Post on 22-Feb-2015
Uke Kurniawan Usman - 20051
GSM Fundamental
By
Uke Kurniawan Usman
Uke Kurniawan Usman - 20052
Agenda
Network Architecture Functional Layer of GSM Air Interface System Capacity Anti Interference Technology Network Planning Numbering arrangement
Uke Kurniawan Usman - 20053
MSC/VLR
HLR/AUC EIR SC/VM
OMC
BSC
BTSPSTNISDN
PSPDN
MS
BSS
MSS
Um
Abis
BIEA
F
C
H
MSC/VLR
E
GSM Network Structure
Uke Kurniawan Usman - 20054
Equipment used by mobile service subscribers for access to services.
Mobile Station ( MS )
Mobile EquipmentSubscriber Identity Module (SIM)
Mobile stations are not fixed to one subscriber. A subscriber is identified with the SIM card.
Uke Kurniawan Usman - 20055
Base Transceiver Station (BTS)
Wireless transmissionWireless diversityWireless channel encryptionConversion between wired and wireless signalsFrequency Hopping
BaseBand Unit: voice and data speed adapting and channel codingRF Unit: modulating/demodulating, transmitter and receiverCommon Control Unit: BTS operation and maintenance
GSM Network Entity Base Transceiver Station
( BTS )
Uke Kurniawan Usman - 20056
Managing Wireless network-BSSMonitoring BTS
Controls:Wireless link distribution between MS and BTSCommunication connection and disconnectionMS location, handover and pagingVoice encoding, transecoding (TC), rate,
adaptation, The operation and maintenance functions of BSS.
Base Station Controller( BSC )
GSM Network Entity
Uke Kurniawan Usman - 20057
holds all the switching functions
manages the necessary radio resources,
updating the location registration
carrying out the inter-BSC and inter-MSC tender
Inter-working with other networks (IWF).
GSM Network Entity
Mobile Service Switching Center( MSC )
Uke Kurniawan Usman - 20058
Manages the mobile subscribers database
subscriber information
part of the mobile location information
3 identities essentialthe International Mobile subscriber Identity
the Mobile station ISDN Numberthe VLR address
GSM Network Entity
Home Location Register( HLR )
Uke Kurniawan Usman - 20059
Visitor Location Register( VLR )
dynamically stores subscriber information needed to handle incoming/outgoing calls Mobile Station Roaming Number When a roaming mobile enters an MSC area. This MSC warns the associated VLR of this situation; the mobile enters a registration procedure through which it is assigned a mobile subscriber roaming number (MSRN)
Temporary Mobile Subscriber Identity, if applicableThe location area in which the mobile has been registeredData related to supplementary service parameters
GSM Network Entity
Uke Kurniawan Usman - 200510
AUC/EIR
Authentication Center(s) (AUC)
Providing the authentication key used for authorizing the subscriber access to the associated GSM PLMN.
Equipment Identity Register(s) (EIR)
Handling Mobile Station Equipment Identity
GSM Network Entity
Uke Kurniawan Usman - 200511
Agenda
Network Architecture Functional Layer of GSM Air Interface System Capacity Anti Interference Technology Network Planning Numbering arrangement
Uke Kurniawan Usman - 200512
O AM
S ervice carrie r
CM
MM
RR
Subsc riber
Tran smissi on
Overview: Function Layers of GSM-1
Uke Kurniawan Usman - 200513
CM
MM
RR
LAPDm
MS
RR
LAP Dm
Um
LAPD
BTSM
LAPD
Abis
RR
BTSM SCCP
MTP3
BS SAP
BTS BSC
MTP2
SCCP
MTP3
BS SAP
MTP2
CM
MM
MSC
A
Protocol Stack Structure of GSM
Uke Kurniawan Usman - 200514
Agenda
Network ArchitectureFunctional Layer of GSMAir InterfaceSystem CapacityAnti Interference TechnologyNetwork Planning Numbering arrangement
Uke Kurniawan Usman - 200515
Concept: channel is composed of a
series of timeslots of periodicity. Different signal energies are distributed into different timeslots. The adjacent channel interference is restricted by connection choosing from time to time. So the useful signal is passed only in the specified timeslot.
