Huawei Confidential. All Rights Reserved
OMA000001GSM Fundamentals
ISSUE 4.0
2 Internal Use
ObjectivesObjectives
Upon completion of this course, you will be
able to:Grasp basic idea of GSM system such as
frequency spectrum, frequency reuse etc.
Grasp the structure of the GSM system and
the protocol used.
Grasp certain numbers that refer to BSS
Grasp the 4 kinds of channel combination
and understand the idea of multi-frame.
Know some radio techniques
Get the idea of EDGE
3 Internal Use
References References
BSS Feature Description
BSS Signaling Analysis Manual
BSC Technical Manual
4 Internal Use
Chapter 1 GSM System Overview
Chapter 2 GSM Network Structure
Chapter 3 Service Area and Number Planning
Chapter 4 Channels on the Wireless Interface
Chapter 5 Radio Techniques
Chapter 6 GPRS & EDGE Introduction
5 Internal Use
GSM system overviewGSM system overview
The GSM system is a frequency- and time-division cellular system, each physical channel is characterized by a carrier frequency and a time slot number
Cellular systems are designed to operate with groups of low-power radios spread out over the geographical service area. Eachgroup of radios serve MSs presently located near them. The area served by each group of radios is called a CELL
Uplink and downlink signals for one user are assigned different frequencies, this kind of technique is called Frequency DivisionDuplex (FDD)
Data for different users is conveyed in time intervals called slots , several slots make up a frame. This kind of technique is called Time Division Multiple Access (TDMA)
6 Internal Use
GSM DevelopmentGSM Development
Standard Protocol for GSM take effect
System was named as Global System for Mobile Communication
GSM system began to provide service in Europe(2G)
Provide services for the whole world
Micro Cell Technique is used in GSM system
1989
1991
1992
1994
1996
7 Internal Use
Cell TechniqueCell Technique
A certain radio coverage area formed by a set of transceivers that
connected to a set of antennas is called a CELL.
Macro Cell
In the beginning , High-Power BTSs are adopted to provide services.
The BTS covers a wider area , but its frequency utilization is not efficient.
So , it can only provide a few channels for subscribers.
Micro Cell
Later the Low-Power BTS joins the system for getting a better service
area with high capacity . At the same time it adopts the frequency reuse
technique to improve the efficiency of the frequency utilization and also
the whole capacity of the network.
Macro Cell and Micro Cell
8 Internal Use
Multiple Access TechniqueMultiple Access Technique
Multiple Access Technique allows many
subscribers to use the same communication
medium.
There are three kinds of basic Multiple Access
Technique : FDMA , TDMA and CDMA.
GSM system adopt FDD-TDMA (FDMA and
TDMA together).
9 Internal Use
FDMAFDMA
FDMA uses different frequency
channels to accomplish
communication.
The whole frequency spectrum
available is divided into many
individual channels (for transmitting
and receiving),every channel can
support the traffic for one subscriber
or some control information.
Frequency
Time
10 Internal Use
TDMATDMA
TDMA accomplishes the
communication in different
timeslot.
A carrier is divided into channels
based on time. Different signals
occupy different timeslots in
certain sequence , that is , many
signals are transmitted on the
same frequency in different time.Time
Frequency
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CDMACDMA
CDMA accomplishes the
communication in different code
sequences.
Special coding is adopted before
transmission, then different
information will lose nothing after
being mixed and transmitted
together on the same frequency
and at the same time.Time
Frequency
12 Internal Use
GSM 900GSM 900
Duplex Separation: 45MHzChannel Bandwidth: 200KHz
The Frequency SpectrumThe Frequency Spectrum
Uplink
890 915 935 960MHz
Downlink
13 Internal Use
Duplex Separation: 95MHzChannel Bandwidth: 200KHz
Base Station Receive
1710 1785 1805 1880MHz
Base Station Transmit
DCS 1800DCS 1800
The Frequency SpectrumThe Frequency Spectrum
14 Internal Use
The Frequency SpectrumThe Frequency Spectrum
Fd(n)=Fu(n)+10259<=n<=293Fu(n)=450.6+0.2(n-259)450.4~457.6460.4~467.6
GSM 450
Fd(n)=Fu(n)+10306<=n<=340Fu(n)=479+0.2(n-306)478.8~486488.8~496
GSM 480
Fd(n)=Fu(n)+45128<=n<=251Fu(n)=824.2+0.2(n-128)824~849869~894
GSM 850
Fd(n)=Fu(n)+80512<=n<=810Fu(n)=1850.2+0.2(n-512)1850~19101930~1990
PCS 1900
Fd(n)=Fu(n)+450<=n<=124
955<=n<=1023Fu(n)=890+0.2n
Fu(n)=890+0.2(n-1024)876~915921~960
R-GSM 900
Fd(n)=Fu(n)+450<=n<=124
975<=n<=1023Fu(n)=890+0.2n
Fu(n)=890+0.2(n-1024)880~915 925~960E-GSM 900
Downlink Frequency
Frequency Point Available
Uplink FrequencyRange (MHz)Frequency Spectrum
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Frequency ReuseFrequency Reuse
The frequency resource of mobile system is very
limited.
