracy

Neighbour relations statisticso Well suited for very tight plan





o Well suited for very tight plan

o Too little information for a less tight plan

o Hand-over statistics not directly related to C/Io Can not model interference from non-

neighbours

Drive Test Datao Measurements done with network set on measure on all





BCCH channelso Independent of accuracy of elevation and clutter data

o Extensive measurements necessary for interferencematrix

o Difficult to deduce interfered traffic from datao Drives are limited to roads and does not include high

rise buildings

o Effort in importing into an AFP

o Often used to supplement propagation predictions

Live Data: Mobile Measurement Reportso Mobile Measurement Reports are collected with the cell





p

set to measure on all BCCHso Data reflect the actual traffic distribution as well as the

actual C/I. (“as the customer sees it”)

o No additional neighbour relations or exceptions required

o Extensive data collection - slow process. Requires thenetwork to be fairly mature and stable.

o Difficult to model new sites

o Takes some effort to import into an AFP.

Prediction vs. MMRP

LIMITED accuracyo Propagation predictions

o Clutter and Height data

I b ildi

Cannot represent newsites

MMR limitations:




o In building

o Traffic distribution o RxLev: -110 -> -48dBmo Only integers

o Only six neighbours

o BSIC decodingproblems

Combining Data Sources

….one of the remaining challenges. E.g:o How to complement the shortcomings of the

mobile measurements reports with the




propagation predictions to include new cells.o How to combine limited measurements with

predictions.

withouto Spoiling good data with bad data.

o Skewing the matrix, e.g. when drive test data isavailable for only part of the network.

Penalties for AFP

A “bare necessity” approach i.e. setpenalties only when

o it is required by law or




o It is required for feasibility – e.g. filter combinerseparation

o it will assist in the improvement of network

qualityo Is penalties to avoid adjacencies required?

The size of the penalties must reflect theirimportance and effect on network quality

Examples of Scaling Factors

Difference in interference introducedo Traffic load on TCH channels

o Power Control




o Discontinuous Transmission (DTX)

o Over-laid Under-laid - depend on effectivenessof implementation

o Synthesizer Hopping - dependant on fractionalload

Difference in immunity to interference

o Frequency Diversity Gain of Hopping Networks

Interference Load

The core questions:o How much interference will assigning the same

frequency to a carrier in Cell A and Cell Bcause ?




cause ?

o How much less will that be after DTX?

o How much less will that be after Power Control?

Interference Loado How much signal or potential interference is

carried on a particular carrier

o Interference Load = Traffic on Cell8 * #Carriers

Interference Load Reduction

For BCCH

o Interference Load = 1




For Non-Hopping TCH without DTX and PCo Interference Load = Traffic on TCH Carriers

o 8 * Number of TCH Carriers

After DTXo Voice Activity Factor 40% on TCH channels

o Interference Load = 0.4 * Traffic on TCH Carriers


Interference Load Reduction

After Power Control ?

o Consider a very simplified model:

C/I Server SS / (6* Interferers SS)




C/I = Server SS / (6* Interferers SS)

Reducing the signal level of the server and of theinterferers by approximately 10dB:

C/I = 0.1* Server SS / (6*0.1* Interferers SS)

Approximately unchanged.

o Practical implementation suggest a definiteinterference reduction - by 60%

o Interference Load = 0.6 * Traffic on TCH Carriers


A few terms

Frequency Allocation Re-useo FAR = Total Number of Frequency Channels

Number of Frequencies per Cell




Effective Re-useReff= Total Number of Frequency Channels

Average number of TRX per Cell

Fractional Loado Lfrac= Number of TRX per Cell .

Number of Frequencies per Cell

Hardware Loado LHW= (Busy Hour Traffic) / (TN /TRX)

A few terms

Frequency Load

o Lfreq= LHW Lfrac




Effective Frequency Load

o EFL =. Busy Hour Traffic per Cell .

