GSM

Chapter 1

BASICS

Tutor: Pradyot Majumdar

GSM

Global System for Mobiles

TOPICS

GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
GSM CHANNELS
GSM RADIO LINK
MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT

TOPICS

GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
GSM CHANNELS
GSM RADIO LINK
MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT

Background to GSM

1G : Advanced Mobile Phone Service (AMPS)

2G : Digital Advanced Mobile Phone Service (D-AMPS)

Digital, Circuit Switched, FDMA, FDD

2G : Global System for Mobile (GSM)

Analog, Circuit Switched, FDMA, FDD

Digital, Circuit Switched, FDMA and TDMA, FDD

2G : Code Division Multiple Access (CDMA)

Digital, Circuit Switched, FDMA, SS, FDD

GSM History

What are the types in GSM Network?

GSM-900 (Channels 125 operating band 900Mhz

carrier spacing 200khz spacing 45Mhz)

GSM -1800 (Channels 374 spacing 95Mhz)

GSM -1900(Used in USA)

GSM - Network Structure

MS
Um
BTS

HLR

VLR
BSC
Abis

MSC
A

MS

GMSC

BTS
E
Abis
A

MSC

F
EIR

E
PSTN

BSC
Um
BTS

X.25
VLR
X.25
OMC Server

AuC

GSM System specifications

Frequency band
Uplink
890 - 915 MHz
Downlink
935 - 960MHz
Duplex Frequency Spacing 45MHz
Carrier separation
200KHz
Frequency Channels
124
Time Slots /Frame(Full Rate)8
Voice Coder Bit Rate
13Kbps
Modulation
GMSK
Air transmission rate
270.833333 Kbps
Access method
FDMA/TDMA
Speech Coder
RPE-LTP-LPC

Paired Radio Channels in GSM Case of GSM 900

Uplink
890 MHz

Frequency

channel #

Downlink
915 MHz

124

935 MHz

Frequency

channel #

Example:
Channel 48

Duplex spacing = 45 MHz

Frequency band spectrum = 2 x 25 MHz
Channel spacing = 200 kHz

BTS
960 MHz

124

GSM Time Division Multiplex Frame and Physical Channels

Time-slot

TDMA frame

TDMA frame

TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS
0

(frames repeat continuously)

Time
0

4.615 ms

Physical channel # 2 = recurrence of time-slot # 2

9.23 ms

Access Techniques

Uplink 890 MHz to 915 MHz

Down Link 935 MHz to 960 MHz
25 MHz divided into 125 channels of 200 KHz
bandwidth
UP

890.0

890.2

890.4

914.8

915.0

DOWN 935.0

935.2

935.4

959.8

960.0

Access Techniques ...

Time Division Multiple Access

Each carrier frequency subdivided in time domain
into 8 time slots
Each mobile transmits data in a frequency, in its
particular time slot - Burst period = 0.577 milli secs.
8 time slots called a TDMA frame. Period is .577 * 8
= 4.616 milli secs
0.577 ms
0

4.616 ms

GSM - Network Structure

MS
Um
BTS

HLR

VLR
BSC
Abis

MSC
A

MS

GMSC

BTS
E
Abis
A

MSC

F
EIR

E
PSTN

BSC
Um
BTS

X.25
VLR
X.25
OMC Server

AuC

GSM Network
SS
External
PSTN &
PDN N/W

AUC

VLR

MS Mobile Station
BTS Base transceiver System
BSC Base Station Controller
MSC Mobile Switching Center
HLR Home Location Register
VLR Visitor Location Register
EIR Equipment Identity Register
AUC Authentication Center
OMC Operation And Maintenance Center

Switching
System

HLR

EIR
OMC

MSC

BSS BSC
BTS
MS

Base Station
System

GSM Architecture
VMSC

GSM
Air interface
B
S
C
Abis
interface

TRAU

BTS
BTS

BTS

BTS

A
interface

B
S
C

SMSC

HLR

AUC

MSC

PSTN
VLR

EIR

OMCS

BTS
BTS

Mobile
Station

Network and switching

subsystem
OMCR

Base Station System

A interface SS7 / speech

X.25
SS7

Mobile Equipment(ME)

Frequency and Time Synchronization

Voice encoding and transmission
Voice encryption/decryption functions
Power measurements of adjacent cells
Display of short messages
International Mobile Equipment Identifier (IMEI)

Base Transceiver Station (BTS)

Handles the radio interface to the mobile station.

Consists of one or more radio terminals for transmission
and reception
Each Radio terminal represents an RF Channel
TRX and MS communicates over Um interface
Received data transcoding
Voice encryption/decryption
Signal processing functions of the radio interface
Uplink Radio channel power measurements

Base Station Controller (BSC)

Provides all the control functions and physical links

between the MSC and BTS
External Interfaces
Abis interface towards the BTS
A interface towards the MSC
Monitors and controls several BTSs
Management of channels on the radio interface
Alarm Handling from the external interfaces
Performs inter-cell Handover
Switching from Abis link to the A link
Interface to OMC for BSS Management

Mobile Switching Center (MSC)

Performs call switching

Interface of the cellular network to PSTN
Routes calls between PLMN and PSTN
Queries HLR when calls come from PSTN to mobile user
Inter-BSC Handover
Paging
Billing

Home Location Register (HLR)

Stores user data of all Subscribers related to the GMSC

International Mobile Subscriber Identity(IMSI)
Users telephone number (MS ISDN)
Subscription information and services
VLR address
Reference to Authentication center for key (Ki)
Referred when call comes from public land network

Visitor Location Register (VLR)

Database that contains Subscriber parameters and

location information for all mobile subscribers currently
located in the geographical area controlled by that VLR
Identity of Mobile Subscriber
Copy of subscriber data from HLR
Generates and allocates a Temporary Mobile Subscriber
Identity(TMSI)
Location Area Code
Provides necessary data when mobile originates call

Authentication Center (AuC)

Stores Subscriber authentication data called Ki, a copy

of which is also stored in in the SIM card
Generates security related parameters to authorize a
subscriber (SRES-Signed RESponse)
Generates unique data pattern called Cipher key (Kc) for
user data encryption
Provides triplets - RAND, SRES & Kc, to the HLR on
request.

