Radio Network Planning and Optimisation Magdaleen Snyman
31 January 2008
3GPP CE at UP
1
References GSM, GPRS and EDGE Performance: evolution towards 3G/UMTS o T.Halonen, J. Romero, J. Melero o Second Edition o John Wiley & Sons o ISBN 0-470-86694-2
Principles & Applications of GSM o V.K.Garg & J.E.Wilkes o Prentice Hall PTR o ISBN 0-13-949124-4 31 January 2008
3GPP CE at UP
2
3GPP ITU IMT2000 3GPP GSM
GPRS
EDGE
UMTS FDD
31 January 2008
3GPP CE at UP
TDD 3
3GPP
TSG SA
Project Coordination Group (PCG) 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 31 January 2008
3GPP CE at UP
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3GPP TSG – Technical Specification Group GERAN – Gsm/Edge Radio Access Network RAN - 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 31 January 2008
3GPP CE at UP
5
3GPP See Numbering Scheme and list of abbreviations
31 January 2008
3GPP CE at UP
6
3GPP - specifications 46 series CODER/DECODER SPEECH
TS 45.010 to all blocks
45.003 INTERLEAVING CODER/DECODER CHANNEL
SYNCHRONIZATION
45.002 43.020 & 23.221 ENCRYPTION
ACCESS & MULTIPLE MULTIPLEXING
45.004
45.005
DEMODULATOR AND MODULATOR
RECEIVER AND TRANSMITTER
44.004 PROTOCOLS LAYER 1
44.005 & 44.006
23.009 & 45.008 & 43.022
PROTOCOLS LAYER 2
(HAND-OVER, POWER CONTROL) LINK CONTROL
24.007 & 44.018 PROTOCOLS LAYER 3 31 January 2008
Relations between specifications
3GPP CE at UP
7
GSM System Access Network: Base Station Subsystem
Core Network: GSM CS network
HLR
BSC
BTS
Mobile
VLR
EIR
AuC
SS7 MSC
Station
PSTN
BTS
Um 31 January 2008
Abis
A 3GPP CE at UP
8
GSM & GPRS network Um
BSS TE
MT
ISDN/ PSTN
BTS Abis
A
BSC
MS Traffic and signaling
GMSC MSC/VLR Gs
Gb
Terminal Equipment Mobile Terminal Mobile Station Base Station System Base Transceiver Station Base Station Controller Gateway Mobile Services Switching Center MSC Mobile services Switching Center VLR Visitor Location Register HLR Home Location Register AUC Authentication Center EIR Equipment Identity Register SGSN Serving GPRS Support Node GGSN Gateway GPRS Support Node Um Air Interface A, Abis Interfaces (GSM) Gx Interfaces (GPRS) 31 January 2008
Gf
AUC
SGSN
Signaling TE MT MS BSS BTS BSC GMSC
EIR
Gr
HLR External IP Network (Internet)
Gn
IP-Backbone Network
GGSN Gi
Gp
Other PLMN
3GPP CE at UP
External IP Network (Corporate LAN)
External X.25 Network
9
CORE(SS)
PSTN (Circuit Switched)
HLR
AuC
Internet (Packet Switched)
EIR
Gi
VLR 3G MSC Gs SGSN Gn
3G GMSC
IuPS
A
TRC BTS
Ater
RNC Iur
Gb
IuCS
RNC
BSC Abis 31 January 2008
Node B
PCU
GERAN(BSS)
GGSN
Iubis 3GPP CE at UP
UTRAN
10
System Frequencies: • Uplink • Downlink Wavelength
GSM BTX
P-GSM 900
E-GSM 900
GSM 1800
GSM 1900
890-915 MHz 935-960 MHz ~33cm
880-915 MHz 925-960 MHz ~33cm
1710-1785 MHz 1805-1880 MHz ~17cm
1850-1910 MHz 1930-1990 MHz ~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
125
175
375
300
270 kbits/s
270 kbits/s
270 kbits/s
270 kbits/s
Radio Channels Transmission Rate 31 January 2008
3GPP CE at UP
960MHz
E-GSM BTX
935MHz
TETRA /GSM-R BTX 925 MHz
GSM MTX
921 MHz
E-GSM MTX
915 MHz
RF ID
890 MHz
880 MHz
876 MHz
TETRA /GSM-R MTX
Frequency Bands - GSM
11
Mapping Channel numbers to Frequencies P-GSM 900 Fl(n) = 890 + 0.2*n E-GSM 900 Fl(n) = 890 + 0.2*n Fl(n) = 890 + 0.2*(n-1024) R-GSM 900 Fl(n) = 890 + 0.2*n Fl(n) = 890 + 0.2*(n-1024) DCS 1 800 Fl(n) = 1710.2 + 0.2*(n-512) PCS 1 900 FI(n) = 1850.2 + 0.2*(n-512) GSM 450 Fl(n) = 450.6 + 0.2*(n-259) GSM 480 Fl(n) = 479 + 0.2*(n-306) GSM 850 Fl(n) = 824.2 + 0.2*(n-128) GSM 750 Fl(n) = 747.2 + 0.2*(n-438)
31 January 2008
1 ≤ n ≤ 124 0 ≤ n ≤ 124 975 ≤ n ≤ 1 023 0 ≤ n ≤ 124 955 ≤ n ≤ 1023 512 ≤ n ≤ 885 512 ≤ n ≤ 810 259 ≤ n ≤ 293 306 ≤ n ≤ 340 128 ≤ n ≤ 251 438 ≤ n ≤ 511
3GPP CE at UP
Fu(n) = Fl(n) + 45 Fu(n) = Fl(n) + 45 Fu(n) = Fl(n) + 45 Fu(n) = Fl(n) + 95 Fu(n) = FI(n) + 80 Fu(n) = Fl(n) + 10 Fu(n) = Fl(n) + 10 Fu(n) = Fl(n) + 45 Fu(n) = Fl(n) + 30
12
Frequency Bands - UTRA UMTS - FDD - Uses 5MHz spacing Operating UL Frequencies DL frequencies Band UE transmit, UE receive, Node B receive Node B transmit 1920 – 1980 MHz 2110 –2170 MHz I II 1850 –1910 MHz 1930 –1990 MHz III 1710-1785 MHz 1805-1880 MHz IV 1710-1755 MHz 2110-2155 MHz V 824 – 849 MHz 869-894 MHz VI 830-840 MHz 875-885 MHz 31 January 2008
3GPP CE at UP
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UMTS channels Uplink (UL) Downlink (DL) UE transmit, Node B receive UE receive, Node B transmit Band General Additional General Additional I 9612 to 9888 10562 to 10838 9262 to 9538 12, 37, 62, 9662 to 9938 412, 437, 462, 87, 112, 137, 487, 512, 537, 162, 187, 212, 562, 587, 612, II 237, 262, 287 637, 662, 687 III 8562 to 8913 9037 to 9388 IV 8562 to 8763 1162, 1187, 1212, 10562 to 10763 1462, 1487, 1512, 1237, 1262, 1287, 1537, 1562, 1587, 1312, 1337, 1362 1612, 1637, 1662 V 4132 to 4233 782, 787, 807, 4357 to 4458 1007, 1012, 1035, 812, 837, 862 1037, 1062, 1087 VI 4162 to 4188 812, 837 4387 to 4413 1037, 1062
31 January 2008
3GPP CE at UP
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GSM Areas BTS
BTS BTS
BTS
BTS BTS
BTS
BSC
BSC
Cell Location Area MSC/VLR Area
MSC
31 January 2008
3GPP CE at UP
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"Hardware" view of a Sample Network MSC Service Area 2 MSC Service Area 1 BSC 1C BSC 2C
BSC 2B
BSC 1B
BSC 2A
MSC/VLR 2
BSC 1A MSC/VLR 1
PSTN AUC
HLR
GMSC
EIR ILR LEGEND
MSC Boundary BSC Boundary PCM Links Base Station 31 January 2008
3GPP CE at UP
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"Software" view of a Sample Network MSC Service Area 2 MSC Service Area 1
LA 2-A
Cell 2-A-25
LA 1-B
LA 2-B LA 2-C LA 1-A
LA 2-D
MSC/VLR 2
MSC/VLR 1
PSTN AUC
HLR EIR
GMSC ILR
LEGEND
MSC Boundary BSC Boundary PCM Links Base Station 31 January 2008
3GPP CE at UP
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31 January 2008
3GPP CE at UP
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Quantisation q7
Quantisation value
Sampled value
}
q6 q5
D = Quantisation error
q4 q3 q2
Ts 2Ts 3Ts 4Ts 5Ts 6Ts 7Ts 8Ts
time
q1 q0 31 January 2008
3GPP CE at UP
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Speech Coding Sampling rate: 8000 samples per second Quantisation: 8192 -> 213, 13bits/sample Required 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) 31 January 2008
3GPP CE at UP
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Different Speech Coders Speech quality
Increasing complexity
Excellent
Hybrid coders
Waveform coders
Good Average
Vocoders Bad 2
31 January 2008
4
8
3GPP CE at UP
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32
64
Bitrate (kbit/s)
21
RPE-LTP Speech Coder Error
20ms speech
Vocal Tract Analysis 8 Taps Long Term Predictor
31 January 2008
3GPP CE at UP
188 bits
36 bits
Speech Synthesis
Source Analysis Regular Pulse
36 bits
22