(TN per TRX for Traffic).(Total # FreqCH)

Optimum # carriers toHop over = 24/6

Optimum frequency Re-use

35

40




0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9

Frequency Reuse = #TCH carriers / #TCH per cell

E r l a n g

p e r S i t e

6MHz available for TCH

Quality vs Capacity

140

145

150

i t y ) The challenge: To maximize Quality * Capacity




100

105

110

115

120

125

130

135

140

6 7 8 9 10 11 12 13 14 15 16

Average Erlang per Cell (Capacity)

(deduced from Spectrum Utilisation)

M i n u t e E r l a n g p e r D r o p ( Q u a

l

Major Interferers

Effect of reducing major interferers

90.00%

100.00%




0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00%

P er cent age of C e l l s cont r i but i ng t o In t e r f e r ence

Cummulative Contribution

With 5 sites' interference removed

What criteria would youuse for site selection?

Close to traffic – most effective Power Control

Contained (high γ )




o In buildingo In valleys rather than on top of mountains

What effect will an unbalanced link have?

What criteria will you provide anAutomatic Cell Planning tool with?

Propagation Predictions

Traffic distribution - GIS

Effective Frequency load

Hand over areas




Interference Matrix

MMR

Frequency Allocation

Possible sites

Equipment used

Income: Coverageof potential traffic

Cost: cost ofchanges / sites

Changes in ACP

Site Selection

o Set of viable sites

o Propagation prediction

Prediction model (accurate)




DEM

Clutter

Buildings

o Traffic distribution Demographic

Antenna parameters (Tilts & Azimuths)

Upgradingo Cell Statistics

Changes in ACP

Radio Parameterso Transmission power

o Cell Hysterises




o Cell Hierarchical Level

Evaluating automatic tools...

Automatic Frequency Planning Toolso Must Allow various data sources to be imported

o Must model the network accurately (e.g. Model




hopping accurately)o Must be simple to use, hence most of the

modelling should be integrated

Automatic Network Optimisationo Must be reliable and accurate enough to allow it to

run free with very little manual input

Automatic Cell Planning

o Cost function is so complex it should come withthe tool... and allow manual changes

MS Sensitivity

GSM 900 MSo for GSM 900 small MS -102 dBm

o for other GSM 900 MS -104 dBm




DCS 1 800 MSo for DCS 1 800 class 1 or class 2 MS -100 / -102 dBm *

o for DCS 1 800 class 3 MS -102 dBm

BTS sensitivity

GSM 900 BTSo for normal BTS -104 dBm

o for micro BTS M1 -97 dBm






o for pico BTS P1 -88 dBm

DCS 1 800 BTS

o for normal BTS -104 dBmo for micro BTS M1 -102 dBm


o for micro BTS M3 -92 dBmo for pico BTS P1 -95 dBm

DefiningQuality




Speech Quality (BER, FER)

Dropped Calls

Coverage

Call Set-up success

Handover stats

To do

Cell Planning

Frequency Planning

Link balancing




Neighbour lists

o Handover parameters

Power ControlDTX

Dimensioning

Idle mode location The path loss criterion parameter C1 used for cell selection and reselection is

defined by:

C1 = (A - Max(B,0))

where

A = RLA_C - RXLEV_ACCESS_MINB = MS_TXPWR_MAX_CCH - P

P Ma im m RF o tp t po er of the MS




P= Maximum RF output power of the MS.

All values are expressed in dBm.

The reselection criterion C2 is used for cell reselection only and is definedby:

C2 = C1 + CELL_RESELECT_OFFSET- TEMPORARY OFFSET * H(PENALTY_TIME - T)

for PENALTY_TIME <> 11111C2 = C1 - CELL_RESELECT_OFFSET

for PENALTY_TIME = 11111

Where for non-serving cells: H(x) = 0 for x < 0= 1 for x >= 0

for serving cells: H(x) = 0.

