3gpp GSM Principles - Basics
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31 January 2008 3GPP CE at UP 1
Radio Network Planning andOptimisation
Magdaleen Snyman
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31 January 2008 3GPP CE at UP 2
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
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3GPP
ITU
IMT2000
3GPP
GSM GPRS EDGE UMTS
FDD TDD
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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
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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
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3GPP
See Numbering Scheme
and list of abbreviations
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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
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GSM System
BSCBTS
BTS
MobileStation
Access Network:Base Station Subsystem
HLR VLR EIR AuC
MSCPSTN
Um Abis A
Core Network:GSM CS network
SS7
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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
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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
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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
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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
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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
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GSM Areas
BTS
BTS
BTS
BTS
BTS
BTS
BTS
BSC BSC
MSC
Cell
Location AreaMSC/VLR Area
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"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
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"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
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Quantisation
q7
q6
q5
q4
q3
q2
q1
q0
Ts 2Ts 3Ts 4Ts 5Ts 6Ts 7Ts 8Tstime
}}}}
Sampledvalue
Quantisationvalue
D = Quantisation error
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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)
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Different Speech Coders
Excellent
Good
Average
Bad
Speechquality
2 4 8 16 32 64
Bitrate(kbit/s)
Hybrid coders
Increasing complexity
Waveform coders
Vocoders
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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
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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
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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
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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
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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
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Interleaving in GPRS and EDGE
EDGE MSC 7-9 interleave over half thetimeslots
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“Burst” Interleaving
57 1 26 1 573 3
Normal Burst
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“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
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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
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Modulation
I
Q
“1”
“0”
“1 bit per symbol”
GMSK – Gaussian Minimum Shift Keying
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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
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0
Frequency 1
1 2 3 4 5 6 7
User 1
User 2
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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
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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
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Logical Channels
SCH AGCH
PCHBCCHFCCH FACCH
SACCH
SDCCH
RACH
FRHR
BCH DCCHCCCH
Control Channels Traffic Channels
Logical Channels
FrequencyCorrectionBurst
AccessBurst
DummyBurst
Synchro=nisationBurst
NormalBurst
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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
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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)
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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
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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
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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
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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
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Multi-frame structure
C TS
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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
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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
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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
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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
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MSISDN
National mobile number
International Mobile Station
ISDN number
MSISDN = CC + NDC + SN
CC NDC SN
IMSI
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IMSI
Maximum 15 digits
3 digits 2-3 digits
National MSI
IMSI
IMSI = MCC + MNC + MSIN
MCC MNC MSIN
IMEI
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IMEI
6 digits 2 digits 6 digits 1 digit
IMEI
IMEI = TAC + FAC + SNR + spare
TAC FAC SNR spare
LAI
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LAI
3 digits 2-3 digits Max. 16 bits
LAI
LAI = MCC + MNC + LAC
MCC MNC LAC
CGI
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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
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BSIC
BSICBSIC = NCC + BCC
NCC BCC
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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
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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,
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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,
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p g,
new MSC/VLR
9805058
BSC/TRC MSC
4.4.
HLR
VLR
2.
3.
3.
1.
MSC/VLR-B GMSC
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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
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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
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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
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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
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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
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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
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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
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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
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HLR VLR EIR AuC
MSC
PSTN
SS7
MSC – Mobile Switching Center
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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
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RPRP
MSC/VLR TRC
ETC
ETC
ETC
ETC
RP
CPSP
RPD
ST7
GS
SMS-C
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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
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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
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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
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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
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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
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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
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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
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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
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RPRP
GroupSwitch
MSC/VLR
SRS
RBS
ETC
ETC
ETC
ETC
RP
CPSP
TRAU
RPRPG
TRH
RPD
ST7
Remote BSCs
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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
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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
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DTX (Discontinuous Transmission)
Dynamic Power ControlFrequency Hopping
Radio Link Measurements
Handovers
DTX- Discontinuous
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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
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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
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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
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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
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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
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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
Radio Link Measurements
R L (i GSM i i l h
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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%
Radio Link Measurements
Th M bil t t th BSC ( i th BTS)
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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
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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
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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
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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
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Raleigh fading is frequency dependant
f0
f1
Position
S i g n a l l e v e l
Frequency Diversity
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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
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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
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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?
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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
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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
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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
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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
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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:
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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
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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
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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
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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
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a g
Erlang B Table
Examples of Traffic channels
Problem
The average traffic generated by one user is10 illiE l /S b ib
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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.
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Sectorisation
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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
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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
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for co-channel interference C/Ic=9 dB
for adjacent (200 kHz) interference C/Ia1=-9 dB
for adjacent (400 kHz) interference C/Ia2=-41 dB
for adjacent (600 kHz) interference C/Ia3=-49 dB
Adjacent channel interferenceRelativepower(dB)
00
Relative
power
(dB)
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-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
(kbs) /TSRequired C/I (dB)
(BLER 10%; TU3 FH)
Modul
ation
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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
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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
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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
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penetration
Less cost for same traffic density
Underlay / Overlay - MRP
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Cell Splitting
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Hierarchical Cells
Umbrella Cell:Macro Cell: Antenna above average rooftop height
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g p gMicro Cell: Antenna below average rooftop height
Pico Cell: Indoors
C/I reduction from DTX
C/I values
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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
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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
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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
Interference
Int. DTX
Int. PC +DTX
Carrier Reduction from PC
Carrier Levels
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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
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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
P r o b a b i l i t y D i s t r i b u t i o n
C/I
C/I DTXC/I PC + DTX
Frequency Hopping
with DTX and PC
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• Power control: 0• DTX: 0
• TS active: 1
• No call: 0
Hopping with DTX and PC
C/I values
0 25
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0
0.05
0.1
0.15
0.2
0.25
-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/I
C/I DTX
C/I PC + DTX
Hopping
Effect of DTX and PC on Quality
10 00%
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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
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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
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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 =
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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
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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
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Coverage
Analysis
Interference
Matrix
Propagation
Predictions
SeparationConstraints,
etc
Frequency
Plan
Requirements
etc
Automatic Frequency Planning
Model of NetworkCost Function:Sum of remaining
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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
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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
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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
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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
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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
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What will really give optimum quality?