RPE-LTP Speech Coder LPC Filter LTP Filter
8 Parameters Delay Parameter Gain Parameter Excitation Signal Subsampling Phase Maximum Amplitude 13 Samples Total
31 January 2008
3GPP CE at UP
36 bits 28 bits 8 bits 8 bits 24 bits 156 bits 260 bits
23
Channel Coding
50
Very important bits
Block coder
53 bits
378 bits 1:2 Convolutional Coder
132 Important bits
456
4 Tail bits
78
Not so important bits
31 January 2008
3GPP CE at UP
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Coding Schemes GSM CS-1 CS-2 CS-3 CS-4 MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9 31 January 2008
# Info # Coding Code Max data rate Required C/I (dB) Modul (BLER <10%; TU3 FH) ation bits bits Rate (kbs) /TS 260 196 0.5 13.3 9 GMSK 181 275 0.45 9.05 9 GMSK 268 188 0.65 13.4 13 GMSK 312 144 0.75 15.6 15 GMSK 428 28 21.4 23 GMSK 176 0.53 8.4 9 GMSK 224 0.69 11.2 13 GMSK 296 0.89 14.8 15 GMSK 352 1 16.8 23 GMSK 448 0.38 22.4 14.5 8PSK 592 0.5 29.6 17 8PSK 896 0.78 44.8 23.5 8PSK 1088 0.92 54.4 29 8PSK 1184 1 59.2 32 8PSK 3GPP CE at UP
25
Bit-interleaving HalfBurst#1 HalfBurst#2 HalfBurst#3 HalfBurst#4 HalfBurst#5 HalfBurst#6 HalfBurst#7 HalfBurst#8
0 8 16 24 32 40 48 56 64 72 80 . . 440 448 31 January 2008
1 9 17 25 33 41 49 57 65 73 81 . . 441 449
2 10 18 26 34 42 50 58 66 74 82 . . 442 450
3 11 19 27 35 43 51 59 67 75 83 . . 443 451
4 12 20 28 36 44 52 60 68 76 84 . . 444 452
3GPP CE at UP
5 13 21 29 37 45 53 61 69 77 85 . . 445 453
6 14 22 30 38 46 54 62 70 78 86 . . 446 454
7 15 23 31 39 47 55 63 71 79 87 . . 447 455 26
Interleaving in GPRS and EDGE EDGE MSC 7-9 interleave over half the timeslots
31 January 2008
3GPP CE at UP
27
“Burst” Interleaving Normal Burst 3
31 January 2008
57
1
26
3GPP CE at UP
1
57
3
28
“Burst” Interleaving A/8 A/8 A/8 A/8
B/8
A/8
B/8
A/8
B/8
A/8
B/8
A/8
C/8
B/8
C/8
B/8
C/8
B/8
C/8
B/8
D/8
C/8
D/8
C/8
D/8 31 January 2008
C/8 3GPP CE at UP
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Equalisation Received burst
Data
S’
Data
}
VITERBI
Correlator
“diff.”
Choose “?” so that “diff.” is minimized
}
Probable transmitted bit pattern: ?
S
?
Channel model
Can compensate for Delay Spread of up to 16µs 31 January 2008
3GPP CE at UP
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Modulation GMSK – Gaussian Minimum Shift Keying Q
“1” I
“0”
“1 bit per symbol” 31 January 2008
3GPP CE at UP
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Modulation Schemes GMSK
8PSK
Q
(0,1,0) (0,0,0)
“1”
Q (0,1,1)
I
I (0,0,1)
“0”
(1,1,1)
(1,0,1)
(1,1,0) (1,0,0)
“1 bit per symbol”
31 January 2008
“3 bits per symbol”
3GPP CE at UP
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Frequency 1 0 1 2 3 4 5 6 7
User 2 User 1
31 January 2008
3GPP CE at UP
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TDMA Frame Structure
Downlink C1 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
Uplink C1
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 N
N+1 TDMA frame no.
31 January 2008
3GPP CE at UP
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Mapping of Logical Channels on Physical Channels MHz 890
TDMA Frame n TDMA Frame n+1 TDMA Frame n+2
915
0
1 2
3
4
5
6
7 Physical Channel 5
TDMA Frame n+x 0
Physical Channel 5:
1 2
5 5 5 5 TDMA Frame n n+1 n+2
3
4
5
5
Logical Channel: TCH TCH FACCH 31 January 2008
3GPP CE at UP
6
7
5
5 n+x TCH 35
Logical Channels Logical Channels
Control Channels
BCH FCCH
AGCH PCH
Frequency Correction Burst 31 January 2008
DCCH
CCCH
SCH BCCH
Synchro =nisation Burst
Traffic Channels
SDCCH
HR
FR
SACCH
RACH
Normal Burst
FACCH
Dummy Burst
3GPP CE at UP
Access Burst
36
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 31 January 2008
3GPP CE at UP
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Control Channels Accessed by: o Idle mode mobiles to exchange signaling information required to change to dedicated mode o Dedicated mode mobiles to monitor surrounding base stations for handover and other information
51 TDMA frame format Broadcast Control Channel (BCCH) o Broadcasts on the downlink information such as base station identity, frequency allocation, frequency-hopping sequences 31 January 2008
3GPP CE at UP
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Control Channels (2) Frequency Correction Channel (FCCH) and Synchronization Channel (SCH) o Synchronize mobile to time slot structure of cell
Random Access Channel (RACH) o Used by mobile to request access to GSM network
Paging 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 31 January 2008
3GPP CE at UP
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Logical Channels ∗Downlink –FCCH –SCH –BCCH
info about frequency info about TDMA structure & BSIC general cell info (LA, Power)
–PCH –AGCH
tells MS its being paged tells MS which signalling channel to use
–SDCCH –SACCH –FACCH
info about call set-up sent to MS info about power and timing advance used for handover
–TCH
speech
31 January 2008
3GPP CE at UP
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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
31 January 2008
speech
3GPP CE at UP
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Frame Structure 1 hyperframe = 2048 superframes = 2,715,648 TDMA frames (3 hours 28 minutes 53 seconds 760 milliseconds) 0
1
2
3
4
5
6
2042 2043 2044 2045 2046 2047
1 superframe = 1326 TDMA frames ( 6.12 seconds ) (= 51 (26 - frame) multiframes or 26 (51 - frame) mulitframes ) 0
1
2
0
3
47
1
48 24
49
50 25
1 (26- frame) multiframe = 26 TDMA frames (120 ms) 1 (51 - frame) multiframe = 51 TDMA frames (235 ms) 0
1
2
3
22
23
24
0
25
1
2
3
47
48
49
50
1 TDMA frame =8 timeslots (120/26 ~4.615 ms) 0
1
2
3
4
5
6
7
1 timeslot = 156.25 bit durations (15/26 ~ 0.577 ms) ( 1 bit duration 48/13 ~ 3.69 micro sec ) Normal burst (NB) TB (Flag is relevant for 3 TCH only) TB Frequecy correction 3 burst (FB) Synchronization burst (SB)
TB 3
Encrypted bits 57
flag Training sequence flag 1 1 26 Fixed bits 142
Encrypted bits 39
Synchronization sequence 64
TB Synchronization sequence Access burst (AB) 8 41
Encrypted bits 36
TB Dummy burst (DB) 3
Training sequence 26
31 January 2008
Encrypted bits 57
Mixed bits 58
3GPP CE at UP
TB 3
Encrypted bits 39
TB 3
GP TB: Tail bits 8.25 GP: Guard period
TB 3
GP 8.25
TB 3
GP 8.25
TB 3
GP 8.25
GP 68.25 Mixed bits 58
42
Multi-frame structure
31 January 2008
3GPP CE at UP
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C0 TS0 F S B B B B C0 C0 C0 C0 F S C1 C1 C1 C1 C2 C2 C2 C2 0
4
9
14
19
F S C3 C3 C3 C3 C4 C4 C4 C4 F S C5 C5 C5 C5 C6 C6 C6 C6 20
24
29
34
39
F S C7 C7 C7 C7 C8 C8 C8 C8 I 40 31 January 2008
44 3GPP CE at UP
49 44
Dedicated Control Channel D0 D0 D0 D0 D1 D1 D1 D1 D2 D2 D2 D2 D3 D3 D3 D3 D4 D4 D4 D4 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
A2 A2 A2 A2 A3 A3 A3 A3 I 40 31 January 2008
44 3GPP CE at UP