The different Subscribers can use the same
frequency in different places.
The quality of communication must be ensured.
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Frequency ReuseFrequency Reuse
7(Site)X 1(Cell) reuse
2
1
2
3
4
5
6
7
17 Internal Use
4 site X 3 cells reuse
1
8
9
210
46
5 3 7
11
12
R
Frequency ReuseFrequency Reuse
18 Internal Use
Cell TypesCell Types
Omni
1
120degree
12
3
Omni-directional CellOmni-directional Cell
120 Degree Cell120 Degree Cell
19 Internal Use
Chapter 1 GSM System Overview
Chapter 2 GSM Network Structure
Chapter 3 Service Area and Number Planning
Chapter 4 Channels on the Wireless Interface
Chapter 5 Radio Techniques
Chapter 6 GPRS & EDGE Introduction
20 Internal Use
GSMGSM--GPRS Network ComponentGPRS Network Component
GSM /GPRS BSS
BTS
BSC
BTS
BSC
PCU SS7
SMS system
PSTNISDN
Internet,Intranet
MSC/VLR GMSC
HLR/AUC
SGSN
CG BG
GGSN
GPRS Backbone
Other PLMN
MS
MS
OMC
21 Internal Use
Interface Between Different EntitiesInterface Between Different Entities
GSM /GPRS BSS
BTS
BSC
BTS
BSC
PCU SS7
SMS system
PSTNISDN
Internet,Intranet
MSC/VLR GMSC
HLR/AUC
SGSN
CG BG
GGSN
GPRS backbone
Other PLMN
A
Gb
Gi
Gp
C/D/Gs
Gr/Gs/Gd/Ge Gc
Ga
Abis
Um
MS
MS
OMC
22 Internal Use
Mobile StationMobile Station——MSMS
International Mobile Equipment Identity (IMEI)
– Mobile Equipment
MS=ME+SIMMS=ME+SIM
International Mobile Subscriber Identity (IMSI)
– Subscriber Identity Module
23 Internal Use
Subscriber Identity Module Subscriber Identity Module –– SIMSIM
International Mobile Subscriber Identity (IMSI)Temporary Mobile Subscriber Identity (TMSI)Location Area Identity (LAI)Subscriber Authentication Key(Ki)
SIM
24 Internal Use
The Base Station Controller – BSCThe Base Transceiver Station – BTSThe Trans-coder – TC and Sub multiplexer (SM)
BTSBTS
BSCBSC
TC/SMTC/SMBSS
MSC
Base Station Subsystem Base Station Subsystem –– BSSBSS
25 Internal Use
Packet data switchingBridge between SGSN and BSCProvide Pb and Gb interface
BTSBTS
BSCBSC
TC/SMTC/SMBSS
MSC
Packet Control UnitPacket Control Unit----------PCUPCU
GPRS Backbone
PCUPCU SGSNSGSN
26 Internal Use
Mobile-service Switching Center – MSC Home Location Register – HLR Visitor Location Register – VLR Equipment Identity Register – EIR Authentication Center – AUC Echo Cancellor – EC
AUCAUCHLRHLR
MSC/VLRMSC/VLR
PSTN
NSSEIREIROMC
BSS
ECEC
The Network Switching SystemThe Network Switching System
27 Internal Use
MobileMobile--service Switching Center service Switching Center –– MSC MSC
Call ProcessingOperations and Maintenance SupportInterface managementInter-network & Inter-workingBilling
28 Internal Use
Home Location Register Home Location Register –– HLR HLR
Subscriber ID (IMSI and MSISDN)Current subscriber VLR (current location)Supplementary service informationSubscriber status (registered/deregistered)Authentication key and AuC functionality
29 Internal Use
Visitor Location Register Visitor Location Register –– VLR VLR
Mobile Status (IMSI attached / detached /
busy / idle etc.)
