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GSM Network - from an Operators View
SWINOG Meeting 10th of April 2003, Bern
[email protected] Mobile AG, Engineering&Operations
Thema: Menü Ansicht, Master, Folien-Master
2Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Agenda
History
Network Architecture
Traffic Cases
Transmission Process and Air Interface
Cell Planning
The Operators Challenge
Network Evolution
Thema: Menü Ansicht, Master, Folien-Master
3Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
History
Early 1800: Theory of Inductance (Faraday, Henry)
1906: Transmission of human voice over radio (Reginald Fessenden)
1935: Invention of frequency modulation (FM)
1947: Cellular Concept (D.H. Ring, Bell Labs)
1969: Standardization of the Nordic Mobile Telephone system
1981: First cellular system launched (NMT450; Ericsson)
1991: GSM standard launched
1993: Start of GSM rollout in Switzerland (Natel D)
2003: GSM networks have similar importance as fixed PSTN’s
Thema: Menü Ansicht, Master, Folien-Master
4Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Fessenden’s Radio Tower (1906) vs. GSM Base Station (2003)
Thema: Menü Ansicht, Master, Folien-Master
5Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Network Architecture
Thema: Menü Ansicht, Master, Folien-Master
6Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
GSM / GPRS Network
GMSCGMSC
GGSNGGSN
HLRHLR
EIREIR
AUCAUC
SCFSCF
SMS-IWMSC
SMS-IWMSC
CN ExternalNetworks
D
Gd,Gp,Gn+
SGSNSGSN
MSCMSC
E,G
SMS-GMSC
SMS-GMSC
SGSNSGSN
MSCMSC
Gb
SMS-SC
ISDNPSTNPSPDNCSPDNPDN:-Intranet-Extranet-Internet
Iu
ANUE
BSCBTSUmSIMSIM MTMT Abis A
BSS
Note:Not all interfaces are shown and named
F
Gf
Gr
Gn+
H
Thema: Menü Ansicht, Master, Folien-Master
7Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
HLR / AUC: Subscribers
HLRHLR AUCAUC
Thema: Menü Ansicht, Master, Folien-Master
8Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
GMSCGMSC
HLRHLR
EIREIR
AUCAUC
SCFSCF
SMS-IWMSC
SMS-IWMSC
CN ExternalNetworks
MSCMSC
SMS-GMSC
SMS-GMSC
MSCMSC
SMS-SC
ISDNPSTN
MSC/VLR, Core Network
Thema: Menü Ansicht, Master, Folien-Master
9Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Base Station SystemANUE
BSCBTSUmSIMSIM MTMT Abis
BSS GMSCGMSC
HLRHLR
EIREIR
AUCAUC
SCFSCF
SMS-IWMSC
SMS-IWMSC
CN ExternalNetworks
MSCMSC
SMS-GMSC
SMS-GMSC
MSCMSC
SMS-SC
ISDNPSTN
Thema: Menü Ansicht, Master, Folien-Master
10Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
GPRS in addition
GMSCGMSC
GGSNGGSN
HLRHLR
EIREIR
AUCAUC
SCFSCF
SMS-IWMSC
SMS-IWMSC
CN ExternalNetworks
D
Gd,Gp,Gn+
SGSNSGSN
MSCMSC
E,G
SMS-GMSC
SMS-GMSC
SGSNSGSN
MSCMSC
Gb
SMS-SC
ISDNPSTNPSPDNCSPDNPDN:-Intranet-Extranet-Internet
Iu
ANUE
BSCBTSUmSIMSIM MTMT Abis A
BSS
Note:Not all interfaces are shown and named
F
Gf
Gr
Gn+
H
Thema: Menü Ansicht, Master, Folien-Master
11Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Good Coverage requires high number of Sites and Cells
Area Coverage 83%Population Coverage 99,5%Area Coverage 83%Population Coverage 99,5%
Thema: Menü Ansicht, Master, Folien-Master
12Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Train Coverage (Intrain Repeater)
Following coaches are or will beequipped: ICN 2000, IC2000, EW 4
Thema: Menü Ansicht, Master, Folien-Master
13Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
MS - Hardware (User Equipment)
Mandatory Display of called
number DTMF tones Indication of call
progress PLMN indication /
selection IMSI / IMEI Algorithms SMS handling Emergency calls
Optional Keypad Key + Datacom
interface ...