EIR (Equipment Identity Register)

EIR is a database that contains a list of all valid

mobile station equipment within the network, where each
mobile station is identified by its International Mobile
Equipment Identity(IMEI).
EIR has three databases.,

White list - For all known,good IMEIs

Black list - For all bad or stolen handsets
Grey list - For handsets/IMEIs that are
observation

on

Location Area Identity

LAI identifies a location area which is a group of cells..

It is transmitted in the BCCH.
When the MS moves into another LA (detected by monitoring LAI transmitted
on the BCCH) it must perform a LU.
LAI = MCC + MNC + LAC
MCC= Mobile Country Code(3 digits), identifies the country
MNC= Mobile Network Code(1-2 digits), identifies the GSM-PLMN
LAC= Location Area Code, identifies a location area within a GSM PLMN
network. The maximum length of LAC is 16 bits,enabling 65536 different
location areas to be defined in one GSM PLMN.

Interfaces and Protocols

Digital
Networks

Abis

LAPD

Um

LAPDm

BSSAP

ISUP
TUP

MAP

MAP

MAP

C
D

POTS

GSM Protocols

CM
- Connection Management
MM
- Mobility Management
RR
- Radio resource
LAPDm
- LAPD for mobile
LAPD - Link Access Procedure for D channel
BTSM - BTS Management Part
BSSAP
- BSS Application Part (BSC - MSC)
DTAP
- Direct Transfer Application Part (MS - MSC)
MAP
- Mobile Application Part
MTP
- Message Transfer part of SS7
SCCP
- Signalling Connection Control Part of SS7
TCAP
- Transaction Capabilities Application Part
ISUP - ISDN User Part

Channels : differentiating between Physical and Logical channels

Physical channels : The combination of an ARFCN and a

time slot defines a physical channel.
Logical channels : These are channels specified by GSM
which are mapped on physical channels.

Channel concept

Physical channel:
One timeslot of a TDMA-frame on one carrier is referred
to as a physical channel. There are 8 physical channels
per carrier in GSM,channel 0-7(timeslot 0-7)
Logical channel:
A great variety of information must be transmitted
between BTS and the MS,for e.g. user data and control
signaling.Depending on the kind of information
transmitted we refer to different logical channels.These
logical channels are mapped on physical channel.

Logical Channels on Air interface

LOGICAL
CHANNELS
COMMON
CHANNELS

COMMON
CONTROL
CHANNELS

BROADCAST
CHANNELS

FCCH

SCH

DEDICATED
CHANNELS

BCCH

PCH

DEDICATED
CONTROL
CHANNELS

SDCCH

RACH

AGCH

SACCH

TCH/F

TRAFFIC
CHANNELS

FACCH

TCH/H

TCH/EFR

Logical channels

Logical channels

Control channels

BCH

FCCH

CCCH

Traffic channels

DCCH

Half
rate

Full
rate

SCH BCCH CBCH PCH AGCH RACH SDCCH SACCH FACCH

Broadcast channels BCH

Broadcast Channel-BCH
Alloted one ARFCN & is ON all the time in every cell. Present in TS0 and
other 7 TS used by TCH.
Frequency correction channel-FCCH
To make sure this is the BCCH carrier.
Allow the MS to synchronize to the frequency.
Carries a 142 bit zero sequence and repeats once in every 10 frames on the
BCH.
Synchronization Channel-SCH
This is used by the MS to synchronize to the TDMA frame structure within
the particular cell.
Listening to the SCH the MS receives the TDMA frame number and also the
BSIC ( in the coded part- 39 bits).
Repeats once in every 10 frames.

Broadcast channels BCH ...

BCCH
The last information the MS must receive in order to receive calls or
make calls is some information concerning the cell. This is BCCH.
This include the information of Max power allowed in the cell.
List of channels in use in the cell.
BCCH carriers for the neighboring cells,Location Area Identity etc.
BCCH occupies 4 frames (normal bursts) on BCH and
repeats
once every Multiframe.
This is transmitted Downlink point to multipoint.
Cell Broadcast Channel - CBCH
Used for the Transmission of generally accessible information like
Short Message Services(SMS)

Common Control Channels CCCH

CCCH Shares TS-0 with BCH on a Multiframe.

Random access channel-RACH:
Used by Mobile Station for requesting for a channel. When the
mobile realizes it is paged it answers by requesting a signaling
channel (SDCCH) on RACH. RACH is also used by the MS if it
wants to originate a call.
Initially MS doesnt know the path delay (timing advance), hence
uses a short burst (with a large guard period = 68.25 bits).
MS sends normal burst only after getting the timing advance info on
the SACCH.
It is transmitted in Uplink point to point.

Common Control Channels CCCH ..

Access Grant Channel-AGCH

On request for a signaling channel by MS the network assigns a

signaling channel(SDCCH) through AGCH. AGCH is transmitted
on the downlink point to point.