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I
39
I
49 45
Mapping of Logical Channels on Air Interface Time slot 0 1 2 Carrier Frequency 0 B,C T
Legend: B: BCH C: CCCH D: DCCH T: TCH
31 January 2008
3
4
5
6
7
D
T
T
T
T
T
1
T
T
D
T
T
T
T
T
2
T
T
T
T
T
T
T
T
3
T
T
T
T
T
T
T
T
3GPP CE at UP
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Call to an MS MSC knows the LAI
MSC/VLR 1
PCH
TRC 1 BSC SDCCH SDCCHisis assigned assigned using usingAGCH AGCH
5
3
2
RACH RACHisisused usedto torequest request Access to the network Access to the network 9805024
31 January 2008
PCH
2 4 AGCH
2
TCH 6 BTS
MSand andBTS BTSswitch switch MS totheidentified identifiedTCH TCH tothe frequencyand and frequency Timeslot slot Time
5 3 PCH 2 4
BTS SDCCH/SACCH
PCH SDCCH/SACCH are used for call set up. SDCCH Used to allocate TCH
RACH
3GPP CE at UP
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MSISDN CC
NDC
SN
National mobile number International Mobile Station ISDN number MSISDN = CC + NDC + SN
31 January 2008
3GPP CE at UP
48
IMSI Maximum 15 digits 3 digits
MCC
2-3 digits
MNC
MSIN
National MSI IMSI IMSI = MCC + MNC + MSIN
31 January 2008
3GPP CE at UP
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IMEI 6 digits
2 digits
6 digits
TAC
FAC
SNR
1 digit
spare
IMEI IMEI = TAC + FAC + SNR + spare
31 January 2008
3GPP CE at UP
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LAI 3 digits
2-3 digits Max. 16 bits
MCC
MNC
LAC
LAI LAI = MCC + MNC + LAC
31 January 2008
3GPP CE at UP
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CGI 3 digits
2-3 digits
MCC
MNC
Max. 16 bits Max. 16 bits
LAC
CI
Location Area Identity Cell Global Identity CGI = MCC + MNC + LAC + CI
31 January 2008
3GPP CE at UP
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BSIC
NCC
BCC BSIC BSIC = NCC + BCC
31 January 2008
3GPP CE at UP
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1.
Traffic Cases When MS is in Idle Mode 9600870 31 January 2008
2. 7.
LA1 4.
MSC/VLR-A (LA1 + LA2)
LA3 5.
LA2
3.
6.
8.
1. 2. 3. 4. 5. 6. 7. 8.
MSC/VLR-B (LA3)
IMSI attach Location updating, type IMSI attach Changing cells within an LA Location updating, same MSC/VLR Location updating, new MSC/VLR Location updating type periodic registration IMSI detach Implicit detach 3GPP CE at UP
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IMSI Attach
RACH is used to access the network AGCH assigns a SDCCH SDCCH is used to send IMSI attach message to The network
IMSI Detach is a complement to this procedure •Remove the SIM •Power Off •HLR is not informed •No Acknowledgement sent to MS
IMSI Attach 1. 4.
BSC/TRC
MSC/VLR
BTS VLR checks for 2. Subscriber record
VLR updates MS 3. status to idle
4. Acknowledgement sent to MS 31 January 2008
9600873
3GPP CE at UP
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Location Updating, same MSC/VLR
BCCH is checked 1. Authentication Authentication performed performed Using UsingSDCCH SDCCH
2. 3. 4.
2 . 3. Location update Request 4. VLR BSC/TRC
HLR
MSC
System acknowledges the location update request. Informs MS and BTS to release SDCCH
31 January 2008
3GPP CE at UP
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Location Updating, new MSC/VLR
4.
4. 1. VLR BSC/TRC
31 January 2008
9805058
HLR
2.
3.
3.
MSC
3GPP CE at UP
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MSC/VLR-B
Cases which Activate a MS and Cases when MS is in Active Mode 31 January 2008
GMSC
BSC/TRC BSC/TRC 5.
3.
4.
1. 2. BSC/TRC MSC/VLR-A
1. 2. 3. 4. 5.
Call from MS (speech, fax, data, short message) Call to MS (speech, fax, data, short message, cell broadcast) Handover - intra - BSC Handover - inter - BSC, intra - MSC Handover - inter - MSC 3GPP CE at UP
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Call set-up MS to PSTN SDCCH used for •Marking the MSM active in VLR •Authentication/Ciphering •Equipment Identity register •sending B-number to the Network
1. RACH
GSM/PLMN PSTN
1. 2. 3. 4.
2. AGCH 3. Call request using SDCCH 4. 4. Allocate idle TCH
BSC/TRC
MSC/VLR
5.
TE
B-number
31 January 2008 9600875
3GPP CE at UP
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Call to MS from PSTN GSM/PLMN
PSTN
3. 5.
1.
GMSC
2.
HLR
5.
Local exchange
1.
6.
4.
MSC/VLR
12
7.
PCH
Allocate TCH and inform MS and RBS of this TCH
11.
BSC/TRC
8.
PCH
SDCCH 11.
AGCH 10. 9.
8.
PCH 8.
8. 9.
RACH
10. 11.
31 January 2008
3GPP CE at UP
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Measurements sent to BSC RBS measures: Signal strength and transmission quality on TCH, uplink Measurement reports from MS are sent to RBS
MSC/TRC
Evaluation and decision about handover BSC/TRC Measurements from RBS and MS
9600877 31 January 2008
3GPP CE at UP
MS measures: Signal strength and transmission quality on TCH, downlink
Signal strength from neighboring BTS
61
Handover Four types of handovers: o Channels (time slots) in same cell o Between cells within same BSC o Between BSCs, within same MSC o Between MSCs
31 January 2008
3GPP CE at UP
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Handover: Cells Controlled by the Same BSC Info on new frequency, TS and output power 2. 6.
2.
Release old TCH
old BSC Handover access burst 3.
Handover complete
1.
4.TA info 5.
Activate a new TCH
5.
new
31 January 2008 9600878
3GPP CE at UP
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Handover: Different BSCs but the same MSC/VLR
Old BSC/TRC
4.
1. HO required message with CGI
4. 9. Release TCH
HO burst 5. 7. HO complete message to MSC
6.TA
4.
MSC
8. Release TCH 3.Activate a TCH 2.
7.
4.
HO request Info on freq, TS and Tx Power
7.
new BSC/TRC
9600879
31 January 2008
3GPP CE at UP
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Handover: Cells Controlled by Different MSCs Freq, ts, output power
1. HO required message with
CGI old BSC/TRC
7.
GSM PLM
11. New path set up in GS
MSC-A
6.
7. HO command
Requests help 2.
5.
PSTN
Link set up to target msc
10.
8.HO burst 4.Activate a TCH 3. HO request 9. 10.
5.Info & HO number
TA 10.HO complete
MSC-B
HO complete new BSC/TRC
9600880
31 January 2008
3GPP CE at UP
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SS Overview VLR
HLR
EIR
AuC
SS7
MSC PSTN
31 January 2008
3GPP CE at UP
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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 Supplementary services are switched through MSC DTI (Data Transmission Interface) handles (HS)CSD ((High Speed) Circuit Switch Data) Call 31 January 2008
3GPP CE at UP
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MSC – Mobile Switching Center ETC
ETC
MSC/VLR
TRC ETC
ETC GS
ST7
RP
RPD
RP
SP
31 January 2008
RP
CP
3GPP CE at UP
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SMS-C 1. RACH AGCH
2.
MSC/VLR
SMS-C
2. SMS on SDCCH
HLR 4.
SMS - C 1.
31 January 2008
2.
3.
SMS - GMSC
5.
8.
MSC/VLR
6. 7.
