www.huawei.com Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. GSM Principles
Jan 28, 2015
www.huawei.com
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
47pt
30pt
反白
:
FrutigerNext LT Medium
: Arial
47pt
黑体
28pt
反白
细黑体
GSM Principles
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
35pt
32pt
) :18pt
Page2
Objectives
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
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
35pt
32pt
) :18pt
Page3
References
BSS Feature Description
BSS Signaling Analysis Manual
BSC Technical Manual
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
35pt
32pt
) :18pt
Page4
Contents
1. GSM System Overview
2. GSM Network Structure
3. Service Area and Number Planning
4. Channels on the Wireless Interface
5. Radio Techniques
6. GPRS & EDGE Introduction
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
35pt
32pt
) :18pt
Page5
Contents
1. GSM System Overview
2. GSM Network Structure
3. Service Area and Number Planning
4. Channels on the Wireless Interface
5. Radio Techniques
6. GPRS & EDGE Introduction
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
35pt
32pt
) :18pt
Page6
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)
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page7
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
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page8
Cell Technique
Macro Cell and Micro Cell
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.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page9
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).
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page10
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
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page11
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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Page12
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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Page13
GSM 900
Duplex Separation: 45MHz
Channel Bandwidth: 200KHz
The Frequency Spectrum
Uplink
890 915 935 960MHz
Downlink
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Page14
Duplex Separation: 95MHz
Channel Bandwidth: 200KHz
Base Station Receive
1710 1785 1805 1880MHz
Base Station Transmit
DCS 1800
The Frequency Spectrum
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Page15
The Frequency Spectrum
Frequency
Spectrum
Range
(MHz) Uplink Frequency
Frequency
Point
Available
Downlink
Frequency
GSM 450
450.4~457.
6
460.4~467.
6
Fu(n)=450.6+0.2(n-
259) 259<=n<=293
Fd(n)=Fu(n)+1
0
GSM 480 478.8~486
488.8~496 Fu(n)=479+0.2(n-306) 306<=n<=340
Fd(n)=Fu(n)+1
0
GSM 850 824~849
869~894
Fu(n)=824.2+0.2(n-
128) 128<=n<=251
Fd(n)=Fu(n)+4
5
E-GSM
900
880~915
925~960
Fu(n)=890+0.2n
Fu(n)=890+0.2(n-1024)
0<=n<=124
975<=n<=102
3
Fd(n)=Fu(n)+4
5
R-GSM
900
876~915
921~960
Fu(n)=890+0.2n
Fu(n)=890+0.2(n-1024)
0<=n<=124
955<=n<=102
3
Fd(n)=Fu(n)+4
5
PCS 1900 1850~1910
1930~1990
Fu(n)=1850.2+0.2(n-
512)
512<=n<=810
Fd(n)=Fu(n)+8
0
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page16
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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Page17
Frequency Reuse
7(Site)X 1(Cell) reuse
2
1
2
3
4
5
6
7
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Page18
4 site X 3 cells reuse
1
8
9
2 10
4 6
5 3
7
11
12
R
Frequency Reuse
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page19
Cell Types
Omni
1
120 degree
1
2 3
Omni-directional Cell
120 Degree Cell
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Page20
Contents
1. GSM System Overview
2. GSM Network Structure
3. Service Area and Number Planning
4. Channels on the Wireless Interface
5. Radio Techniques
6. GPRS & EDGE Introduction
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page21
GSM-GPRS Network Component
GSM /GPRS BSS
BTS
BSC
BTS
BSC
PCU
SS7
SMS system
PSTN
ISDN
Internet,
Intranet
MSC/VLR GMSC
HLR/AUC
SGSN
CG BG
GGSN
GPRS Backbone
Other PLMN
MS
MS
OMC
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page22
Interface Between Different Entities
GSM /GPRS BSS
BTS
BSC
BTS
BSC
PCU
SS7
SMS system
PSTN
ISDN
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
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page23
Mobile Station—MS
International Mobile Equipment Identity
(IMEI)
– Mobile Equipment
MS=ME+SIM
International Mobile Subscriber Identity (IMSI)
– Subscriber Identity Module
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Page24
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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Page25
BTS
BSC
TC/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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Page26
BTS
BSC
TC/SM
BSS
MSC
Packet Control Unit-----PCU
Packet data
switching
Bridge between
SGSN and BSC
Provide Pb and Gb
interface GPRS
Backbone
PCU SGSN
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Page27
Mobile-service Switching Center – MSC Home Location Register – HLR Visitor Location Register – VLR Equipment Identity Register – EIR Authentication Center – AUC
Echo Cancellor – EC
AUC HLR
MSC/VLR
PSTN
NSS
EIR OMC
BSS
EC
The Network Switching System
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Page28
Mobile-service Switching Center –
MSC Call Processing
Operations and Maintenance Support
Interface management
Inter-network & Inter-working
Billing
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Page29
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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Page30
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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Page31
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
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page32
OMC Functional Architecture
OS
MMI
DB
Event/Alarm
Management
Security
Management
Configuration
Management
Performance
Management
Fault
Management
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page33
Contents
1. GSM System Overview
2. GSM Network Structure
3. Service Area and Number Planning
4. Channels on the Wireless Interface
5. Radio Techniques
6. GPRS & EDGE Introduction
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page34
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