GPRS cell selectionA= RLA_P - GPRS_RXLEV_ACCESS_MIN

B= GPRS_MS_TXPWR_MAX_CCH - PC32(s) = C1(s) (serving cell)C32(n) = C1(n) + GPRS_RESELECT_OFFSET(n) -

TO(n) * (1-L(n)) (neighbour cell)

TO( ) GPRS TEMPORARY OFFSET( ) *




TO(n) = GPRS_TEMPORARY_OFFSET(n) *(GPRS_PENALTY_TIME(n) - T(n)).

L(n) = 0 if PRIORITY_CLASS(n) = PRIORITY_CLASS(s)1 if PRIORITY_CLASS(n) ≠ PRIORITY_CLASS(s)

H(x) = 0 for x < 01 for x ≥ 0

C31(s) = RLA_P(s) - HCS_THR(s) (serving cell)C31(n) = RLA_P(n) - HCS_THR(n) - TO(n) * L(n)

(neighbour cell)

The inputs to RadioNetwork Optimisation

T r a f f i c : ( Tra

b l e

G S




T r a f f i c d i s t r i b u t i o n m

a p s )

S p e

c t r u m

A v a i l a

Cost / Money

GoSQoSQuality

CoverageSpeech Quality

System Choice - C/I

Quality Capacity product

Quality vs Capacity

140

145

150

t

y ) The challenge: To maximize Quality * Capacity




100

105

110

115

120

125

130

135

140

6 7 8 9 10 11 12 13 14 15 16

Average Erlang per Cell (Capacity)

(deduced from Spectrum Utilisation)

M i n u t e E r l a n g p e r D r o p ( Q u a l i t

Link balance




Neighbour

List for1883B:

Propagation




PropagationPredictions

1883A1883A1883C1883C

236A236A

236D236D

1569B1569B294C294C

Neighbour Lists for 1883B :Measurement Based Methods and Handover Statistics

PotentialNeighbour

Percentage of

Reports it wasthe Strongest

Percentage of times it

was 3dB strongerthan the server

Recommended

by CompleteMMR method? HandoverAttempts SuccesfulHandovers

Hand

oversReturned

Drops at

Handover

1883A 10.36% 4.64% Yes 742 730 9 3

236B 8.73% 6.03% Yes 1186 1166 3 17

1883C 5.56% 2.01% Yes 449 444 4 1

294C 5.49% 5.56% Yes 1052 1031 9 12

236D 4.02% 1.78% Yes 479 472 1 6

236A 3.25% 3.01% Yes 251 241 3 7




236A 3.25% 3.01% Yes 251 241 3 7

1569B 2.86% 2.63% Yes 498 488 8 2

980C 2.01% 1.85% Yes 413 401 5 7

1569C 1.70% 1.16% Yes 0 0 0 0

294B 1.62% 2.32% No 117 112 4 1

2150B 1.47% 2.16% No 295 268 24 3

340B 1.00% 1.31% No

251A 0.93% 2.47% No

1933C 0.70% 2.86% No 328 1 319 8

408C 0.62% 1.70% No 21 21 0 0

251B 0.54% 1.55% No

409B 0.46% 1.47% No

2441B 0.39% 3.09% No 424 421 0 3236C 0.31% 2.09% No 127 119 8 0

519B 0.23% 1.93% No 59 57 0 2

84A 0.15% 2.09% No

Example 2 : Neighbour Lists

Unnecessary“Neighbour”

Typical




Small but

essentialneighbour

TypicalNeighbour

TypicalNeighbour

Server



Example 3: Link Balance




Performance in Technical Terms (1)

Traffic carried

o Erlang: “Average number of trunks

occupied during a period”




occupied during a periodo “MinuteErlang” or “Accumulated Traffic”

Perceived Grade Of Service

PGoS#ofCallAttemps - #ofCallSuccesses

#ofCallAttempts100%= ×

Performance in Technical Terms (2)

Dropped Call Rate

Dropped%#ofDroppedCalls

# ActiveofCalls= × 100%




Average traffic carried before a call

drops

Dropped% # ActiveofCalls 100%

MinuteErlangPerDropMinuteErlangCarried

ofDroppedCalls=

#

Contributors to Lack ofPerformance

Failures at any point of the network

contribute performance degradation




contribute performance degradationA chain is as strong as its weakest link:

The Radio Link

Hence the emphasize on theperformance at cell level.