The inputs to Cell PlanningT r a f f i c : ( T b l
eG S
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(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
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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
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-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
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y g g g p
Interference Matrix?
The first MeasurementBased Plan
Johannesburg’s Central Business District
12km×12km
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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
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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
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TheSanity
Check
Using
Dropped Call Rate
1 90%
2.10%
2.30%
n t e d
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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
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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
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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
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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
Data Sources for theInterference Matrix (2)
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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
Data Sources for theInterference Matrix (3)
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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
Data Sources for theInterference Matrix (4)
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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:
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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
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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
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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
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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 ?
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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
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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
o 8 * Number of TCH Carriers
Interference Load Reduction
After Power Control ?
o Consider a very simplified model:
C/I Server SS / (6* Interferers SS)
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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
o 8 * Number of TCH Carriers
A few terms
Frequency Allocation Re-useo FAR = Total Number of Frequency Channels
Number of Frequencies per Cell
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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
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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
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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
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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%
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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 )
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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
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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)
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DEM
Clutter
Buildings
o Traffic distribution Demographic
Antenna parameters (Tilts & Azimuths)
Upgradingo Cell Statistics
Changes in ACP
Radio Parameterso Transmission power
o Cell Hysterises
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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
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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
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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 micro BTS M2 -92 dBm
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o for micro BTS M3 -87 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 M2 -97 dBm
o for micro BTS M3 -92 dBmo for pico BTS P1 -95 dBm
DefiningQuality
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Speech Quality (BER, FER)
Dropped Calls
Coverage
Call Set-up success
Handover stats
To do
Cell Planning
Frequency Planning
Link balancing
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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
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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( ) *
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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
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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
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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
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Neighbour
List for1883B:
Propagation
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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
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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
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Small but
essentialneighbour
TypicalNeighbour
TypicalNeighbour
Server
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Example 3: Link Balance
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Performance in Technical Terms (1)
Traffic carried
o Erlang: “Average number of trunks
occupied during a period”
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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%
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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
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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)
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Cell Statistics (2)
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Cell Statistics (3)
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Cell Statistics (4)
Traffic in Erlang:
Minute Erlang
Average ErlangTraffic Level Accumulator
Number of Accumulations.
. .
. .====
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ute a g
MinuteErlang Average Erlang Measurement Period= ×. .
Cell Statistics (5)
Dropped Call Rate
o DroppedDroppedCalls
CallsActiveOnCell
% ==== ×××× 100%
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o %100
HOINSUCTMSESTB
TNDROP%Dropped ×
−
=
Ca s ct eO Ce
Cell Statistics (6)
Perceived Grade Of Service
PGoSCallAttemptsToCell CallSuccessesToCell
CallAttemptsToCell=
−# #
#
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( )
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
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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
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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.
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e.g.
PGoStassell tcassel
tassell
AllCells AllCells
AllCells
=
−
∑ ∑∑
MSC statistics (1)Traffic and congestion counters are
available for each directions and origin oftraffic flow.
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GoS
NICONG
NCALLS NICONG
ORG IEX
ORG IEX ORG IEX
=+
×
∑
∑ ∑,
, ,
100%
MSC Statistics (2)
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Overall Network Performance
SuccRate
tcassel tndrop
tassellAllCells AllCells=
−
−
∑ ∑
∑
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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
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o Setup failures of calls.
Problem Diagnostics (2)
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Problem Diagnostics (3)
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Problem Diagnostics (4)
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Problem Diagnostics (5)
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
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Missing Neighbour Relation or Measurementfrequency - Cell 1375A
o High dropped call rate
o High Tfail%
o Possibly high congestion.
ProblemDiagnostics
(6)
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Problem Diagnostics (7)
Transceiver failure - 1456A. (see next slide)
o High dropped call rate
o High Tfail%o High ICM counters
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o High ICM counters
Congestion due to limited capacity - 184A
o High Congestion rate
o Other counters are normal.
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Problem diagnostics (8)
Neighbour Failing - 184A
o Sudden rise in traffic
o Sudden rise in congestion
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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)
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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
GSM Signaling Layers
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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 )
GSM Signaling Layers
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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
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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
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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
Layer 3 Signaling Protocols
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o SACCH procedures Power Control, Timing Advance,
Mobile Measurement Reportso BCCH info
Cell Selection info
CGI
Idle mode info (other BCCH frequencies)
Layer 3 Signaling Protocols
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
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o SAPI 63 is used for layer 2 management
functions
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Layer 2 Signaling Protocols
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
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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
Layer 3 Signaling Protocols
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
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o Handles messages not transparent to BSC
o Supports all procedures related to single callsand resource management
Layer 3 Signaling Protocols
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
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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
Layer 3 Signaling Protocols
Transaction Capabilities Application Part:
TCAPo Provides universal calls and functions for
handling requests to distributed application
processesISDN User Part : ISUP
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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)
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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
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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/
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GPRS protocol stack
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Air InterfaceShare the Physical Layer with GSM
On demand PDCHo PILTIMER
Dedicated PDCH
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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
(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 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
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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
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(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
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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
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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
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(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
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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
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o Mean
o Peak
What does EDGE require?
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