3GPP CE at UP
69
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) HLR e let o LA (Location Area) of MS e D o MSISDN MSC/VLR o TMSI o IMSI
31 January 2008
3GPP CE at UP
Up d
ate
MSC/VLR
70
HLR – Home Location Register Is a database that stores information on all subscribers on the network: o IMSI o MSISDN o Subscribed Supplementary Services o MSC/VLR area o Authentication information
Interacts with AUC (Authentication Center) Coordinate info in VLR’s 31 January 2008
3GPP CE at UP
71
EIR – Equipment Identity Register Database containing three lists of IMEI: o White listed o Black list of all IMEI that has been barred o Gray list – faulty or non-approved phones
31 January 2008
3GPP CE at UP
72
AUC – Authentication Center Request for triplets from HLR (IMSI)
AUC RAND generator Database IMSI Ki
RAND
Ki
A3 Authentication Algorithm A8 Ciphering Algorithm
RAND SRES Kc Ki IMSI
31 January 2008
SRES Triplets (or many per request) Kc
Random number Signed Response Ciphering key Subscriber authentication key International Mobile Subscriber Identity
Subscriber Authentication Provides ciphering keys
3GPP CE at UP
73
Information stored on SIM Security information o Subscriber authentication key, Ki o Ciphering key, Kc o Supports Authentication Algorithm, A3 o Supports Ciphering key generation algorithm, A8
Other o IMSI (International Mobile Subscriber Identity) o LAI (Location Area Identity) o List of frequencies to be used for cell selection o Forbidden PLMN 31 January 2008
3GPP CE at UP
74
Authentication Procedure 1. RAND
MSC/VLR
3. SRES
4. Compare SRES received from MS with SRES in triplet. If they are equal access is granted.
MS 2. MS calculates SRES using RAND + Ki (SIM-card) through A3 and Kc using RAND+Ki through A8. MSC/VLRMobile service Switching Center MS Mobile Station RAND Random number SRES Signed Response
31 January 2008
3GPP CE at UP
75
Ciphering Procedure 2. M
1. M + Kc
VLR
4. Encrypted M’ c
MSC
MS
TDMA frame no. Kc
M’ 6. Ciphering mode complete
Encryption process using A5
Decryption process using A5
3. Encrypt M
5. Decryption of M’ successful?
If yes
31 January 2008
A5 M M’ M’ c Kc MSC VLR 3GPP CE at UP
Kc TDMA frame no.
Encryption and decryption algorithm Ciphering Mode Command Ciphering Mode Complete Ciphering Mode Complete, ciphered Ciphering key Mobile services Switching Center Visitor Location Register 76
BSS Overview: BSC/TRC ETC
ETC
MSC/VLR
RBS
ETC
ETC Group Switch
RP
ST7
SRS
TRH
RPD
RP
RPG
SP
31 January 2008
TRAU
RP
RP
CP
3GPP CE at UP
77
Remote BSCs MSC A
BSC/TRC
Abis
A 64kb/s per TCH “multiplexed”
Abis
TRC
Ater 16kb/s per TCH “multiplexed”
(Remote) BSC 31 January 2008
3GPP CE at UP
Abis 3 E1 TS per TRX; 16kb/s per TCH
78
Usage of E1 LAP-D Concentration
TRX2
TCH TCH TCH TCH TCH TCH TCH TCH
Synch TCH TCH TCH TCH TCH TCH TCH TCH LAPD TCH TCH TCH TCH TCH TCH TCH TCH
Ater 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 LAPD TCH TCH TCH TCH
TRX10
TRX9
TRX8
TRX7
TRX6
TRX5
TRX4
TRX3
Synch TCH TCH TCH TCH TCH TCH TCH TCH LAPD TCH TCH TCH TCH TCH TCH TCH TCH LAPD
TRX1
Abis
31 January 2008
3GPP CE at UP
Synch 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 TCH
A 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
Synch TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH Signalling TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH TCH 79
Radio Link Features DTX (Discontinuous Transmission) Dynamic Power Control Frequency Hopping Radio Link Measurements Handovers
31 January 2008
3GPP CE at UP
80
DTX- Discontinuous Transmission Average Voice activity is around 50% DTX is a feature that allows to be transmitted only when there is something to be transmitted o Uses VAD (Voice Activity Detector)
Battery power Improves the overall network quality by reducing unnecessary interference 31 January 2008
3GPP CE at UP
81
Dynamic Power Control This enable the BTS and the Mobile to transmit only the power necessary for effective communications Power Control Commands are via the SACCH This improves the battery life of Mobile Phones And it improve the overall network quality by reducing unnecessary interference 31 January 2008
3GPP CE at UP
82
MS power output levels For GMSK modulation Power class
GSM 400 & GSM 900 & GSM 850 & GSM 700
DCS 1 800
PCS 1 900
Tolerance (dB)
Nominal Maximum
1 2 3 4 5
Nominal Nominal for conditions Maximum Maximum normal extreme 1 W (30 dBm) 1 W (30 dBm) ±2 ±2,5 8 W (39 dBm) 0,25 W (24 dBm) 0,25 W ±2 ±2,5 (24 dBm) 5 W (37 dBm) 4 W (36 dBm) 2 W (33 dBm) ±2 ±2,5 2 W (33 dBm) ±2 ±2,5 0,8 W (29 dBm) ±2 ±2,5
For 8-PSK modulation Power class
E1 E2 E3 31 January 2008
GSM 400 & GSM 900 & GSM 850 & GSM 700
DCS 1 800
Nominal Maximum output Power 33 dBm 27 dBm 23 dBm
Nominal Maximum output Power 30 dBm 26 dBm 22 dBm
PCS 1 900
GSM 400 and GSM 900 & GSM 850 & GSM 700
DCS 1 800 & PCS 1 900
Nominal Tolerance (dB) Tolerance (dB) Maximum for conditions for conditions output Power normal extreme normal extreme 30 dBm ±2 ±2,5 ±2 ±2,5 26 dBm ±3 ±4 -1.33 -4,5/+4 22 dBm ±4 ±3 ±3 ±4
3GPP CE at UP
83
MS Power Control levels GSM 900 Power control level 0-2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19-31 31 January 2008
Nominal Output power (dBm) 39 37 35 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5
DCS 1 800
Tolerance (dB) for conditions norma extrem l e ±2 ±2,5 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±5 ±6 ±5 ±6 ±5 ±6 ±5 ±6 3GPP CE at UP
Power control level 29 30 31 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15-28
Nominal Output power (dBm) 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0
Tolerance (dB) for conditions norma extrem l e ±2 ±2,5 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±3 ±4 ±4 ±5 ±4 ±5 ±4 ±5 ±4 ±5 ±4 ±5 ±5 ±6 ±5 ±6 84
BTS Power Control Levels For a normal BTS, the maximum output power measured at the input of the BSS Tx combiner GSM 400 & GSM 900 & DCS 1 800 & PCS 1 900 GSM 850 & MXM 850 & MXM 1900 TRX Maximum TRX Maximum power output power power output power class class 1 2 3 4 5 6 7 8
320 - (< 640) W 160 - (< 320) W 80 - (< 160) W 40 - (< 80) W 20 - (< 40) W 10 - (< 20) W 5 - (< 10) W 2,5 - (< 5) W
1 2 3 4
20 - (< 40) W 10 - (< 20) W 5 - (< 10) W 2,5 - (< 5) W
For a micro-BTS or a pico-BTS, the maximum output power per carrier measured at the antenna connector after all stages of combining GSM 900 & GSM 850 & DCS 1 800 & PCS 1 900 MXM 850 and GSM 700 & MXM 1900 micro and TRX Maximum TRX Maximum power output power power output power class class Micro Micro M1 (> 19) - 24 dBm M1 (> 27) - 32 dBm M2 (> 14) - 19 dBm M2 (> 22) - 27 dBm M3 (> 9) - 14 dBm M3 (> 17) - 22 dBm Pico Pico P1 (> 13) - 20 dBm P1 (> 16) - 23 dBm
BTS actual power level is Max. power (dBm) – 2*N (i.e. 2dB at a time) 31 January 2008
3GPP CE at UP
85
Effect of DTX and PC on Quality 10.00% DTX + PC Off
%HOIU
9.00%
%HOID
Percentage
8.00% PC Off
7.00% 6.00% 5.00% 4.00% 3.00% 2.00% 0
31 January 2008
10
20 Tim e (hours)
3GPP CE at UP
30
40
86
Radio Link Measurements RxLev (in GSM units: reports signal strength above –110dBm – maximum 63 i.e. –47dBm RxQual
31 January 2008
RxQual 0 1 2 3 4 5 6 7
BER (%) <0.2% 0.2% -0.4% 0.4%-0.8% 0.8%-1.6% 1.6%-3.2% 3.2%-6.4% 6.4%-12.8% >12.8%
3GPP CE at UP
87
Radio Link Measurements The Mobile reports to the BSC (via the BTS) every SACCH 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 o o o o 31 January 2008
The Signal Strength from the Mobile The Signal Quality from the Mobile The BTS power control level The MS power control level The TA (timing Advance) 3GPP CE at UP
88
Handovers A handover is initiated when o 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) drops below a said minimum o The signal quality (uplink or downlink) drops below a said minimum
31 January 2008
3GPP CE at UP
89
Handover The BSC contains the following info o 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 Reselection Hysteresis) and other handover parameters
31 January 2008
3GPP CE at UP
90
Frequency Hopping Downlink C1
Uplink C1
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 N
Downlink C2
Uplink C2
N+1
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 N
31 January 2008
TDMA frame no.