Cell Statistics (1)




Cell Statistics (2)




Cell Statistics (3)




Cell Statistics (4)

Traffic in Erlang:

Minute Erlang

Average ErlangTraffic Level Accumulator

Number of Accumulations.

. .

. .====




ute a g

MinuteErlang Average Erlang Measurement Period= ×. .

Cell Statistics (5)

Dropped Call Rate

o DroppedDroppedCalls

CallsActiveOnCell

% ==== ×××× 100%




o %100

HOINSUCTMSESTB

TNDROP%Dropped ×

−

=

Ca s ct eO Ce

Cell Statistics (6)

Perceived Grade Of Service

PGoSCallAttemptsToCell CallSuccessesToCell

CallAttemptsToCell=

−# #

#




( )

100%

HOINxQATCALL

HOINSUCTMSESTBHOINxQATCALL

PGOS

BD,U,x

BD,U,x×

−

−−

−

=

∑

∑

=

=

Cell Statistics (7)

Call Success Rate

o A parameter that combines the effect of

congestion, setup failures and dropped calls




o CallSuccessRatetmsestb hoinsuc tndrop

tcall hoinxqax U D B

=− −

−=∑, ,

Cell Statistics (8)

Congestion and Failures on ControlChannels also influence PGOS.

o Hard to distinguish between call setup andl i d i




location updating

o Hence to need to determine performance

of Control channels: Dropped Control Channel Rate

Control Channel PGOS

BSC statistics (1)

In essence the BSC statistics is asummation of the Cell statistics.




e.g.

PGoStassell tcassel

tassell

AllCells AllCells

AllCells

=

−

∑ ∑∑

MSC statistics (1)Traffic and congestion counters are

available for each directions and origin oftraffic flow.




GoS

NICONG

NCALLS NICONG

ORG IEX

ORG IEX ORG IEX

=+

×

∑

∑ ∑,

, ,

100%

MSC Statistics (2)




Overall Network Performance

SuccRate

tcassel tndrop

tassellAllCells AllCells=

−

−

∑ ∑

∑




tassell

NICONG NUNSUCC

tassell

AllCells

AllMSC ORG IEX AllMSC ORG IEX

AllCells

−

×

∑

∑ ∑

∑

( , ) ( , ) 100%

Problem Diagnostics (1)

A problem is a problem if it affectsperformance:

o Dropped calls

o Congestion on traffic or control channel




o Setup failures of calls.






Interference - Cell 234B

o High number of dropped calls

o High intra-cell handovers due to bad quality

o High U2-U5 uplink interference counters




Missing Neighbour Relation or Measurementfrequency - Cell 1375A

o High dropped call rate

o High Tfail%

o Possibly high congestion.

ProblemDiagnostics

(6)





Transceiver failure - 1456A. (see next slide)

o High dropped call rate

o High Tfail%o High ICM counters




o High ICM counters

Congestion due to limited capacity - 184A

o High Congestion rate

o Other counters are normal.




Problem diagnostics (8)

Neighbour Failing - 184A

o Sudden rise in traffic

o Sudden rise in congestion




GSM Signaling Layers

Layer 1 (physical layer)

o Physical transmission

o Channel Quality Measurements

o Uses many channel structureso E1 2Mb/s links (64kb/s PCM)




o GSM 44.04 for Air interface;

o GSM 48.54 for Abiso GSM 48.04 for A

Layer 2 (data link layer)

o Multiplexing of layer 2 connections on signalingchannels

o Error detection and correction

o Flow controlo Routing





o Across Um interface uses LAPDm (a slight modification

of LAPD protocol used in ISDN)o Across Abis uses LAPD

o Across A interface, uses MTP and SCCP of SS7

o SAPI=0 Identifies radio signaling procedures

SAPI: Service Access Point Indicator

Layer 3 is sub-divided into 3 sub-layers

o Connection Management

o Management of Location data

o Subscriber identificationo Management of added services ( SMS, call

f di )





forwarding)