Paging Channel-PCH

The information on this channel is a paging message including

the MSs identity(IMSI/TMSI).This is transmitted on Downlink,
point-to-multipoint.

Dedicated Control Channels-DCCH

Stand alone dedicated control channel(SDCCH)

AGCH assigns SDCCH as signaling channel on request
by MS.The MS is informed about which
frequency(ARFCN) & timeslot to use for traffic.
Used for location update, subscriber authentication,
ciphering information, equipment validation and
assignment of TCH.
This is used both sides, up and Downlink point-point.

Dedicated Control Channels-DCCH

Slow associated control channel-SACCH

Transmission of radio link signal measurement, power control etc.
Average signal strengths(RXLev) and quality of service (RXQual) of
the serving base station and of the neighboring cells is sent on
SACCH (on uplink).
Mobile receives information like what TX power it has to transmit
and the timing advance. It is associated with TCH or SDCCH
Fast associated control channel-FACCH
Used for Hand over commands and during call setup and release.
FACCH data is sent over TCH with stealing flag set

Traffic Channels-TCH

TCH carries the voice data.

Two blocks of 57 bits contain voice data in the normal
burst.
One TCH is allocated for every active call.
Full rate traffic channel occupies one physical
channel(one TS on a carrier) and carries voice data at
13kbps
Two half rate (6.5kbps) TCHs can share one physical
channel.

GSM Channels
GSM Channels
Traffic Channels
(TCHs)

Control Channels

Broadcast
Channels
(BCHs)
Full
rate

TCH /F

Half
rate

Common Control
Channels
(CCCHs)

Downlink

Downlink

Uplink

(down uplink)
Fast

TCH /H FCCH SCH BCCH PCH

Traffic Multiframing

Dedicated Control
Channels
(DCCHs)

AGCH

CBCH

Signaling Multiframing

RACH SDCCH

FACCH

Slow

SACCH

Traffic Multiframing

Logical Channel Description (1/2)

SACCH MESSAGES

TCH MESSAGES

Measures:

power level of the communication

Speech

quality level of the communication

Data

level on the beacon frequency of

Handover Access message (uplink)

the neighboring cells

Timing Advance
Power Control

FACCH MESSAGES

SMS

Connection establishment from

SDCCH MESSAGES
Request for a SDCCH assignment
Request for the end of channel

assignment
Order of commutation from SDCCH to

TCH
SMS

SDCCH to TCH
End validation of a SDCCH-TCH

commutation
Characteristics of the future used BS

after handover
Connection establishment to BS after

handover
Validation of an handover

Logical Channel Description (2/2)

FCCH MESSAGES
no message is sent (all bits 0)

SCH MESSAGES
Frame Number

AGCH MESSAGES
For dedicated channel assignment:

frequency number
slot number
frequency hopping description
Timing Advance (1st estimation)
MS identification

Base Station Identity Code (BSIC)

CBCH MESSAGES
BCCH MESSAGES

Specific information

(weather, road information

rmation type 1, 2, 2bis,

8
(idle mode)

RACH MESSAGES

Service request:

PCH MESSAGES
messages containing a mobile

identity for a call, a short message

or an authentication

emergency call
answer to an incoming call
outgoing call
short message
call re-establishment
inscription

Traffic and Control Multiframing

Control channel

Traffic channel
Frame
4.615 ms
TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS TS
0
1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7

26 traffic frames = 120 ms

0 1 2 3 4
1326
frames
0

21 22 23 24 25

26 x 51 control frames = 6.12 s

TS TS TS TS TS TS TS TS
0 1 2 3 4 5 6 7

51 x 26 traffic frames = 6.12 s

TS TS TS TS TS TS TS TS
0 1 2 3 4 5 6 7

46 47 48 49 50

46
22

47
23

48
24

49

50
25

2042 2043 2044 2045 2046 2047

1 Hyperframe = 2,715,648 frames= 3h 28 min. 53 s 760 ms

Logical Channel Mapping

1 - Traffic Channel Combination
T

Full Rate - Downlink & Uplink

26 frames = 120 ms

T T T T T T T T T T T T A T T T T T T T T T T T T

time

Half Rate - Downlink & Uplink

26 frames = 120 ms

T0 T1 T0 T1 T0 T1 T0 T1 T0 T1 T0 T1 A0 T1 T0 T1 T0 T1 T0 T1 T0 T1 T0 T1 T0 A1

T : TCH

Ti : TCH

sub-channel no. i

A : SACCH

Ai : SACCH

sub-channel no. i

: IDLE

time

Logical Channel Mapping

2 - Dedicated Signaling Channel Combination
A

Downlink
51 frames = 235 ms

D0

D1

D2

D3

D4

D5

D6

D7

A0

A1

A2

A3

D0

D1

D2

D3

D4

D5

D6

D7

A4

A5

A6

A7
time

Uplink
51 frames = 235 ms

A5

A6

A7

D0

D1

D2

D3

D4

D5

D6

D7

A0

A1

A2

A3

D0

D1

D2

D3

D4

D5

D6

D7

A4
time

A : SACCH

D : SDCCH

: IDLE

Logical Channel Mapping

3 - Common Channel Combination
Downlink

Multiframe
m-1

Multiframe m
Multiframe
m+1

51 frames = 235.38 ms

FS

FS

FS

FS

FS

FS

time

Frames repeat continuously

BTS

PCH/AGCH

Physical Channel
ARFCN (n)

TS (s)

SCH

MS

BCCH

FCCH

Uplink
51 frames = 235.38 ms
R R R RR R R RR R RRR R R RR R R RRR R RR R R RR R R R R R R R R R RRR R RR RR RR R R R