GSM adopts TDMA/FDMA mode channel width: 200KHz each channel has 8 timeslots
GSM adopts TDMA/FDMA mode channel width: 200KHz each channel has 8 timeslots
User 1
User 2
User 3
Frequency
time
TDMA
Uke Kurniawan Usman - 200516
GSM Timeslot and Frame structure
time
Frequency
BP15/26ms
200KHz
interval
Uke Kurniawan Usman - 200517
Frequency Resource
GSM900 :
up: 890~915MHz
down: 935~960MHz
duplex interval: 45MHz
bandwidth: 25MHz ,frequency interval: 200KHz
GSM1800 :up: 1710-1785MHz down: 1805-1880MHzduplex interval: 95MHz , working bandwidth: 75MHz ,frequency interval: 200KHz
EGSM900 :
up: 880~890MHz
down: 925~935MHz
duplex interval: 45MHz
bandwidth: 10MHz ,frequency interval: 200KHz
GSM1900MHz:up:1850~1910MHzdown:1930~1990MHzduplex interval: 80MHz , working bandwidth: 60MHz ,frequency interval: 200KHz
Uke Kurniawan Usman - 200518
1800MHz
1900MHz
900MHzWhich one?
Single Band Network General Priority
High
Low
Reason
For SubscriberFor Operator
Propagation Characteristic
New Operator
Frequency Resource
Uke Kurniawan Usman - 200519
1800MHz
1900MHz
900MHz
Single Band Network
Single Band
Dual Band
Triple Band
In a sense, the network determines the handsets can be selected.But nowadays, most handsets support dual band.
Frequency Resource
Uke Kurniawan Usman - 200520
Propagation characteristic
Cell coverage radius :
The higher the propagation frequency
The higher the propagation loss
The smaller the cell coverage radius.
900MHz
1800MHz
1900MHz
Single Band Network
Frequency Resource
We know
Uke Kurniawan Usman - 200521
0 2045 2046 2047321 2044
3210 4947 48 50
0 24 251
1 super high frame = 2048 super frame = 2715648 TDMA frame
1 super frame = 1326 TDMA frame ( 6.12s )
0 1 2524 504910
1 multiplex frame = 26 TDMA frames ( 120ms )1 multiplex frame = 51 TDMA frame
0 1 765432
1 TDMA frame = 8 timeslot ( 120/26 = 4.615ms )
BCCHCCCHSDCHSACCH/TCH
FACCH
Timeslot and Frame structure
Uke Kurniawan Usman - 200522
0 1 765432
8 9 151413121110
16 17 232221201918
The physical channel adopts FDMA and TDMA techs.On the time domain, a specified channel occupies the same timeslots in each TDMA frame, so it can be identified by the timeslot number and frame number.
Physical Channel
Uke Kurniawan Usman - 200523
channel
TCH
CCH
Voice CH
Data CH
FR Voice Traffic Channel (TCH/FS)
HR Traffic Channel (TCH/HS)
4.8Kbit/s HR TCH (TCH/H4.8)
9.6Kbit/s FR TCH(TCH/F9.6)
4.8Kbit/s FR TCH (TCH/F4.8)
BCH
FCCH (down)SCH (down)BCCH (down)
CCCHRACH (up)AGCH (down)
PCH (down)
DCCHSDCCHFACCHSACCH
14.4Kbit/s FR TCH (TCH/F14.4)
Enhanced FR Traffic Channel (TCH/EFR)
Channel Type-Summary
Uke Kurniawan Usman - 200524
Channel Type
Traffic ChannelTransmit voice and data
Signaling Channeltransmit the signaling and synchronous data between BTS and MS.