Location Area Identity(LAI)
Temporary Mobile Subscriber Identity(TMSI)
Allocating the Roaming Number
30 Internal Use
IMEI is Checked In White List
IMEI is Checked in Black/Grey List
If NOT found
EIR focus on the equipment , not the subscriber!!
•White List•Black List•Grey List
Equipment Identity Register Equipment Identity Register –– EIR EIR
31 Internal Use
OMC Functional ArchitectureOMC Functional Architecture
OS
MMIDB
Event/AlarmManagement
SecurityManagement
ConfigurationManagement
Performance Management
Fault Management
32 Internal Use
Chapter 1 GSM System Overview
Chapter 2 GSM Network Structure
Chapter 3 Service Area and Number Planning
Chapter 4 Channels on the Wireless Interface
Chapter 5 Radio Techniques
Chapter 6 GPRS & EDGE Introduction
33 Internal Use
Service AreaService Area
PLMN service area
......
Service Area
MSC service area...
Location area...
cell
PLMN service area PLMN service areaMSC service area...
Location area...
cell
34 Internal Use
LAILAI
Location Area Identification
The LAI is the international code for a location area.
MCC: Mobile Country Code,It consists of 3 digits .For example: The MCC of China is "460"
MNC: Mobile Network Code,It consists of 2 digits .For example: The MNC of China Mobile is "00"
LAC: Location Area Code,It is a two bytes hex code.The value 0000 and FFFF is invalid.
For example: 460-00-0011
MCC MNC LAC
35 Internal Use
CGICGI
The CGI is a unique international identification for a cellThe format is LAI+CILAI: Location Area IdentificationCI: Cell Identity. This code uses two bytes hex code to
identify the cells within an LAI.For example : 460-00-0011-0001
CGI: Cell Global Identification
36 Internal Use
BSICBSIC
NCC: PLMN network color code. It comprises 3 bit. It allows various neighboring PLMNs to be distinguished.
BCC: BTS color code. It comprises 3 bit, used to distinguish different cells assigned the same frequency!
NCC BCC
BSIC
BSIC(Base Station Identification Color Code)
37 Internal Use
CC: Country Code. For example: The CC of China is "86".NDC: National Destination Code. For example: The NDC of
China Telecom is 139, 138, 137, 136, 135.SN: Subscriber Number. Format:H0 H1 H2 H3 ABCDExample: 86-139-0666-1234
MSISDNMSISDN
CC NDC SNNational (significant)
Mobile number
Mobile station internationalISDN number
38 Internal Use
MCC: Mobile Country Code,It consists of 3 digits .For example: The MCC of China is "460"。
MNC: Mobile Network Code,It consists of 2 digits .For example: The MNC of China Telecom is "00"。
MSIN: Mobile Subscriber Identification Number. H1H2H3 S ABCDEFFor example: 666-9777001
NMSI: National Mobile Subscriber Identification,MNC and MSIN form it together.
For Example of IMSI : 460-00-666-9777001
Not more than 15 digits
3 digits 2 digits
IMSI
MCC MNC MSINNMSI
IMSI IMSI
39 Internal Use
The TMSI is assigned only after successful subscriber authentication. The VLR controls the allocation of new TMSI numbers and notifies them to the HLR.TMSI is used to ensure that the identity of the mobile subscriber on the air interface is kept secret.The TMSI consists of 4 bytes( 8 HEX numbers) and determined by the operator.
TMSITMSI
TMSI: Temporary Mobile Subscriber Identification)
40 Internal Use
IMEIIMEI
TAC FAC SNR SP
IMEI
IMEI: International Mobile Station Equipment Identification
TAC: Type approval code, 6 bit, determined by the type approval centerFAC: Final assembly code, 2 bit, It is determined by the manufacturer.SNR: Serial number, 6 bits, It is issued by the manufacturer of the MS. SP: 1 bit , Not used.Check the IMEI in your MS : *#06#
TAC: Type approval code, 6 bit, determined by the type approval centerFAC: Final assembly code, 2 bit, It is determined by the manufacturer.SNR: Serial number, 6 bits, It is issued by the manufacturer of the MS. SP: 1 bit , Not used.Check the IMEI in your MS : *#06#
41 Internal Use
Chapter 1 GSM System Overview
Chapter 2 GSM Network Structure
Chapter 3 Service Area and Number Planning
Chapter 4 Channels on the Wireless Interface
Chapter 5 Radio Techniques
Chapter 6 GPRS & EDGE Introduction
42 Internal Use
2 30 16 74 52 3
The physical channel is the medium over which the information is carried: 200KHz and 0.577ms
0 1
TDMA FRAME
TimeslotThe information carried in one time
slot is called a “burst”The information carried in one time
slot is called a “burst”
Physical Channel and Logical ChannelPhysical Channel and Logical Channel
The logical channel consists of the information carried over the physical channels
TDMA FRAME
43 Internal Use
Two types of Logical ChannelTwo types of Logical Channel
Traffic Channel (TCH) :Transmits traffic information, include data and speech.