TDMA frame no. N + 1
3GPP CE at UP
91
Frequency Diversity
Signal level
Raleigh fading is frequency dependant
31 January 2008
f0 f1
3GPP CE at UP
Position
92
Frequency Diversity Diversity: combining two or more uncorrelated versions of the same signal For “conventional” frequency diversity the info is sent on two different frequencies at the same time. To be uncorrelated the two frequencies should be more than 1/(multi-path spread), where the multi-path spread is dependant on the environment. For urban areas the frequencies should be more than 600kHz apart 31 January 2008
3GPP CE at UP
93
Base Band Frequency Hopping Number of frequencies equal to number of transceivers
Tx and Rx on f0
Controller CALL 2
Tx and Rx on f1
Controller CALL 3
Tx and Rx on f2
f0 f1 f2 f3
Combiner
Controller CALL 1
f1 f2 f3 f0 f2 f3 f0 f1 f3 f0 f1 f2
Controller CALL 4
31 January 2008
Tx and Rx on f3 “Baseband Bus” for routing bursts
3GPP CE at UP
94
Synthesised Hopping Number of frequencies more or equal to number of transceivers
31 January 2008
Controller CALL 1
Tx and Rx hopping
f0 f1 f2 f3
Controller CALL 2
Tx and Rx hopping
f1 f2 f3 f0
Controller CALL 3
Tx and Rx hopping
f2 f3 f0 f1
Controller CALL 4
Tx and Rx hopping
f3 f0 f1 f2
3GPP CE at UP
95
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.
31 January 2008
3GPP CE at UP
96
Interleaving and Channel Coding work always FER and SQI vs.RxQual 30
SQI 20
SQI/ %FER
Non-Hopping (calls on BCCH-carrier) Non-Hopping (calls on BCCH-carrier) Hopping w ith 20% load
10
Hopping w ith 20% load
0
FER -10 0
1
2
3
4
5
6
7
RxQual 31 January 2008
3GPP CE at UP
97
Synthesized hopping Synthesised hopping provides: o Higher capacity for the same quality. o Simplified frequency planning. o Can implement new transceivers without new frequency plans
But o It costs more o Can not be implemented with filter combiners - might impose limit on #TRX/cell o Complications with implementation combined with Base Band hopping
31 January 2008
3GPP CE at UP
98
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’s
But o Require frequency plan with upgrade o More complex planning 31 January 2008
3GPP CE at UP
99
Frequency Diversity Gain Frequency Diversity Gain vs Number of Hopping Channels 8 7 6
Gain (dB)
5 4 3 2 1 0 1
2
3
4
5
6
7
8
Number of Carriers Cyclic 31 January 2008
Random
Poly. (Cyclic)
3GPP CE at UP
Poly. (Random) 100
Interference Diversity 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 with random hopping is 2.5dB - mostly it is less. 31 January 2008
3GPP CE at UP
101
Co-channel interference The total co-channel interference experienced at the yellow spot is the sum of interference of all six cells with the same frequency
R
The interference from one co-channel interferer can be written as I =KD-γ
D
The carrier level is C= KR-γ C/I = (D/R)γ /6 31 January 2008
3GPP CE at UP
102
Re-use distance D = (i2 + ij + j2)½2Rcos 30° D = (i2 + ij + j2)½ (3) ½ R
v j
D
u i
30°
Number of cells in the re-use pattern N = i2 + ij + j2 i (1,2,3,4 …..) j (0,1,2,3,4 …..) D/R = (3N)½
31 January 2008
3GPP CE at UP
103
The Hexagon
Area of a hexagon: A = ½. 3 (3)½R2 R d
31 January 2008
Distance between centers of two adjacent cells: d = (3)½R
3GPP CE at UP
104
Traffic calculations revision An Erlang Erlang B Table Examples of Traffic channels
31 January 2008
3GPP CE at UP
105
Problem The average traffic generated by one user is 10milliErlang/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. 31 January 2008
3GPP CE at UP
106
31 January 2008
3GPP CE at UP
107
Sectorisation
C/I = (D/R)γ /2
31 January 2008
3GPP CE at UP
108
4/12 Cell Pattern Frequency Groups Channels
A1 B1 C1 D1
A2 B2 C2 D2
A3 B3 C3 D3
1 13
5 17
9 10 21 22
2 14
3 15
4 16
6 18
7 19
8 20
11 12 23 24
12 D3 24 4
8
D1
3
D2 16
C1 15
20 1
11
A1
C3 13 5
2
A2 21
19
23
9 A3
7 C2
B1 17
14 10 B3 22
31 January 2008
3GPP CE at UP
6 B2 18 109
Adjacent Channel interference 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
31 January 2008
3GPP CE at UP
110
Adjacent channel interference Relative power (dB)
Relative power (dB)
0
0
-10
-10
-20
-20
-30
-30
-40
-40
measurement bandwidth 30 kHz measurement bandwidth 100 kHz -50
-50 measurement bandwidth 30 kHz measurement bandwidth 100k Hz
-60
-60
-70
-70
-80
-80
0
200
400
600
Frequency from the carrier (kHz) 31 January 2008
1200
1800
3000
6000
0
200
400
600
1200
1800
3000
6000
Edge of TX band + 2 MHz
Frequency from the carrier (kHz)
3GPP CE at UP
111
Co-channel interference GSM CS-1 CS-2 CS-3 CS-4 MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9 31 January 2008
# Info # Coding Code Max data rate Required C/I (dB) Modul (BLER <10%; TU3 FH) ation bits bits Rate (kbs) /TS 260 196 0.5 13.3 9 GMSK 181 275 0.45 9.05 9 GMSK 268 188 0.65 13.4 13 GMSK 312 144 0.75 15.6 15 GMSK 428 28 21.4 23 GMSK 176 0.53 8.4 9 GMSK 224 0.69 11.2 13 GMSK 296 0.89 14.8 15 GMSK 352 1 16.8 23 GMSK 448 0.38 22.4 14.5 8PSK 592 0.5 29.6 17 8PSK 896 0.78 44.8 23.5 8PSK 1088 0.92 54.4 29 8PSK 1184 1 59.2 32 8PSK 3GPP CE at UP
112
Effect of γ and C/I Minimum Assuming 3 sectored sites C/I (dB frequencies gamma 9 12 13 17 36 2 18 33 42 102 7965 2.5 12 18 21 42 1323 3 9 12 12 24 399 3.5 6 9 9 15 171 4 6 6 9 12 90 31 January 2008
3GPP CE at UP
113
Spectral Efficiency Erlang/Hz/km2 Using the previous problem as starting point – calculate the spectrum density that could be achieved if the sites were sectorised. Compare with the omni-cells
31 January 2008
3GPP CE at UP
114
Benefits of sectorisation Higher gain antennas are available – better penetration Less cost for same traffic density
31 January 2008
3GPP CE at UP
115
Underlay / Overlay - MRP
31 January 2008
3GPP CE at UP
116
Cell Splitting
31 January 2008
3GPP CE at UP
117
Hierarchical Cells Umbrella Cell: Macro Cell: Antenna above average rooftop height Micro Cell: Antenna below average rooftop height Pico Cell: Indoors
31 January 2008
3GPP CE at UP
118
C/I reduction from DTX C/I values 0.12 C/I
Probability Distribution
0.1
C/I DTX 0.08
0.06
0.04
0.02
0 -50
-40
-30
-20
-10
0
10
20
30
40
50
Signal Level 31 January 2008
3GPP CE at UP
119
Interference reduction from Power Control The level of the transmitted signal is reduced to what is required for the specified Receive Signal 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 interference level, and the average signal level will be down by 32dB.