F : FCCH

S : SCH

B : BCCH

: PCH /
C AGCH

time

R : RACH

: IDLE

Logical Channel Mapping

4 - Common Channel Combination
Downlink
51 frames = 235 ms

FS

FS

FS

D0

D1

FS

D2

D3

FS

A0

A1

FS

FS

FS

D0

D1

FS

D2

D3

FS

A2

A3
time

Uplink
51 frames = 235 ms

D3

RR

A2

A3

RRRRRRRRRRRRRRRRRRRRRRR

D0

D1

RR

D2

D3

RR

A0

A1

RRRRRRRRRRRRRRRRRRRRRRR

D0

D1

RR

D2
time

: AGCH

F : FCCH S : SCH B : BCCH C /PCH

R : RACH

A : SACCH

D : SDCCH

: IDLE

Why 26 and 51 Frames per Multiframe?

0 1
10
20

FS

FS

30

FS

TTTTTTTTTTTTATTTTTTTTTTT T
01

12

40

FS

FS

50 0 1

TTTTTTTTTTTTATTTTTTTTTTTT

25 0 1

12

25

Downlink
message
Uplink
message
Mobile
activity

Rx
(n)

Rx

FS

Tx Rx Rx
(n)

Tx

Rx
(n)

Rx

Tx

Neighboring BTS
(downlink)
Measurement Windows

From Speech to Radio Transmission

Speech

Step 1

Digitizing and
source coding

Source
decoding

Step 2

Channel
coding

Channel
decoding

Interleaving

De-interleaving

Step 3
Burst formatting

Step 4

Ciphering

Step 5

Modulation

Step 6

Transmission

Burst deformatting

Deciphering

Demodulation
equalization

Diversity

GSM Radio Link

Speech Coding -Done at Transcoder of BSC and MS

The Linear Predictive Coder uses RPE-LTP(Regular
Pulse Excitation- Long Term Prediction)
Converts 64kbps voice to 13kbps(260 bits every 20ms)
Channel Coding - Done at BTS and MS
Uses Convolution Coding and CRC (Cyclic
Redundancy Check)
Converts 13 kbps to 22.8 kbps (456 bits per 20ms)

GSM Radio Link

Bit Interleaving - Done at BTS and MS

Encryption - Done at BTS and MS
EX OR data with cipher block, which is generated by applying A5
Algorithm to the Ciphering Key(Kc)
Multiplexing - Done at BTS
Modulation - Done at BTS and MS
GMSK(Gaussian filtered Minimum Shift Keying)
Phase change of +90 for 0 and -90 for 1

Speech Coding
BP

A/D

BAND
PASS
300 Hz 3.4 kHZ

SPEECH
ENCODER

Every 125 s value is

sampled from analog
signal and quantised by
13 bit word
Data rate = 13/125*10 -6
= 104 kbps

CHANNEL
CODING

Every 20ms 160 samples

taken
Data rate = 160 * 13/20ms
= 104 kbps

To modulator

1A

1B

50

132

78

3 crc bits

Four 0 bits for codec

50 3

132

Conv coding rate = 1/2 delay = 4

Linear Predictive Coding & Regular

Pulse Excitation Analysis
1. Generates 160 filter coeff
2. These blocks sorted in 4 sequence
1,5,9,37 / 2,6,10----38/
3,7,1139/8,12,1640
3. Selects the sequence with most
energy
So data rate = 104/4 = 26 kbps

LP

D/A

Long term prediction analysis

1. Previous sequences stored in memory
2. Find out the correlation between the
present seq. And previous sequences
3. Select the highest correlation sequence
4. Find a value representing the difference
between the two sequences.

378 coded bits

456 bits in 20 ms = 22.8 kbps
57 x 8 = 456

1A = Filter Coeff
block ampl, LTP
params
1B = RPE pointers &
pulses
2 = RPE pulse & filter
params

Reduces data rate = 26 kbps/2 = 13 kbps

ie 260 bits in 20ms

SPEECH
DECODER

78

CHANNEL
DECODING

Channel Processing in GSM

Overview for Full Rate
20 ms

Speech blocks

20 ms

20 ms

Codec dependent

Codec dependent

Codec dependent

Source coding
Channel coding

456 bits

A A A A
5 6 7 8

Normal
burst

A5
B1

A6
B2

A7
B3

A8
B4

B5
C1

B6
C2

456 bits

8 Sub blocks
of 57 bits

B B B B B B B B
1 2 3 4 5 6 7 8

Interleaving

8 Bursts

456 bits

B7
C3

C C C C
1 2 3 4

B8
C4

57 bits

26 bits

57 bits

Tail

Information

CRL

Training

CRL

Information

Tail

Channel Processing in GSM

Overview for Half Rate
Speech blocks

20 ms

20 ms

20 ms

Codec dependent

Codec dependent

Codec dependent

Source coding
Channel coding

228 bits

A A A A
1 2 3 4

A3
B1

A4
B2

B3
C1

228 bits

4 Sub blocks
of 57 bits

B B B B
1 2 3 4

Interleaving

4 Bursts
Normal
burst

228 bits

C C C C
1 2 3 4

B4
C2

Interleaving: TCH Full Rate

0 1 2 3 4 5 6 7 8 ...

...