Control Channel (CCH) :Or Signaling Channel, transmits all kinds of control information.
44 Internal Use
Traffic Channel (TCH)Traffic Channel (TCH)
TCHTraffic Channels
Speech
TCH/FS
Data
TCH/HSTCH/9.6 TCH/2.4
TCH/4.8
TCH Traffic ChannelTCH/FS Full rate Speech Channel TCH/HS Half rate Speech Channel TCH/9.6 Data Channel 9.6kb/sTCH/4.8 Data Channel 4.8kb/sTCH/2.4 Data Channel 2.4Kb/s
45 Internal Use
FCCHSCH
CCH (Control Channels)
DCCH
SDCCH
BCH
BCCH Synch. CH.ACCH
SACCHFACCH CCCH
RACH CBCH
PCH/AGCH
Broadcast Control Channel – BCCHCommon Control Channel – CCCHDedicated Control Channel – DCCHAssociated Control Channel – ACCH
Control Channel (CCH)Control Channel (CCH)
46 Internal Use
CCH
BCH
BCCH Synch.
Channels
SCH FCCH
The information carried on the BCCH
is monitored by the MS
periodically when it is in idle mode
BCCH: Broadcast Control Channel
FCCH: Frequency Correction Channel
SCH: Synchronization Channel
Broadcast Control Channel Broadcast Control Channel –– BCCHBCCH
47 Internal Use
CCH
CCCH
RACHuplink
CBCH downlink
PCH/AGCHdownlink
The CCCH is responsible for transferring control information between all mobiles and the network.
RACH: Random Access Channel
PCH: Paging Channel
AGCH: Access Granted Channel
CBCH: Cell Broadcast Channel
Common Control Channel Common Control Channel –– CCCHCCCH
48 Internal Use
CCH
DCCH
SDCCH
FACCH SACCH
DCCH is assigned to a single wireless connection for measurement and handover purpose.SDCCH: Stand-alone Dedicated
Control Channel ACCH: Associated Control Channel SACCH: Slow Associated
Control Channel FACCH: Fast Associated Control
Channel
ACCH
Dedicated Control Channel Dedicated Control Channel –– DCCH DCCH
49 Internal Use
RACH CCCHCCH
SDCCH
SACCHFACCH
TCH/F
TCH/H
DCCH
TCH
DCH
Uplink Logical channelUplink Logical channel
50 Internal Use
FCCHSCHBCCH
PCH
AGCH
BCCH
CCCH
CCH
SDCCHSACCHFACCH
TCH/F
TCH/H
DCCH
TCH
DCH
Downlink Logical channelDownlink Logical channel
51 Internal Use
Allocate signaling channel
FCCHSCHBCCH
PCHRACHAGCHSDCCHSDCCHTCHFACCH
Power-off
Idle mode
Dedicated mode
Idle mode
How to use these channels?How to use these channels?