The effect on the C/I is difficult to determine. 31 January 2008
3GPP CE at UP
120
Interference Reduction from PC Interference Levels 0.2 Interference
Probability Distribution
0.18
Int. DTX
0.16
Int. PC +DTX
0.14 0.12 0.1 0.08 0.06 0.04 0.02 0
-140
-120
-100
-80
-60
-40
-20
0
Signal Level
31 January 2008
3GPP CE at UP
121
Carrier Reduction from PC Carrier Levels 0.2 Carrier
Probability Distribution
0.18
Car. DTX
0.16
Car. PC + DTX 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 -140
-120
-100
-80
-60
-40
-20
0
Signal Level
31 January 2008
3GPP CE at UP
122
Impact of PC on the C/I ? C/I values 0.16 C/I
Probability Distribution
0.14
C/I DTX 0.12
C/I PC + DTX
0.1 0.08 0.06 0.04 0.02 0 -50
-40
-30
-20
-10
0
10
20
30
40
50
Signal Level
31 January 2008
3GPP CE at UP
123
Frequency Hopping with DTX and PC • Power control: 0
31 January 2008
3GPP CE at UP
• DTX: • TS active:
0 1
• No call:
0
124
Hopping with DTX and PC C/I values 0.25
Probability Distribution
C/I C/I DTX
0.2
C/I PC + DTX Hopping
0.15
0.1
0.05
0 -50
-40
-30
-20
-10
0
10
20
30
40
50
Signal Level 31 January 2008
3GPP CE at UP
125
Effect of DTX and PC on Quality 10.00% DTX + PC Off
%HOIU
9.00%
%HOID
Percentage
8.00% PC Off
7.00% 6.00% 5.00% 4.00% 3.00% 2.00% 0
31 January 2008
10
20 Tim e (hours)
3GPP CE at UP
30
40
126
Planning for FH network Use separate frequency blocks for TCH and BCCH o BCCH frequency channel must be Always On o No hopping over BCCH.
Plan TCH layer: o MAL : Mobile radio frequency channel Allocation List o HSN: Hopping sequence number o MAIO: Mobile Allocation Index Offset o MAI: Mobile Allocation Index 31 January 2008
3GPP CE at UP
127
Selecting a BCCH block Why a BCCH block? o Identifying the source of interference 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 change in a TCH carrier in the optimised plan 31 January 2008
3GPP CE at UP
128
Selecting a BCCH block BlockSizeBCCH = Total _ Number _ of _ Carriers _ Available ( AverageTrafficonTCHlayerperCell / 8) × Scaling ( DTX , PC ) + 1
31 January 2008
3GPP CE at UP
129
Frequency Hopping MAI 1 2 3 4
MAIO 0 2 1 3 2 4 3 1 4 2
1A 1 10 19 28
HSN =x TRX1 on 1A has MAIO = 0 TRX2 on 1A has MAIO = 2 31 January 2008
2A 2 11 20 29
3A 3 12 21 30
1B 4 13 22 31
MA 2B 3B 5 6 14 15 23 24 32 33
1C 7 16 25 34
2C 8 17 26 35
3C 9 18 27 36
4 1 2 3 2 4 3 1 28 1 10 19 10 28 19 1 10 19 28 1 28 10 1 19 3GPP CE at UP
130
Automatic Frequency Planning Tools TRX Requirements etc
Propagation Predictions
Coverage Analysis
Interference Matrix
AFP Tool
Frequency Plan
Separation Constraints, etc 31 January 2008
3GPP CE at UP
131
Automatic Frequency Planning Model of Network Model effect of particular assignment on quality Propagation Predictions Drive Test Data Handover Statistics Live Measurements
Cost Function: Sum of remaining interference and other penalties. Quality
Change: Frequency BSIC HSN, MAIO
31 January 2008
3GPP CE at UP
132
Interference Matrix The “conventional” interference matrix represent: 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 and traffic distribution maps. o What is the cost of accurate enough predictions? 31 January 2008
3GPP CE at UP
133
Generating the Interference Matrix 50 m Resolution
2.0 km
2 m Resolution
2.0 km
2.5 km
2.5 km
Microcell Service Area ≈ 1 pixel 31 January 2008
3GPP CE at UP
134
Probability of C/I>9dB Cummulative Probability Distribution for C/I exceeding 9dB 1
Probability that C/I will be below 9dB
0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -20
-15
-10
-5
0
5
10
15
20
25
30
Calculated C/I (dB) 31 January 2008
3GPP CE at UP
135
AFP Implements a mathematical optimisation method or Artificial Intelligence method to 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 to the different cells
31 January 2008
3GPP CE at UP
136
What are the true aims in Cell and Frequency Planning
What will really give optimum quality? 31 January 2008
3GPP CE at UP
137
The inputs to Cell Planning aff Tr f raf (T
le
ic: ic
Av a
ila b
GoS QoS Quality Coverage Speech Quality System Choice - C/I
tio nm
Sp ec
u rib
tru
m
t dis s) ap
Cost / Money 31 January 2008
3GPP CE at UP
138
Quality Voice Quality o Impacted by the FER (Frame Erasure Rate / 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
31 January 2008
3GPP CE at UP
139
C/I to FER Frame Erasure Rate 0
-5
10 log(FER)
-10 Non-Hopping -15
-20 Frequency Hopping on 8 freqquencies, Random Hopping
-25
-30 -5
0
5
10
15
20
C/I(dB)
31 January 2008
3GPP CE at UP
140
Measurement Based Frequency Planning Using Mobile Measurement Reports how will you go about generating the optimal Interference Matrix?
31 January 2008
3GPP CE at UP
141
The first Measurement Based Plan Johannesburg’s Central Business District 12km×12km 65 sites (≈350 cells) 477 carriers Despite questioned cluttered data and propagation prediction models very low dropped call rate of about 1.4% was very often achieved partly due to dedicated optimisation 31 January 2008
3GPP CE at UP
142
Measurement Based Frequency Planning Cell Traffic Recordings was used to collect Mobile Measurement Reports on all the cells 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 the C/I and eventually the FER. The average FER for each server-interferer relation was calculated. and multiplied with the traffic on the serving cell 31 January 2008
3GPP CE at UP
143
The Sanity Check
31 January 2008
3GPP CE at UP
144
Dropped Call Rate 2.30%
1.90% Percentage
Using MMRs in Frequency Planning
Plan Im plem ented
2.10%
1.70%
Traffic 1.29%
1.50%
%Drop DayAvg
1.30%
1.10%
0.90% 0 31 January 2008
10 3GPP CE at UP
20 Time
30
40 145
Measurement Based Frequency Plan
Percentage (0.1% per devision)
2.30%
2.10%
1.90%
1.70%
1.50%
1.30%
Predictions and Drive Tests
Measurem ent Based Plan run in
Dropped Call Rate
Traffic Previous Minim um
1.10%
%Drop DayAvg
0.90%
0
10
20
30
40
50
60
Time
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Intra-cell Hand-over and TCH Dropped due to Bad Quality Plan Im plem ented
The Results: Quality
Percentage (of tcalls for H and tcassal for T)
8.00%
7.00%
6.00%
%HoBUQ %HoBDQ Traffic %TBQDis*50
5.00%
4.00%
3.00%
2.00% 0
10
20
30
40
Tim e 31 January 2008
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Data Sources for the Interference Matrix (1) Propagation Predictions o Well established conventional method o Based on Predicted Carrier to Interference ratios that is often translated with a “C/I weights” curve o Integration with AFP tools eases use o Suited for new networks with many new cells o Dependant on elevation and clutter data that often has limited accuracy 31 January 2008
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Data Sources for the Interference Matrix (2) Neighbour relations statistics 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/I o Can not model interference from nonneighbours
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Data Sources for the Interference Matrix (3) Drive Test Data o Measurements done with network set on measure on all BCCH channels o Independent of accuracy of elevation and clutter data o Extensive measurements necessary for interference matrix o Difficult to deduce interfered traffic from data o 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 31 January 2008
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Data Sources for the Interference Matrix (4) Live Data: Mobile Measurement Reports o Mobile Measurement Reports are collected with the cell set to measure on all BCCHs o 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 the network to be fairly mature and stable. o Difficult to model new sites o Takes some effort to import into an AFP.
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Prediction vs. MMRP LIMITED accuracy o o o o
31 January 2008
Propagation predictions Clutter and Height data In building Traffic distribution
Cannot represent new sites MMR limitations:
3GPP CE at UP
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RxLev: -110 -> -48dBm Only integers Only six neighbours BSIC decoding problems
152
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.
without o Spoiling good data with bad data. o Skewing the matrix, e.g. when drive test data is available for only part of the network. 31 January 2008
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Penalties for AFP A “bare necessity” approach i.e. set penalties only when o it is required by law or o It is required for feasibility – e.g. filter combiner separation o it will assist in the improvement of network quality o Is penalties to avoid adjacencies required?