Additional Last numbers list Voice dialling ...
Thema: Menü Ansicht, Master, Folien-Master
14Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Security Features (Authentication, Ciphering)
Forbidden PLMN BCCH Information (Neighbor Frequencies)
IMSI (International Mobile Subscriber Identity)
LAI (Location Area Identity)
PIN (Personal Identification Number)
PUK Personal Phonebook SIM Service Table (Optional Services)
SIM CARD
SIM Card - The Subscriber
Thema: Menü Ansicht, Master, Folien-Master
15Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Traffic Cases
Thema: Menü Ansicht, Master, Folien-Master
16Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Key Terms
Idle Mode
Active Mode
Detached
Roaming
Handover
Registration (Location Update)
Paging
Idle Mode
Active Mode
Detached
Roaming
Handover
Registration (Location Update)
Paging
Thema: Menü Ansicht, Master, Folien-Master
17Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Location Updating
9805057
BSC/TRC MSC
4.
3.
2.
1.2.
3.
4.
HLR
VLR
1-new LAI detected by MS 2-Authentication 3-LA update request to VLR4-VLR stores LAI & sends LA update acknowledge to MS
“Keep the network informed on the actual location of each MS”
Thema: Menü Ansicht, Master, Folien-Master
18Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
9600877
Evaluationand decision
about handover
Measurements from RBS and MS
RBS measures:Signal strength andtransmission qualityon TCH, uplink
MS measures:Signal strength andtransmission qualityon TCH, downlink
Signal strengthfrom neighboringBTS
Measurementreports from MSare sent to RBS
BSC/TRC
MSC/TRC
Measurements sent to BSC
“Keep in touch with the network”
Thema: Menü Ansicht, Master, Folien-Master
19Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
9600878
old
new
BSC
2.
6.
1.
5.
3.
4.
5.
2.
Handover: Cells controlled by the same BSC
1-BSC activates call channel in new BTS
2-BSC informs MS on new freq via old BTS
3-MS sends handshake on new frequency
4-New BTS answers
5-MS sends HO complete via new BTS
6-Old BTS is released
“Do not drop the call when moving”
Thema: Menü Ansicht, Master, Folien-Master
20Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
PSTN/PSTN/ISDNISDN
BTSBTS
BTSBTS
BTSBTS
MSCMSC
HLHLRR
VLVLRRBSCBSC
BSCBSC
PSTN/PSTN/ISDNISDN
BTSBTS
BTSBTS
BTSBTS
MSCMSC
HLHLRR
VLVLRRBSCBSC
BSCBSC
1. Status of the mobile is stored in the HLR of the home network 2. If switched on in a foreign country it searches for an allowed GSM network3. The foreign VLR asks for a copy of the subscription info in the HLR of the home network4. The VLR registers the CH mobile as a visitor and updates the status of the mobile to idle The data is stored temporarely in the foreign VLR 5. In case of a PSTN call (CH) the foreign VLR checks the status of the CH mobile6. If the mobile is switched on, the PSTN call is routed to the foreign GSM network
International Call
Thema: Menü Ansicht, Master, Folien-Master
21Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Transmission Process and Air Interface
Thema: Menü Ansicht, Master, Folien-Master
22Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Transmission ProcessBSC SPP RRX
ReceiverDemodulator
ReceiverDemodulator
270 kBit/s, for 8TS
ViterbiEqualizer
ViterbiEqualizer
DeCiphering
DeCiphering
De interleaving
De interleaving
ViterbiDecoder
ViterbiDecoder
SpeechDecoder
SpeechDecoder
A/D SpeechCoding
SpeechCoding
Segmentation
Segmentation
160 Sample20 ms
8 kHz,13 Bit104 kbit/s
ChannelCoding
ChannelCoding
50 Hz, 260 Bits 13 kBit/s