Layer 3 Signaling ProtocolsMM: Mobility Management

o Location updatingo Registration

o Security and authentication procedures

o Assignment of TMSICM: Connection Management

o Call control (CC): Manages call connections




o Call control (CC): Manages call connections

o Supplementary Service support (SS)

o Short Message Service support (SMS)

MM and CM pass un-interpreted by BTS or BSC

to MSC via DTAP

RR: Radio Resources Management

o Establishment, maintenance, and termination

of radio link between MS and MSC despite MSmovements.

o Allow point-to-point dialogue even duringincluding cell selection and handover

Layer 3 Signaling Protocols




including cell selection and handoverprocedures

o Monitoring and forwarding of radio connections

o Handled by BSC, BTS and MS

RR messages are mapped on BSSAP:

o Cipher mode managemento DTX management

o Handovers

o Call re-establishmento Load Management

o SACCH procedures





o SACCH procedures Power Control, Timing Advance,

Mobile Measurement Reportso BCCH info

Cell Selection info

CGI

Idle mode info (other BCCH frequencies)


BTS Management (BTSM)

o SAPI 0 is used for messages to and from the

radio interface

o SAPI 62 is used for Operation and Maintenancemessages between BTS and BSC

o SAPI 63 is used for layer 2 management




o SAPI 63 is used for layer 2 management

functions




Signaling Connection Control Part: SCCP

o Managed by MSC

o Involves the following protocols:

From the Mobile

• MM: CM service request• RR: Paging Response

• MM: Location updating request




MM: Location updating request

• MM: CM re-establishment request

From the MSC

• BSSMAP: handover request

o Uses local addressing based on subsystem numbers

o Provides functions to handle congestion and failureconditions


Base Station System Application Part:BSSAP

o Split into Base Station System ManagementApplication Part : BSSMAP and Direct Transfer

Application Part : DTAP

o Handles messages not transparent to BSC




o Handles messages not transparent to BSC

o Supports all procedures related to single callsand resource management


Direct Transfer Application Part : DTAP

o Transfers messages between MSC and MS

o (MM & CM messages are transparent to the BSC

MAP (Mobile Application Part)

o SS7 top layer protocol




o Responsible for signaling between different entities in

network, such as between HLR and VLR and EIRo Access and Location management

o MSC-MSC handover,

o Security functionso SMS and supplementary services


Transaction Capabilities Application Part:

TCAPo Provides universal calls and functions for

handling requests to distributed application

processesISDN User Part : ISUP




o Controls interworking (e.g. call setup) between

PLMN and other networks.Intelligent Network Application Part: INAP

o Implements intelligent supplementary services

(e.g. free call, time dependent routing functions)

CSD call

BSC/TRC MSC/VLR

PSTN

PAD

PSPDN

1.

2.

1.

2.

6.

2. Connection between msand network is set up.

Authentication performed

5. DTI reroutesthe call to MSC

6. MSC routes the call to thedestination NW. The

connection may be throughan existing NW (PSTN/ISDN)




DTI

ISDN

PAD

3. 5.

4. 6.