The size of the penalties must reflect their importance and effect on network quality 31 January 2008
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Examples of Scaling Factors Difference in interference introduced o Traffic load on TCH channels o Power Control o Discontinuous Transmission (DTX) o Over-laid Under-laid - depend on effectiveness of implementation o Synthesizer Hopping - dependant on fractional load
Difference in immunity to interference o Frequency Diversity Gain of Hopping Networks 31 January 2008
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Interference Load The core questions: o How much interference will assigning the same frequency to a carrier in Cell A and Cell B cause ? o How much less will that be after DTX? o How much less will that be after Power Control?
Interference Load o How much signal or potential interference is carried on a particular carrier o Interference Load = Traffic on Cell 8 * #Carriers 31 January 2008
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Interference Load Reduction For BCCH o Interference Load = 1
For Non-Hopping TCH without DTX and PC o Interference Load = Traffic on TCH Carriers o 8 * Number of TCH Carriers
After DTX o Voice Activity Factor 40% on TCH channels o Interference Load = 0.4 * Traffic on TCH Carriers o 8 * Number of TCH Carriers
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Interference Load Reduction After Power Control ? o Consider a very simplified model: C/I = Server SS / (6* Interferers SS) Reducing the signal level of the server and of the interferers by approximately 10dB: C/I = 0.1* Server SS / (6*0.1* Interferers SS) Approximately unchanged.
o Practical implementation suggest a definite interference reduction - by 60% o Interference Load = 0.6 * Traffic on TCH Carriers o 8 * Number of TCH Carriers 31 January 2008
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A few terms Frequency Allocation Re-use o FAR = Total Number of Frequency Channels Number of Frequencies per Cell
Effective Re-use Reff= Total Number of Frequency Channels Average number of TRX per Cell
Fractional Load o Lfrac=
Number of TRX per Cell . Number of Frequencies per Cell
Hardware Load o LHW= (Busy Hour Traffic) / (TN /TRX) 31 January 2008
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A few terms Frequency Load o Lfreq= LHW Lfrac
Effective Frequency Load o EFL =.
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Busy Hour Traffic per Cell . (TN per TRX for Traffic).(Total # FreqCH)
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Optimum # carriers to Hop over = 24/6 Optimum frequency Re-use 40
Erlang per Site
35 30 25 20
6MHz available for TCH
15 10 5 0 1
2
3
4
5
6
7
8
9
Frequency Reuse = #TCH carriers / #TCH per cell
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Quality vs Capacity 150 Minute Erlang per Drop (Quality)
145
The challenge: To maximize Quality * Capacity
140 135 130 125 120 115 110 105 100 6
7
8
9
10
11
12
13
14
15
16
Average Erlang per Cell (Capacity) (deduced from Spectrum Utilisation) 31 January 2008
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Major Interferers Effect of reducing major interferers 1 00.00%
90.00%
80.00%
70.00%
60.00%
50.00%
40.00%
Cummulative Contribution
30.00%
With 5 sites' interference removed
20.00%
1 0.00%
0.00% 0.00%
1 0.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
1 00.00%
P e r c e nt a ge of C e l l s c ont r i but i ng t o I nt e r f e r e nc e
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What criteria would you use for site selection? Close to traffic – most effective Power Control Contained (high γ ) o In building o In valleys rather than on top of mountains
What effect will an unbalanced link have? 31 January 2008
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What criteria will you provide an Automatic Cell Planning tool with? Propagation Predictions
Effective Frequency load
Traffic distribution - GIS
Hand over areas
Possible sites
Income: Coverage of potential traffic
Equipment used Frequency Allocation
Cost: cost of changes / sites
Interference Matrix MMR 31 January 2008
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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) Upgrading o Cell Statistics 31 January 2008
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Changes in ACP Radio Parameters o Transmission power o Cell Hysterises o Cell Hierarchical Level
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Evaluating automatic tools... Automatic Frequency Planning Tools o 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 Optimisation o 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 with the tool... and allow manual changes 31 January 2008
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MS Sensitivity GSM 900 MS o for GSM 900 small MS o for other GSM 900 MS
-102 dBm -104 dBm
DCS 1 800 MS o for DCS 1 800 class 1 or class 2 MS -100 / -102 dBm * o for DCS 1 800 class 3 MS -102 dBm
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BTS sensitivity GSM 900 BTS o o o o o
for normal BTS -104 dBm for micro BTS M1 -97 dBm for micro BTS M2 -92 dBm for micro BTS M3 -87 dBm for pico BTS P1 -88 dBm
DCS 1 800 BTS o o o o o 31 January 2008
for normal BTS -104 dBm for micro BTS M1 -102 dBm for micro BTS M2 -97 dBm for micro BTS M3 -92 dBm for pico BTS P1 -95 dBm 3GPP CE at UP
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Defining Quality Speech Quality (BER, FER) Dropped Calls Coverage Call Set-up success Handover stats 31 January 2008
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To do Cell Planning Frequency Planning Link balancing Neighbour lists o Handover parameters
Power Control DTX Dimensioning 31 January 2008
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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_MIN B = MS_TXPWR_MAX_CCH - P 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 defined by:
C2 = C1 + CELL_RESELECT_OFFSET - TEMPORARY OFFSET * H(PENALTY_TIME - T) for PENALTY_TIME <> 11111
C2 = 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: 31 January 2008
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GPRS cell selection A= RLA_P - GPRS_RXLEV_ACCESS_MIN B= GPRS_MS_TXPWR_MAX_CCH - P C32(s) = C1(s) (serving cell) C32(n) = C1(n) + GPRS_RESELECT_OFFSET(n) TO(n) * (1-L(n)) (neighbour cell) 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 < 0 1 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) 31 January 2008
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The inputs to Radio Network Optimisation aff Tr
le
ic:
ic
Av a
ila b
f raf (T
GoS QoS Quality Coverage Speech Quality System Choice - C/I
s) ap
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Cost / Money
tio
Sp ec
u rib
tru
m
t dis
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175
Quality Capacity product Quality vs Capacity 150 Minute Erlang per Drop (Quality)
145
The challenge: To maximize Quality * Capacity
140 135 130 125 120 115 110 105 100 6
7
8
9
10
11
12
13
14
15
16
Average Erlang per Cell (Capacity) (deduced from Spectrum Utilisation) 31 January 2008
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Link balance
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Neighbour List for 1883B: Propagation Predictions 1883A 1883C 236A 236D 1569B 294C 31 January 2008
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Neighbour Lists for 1883B : Measurement Based Methods and Handover Statistics Percentage of Percentage of times it Recommended Potential Reports it was was 3dB stronger by Complete Neighbour the Strongest than the server MMR method?
1883A 236B 1883C 294C 236D 236A 1569B 980C 1569C 294B 2150B 340B 251A 1933C 408C 251B 409B 2441B 236C 519B 84A 31 January 2008
10.36% 8.73% 5.56% 5.49% 4.02% 3.25% 2.86% 2.01% 1.70% 1.62% 1.47% 1.00% 0.93% 0.70% 0.62% 0.54% 0.46% 0.39% 0.31% 0.23% 0.15%
4.64% 6.03% 2.01% 5.56% 1.78% 3.01% 2.63% 1.85% 1.16% 2.32% 2.16% 1.31% 2.47% 2.86% 1.70% 1.55% 1.47% 3.09% 2.09% 1.93% 2.09%
Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No No 3GPP CE at UP
Handover Attempts
Succesful Handovers
Hand Drops at overs Hand Returned over
742 1186 449 1052 479 251 498 413 0 117 295
730 1166 444 1031 472 241 488 401 0 112 268
9 3 4 9 1 3 8 5 0 4 24
3 17 1 12 6 7 2 7 0 1 3
328 21
1 21
319 0
8 0
424 127 59
421 119 57
0 8 0
3 0 2 179
Example 2 : Neighbour Lists Unnecessary “Neighbour” Typical Neighbour Typical Neighbour Server Small but essential neighbour 31 January 2008
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Example 3: Cell Planning
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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” o “MinuteErlang” or “Accumulated Traffic”
Perceived Grade Of Service # ofCallAttemps - # ofCallSuccesses PGoS = × 100% # ofCallAttempts
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Performance in Technical Terms (2)
Dropped Call Rate # ofDroppedCalls Dropped% = × 100% # ActiveofCalls
Average traffic carried before a call drops MinuteErlangCarried MinuteErlangPerDrop = # ofDroppedCalls
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Contributors to Lack of Performance Failures at any point of the network contribute performance degradation A chain is as strong as its weakest link: The Radio Link Hence the emphasize on the performance at cell level.
