HUAWEI TECHNOLOGIES CO., LTD. All rights reserved www.huawei.com Internal OMA000001 GSM Fundamentals ISSUE 4.0
Dec 23, 2015
HUAWEI TECHNOLOGIES CO., LTD. All rights reserved
www.huawei.com
Internal
OMA000001GSM Fundamentals
ISSUE 4.0
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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
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References
BSS Feature Description
BSS Signaling Analysis Manual
BSC Technical Manual
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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
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GSM 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. Each group 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 Division Duplex
(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)
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GSM 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
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Cell 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
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Multiple 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).
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FDMA
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
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TDMA
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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CDMA
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
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GSM 900
Duplex Separation: 45MHz
Channel Bandwidth: 200KHz
The Frequency Spectrum
Uplink
890 915 935 960MHz
Downlink
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Duplex Separation: 95MHzChannel Bandwidth: 200KHz
Base Station Receive
1710 1785 1805 1880MHz
Base Station Transmit
DCS 1800
The Frequency Spectrum
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The Frequency Spectrum
Frequency Spectrum Range (MHz) Uplink Frequency
Frequency Point Available
Downlink Frequency
GSM 450 450.4~457.6460.4~467.6 Fu(n)=450.6+0.2(n-259) 259<=n<=293 Fd(n)=Fu(n)+10
GSM 480 478.8~486488.8~496 Fu(n)=479+0.2(n-306) 306<=n<=340 Fd(n)=Fu(n)+10
GSM 850 824~849869~894 Fu(n)=824.2+0.2(n-128) 128<=n<=251 Fd(n)=Fu(n)+45
E-GSM 900 880~915 925~960
Fu(n)=890+0.2nFu(n)=890+0.2(n-1024)
0<=n<=124975<=n<=1023 Fd(n)=Fu(n)+45
R-GSM 900 876~915921~960
Fu(n)=890+0.2nFu(n)=890+0.2(n-1024)
0<=n<=124955<=n<=1023 Fd(n)=Fu(n)+45
PCS 1900 1850~19101930~1990
Fu(n)=1850.2+0.2(n-512) 512<=n<=810 Fd(n)=Fu(n)+80
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Frequency 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 Reuse
7(Site)X 1(Cell) reuse
2
1
2
3
4
5
6
7
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4 site X 3 cells reuse
1
8
9
210
46
5 37
11
12
R
Frequency Reuse
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Cell Types
Omni
1
120degree
1
23
Omni-directional CellOmni-directional Cell
120 Degree Cell120 Degree Cell
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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
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GSM-GPRS 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
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Interface 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
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Mobile Station—MS
International Mobile Equipment Identity (IMEI)
– Mobile Equipment
MS=ME+SIMMS=ME+SIM
International Mobile Subscriber Identity (IMSI)
– Subscriber Identity Module
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Subscriber Identity Module – SIM
International Mobile Subscriber Identity
(IMSI)
Temporary Mobile Subscriber Identity
(TMSI)
Location Area Identity (LAI)
Subscriber Authentication Key (Ki)
SIM
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BTSBTS
BSCBSC
TC/SMTC/SM
BSS
MSC
Base Station Subsystem – BSS
The Base Station Controller –
BSC
The Base Transceiver Station
– BTS
The Trans-coder – TC and
Sub multiplexer (SM)
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BTSBTS
BSCBSC
TC/SMTC/SM
BSS
MSC
Packet Control Unit-----PCU
Packet data
switching
Bridge between
SGSN and BSC
Provide Pb and
Gb interface
GPRS Backbone
PCUPCU SGSNSGSN
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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
NSS
EIREIROMC
BSS
ECEC
The Network Switching System
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Mobile-service Switching Center – MSC
Call Processing
Operations and Maintenance Support
Interface management
Inter-network & Inter-working
Billing
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Home Location Register – HLR
Subscriber ID (IMSI and MSISDN)
Current subscriber VLR (current location)
Supplementary service information
Subscriber status (registered/deregistered)
Authentication key and AuC functionality
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Visitor Location Register – VLR
Mobile Status (IMSI attached / detached / busy / idle etc.)