456
coded bits

452 453 454 455

Divide 456 bits in 8 sub-blocks

1
9

2
10

3
11

4
12

5
13

6
14

7
15

57 Rows

0
8

reordering
&
partitioning
out

448 449 450 451 452 453 454 455

diagonal
interleaving

bit
interleaving

b0 b1

b56

b0 b1

b56

burst

Burst Formatting
Normal Burst
1 frame:
4.615 ms
0

DATA

Training
sequence

57

26

S
1

Burst
148 bits
156.25 bits duration
(0.577 ms)

Guard
Band

DATA
57

8.25

Guard

Burst Formats
Frequency Correction Burst
(FCCH)
Tail

Data

3 bits

Tail

142 fixed bits (0)

3 bits

Guard
Period
8.25 bits

156.25 bits duration

(0.577 ms)

Synchronization Burst
(SCH)
Tail

Data

3 bits 39 encrypted bits

Extended Training Sequence

Data

64 synchronization bits

39 bits

156.25 bits duration

(0.577 ms)

Tail

Guard
Period

3 bits 8.25 bits

Burst Formats
Tail

Normal Burst

Data

3 bits 57 encrypted bits

Training Sequence
1

26 bits

Data
1

Tail

57 encrypted bits

Guard
Period

3 bits 8.25 bits

156.25 bits (0.577 ms)

Dummy Burst
Tail Dummy Sequence
3 bits 58 mixed bits

Training Sequence

Dummy Sequence Tail

26 midamble bits

58 mixed bits

Guard
Period

3 bits 8.25 bits

156.25 bits (0.577 ms)

Tail

Training
Sequence

8 bits

41 synch bits

Access Burst
Data

Tail

36 encrypted bits 3 bits

156.25 bits (0.577 ms)

Guard Period
68.25 bits

Ciphering
Burst to be
transmitted

Data

Data

Plain data:
0 1 1 1 0 0 1 0.....
Ciphering sequence:
0 0 0 1 1 0 1 0.....
XOR:
Ciphered data (transmitted): 0 1 1 0 1 0 0 0.....
Ciphered sequence:
0 0 0 1 1 0 1 0.....
XOR:
Recovered data:
0 1 1 1 0 0 1 0.....

Received
burst

Data

S Training S
sequence

Data

Interleaving
Encoded speech blocks - Diagonal Interleaving
57 57 57 57 57 57 57 57

57 57 57 57 57 57 57 57

57 57 57 57 57 57 57 57

57

57

57

57

57

57

57

57

57

57

57

57

57

57

Bn-4 Bn-3 Bn-2 Bn-1

57
57

57

57

57

57

57

57

57

57

57

57

57

57

57

57

57

57

Even bits
Odd bits

Bn Bn+1 Bn+2 Bn+3

Encoded control channel blocks - Rectangular Interleaving

57 57 57 57 57 57 57 57

57
57

57
57

57 57 57 57 57 57 57 57

57
57

57
57

Bn-4 Bn-3 Bn-2 Bn-1

Tb
3

Coded Data
57

57 57 57 57 57 57 57 57

57

57

57

57

57

57

57

57

57

57

57

57

57

57

57

57

Even bits
Odd bits

Bn Bn+1 Bn+2 Bn+3

F Training Sequence F
1
26
1

Coded Data
57

Tb
3

Gp
8.25

Burst

The information format transmitted during one timeslot in the TDMA

frame is called a burst.
Different Types of Bursts
Normal Burst
Random Access Burst
Frequency Correction Burst
Synchronization Burst

Normal Burst
156.25 bits 0.577 ms

T
3

Coded Data
57

S
1

T. Seq.
26

S
1

Coded Data
57

T
3

GP
8.25

Tail Bit(T) :Used as Guard Time

Coded Data
:It is the Data part associated with the burst
Stealing Flag :This indicates whether the burst is carrying
Signaling data (FACCH) or user info (TCH).
Training Seq. :This is a fixed bit sequence known both to
the BTS & the MS.This takes care of the
signal deterioration.

156.25 bits 0.577 ms

T
3

Training Sequence
41

Coded Data
36

T
3

GP
68.25

Random Access Burst

156.25 bits 0.577 ms
T
3

Fixed Bit Sequence

142

T
3

GP
8.25

Freq. Correc. Burst

156.25 bits 0.577 ms
T
3

Coded Data
39

Training Sequence
64

Synchronization Burst

Coded
Data 39

T
3

GP
8.25

Transmission on the radio channels

A timeslot has a duration of .577 m seconds (148 Bits)

8 timeslots(8 x 0.577 = 4.62 ms) form a TDMA frame
If a mobile is assigned one TS it transmits only in this time
slot
and stays idle for the other 7 with its transmitter off, called
bursting
The start on the uplink is delayed from downlink by 3 TS
periods
One TS = duration of 156.25 bits, and its physical contents
is
called a burst

Downlink 0
BTS > MS

Uplink
MS > BTS

Offset

Timing Advance
MS1 0
near

MS2
0
far

MS1 0
near
MS2
0
far

At
BTS

At
BTS
0

1
0

2
1

3
2

4
3

5
4

6
5

7
6

Frames Types On Um Interface

TDMA Frame
8 Time slots (Burst Period)
Length is 4.62 ms(8 * 0.577ms)
26-TDMA Multiframe
26 TDMA Frames (24 TCH, SACCH, Idle)
120 ms (26 * 4.62ms)
51-TDMA Multiframe
26 TDMA Frames (FCCH, SCH, BCCH, SDCCH,
CCCH)
235.6 ms (51 * 4.62ms)

Frames Types On Um Interface

Super Frame

51* 26 TDMA Frames

6.12 S

Hyper Frame

2048 * 51* 26 TDMA Frames

3 Hours, 28 Minutes, 53 Secs and 760 ms

TOPICS

GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
GSM CHANNELS
GSM RADIO LINK
MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT

Mobility Management

Mobility Management (MM)

Location updating- normal,periodic, IMSI attach
Paging
Security Management

Preventing unauthorized users- authentication

Maintaining Privacy of users- ciphering

Providing roaming facility

MM functionality mainly handled by MS, HLR, MSC/VLR.