3. MSC analysesthe BC. B. no andBC are transferredto the DTI

4. The DTI isconfigured to performthe required service

(fax, modem service)

GPRS network

Traffic and signalingSignaling

TE Terminal EquipmentMT Mobile Terminal

TE MT

MS

BSC

GMSC

MSC/VLR

SGSN

EIR

HLR

AUC

IP B kb

ExternalIP Network(Internet)

GsGf

Gr

BTS

Gb

Um

ISDN/

PSTN

Gn

ABSS Abis




MS Mobile StationBSS Base Station SystemBTS Base Transceiver StationBSC Base Station ControllerGMSC Gateway Mobile Services Switching

CenterMSC Mobile services Switching CenterVLR Visitor Location RegisterHLR Home Location RegisterAUC Authentication CenterEIR Equipment Identity Register

SGSN Serving GPRS Support NodeGGSN Gateway GPRS Support NodeUm Air InterfaceA, Abis Interfaces (GSM)Gx Interfaces (GPRS)

ExternalIP Network(CorporateLAN)

Gi

GGSNIP-BackboneNetwork

( )

External

X.25 Network

Other

PLMN

Gp

Reference

http://www.cs.hut.fi/~hhk/GPRS/




GPRS protocol stack




Air InterfaceShare the Physical Layer with GSM

On demand PDCHo PILTIMER

Dedicated PDCH




PDCH can be shared by userso TFI – Temporary ID to distinguish between

mobiles on same PDCH

o USF – Indicates when the MS can transmit onthe uplink.

Coding Schemes

# Info

bits

# Coding

bits

Code

Rate

Max data rate


(BLER <10%; TU3 FH)

Modul

ation

GSM 260 196 0.5 13.3 9 GMSK

CS-1 181 275 0.45 9.05 9 GMSK

CS-2 268 188 0.65 13.4 13 GMSK

CS-3 312 144 0.75 15.6 15 GMSKCS-4 428 28 21.4 23 GMSK

MCS-1 176 0.53 8.4 9 GMSK

MCS 2 224 0 69 11 2 13 GMSK




MCS-2 224 0.69 11.2 13 GMSK

MCS-3 296 0.89 14.8 15 GMSKMCS-4 352 1 16.8 23 GMSK

MCS-5 448 0.38 22.4 14.5 8PSK

MCS-6 592 0.5 29.6 17 8PSK

MCS-7 896 0.78 44.8 23.5 8PSK

MCS-8 1088 0.92 54.4 29 8PSK

MCS-9 1184 1 59.2 32 8PSK

Modulation Schemes

I

Q

(0,1,1)(0,0,0)

(0,0,1) (1,1,1)

(0,1,0)

I

Q

“1”

GMSK 8PSK




(1,1,0)(1,0,1)

(1,0,0)

“0”

“1 bit per symbol” “3 bits per symbol”

Routing Areas

BTS

BTS

BTS

BTS

BTS

BTS

BTS

BSC BSC

BTS

BTS

BTS

BTS

BTS

BTS

BTS

BSC BSC




MSC MSC

PSTN

Similar to Location Areas in GSM(Very often the same as LA, RA<=LA)RA update is send to SGSN

•(if SGSN changes all GGSNs are informed•Done when MS is in Ready state

Active Mode

The Mobile does cell selection

o Based on “idle mode” type measurements

o Send message to the network when it changescells




BSC SGSN

HLR

AUC

MSC/VLR

6. Update MSC/VLR if it’s a newLocation Area

7. SGSN tells MS about

new TLLI

GPRS ATTACH




(OLD)SGSN

1. MS sends message to SGSN “Attach Request”

2. If the MS is unknown to the SGSN it asks the old SGSN about IMSI and Triplets

3. If MS is not known by old SGSN it sends an error message to the new SGSN andthe new SGSN asks the MS about the IMSI

PDP ContextPDP: Packet Data Protocol

It is the connection between the MS and theGGSN

Typically it is a IP-connection

PDP address = IP address

APN: Access Point Name = Internet Domain




Name – GGSN translate that to an IPaddress

NSAPI: Network Service Access Point ID

TID = IMSI + NSAPI

QoSPrecedence / Priority

o High, Medium or Low

Reliability

DelayThroughput

o Mean




o Mean

o Peak

What does EDGE require?

3gpp GSM Principles - Basics

Documents

Transcript of 3gpp GSM Principles - Basics