Uke Kurniawan Usman - 200525
Channel Type
BCH :
Frequency Correction CHannel ( FCCH)-- for MS error correction
Synchronous Channel ( SCH)
-- for MS frame synchronization and BTS recognization
Broadcasting Control CHannel ( BCCH)-- broadcasting information(cell selection information, etc..)
Uke Kurniawan Usman - 200526
Channel Type
DCCH
Self-help Dedicated Control Channel ( SDCCH )for channel distribution information transmission
Slow Associated Control Channel ( SACCH )combined with one traffic channel or SDCCH, to transmit some specific information of user information
Fast Associated Control Channel ( FACCH )combined with one traffic channel, taking the same signal as SDCCH. It occupies the service channel to transmit signaling information.
Uke Kurniawan Usman - 200527
Structure of 51-frame Control CH
SF B C
R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R
51 Frame
SF C C SF C C SF C C I
R R R R R R R R R R
D0 D1 D2 D3 D4 D5 D6 D7 A0 A1 A2 A3
SF C C
R R R R R R R R R R
III
D0 D1 D2 D3 D4 D5 D6 D7 A4 A5 A6 A7 III
A1 A2 A3 III
A5 A6 A7 III
D0 D1 D2 D3 D4 D5 D6 D7 A0
D0 D1 D2 D3 D4 D5 D6 D7 A4
SF B C SF C C SF D0 D1 SF D2 D3 ISF A0 A1
SF B C SF C C SF D0 D1 SF D2 D3 ISF A2 A3
D3
D3
R R
R R
A2 A3
A0 A1
D2
D2
SF
SF
D0 D1
D0 D1
R R R R R R R R R R R R R R R R R R R R R R R
R R R R R R R R R R R R R R R R R R R R R R R
F:FCCH S:SCHB:BCCH C:CCCH(CCCH=PCH+AGCH+RACH)R:RACH D:SDCCHA:SACCH/C I: idle
BCCH+CCCH(Downlink)
BCCH+CCCH(uplink)
8 SDCCH/8(Downlink)
8 SDCCH/8(uplink)
BCCH+CCCH+4SDCCH/4(Downlink)
BCCH+CCCH+4SDCCH/4
(uplink)
(a) FCCH+SCH+BCCH+CCCH
(b) SDCCH/8(0,...,7)+SACCH/C8(0,...,7)
(c) FCCH+SCH+CCCH+SDCCH/4(0,...,3)+SACCH/C4(0,...,3)
Uke Kurniawan Usman - 200528
Channel Combination Type
Several logic channels combine together in some way to form some specific types of channel to transmit user data or signaling information. They are called combined channels. One combined channel can be mapped to a physical channel.
There are the following combined channels:a TCH/F + FACCH/F + SACCH/TFb TCH/H(0,1) + FACCH/H(0,1) + SACCH/TH(0,1)c TCH/H(0,0) + FACCH/H(0,1) + SACCH/TH(0,1) + TCH/H(1,1)d FCCH + SCH + BCCH + CCCHe FCCH + SCH + BCCH + CCCH + SDCCH/4(0...3) +
SACCH/C4(0...3)f BCCH + CCCHg SDCCH/8(0 ..7) + SACCH/C8(0 .. 7)
CCCH = PCH + RACH + AGCH
Uke Kurniawan Usman - 200529
Small capacity cell with only 1 TRX
TN0: FCCH+SCH+CCCH+BCCH+SDCCH/4(0,_,3)+SACCH/C4(0,_,3);TN1-7: TCH/F+FACCH/F+SACCH/TF
The medium-size cell with 4 TRXs1TN0 group: FCCH+SCH+BCCH+CCCH;
2 SDCCH/8(0,_,7)+SACCH/C8(0,_,7);29 TCH/F+FACCH/F+SACCH/TF
Channel Assignment inside cells
Uke Kurniawan Usman - 200530
Large-size cell with 12 TRXs1 TN0 group: FCCH+SCH+BCCH+CCCH;1 TN2 group, 1 TN4 group and 1 TN6 group: BCCH+CCCH;5 SDCCH/8(0,_,7)+SACCH/C8(0,_,7);87 TCH/F+FACCH/F+SACCH/TF
Channel Assignment inside cells
Uke Kurniawan Usman - 200531
Agenda
Network ArchitectureFunctional Layer of GSMAir InterfaceSystem CapacityAnti Interference TechnologyNetwork Planning Numbering arrangement
Uke Kurniawan Usman - 200532
Cell Mode Layout
O
Omni-directional cell
Adopt omni-directional antenna ,the overall directional propagation characteristic is the same.