Network Attachment

Cell Identification

MS scans complete GSM frequency band for highest

power

Tunes to highest powered frequency and looks for FCCH.

Synchronizes in frequency domain

Get training sequence from SCH which follows FCCH.

Synchronizes in time domain.

Accesses BCCH for network id, location area and

frequencies of the neighboring cells.

Stores a list of 30 BCCH channels

Network Attachment..

PLMN Selection

Get the operator information from SIM.

Cell Selection

Selected cell should be a cell of the selected PLMN

Signal strength should be above the threshold.

Cell should not be barred

Location Update

Register with the network by means of location

updation procedures.

MS Location Update (registration)

MS

BTS

BSC

(G)MSC

VLR

HLR

Action
Channel Request (RACH)
Channel Assignment (AGCH)

TMSI + old LAI

Location Update Request (SDCCH)

Authentication Request (SDCCH)
Authentication Response (SDCCH)
Comparison of Authentication params
Accept LUP and allocTMSI (SDCCH)
Ack of LUP and TMSI (SDCCH)
Entry of new area and identity into
VLR and HLR
Channel Release (SDCCH)

Security - Authentication
MS
Ki

RAND

A3
SRES
MS

BTS

AuC

RAND
SRES
SRES
Auth
Result

Authentication center
provides RAND to Mobile
AuC generates SRES using
Ki of subscriber and RAND
Mobile generates SRES
using Ki and RAND
Mobile transmits SRES to
BTS
BTS compares received
SRES with one generated
by AuC

Security - Ciphering
MS
Ki

RAND

A8

Kc

Um interface

MS

Network
Kc

Data

A5

Kc
Ciphered
Data

A5

Data

Data sent on air

interface ciphered
for security
A5 and A8
algorithms used to
cipher data
Ciphering Key is
never transmitted
on air

Communication Management (CM)

Setup of calls between users on request

Routing function i.e. Choice of transmission segments
linking users
Point to Point Short message services

PLMN Selection
Yes

Is there an up to date
found PLMNs list?

Yes

No
Creation of a found
PLMN list
manual
mode
The user selects a
PLMN from the
displayed PLMNs

No (manual)

automatic
mode
The MS selects the first
PLMN from the preferred
PLMNs list (if it is not in
the forbidden PLMNs list)
Cell Selection
succeed?
Yes
End of PLMN
selection

No (automatic)

Selection of the
next preferred
possible PLMN

PLMN Selection
Constitution of the "Found PLMN list"
Listen to all the
frequencies of the GSM
spectrum:
power level measurement
and average on these
measurements

Select the best

frequencies
according to the
power level

(30 in GSM 900 and 40 in GSM 1800)

Memorize the beacon

frequencies in the
precedent selection

=> Create the

Found PLMN list

(124 channels in GSM

900, 374 in GSM 1800
and 299 in GSM 1900

Initial Cell Selection

List of the
frequencies of the
selected PLMN
Selection of
another PLMN

Eligible cell?
No
Yes
C1 Computation for
eligible cells

Suitable cell:
Eligible cell

- cell of the selected PLMN

- cell not barred
- C1 > 0

Suitable cell?
No
Yes

Look for the cell with the best

C1 in the suitable cells list
PLMN set in the
forbidden
PLMN list

IMSI Attach
End of Cell Selection
Rejected?
No

Yes

Cell Selection
Purpose: get synchronization
with the GSM network
prior establishing any communication.

1
BTS-5

BTS-4

H
FCC

1
5

BTS-3

SCH
CH
BC

BTS-2

This cell

2
3
4
BTS-1

Immediate Assignment
BTS

MS
1

CHANNEL REQUEST

RACH

CHANNEL REQUIRED
CHANNEL ACTIVATION

IMMEDIATE ASSIGNMENT

AGCH

OR
6

CM SERVICE REQUEST

SDCCH or TCH
LOCATION UPDAT. REQU.

SDCCH or TCH

MSC

BSC

CHANNEL ACTIVATION
ACK.
IMMEDIATE ASSIGNMENT
COMMAND

Immediate
Assignment

Registration: the Very First Location Update

1
2

BSS

IMSI
BSC

4
TMSI
Release

4
TMSI

MSC
5
6

BTS

TMSI
5

LAI

VLR

HLR
IMSI
VLR id

IMSI
TMSI
LAI

Intra VLR Location Update

1
2

BSS

TMSI + old LAI

new TMSI

2
BSC
3
4

BTS

MSC
3
4
2
New TMSI

TMSI

3
New LAI

VLR
IMSI
TMSI
LAI

IMSI not Required

Inter VLR Location Update

BSS

1
2

TMSI + old LAI

newTMSI

BSC

MSC

5
7

BTS

2
TMSI New TMSI
5

New LAI

New VLR

Old VLR
IMSI, TMSI
Old LAI

RAND, SRES, 4
Kc

IMSI,TMSI
LAI
RAND, SRES,
Kc

IMSI not Required

HLR
6
new
VLR id

subscriber
data

IMSI Attach
1

CHANNEL
REQUEST
IMMEDIATE
ASSIGNMENT

BSS
2

3 LOCATION UPDATING

REQUEST (IMSI Attach)