Search for frequency correction burst
Search for synchronous burst
Extract system information
Monitor paging message
Send access burst
Set up the call
Allocate voice channel
Conversation
Release the call
52 Internal Use
Packet data channel (PDCH)Comprising packet service channel and packet control channel
Packet service channel (PDTCH) Combined into the single-directional service channel
Packet control channelBroadcast control channel: PBCCHPublic control channel: PPCH, PRACH, PAGCHPrivate control channel: PACCH, PTCCH
TCH
BCCH
SACCH
Packet logic channelPacket logic channel
CCCH
TCH
53 Internal Use
GSM Logical Channel CombinationGSM Logical Channel Combination
Main BCCH combination – FCCH + SCH + BCCH + CCCH SDCCH combination – SDCCH/8 + SACCH/8Combined BCCH – BCCH + CCCH +SDCCH/4 + SACCH/4TCH/FR combination – TCH/F + FACCH/F + SACCH/FTCH/HR combination – TCH/H + FACCH/H + SACCH/H
54 Internal Use
Packet logic channels (PDCH) can be combined via the following three modes
Mode 1: PBCCH+PCCCH+PDTCH+PACCH+PTCCH; Mode 2: PCCCH+PDTCH+PACCH+PTCCH; Mode 3: PDTCH+PACCH+PTCCH
In case of small GPRS traffic, GPRS and circuit services use the same BCCH and CCCH in the cell. In this case, only combination mode 3 is needed in the cell
With the increase of traffic, the packet public channel should be configured in the cell. Channel combination mode 1 and mode 2 should be adopted
Combination of Combination of packet logic channelpacket logic channel
55 Internal Use
TDMA Frames
0 1
0 1 2 43 46 47 48 5049
51 – Frame Multi-frames
0 1 10
CONTROL CHANNELS
2 3 4 5 6 7 2 3 5 764
GSM MultiGSM Multi--framesframes
56 Internal Use
GSM MultiGSM Multi--framesframes
TDMA Frames
0 1
0 1 2 43 21 22 23 2524
26 – Frame Multi-frames
0 1 10
TRAFFIC CHANNELS
2 3 4 5 6 7 2 3 5 764
57 Internal Use
Chapter 1 GSM System Overview
Chapter 2 GSM Network Structure
Chapter 3 Service Area and Number Planning
Chapter 4 Channels on the Wireless Interface
Chapter 5 Radio Techniques
Chapter 6 GPRS & EDGE Introduction
58 Internal Use
Power ControlPower Control
Saves battery powerReduces co-channel andadjacent channel interference
8W
0.8W
5WBoth Uplink and Downlink power settings can be controlled independently and individually.
BCCH -------Does not attend Power control
59 Internal Use
DTX and VADDTX and VAD
Voice Activity Detection – VAD
Discontinuous Transmission – DTX
Battery SavingInterference reduction
60 Internal Use
Timing Advance (TA)Timing Advance (TA)
Transmission delay t
Transmission delay t
TA
The mobile phone shouldsend the signal in advance!
61 Internal Use
MultiMulti--path Fadingpath Fading
Diversity
Frequency Hopping
Time Dispersion
62 Internal Use
Diversity Diversity –– WhatWhat’’s Diversity?s Diversity?
Receive diversity provides an effective technique for both overcoming the impact of fading across the radio channel and increasing the received signal to interference ratio.
The former is achieved by ensuring “uncorrelated” (i.e. low enough correlated) fading between antenna branches i.e. not all antennas experience fades at the same time.
63 Internal Use
Kinds of DiversityKinds of Diversity
Time diversityCoding, interleaving
Frequency diversityFrequency hopping
Space diversityMultiple antennas
Polarization diversityDual-polarized antennas
Multi-path diversityEqualizer
t
f
64 Internal Use
Frequency HoppingFrequency Hopping
Frequency
f 0
Frame
f 1
f 2
f 3
f 4
Time
65 Internal Use
Chapter 1 GSM System Overview
Chapter 2 GSM Network Structure
Chapter 3 Service Area and Number Planning
Chapter 4 Channels on the Wireless Interface
Chapter 5 Radio Techniques
Chapter 6 GPRS & EDGE Introduction
66 Internal Use
57.6 kbps
115 kbps
384kbps
2Mbps
GSM
HSCSD
GPRS
EDGE
IMT-2000
9.6 kbps
2G
2.5G
3G
GSM Development EvolutionGSM Development Evolution
67 Internal Use
Data rate of EDGE and GPRSData rate of EDGE and GPRS
8PSKGMSK
9.013.4
15.6
21.4
8.811.2
14.817.6
22.4
29.6
44.8
54.4
59.2
0.0
10.0
20.0
30.0
40.0
50.0
60.0
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
Kbps
GPRS
EGPRS
68 Internal Use
Downlink, 4 TS, MCS-9:
Huawei EDGE Test ResultHuawei EDGE Test Result
69 Internal Use
SummarySummary
The basic idea of GSM The frequency spectrum used in GSMThe structure of GSMCertain service area and numbersSome radio techniques used in GSMEvolution of GSM
SummarySummary
Huawei Confidential. All Rights Reserved