Directional cell
In general, cell with multi-sector is in common use. Every directional cell adopts directional antenna.
Uke Kurniawan Usman - 200533
Capacity
When the traffic is very low, and no possibility for quick increment, Omni-directional cell is used in common. Otherwise, we suggest to adopt the sector cell.
Note: TRX-transceiver,each TRX handles 1 frequency.
Coverage AreaSector cell is often used to enlarge the cell coverage radius because of the higher antenna gain.For special coverage ,such as road coverage, two-sector cell is adopted firstly.
BTS Mode
Uke Kurniawan Usman - 200534
Erlang :
the traffic intensity of a totally occupied channel (i.e. the call hour of a unit hour or the call minute of a unit minute). For example, the traffic of a channel occupied for 30 minutes in an hour is 0.5 Erlang)
GOS:
defined as the probability of call blocking or the probability when the call delay time is longer than a given queuing time.
System capacity
Uke Kurniawan Usman - 200535
Agenda
Network ArchitectureFunctional Layer of GSMAir InterfaceSystem CapacityAnti Interference TechnologyNetwork Planning Numbering arrangement
Uke Kurniawan Usman - 200536
Reasons for Interference
The transmission path is very complex, ranging from the simple line-of-sight transmission to encountering such terrain as buildings, hills and trees. Wireless channels are extremely unpredictable.
Abrupt drop, or fading, of signal strength in the land mobile wireless channel is quite common. The fading feature of the mobile channel depends on the radio wave propagation environment.
Uke Kurniawan Usman - 200537
Reasons for interference
Environmental factors:
• Terrain (mountains, hills, plains, water bodies, etc.);
• The quantity, heights, distribution and materials of buildings;
• The vegetation of the region;
• Weather conditions;
• Natural and artificial electromagnetic noises;
• Frequency;
• How MS is moved.
Uke Kurniawan Usman - 200538
Co-Channel Interference
Conception: the interference among the signals of co-
channel cells is called co-channel interference.
Result from :Frequency reuse
Reduction method:co-channel cells must physically be
spaced at a minimum interval to ensure adequate isolation of transmissions.
Interference
Uke Kurniawan Usman - 200539
Adjacent Channel InterferenceConception:
The signal interference from the frequency adjacent to that of the signal used is called adjacent channel interference.
Reduction method: accurate filtering and channel allocation
(maximizing channel intervals of the cell). Interval of frequency reuse inter-cell interference, such as C/I, C/A
Interference
Uke Kurniawan Usman - 200540
FH technology
Dynamic power control (DPC)
Discontinuous Transceiving
(DTX)
Diversity receiving technique
Solution -Anti-interference
Uke Kurniawan Usman - 200541
Reason: counteract Rayleigh Fading scatter interference among multiple calls
Types: Base band frequency hopping
keeps the transmission and receiving frequency of each carrier unit unchanged, but merely sends FU transmission data to different carrier units at different FN moments.
radio frequency hoppingcontrols the frequency synthesizer of each transceiver, making it hop according to different schemes in different time slots.
Frequency Hopping Technique
Uke Kurniawan Usman - 200542
Discontinuous Speech Transmission (DTX)
TRAU BTS
BTS MS
Speech frame
480 ms
comfort noise frame
Two aims can be achieved by adopting DTX mode:
•lower the total interference electric level in the air
•save transmitter power.
Uke Kurniawan Usman - 200543
The multi-path propagation of radio signals causesmagnitude fading and delay time.