Location Area Identity(LAI)
Temporary Mobile Subscriber Identity(TMSI)
Allocating the Roaming Number
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IMEI is Checked In White List
IMEI is Checked in Black/Grey List
If NOT found
EIR focus on the equipment , not the subscriber!!
Equipment Identity Register – EIR
White List
Black List
Grey List
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OMC Functional Architecture
OS
MMI
DB
Event/AlarmManagement
SecurityManagement
ConfigurationManagement
Performance Management
Fault Management
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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
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Service Area
PLMN service area
......
Service Area
MSC service area...
Location area...
cell
PLMN service area PLMN service area
MSC service area...
Location area...
cell
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LAI
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
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CGI
The CGI is a unique international identification for a cell
The format is LAI+CI
LAI: Location Area Identification
CI: 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
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BSIC
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)
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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
MSISDN
CC NDC SN
National (significant)Mobile number
Mobile station internationalISDN number
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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 ABCDEF For example: 666-9777001NMSI: 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 MSIN
NMSI
IMSI
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TMSI
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.
TMSI: Temporary Mobile Subscriber Identification)
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IMEI
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#
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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
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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 Channel
The logical channel consists of the information carried over the physical channels
TDMA FRAME
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Two 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.
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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
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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)
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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 – BCCH
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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 – CCCH
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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 – DCCH
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RACH CCCHCCH
SDCCH
SACCH
FACCH
TCH/F
TCH/H
DCCH
TCH
DCH
Uplink Logical channel
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FCCH
SCH
BCCH
PCH
AGCH
BCCH
CCCH
CCH
SDCCH
SACCH
FACCH
TCH/F
TCH/H
DCCH
TCH
DCH
Downlink Logical channel
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Allocate signaling channel
FCCHSCHBCCH
PCHRACHAGCHSDCCHSDCCHTCHFACCH
Power-off
Idle mode
Dedicated mode
Idle mode
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
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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 channel
Broadcast control channel: PBCCH
Public control channel: PPCH, PRACH, PAGCH
Private control channel: PACCH, PTCCH
TCH
BCCH
SACCH
Packet logic channel
CCCH
TCH
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GSM Logical Channel Combination
Main BCCH combination – FCCH + SCH + BCCH + CCCH
SDCCH combination – SDCCH/8 + SACCH/8
Combined BCCH – BCCH + CCCH +SDCCH/4 + SACCH/4
TCH/FR combination – TCH/F + FACCH/F + SACCH/F
TCH/HR combination – TCH/H + FACCH/H + SACCH/H
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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 packet logic channel
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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 Multi-frames
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GSM Multi-frames
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
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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
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Power Control
Saves battery power
Reduces co-channel and
adjacent channel interference
8W
0.8W
5WBoth Uplink and Downlink power settings can be controlled independently and individually.
BCCH -------
Does not attend Power control
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DTX and VAD
Voice Activity Detection – VAD
Discontinuous Transmission – DTX
Battery SavingInterference reduction
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Timing Advance (TA)
Transmission delay t
Transmission delay t
TA
The mobile phone should
send the signal in advance!
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Multi-path Fading
Diversity
Frequency Hopping
Time Dispersion
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Diversity – What’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.
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Kinds of Diversity
Time diversity
Coding, interleaving
Frequency diversity Frequency hopping
Space diversity Multiple antennas
Polarization diversity
Dual-polarized antennas
Multi-path diversity
Equalizer
t
f
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Frequency HoppingFrequency
f 0
Frame
f 1
f 2
f 3
f 4
Time
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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
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57.6 kbps
115 kbps
384 kbps
2 Mbps
GSM
HSCSD
GPRS
EDGE
IMT-2000
9.6 kbps
2G
2.5G
3G
GSM Development Evolution
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Data rate of EDGE and GPRS
8PSKGMSK
9.0
13.415.6
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
GPRSEGPRS
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Downlink, 4 TS, MCS-9:
Huawei EDGE Test Result
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The basic idea of GSM
The frequency spectrum used in GSM
The structure of GSM
Certain service area and numbers
Some radio techniques used in GSM
Evolution of GSM
Summary