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page35
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
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page36
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
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page37
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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Page38
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 ABCD
Example: 86-139-0666-1234
MSISDN
CC NDC SN
National (significant)
Mobile number
Mobile station international
ISDN number
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Page39
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: 666-9777001 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 MSIN
NMSI
IMSI
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Page40
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)
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page41
IMEI
TAC FAC SNR SP
IMEI
IMEI: International Mobile Station Equipment Identification
TAC: Type approval code, 6 bit, determined by the type approval center
FAC: 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#
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page42
Contents
1. GSM System Overview
2. GSM Network Structure
3. Service Area and Number Planning
4. Channels on the Wireless Interface
5. Radio Techniques
6. GPRS & EDGE Introduction
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page43
2 3 0 1 6 7 4 5 2 3
The physical channel is the medium over which the
information is carried: 200KHz and 0.577ms
0 1
TDMA FRAME
Timeslot 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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Page44
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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Page45
Traffic Channel (TCH)
TCH
Traffic Channels
Speech
TCH/FS
Data
TCH/HS TCH/9.6 TCH/2.4
TCH/4.8
TCH Traffic Channel
TCH/FS Full rate Speech Channel
TCH/HS Half rate Speech Channel
TCH/9.6 Data Channel 9.6kb/s
TCH/4.8 Data Channel 4.8kb/s
TCH/2.4 Data Channel 2.4Kb/s
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
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Page46
FCCH SCH
CCH (Control Channels)
DCCH
SDCCH
BCH
BCCH Synch. CH. ACCH
SACCH FACCH CCCH
RACH CBCH
PCH/AGCH
Broadcast Control Channel – BCCH
Common Control Channel – CCCH
Dedicated Control Channel – DCCH
Associated Control Channel – ACCH
Control Channel (CCH)
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Page47
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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Page48
CCH
CCCH
RACH
uplink CBCH
downlink
PCH/AGCH
downlink
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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Page49
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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Page50
RACH CCCH CCH
SDCCH
SACCH
FACCH
TCH/F
TCH/H
DCCH
TCH
DCH
Uplink Logical channel
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Page51
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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Page52
Allocate signaling channel
FCCH
SCH
BCCH
PCH
RACH
AGCH
SDCCH
SDCCH
TCH
FACCH
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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Page53
Packet logic channel
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
CCCH
TCH
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Page54
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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Page55
Combination of packet logic
channel 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
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Page56
TDMA Frames
0 1
0 1 2 4 3 46 47 48 50 49
51 – Frame Multi-frames
0 1 1 0
CONTROL
CHANNELS
2 3 4 5 6 7 2 3 5 7 6 4
GSM Multi-frames
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Page57
GSM Multi-frames
TDMA Frames
0 1
0 1 2 4 3 21 22 23 25 24
26 – Frame Multi-frames
0 1 1 0
TRAFFIC
CHANNELS
2 3 4 5 6 7 2 3 5 7 6 4
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Page58
Contents
1. GSM System Overview
2. GSM Network Structure
3. Service Area and Number Planning
4. Channels on the Wireless Interface
5. Radio Techniques
6. GPRS & EDGE Introduction
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Page59
Power Control
Saves battery power
Reduces co-channel and
adjacent channel interference
8W
0.8W
5W
Both Uplink and Downlink
power settings can be
controlled independently and
individually.
BCCH -------
Does not attend Power
control
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Page60
DTX and VAD
Voice Activity Detection – VAD
Discontinuous Transmission – DTX
Battery Saving
Interference reduction
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Page61
Timing Advance (TA)
Transmission delay t
Transmission delay t
TA
The mobile phone should
send the signal in advance!
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Page62
Multi-path Fading
Diversity
Frequency Hopping
Time Dispersion
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Page63
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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Page64
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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Page65
Frequency Hopping Frequency
f 0
Frame
f 1
f 2
f 3
f 4
Time
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Page66
Contents
1. GSM System Overview
2. GSM Network Structure
3. Service Area and Number Planning
4. Channels on the Wireless Interface
5. Radio Techniques
6. GPRS & EDGE Introduction
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Page67
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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Page68
Data rate of EDGE and GPRS
8PSK GMSK
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
GPRS
EGPRS
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Page69
Huawei EDGE Test Result
Downlink, 4 TS, MCS-9:
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
35pt
32pt
) :18pt
Page70
Summary
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
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