Interleaving
Interleaving
50 Hz, 456 Bits22,8 kBit/s
CipheringCiphering BurstFormatting
BurstFormatting
ModulatorTransmitter
ModulatorTransmitter
33,8 kBit/s, for 1TS
Mobile Station
Thema: Menü Ansicht, Master, Folien-Master
23Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
GSM FrequenciesExample: 900MHz Band
• Separate bands for transmit and receive direction (duplex spacing)• 124 carriers with 8 TDMA channels each• Neighbor channel spacing is 200 kHz• Time separation of transmission and reception signal allows for
simpler RF front end in the mobile station (TDMA)• Frequency resources must be shared between the national
operators
Duplex spacing
Thema: Menü Ansicht, Master, Folien-Master
24Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Multiple Access Methods
FDMA TDMA W-CDMA
Frequency
Time
Power
Frequency
Time
Power
Frequency
Time
Power
GSM is a combination of FDMA and TDMA
1 user per freq several users per freq all users per freq
Thema: Menü Ansicht, Master, Folien-Master
25Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Packing Voice Calls into Time Slots
Frequency
Time
Power
Cal
l 1 Cal
l 3 Cal
l 1
Cal
l 2
Cal
l 1
Frequency
Time
Power
Cal
l 1 Cal
l 3 Cal
l 1
Cal
l 2
Frequency
Time
Power
Cal
l 1 Cal
l 3 Cal
l 1
Cal
l 2
Carrier 1 Carrier 2 Carrier 3
Thema: Menü Ansicht, Master, Folien-Master
26Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Time Slot and Bit Rate
•Timeslot = window in time in which a portion of bits are transported over the air interface from the transmitter to the receiver
•The length of the time slot (577s) allows to send approximately 160 bits, this is called a „Burst“
•1 bit length is 3.7s
•During a connection the burst is repeated 217x per second
•Based on the modulation type of GSM a gross bit rate of 271 kbps per carrier is achieved
Thema: Menü Ansicht, Master, Folien-Master
27Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
TDMA Frame
Carrier with 8 Time Slots,8 Physical Channels
0 1 2 3 4 5 6 7
0 1 2 3 4 5 6 7Uplink
Downlink
915 MHz
960 MHz
4.615 mS0.577 mS
Thema: Menü Ansicht, Master, Folien-Master
28Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Close to BTS
BTS
TDMA-frame
Far away from BTS
The Time Alignment Problem
TS6
TS7
TS7TS6TS5
•1 bit travels 1 km within 1 bit period (radio wave propagation)
•Far away user must send earlier to compensate for the higher time delay
Thema: Menü Ansicht, Master, Folien-Master
29Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Shadowing
Thema: Menü Ansicht, Master, Folien-Master
30Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Rayleigh Fading
Thema: Menü Ansicht, Master, Folien-Master
31Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Frequency selective Quality Degradation due toRayleigh Fading
Thema: Menü Ansicht, Master, Folien-Master
32Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
The Antenna: A crucial Element for Radio Coverage and Performance
Thema: Menü Ansicht, Master, Folien-Master
33Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Example: Repeater Intrain Air Interface
Radiating Cable
Thema: Menü Ansicht, Master, Folien-Master
34Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Example: Intrain Repeater Air Interface
Antenna to/from intrain repeater
Thema: Menü Ansicht, Master, Folien-Master
35Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Cell Planning
Thema: Menü Ansicht, Master, Folien-Master
36Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
The Cellular Principle
Why do we use cells?