Space Diversity (antenna diversity)
Polarization Diversityorthogonal polarization diversity. horizontal polarization and vertical polarization.
Frequency DiversityThe working principle of this technology is that such fading won’t take place on the frequency outside the coherence bandwidth of the channel.
Diversity Reception Technology
Uke Kurniawan Usman - 200544
Agenda
Network ArchitectureFunctional Layer of GSMAir InterfaceSystem CapacityAnti Interference TechnologyNetwork Planning Numbering arrangement
Uke Kurniawan Usman - 200545
“4 3” reuse mode: one group includes 3 sectors /site ,12 frequency which
are distributed to 4 sites. Every site owns 3 frequency.
Frequency Reuse
A3
D2B1
C3
B2D1
D3
A2C1
B3
C2A1
B3
C2A1
A3
A1B1
D1
D3D2
C3
B2A1
C3D2
C3
C1
D2B1C2A1
A2C1
D3
Uke Kurniawan Usman - 200546
A3
C2B1
B3
A2C1
C3
B2A1
A3
C2B1
B3
A2C1
B3
A1C1
A1
A3A2
C3
B2A1
A3A3
C3
C1
B2A1B2A1
A2C1
B3
Frequency Reuse
“3 3” reuse mode: one group includes 3 sectors /site ,9 frequency which are
distributed to 3 sites. Every site owns 3 frequency.
Uke Kurniawan Usman - 200547
Agenda
Network ArchitectureFunctional Layer of GSMAir InterfaceSystem CapacityAnti Interference TechnologyNetwork Planning Numbering arrangement
Uke Kurniawan Usman - 200548
Numbering Arrangement
International Mobile Subscriber Identification number (IMSI)
International Mobile Subscriber Identification number (IMSI)
It identifies a unique international universal number of a mobile subscriber, which consists of MCC+MNC+MSIN.1) MCC: country code, 4602 ) MNC: network code, 00 or 013 ) MSIN: subscriber identification, H1H2H3H4 9XXXXXX, H1H2H3H4: subscriber registering place H1H2: assigned by the P&T Administrative Bureau (operator )to different provinces, to each province H3H4: assigned by each province/city
the IMSI of user will be written into the SIM card by specific device and software and be stored into the HLR with other user information.
Uke Kurniawan Usman - 200549
It is the subscriber number commonly used. China uses the TDMA independent numbering plan:
CC+NDC+ H1H2H3H4 +ABC
CC: country code, 86NDC: network code, 135—139, 130H1H2H3H4: HLR identification code ABCD: mobile subscriber number inside each HLR
Mobile Subscriber ISDN Number ( MSISDN)Mobile Subscriber ISDN Number ( MSISDN)
Numbering Arrangement
Uke Kurniawan Usman - 200550
International Mobile Equipment Identification code(IMEI)
International Mobile Equipment Identification code(IMEI)
It will uniquely identify a mobile station. It is a decimal number of 15 digits. Its structure is:
TAC+FAC+SNR+SP
TAC=model ratification code, 6 digitsFAC=factory assembling code, 2 digitsSNR=sequence code, 6 digitsSP=reserved, 1 digit
Numbering Arrangement
Uke Kurniawan Usman - 200551
Mobile Subscriber Roaming Number (MSRN)
Mobile Subscriber Roaming Number (MSRN)
The MSRN is temporarily distributed to the subscriber by the VLR according to the request by the HLR when this subscriber is called. The MSRN is released and can be assigned to other subscriber later.
CC + NDC + 00 + M1M2M3 + ABC CC: country code, 86 NDC: mobile network code, 135—139, 130 M1M2: same as the H2H3 of MSISDN ABC: 000 -- 999
Numbering Arrangement
Uke Kurniawan Usman - 200552
Temporarily Mobile Subscriber Identification Number (TMSI)
Temporarily Mobile Subscriber Identification Number (TMSI)
To insure the IMSI security, the VLR will assign an unique TMSI number for the accessed subscriber. It is used locally only and is a 4-byte TMSI number BCD code.
Numbering Arrangement