Authentication
4
Procedure

LOCATION UPDATING
5
ACCEPT (LAC, TMSI)

BSC
BTS

3
4

MSC

5
4

VLR
6

IMSI Detach
1

CHANNEL
REQUEST
IMMEDIATE
ASSIGNMENT

BSS
2
BSC

IMSI DETach
INDication
CHANNEL
RELEASE

BTS

IMSI DETach
INDication

MSC

VLR

Mobile Originating Call

BSS

MS
CHANNEL REQUEST

Dialing 1

VLR

IMMEDIATE ASSIGNMENT

CM SERVICE REQUEST

3
3

Sending
Number

PSTN

MSC

Authentication procedure
Ciphering procedure

SETUP (basic) or
EMERGENCY

CALL PROCEEDING
7

CM SERVICE REQUEST

SETUP
5

CALL PROCEEDING

Assignment procedure

CONNECT

Path
Established
11

IAM

Ring
Ringing

ALERTING 9

Ringing

ACM
ANM

11

CONNECT ACKnowledge

8
10

ACM = Address Complete Message

ANM = ANswer Message
IAM = Initial Address Message

Mobile Terminating Call

1 - Paging Principle
LA1
6

BSC1

BTS11

4
5

BTS12

MSC/
VLR

GMSC

BSC2

BTS21

2
BTS22

LA2

HLR
BSC3

BTS23

BTS31

PSTN

Mobile Terminating Call

2 - Detailed Procedure
Visitor PLMN
Home PLMN

International
SS7

VLR

Provide Roaming Number

(IMSI)

HLR
4

Roaming Number
(MSRN)

9
PAGING
REQUEST
(TMSI)

Send info
to I/C
(MSRN)

PAGE
(TMSI + LA)

11

Routing
Information
(MSRN)

PAGING
REQUEST 10
(TMSI + LA)

VMSC

1
MSISDN

BSS

Send
Routing
Information
(MSISDN)

IAM (MSRN)

GMSC

IAM
(MSISDN) 2

ISDN

PN
IAM
MSISDN
MSRN

: Initial Address Message

: Mobile Station Integrated Services Digital
network Number
: Mobile Station Roaming Number

IMSI
GMSC
VMSC
TMSI

:
:
:
:

International Mobile Subscriber Identity

Gateway MSC
Visitor MSC
Temporary Mobile Subscriber Identity

Mobile Terminating Call

3 - End to End Procedure
VMSC

BSS

MS

PAGING REQUEST

PAGING REQUEST
(TMSI or IMSI, LA)

IAM
(MSRN)

PSTN

GMSC
2

IAM
(MSISDN)

Dialing

CHANNEL REQUEST
(LAC, Cell ID)

IMMEDIATE ASSIGNMENT 6
(SDCCH or TCH)
CM SERVICE REQUEST
(Paging Response)

8
9

Ringing
10
12

PAGING RESPONSE
(TMSI or IMSI, LA)

Authentication procedure
Ciphering procedure
Setup, Assignment, Alerting
CONNECT

11
12

Address Complete Message

ANswer Message
Path
Established

Call Release
1 - Mobile Initiated

DISCONNECT

RELEASE
4

PSTN

Call in progress

DISCONNECT
RELEASE

RELEASE COMPLETE

CHANNEL RELEASE 6
7

MSC

BSS

MS

Release

RELEASE INDICATION
RF Channel Release
8
procedure
9

Release
tone

Call Release
2 - PSTN Initiated
1

3
BSC

4
5

BSS

BTS

4
5

MSC

REL
6

RLC

PSTN

Purpose:
informs the mobile
then releases radio
and network resources.
On hook

Mobile Originated Call

Request for Service

Authentication
Ciphering
Equipment Validation
Call Setup
Handovers
Call Release

Mobile Terminated Call

Paging
Authentication
Ciphering
Equipment Validation
Call Setup
Handovers
Call Release

Mobile Terminated Call

MS
Paging
Assignment CMD
(=TCH) on SDCCH

BTSTMSI Paged
on PCH
BSC

*RESP
MS
tunes
Allocate
Page
SDCCH
on SDCCH
REQ
MS Ch.
*
Assgn
CMP
over
( TMSI
AGCH
+ LAI)
over
RACH
BTS
* Phone rings

HLR
VLR
Query for
VLR info

Connect traffic Ch.to trunk

GMSC
frees SDCCH Query VLR
Page
Page RES
Assgn CMP for LAC and
Assign.
REQ
Paging
TMSI
the area
(+TMSI)
Route
toNetwork
MSC Alerting
MSC
BSC

AuC

Reply
(MSRN)
EIR

PSTN

BTS
Land to
Mobile call
(MSISDN)

Authentication and Ciphering procedure done as seen in Location Updation

TOPICS

GSM CONCEPTS
GSM SYSTEM ARCHITECTURE
GSM CHANNELS
GSM RADIO LINK
MOBILITY MANAGEMENT
CALL MANAGEMENT
RADIO RESOURCE MANAGEMENT

Radio Resource Management

Establish maintain and release stable connections

between MS and MSC
Manage Limited Radio and Terrestrial resources
Handover process is the sole responsibility of the RR
Layer
Functions of RR layer are performed by MS and BSC
and partly by MSC

Radio Resource Management

Power Control
Hand over Control
Discontinuous Transmission
Frequency Hopping

Power Control

BTS commands MS at different

distances to use different power levels
so that the power arriving at the BTSs Rx is
approximately the same for each TS
- Reduce interference
- Longer battery life