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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: Traffic. Level. Accumulator Average. Erlang = Number. of. Accumulations
Minute Erlang MinuteErlang = Average. Erlang × Measurement. Period
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Cell Statistics (5) Dropped Call Rate o
DroppedCalls Dropped% = × 100% CallsActiveOnCell
TNDROP × 100% o Dropped% = TMSESTB − HOINSUC
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Cell Statistics (6) Perceived Grade Of Service # CallAttemptsToCell − # CallSuccessesToCell PGoS = # CallAttemptsToCell HOINxQA − (TMSESTB − HOINSUC ) TCALL − x =∑ U,D,B × 100% PGOS = TCALL − HOINxQA ∑ x =U,D,B
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Cell Statistics (7) Call Success Rate o A parameter that combines the effect of congestion, setup failures and dropped calls tmsestb − hoinsuc − tndrop o CallSuccessRate = tcall − ∑ hoinxqa x = U,D,B
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Cell Statistics (8) Congestion and Failures on Control Channels also influence PGOS. o Hard to distinguish between call setup and location updating o Hence to need to determine performance of Control channels: Dropped Control Channel Rate Control Channel PGOS
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BSC statistics (1) In essence the BSC statistics is a summation of the Cell statistics. e.g.
PGoS =
∑ tassell − ∑ tcassel ∑ tassell
AllCells
AllCells
AllCells 31 January 2008
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MSC statistics (1) Traffic and congestion counters are available for each directions and origin of traffic flow.
GoS =
∑ NICONG × 100% ∑ NCALLS + ∑ NICONG ORG , IEX
ORG , IEX
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MSC Statistics (2)
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Overall Network Performance
∑ tcassel − ∑ tndrop SuccRate =
AllCells
AllCells
∑ tassell
−
AllCells
∑ NICONG − AllMSC ( ORG,IEX )
∑ NUNSUCC AllMSC ( ORG,IEX )
∑ tassell
× 100%
AllCells
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Problem Diagnostics (1) A problem is a problem if it affects performance: o Dropped calls o Congestion on traffic or control channel o Setup failures of calls.
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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
Missing Neighbour Relation or Measurement frequency - Cell 1375A o High dropped call rate o High Tfail% o Possibly high congestion.
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Problem Diagnostics (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
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 structures o E1 2Mb/s links (64kb/s PCM) o GSM 44.04 for Air interface; o GSM 48.54 for Abis o GSM 48.04 for A
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GSM Signaling Layers Layer 2 (data link layer) o Multiplexing of layer 2 connections on signaling channels o Error detection and correction o Flow control o 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 31 January 2008
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GSM Signaling Layers Layer 3 is sub-divided into 3 sub-layers o Connection Management o Management of Location data o Subscriber identification o Management of added services ( SMS, call forwarding)
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Layer 3 Signaling Protocols MM: Mobility Management o Location updating o Registration o Security and authentication procedures o Assignment of TMSI
CM: Connection Management 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 31 January 2008
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Layer 3 Signaling Protocols RR: Radio Resources Management o Establishment, maintenance, and termination of radio link between MS and MSC despite MS movements. o Allow point-to-point dialogue even during including cell selection and handover procedures o Monitoring and forwarding of radio connections o Handled by BSC, BTS and MS
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Layer 3 Signaling Protocols RR messages are mapped on BSSAP: o o o o o o
Cipher mode management DTX management Handovers Call re-establishment Load Management SACCH procedures Power Control, Timing Advance, Mobile Measurement Reports
o BCCH info Cell Selection info CGI Idle mode info (other BCCH frequencies) 31 January 2008
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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 Maintenance messages between BTS and BSC o SAPI 63 is used for layer 2 management functions
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Layer 2 Signaling Protocols Message Transfer Part: MTP o Interface to Physical Layer o Ensures reliable transmission and delivery of the signaling traffic o Provides flow control – sensing node failure o Routing, Distribution, Traffic Discrimination and Network Management
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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 • 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 failure conditions 31 January 2008
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Layer 3 Signaling Protocols Base Station System Application Part: BSSAP o Split into Base Station System Management Application Part : BSSMAP and Direct Transfer Application Part : DTAP o Handles messages not transparent to BSC o Supports all procedures related to single calls and resource management
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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 o Responsible for signaling between different entities in network, such as between HLR and VLR and EIR o Access and Location management o MSC-MSC handover, o Security functions o SMS and supplementary services 31 January 2008
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Layer 3 Signaling Protocols Transaction Capabilities Application Part: TCAP o Provides universal calls and functions for handling requests to distributed application processes
ISDN 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) 31 January 2008
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CSD call 2. Connection between ms and network is set up. Authentication performed
6. MSC routes the call to the destination NW. The connection may be through an existing NW (PSTN/ISDN)
1.
PSTN
2. 1. 6. 2.
PAD
5. DTI reroutes the call to MSC BSC/TRC 3. MSC analyses the BC. B. no and BC are transferred to the DTI
PSPDN
MSC/VLR 3. 4.
5. DTI
PAD
6. ISDN
4. The DTI is configured to perform the required service (fax, modem service)
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GPRS network Um
BSS TE
MT
ISDN/ PSTN
BTS Abis
A
BSC
MS Traffic and signaling
GMSC MSC/VLR Gs
Gb
Terminal Equipment Mobile Terminal Mobile Station Base Station System Base Transceiver Station Base Station Controller Gateway Mobile Services Switching Center MSC Mobile services Switching Center VLR Visitor Location Register HLR Home Location Register AUC Authentication Center EIR Equipment Identity Register SGSN Serving GPRS Support Node GGSN Gateway GPRS Support Node Um Air Interface A, Abis Interfaces (GSM) Gx Interfaces (GPRS) 31 January 2008
Gf
AUC
SGSN
Signaling TE MT MS BSS BTS BSC GMSC
EIR
Gr
HLR External IP Network (Internet)
Gn
IP-Backbone Network
GGSN Gi
Gp
Other PLMN
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External IP Network (Corporate LAN)
External X.25 Network
224
Reference http://www.cs.hut.fi/~hhk/GPRS/
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GPRS protocol stack
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Air Interface Share the Physical Layer with GSM On demand PDCH o PILTIMER
Dedicated PDCH PDCH can be shared by users o TFI – Temporary ID to distinguish between mobiles on same PDCH o USF – Indicates when the MS can transmit on the uplink. 31 January 2008
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Coding Schemes GSM CS-1 CS-2 CS-3 CS-4 MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9 31 January 2008
# Info # Coding Code Max data rate Required C/I (dB) Modul (BLER <10%; TU3 FH) ation bits bits Rate (kbs) /TS 260 196 0.5 13.3 9 GMSK 181 275 0.45 9.05 9 GMSK 268 188 0.65 13.4 13 GMSK 312 144 0.75 15.6 15 GMSK 428 28 21.4 23 GMSK 176 0.53 8.4 9 GMSK 224 0.69 11.2 13 GMSK 296 0.89 14.8 15 GMSK 352 1 16.8 23 GMSK 448 0.38 22.4 14.5 8PSK 592 0.5 29.6 17 8PSK 896 0.78 44.8 23.5 8PSK 1088 0.92 54.4 29 8PSK 1184 1 59.2 32 8PSK 3GPP CE at UP
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Modulation Schemes GMSK
8PSK
Q
(0,1,0) (0,0,0)
“1”
Q (0,1,1)
I
I (0,0,1)
“0”
(1,1,1)
(1,0,1)
(1,1,0) (1,0,0)
“1 bit per symbol”
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“3 bits per symbol”
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Routing Areas BTS
BTS BTS
BTS
BTS
BTS
BTS BTS
BSC
PSTN
BTS BTS
BSC
MSC
BTS
BTS BTS
BTS
BSC
BSC
MSC
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
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Active Mode The Mobile does cell selection o Based on “idle mode” type measurements o Send message to the network when it changes cells
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GPRS ATTACH 6. Update MSC/VLR if it’s a new Location Area
AUC
MSC/VLR HLR
7. SGSN tells MS about new TLLI
BSC
SGSN
(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 and the new SGSN asks the MS about the IMSI 31 January 2008
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PDP Context PDP: Packet Data Protocol It is the connection between the MS and the GGSN Typically it is a IP-connection PDP address = IP address APN: Access Point Name = Internet Domain Name – GGSN translate that to an IP address NSAPI: Network Service Access Point ID TID = IMSI + NSAPI 31 January 2008
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QoS Precedence / Priority o High, Medium or Low
Reliability Delay Throughput o Mean o Peak
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What does EDGE require?
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