•Traffic capacity
•Limited frequency resources (re-use)
•NIS electromagnetic radiation limitations
•User location
Thema: Menü Ansicht, Master, Folien-Master
37Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Cell Planning; Theoretical Cell PatternExample: 4/12 = 4 three-sector sites supporting 12 cellsB2B3
C1
C2C3
B1
B2B3
C1
C2C3
B1
B2B3
C1
C2C3
A1
A2A3
D3
D2D1
A1
A2A3
D3
D2D1
A1
A2A3
D3
C2C3
B1
B2B3
C1
C2C3
B1
B2B3
C1
C2C3
B1
B2B3
D3
D2D1
A1
A2A3
D3
D2D1
A1
A2A3
D3
D2D1
A1
B2B3
C1
C2C3
B1
B2B3
C1
C2C3
B1
B2B3
C1
C2C3
A1
A2A3
D3
D2D1
A1
A2A3
D3
D2D1
A1
A2A3
D3
Thema: Menü Ansicht, Master, Folien-Master
38Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Cell Planning: Real Cell Boarders
Thema: Menü Ansicht, Master, Folien-Master
39Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
The Operators Challenge
Thema: Menü Ansicht, Master, Folien-Master
40Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
The Operators Challenge; some Issues
•Customer Needs
•Service Creation
•Billing
•Interoperability (e.g. International Roaming)
•Public Relations (e.g. NIS)
•Technical Operations
Thema: Menü Ansicht, Master, Folien-Master
41Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Traffic: Week- and Daytime, but also Event dependant
Thema: Menü Ansicht, Master, Folien-Master
42Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Hot Spots Load/Overload according to Workday
Workday Sunday
Thema: Menü Ansicht, Master, Folien-Master
43Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Verify where the Traffic takes place
Thema: Menü Ansicht, Master, Folien-Master
44Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Managing the Mobility: Neighbor Relations
Thema: Menü Ansicht, Master, Folien-Master
45Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Operator Benchmarking: Focus on the relevant Issues
Thema: Menü Ansicht, Master, Folien-Master
46Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Example: Inbound Roaming
Thema: Menü Ansicht, Master, Folien-Master
47Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Building Permissions
Thema: Menü Ansicht, Master, Folien-Master
48Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Network Environment
Radiation Measurements
Calculation and preparation of NIS data for local authorities
Negotiations with all involved parties
Thema: Menü Ansicht, Master, Folien-Master
49Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Network Evolution
Thema: Menü Ansicht, Master, Folien-Master
50Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Evolution towards 3G
GMSCGMSC
GGSNGGSN
HLRHLR
EIREIR
AUCAUC
SCFSCF
SMS-IWMSC
SMS-IWMSC
CN ExternalNetworks
D
Iu
Gd,Gp,Gn+
SGSNSGSN
MSCMSC
E,G
SMS-GMSC
SMS-GMSC
SGSNSGSN
MSCMSC
Gb
SMS-SC
ISDNPSTNPSPDNCSPDNPDN:-Intranet-Extranet-Internet
Iu
ANUE
BSCBTSUmSIMSIM MTMT Abis A
BSS
RNCBSUu
Iur
USIMUSIM MEME
RNCBSUuUSIMUSIM MEME
Iub
Iub
Cu
Cu
RNS
RNS
UTRAN
Note:Not all interfaces are shown and named
F
Gf
Gr
Gn+
H
Thema: Menü Ansicht, Master, Folien-Master
51Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
10 50 100 384 500 1’000 2’000 5’000
GSM CS9.6
UMTS local
Data rate (kbps)
Voice
HSCSD
GPRS
EDGE / EHSCSD
EDGE / EGPRS
UMTS wide area
E-Maildata base access, info services
telebanking, financial services
electronis newspaper, images, sound
teleshopping
video telephony
video conferencing
Mobile Services and Data Rates
Thema: Menü Ansicht, Master, Folien-Master
52Vorname, Name, Dateiname (Menü Ansicht, Kopf-und Fusszeile)tt. MMMM jjjj
Thank you for your attention!