Handover
Means to continue a call even a mobile crosses the border of
one cell to another Procedure which made the mobile station
really roam
Handover causes
RxLev (Signal strength , uplink or downlink)
RxQual (BER on data)
O & M intervention
Timing Advance
Traffic or Load balancing

Handover Types

Internal Handover (Intra-BSS)

Within same base station - intra cell
Between different base stations - inter cell
External Handover (Inter-BSS)
Within same MSC -intra MSC
Between different MSCs - inter-MSC

Handover Types

GMSC

MSC
BSC

BSC

C-3
BSC
MSC

C-4

C-1

C-2

BSC

Intra BSC handover

HO performed
HO required
Activate TCH(facch)
with HoRef#

BSC

Acknowledges and
alloctes TCH (facch) if
1. Check for HO passed
2. Channel avail in new BTS

BTS 2

Periodic Measurement
Reports (SACCH)

Periodic Measurement
Reports

MS tunes into new frequency

and TS and sends HO message to
new BTS (facch)

HO cmd with HoRef#

Receives new BTS data(FACCH)

Release TCH

Cell 2
Periodic Measurement
Reports (SACCH)

Cell 1

BTS 1

Frequency plan and importance of BCCH

Sectored
antennas

B5
B6

B4

BPL frequency plan:

Broadcast frequencies :

B7

15 Broadcast channels = 48-62

15 Hopping channels

B3
B1

B8

= 32-46

B2
B12

MS ( monitoring the
broadcast radio B1 in idle
mode )

B9
B10
B11
F0

F1

F2

F3

F4

F5

F10

.. F

F11

F50

.. .. I

F,S,B exist in time slot 0 of each frame

What information does Broadcast Control channel

(BCCH) contain?

Serves as a Beacon for the Cell

Country Code (CC) and the Network Code (NC)

Location Area Identity (LAI)

List of neighboring cells which should be monitored by MS

List of frequencies used in the cell

Cell identity

Back

Location Updates
Location Updates can be classified into two:
Periodic Location Updates:
This occurs as per the timer set by the network operator. If the
MS does not perform this update the MSC marks the MS as
Detached on the VLR.
Location Update on a handover:
This occurs if during a handover the MS is moved into a new
Location Area Code (LAC).

1.

The MS is monitoring the BCCH and has all the decoded

information stored on the SIM ( including the LAC)

2.

As soon as the mobile is on a TCH it sends the signal

strength indication on the corresponding SACCH

3.

The BSC monitors the signal strengths and on analysis

sends a handoff request on FACCH. The handoff
process is completed on the FACCH.

4.

After the completion of call, the MS starts monitoring the

BCCH again. On finding the LAC (stored on SIM) and that
decoded from the BCCH to be different , the MS requests
a Location Update through SDCCH.

Back

Discontinuous Transmission

Discontinuous Transmission(DTX) allows the radio transmitter to

be switched off most of the time during speech pauses.
A Silence Indicator Block is transmitted at 500bps, which
generates a comfort noise
Down Link interference is decreased.
Up link battery is saved

Frequency Hopping

Frequency Hopping permits the dynamic switching of radio links from one
carrier frequency to another.
Base Band Hopping
At the BTS each the timeslot is shifted to another transceiver, which is
transmitting at the hop frequency. User will be connected to different
Transceivers depending on hop sequence.
Synthesis Hopping
At the BTS transceiver changes the frequencies used. The user will be
connected to only one transceiver.
Decreases the probability of interference
Suppresses the effect of Rayleigh fading

Add-on to GSM
network
: rate for GSM Evolution
Enhanced
Data
PCU; Packet Segmentation/re-assembly
and
scheduling
EDGETelecommunication
is an enhancementStandards
of GPRS
and CSD technologies.
Mobile
Universal
Radio channel
access
control
and
management
Based
on Architecture
the current GSM
technology
same TDMA
Innovative
Service
: VHE
Concept - -providing
the frame
us
Transmission
error
detection
and
retransmission.
structure,
same
bandwidth
(200
kHz).
same
look and feel of its personalized services independent of
the
Power
control

Uses
8-PSK modulation instead of GMSK. Surf the Internet while on the move
network
andmobility
terminal.
SGSN:
GPRS
Requires
good
propagation
conditions.
High Convergence
Speed
Circuit
Data Telecom/Datacom,
Global
:Switched
Fixed/Mobile,
Encryption
Allows
upto 48 kbps (EGPRS) and upto 28.8W@P
kbpsGateway
(ECSD) on
User Data
Rate:14.5kbps
:
public/private
Charging
every
radio
channel

Use multiple
timeslots
(max=8),
Adaptation of the information to the mobile
SMS
Mobile
Multimedia
driven
market.
160 to
-numeric
characters
GGSN
: Data:
Interface
the
PDN,
Internet

EDGE
helps
GSM-Only
operators
to
compete
with
UMTS.
Compression
henceRate
max
=- 115.2kbps.
of the
data
User
UMTS
Wideband
bearers
2GHz band ( 5 MHz per carrier), -max.
2Mbps
Data
: rate
9.6kbps
UMTS
Buffering of the information
Needs
duplexor
in interface
MS for
One
time
slotarate
over
the air
Max
user
data
: 21.4
kbps
simultaneous Tx and Rx
Dynamic rate adaptation to suit the radio conditions at
EDGE
EDGE
that time ( 9.05 kbps, 13.4 kbps, 15.6 kbps 21.4 kbps)

Wireless
Data
Data Application

GPRS
GPRS

HSCSD
HSCSD
SIM
SIM
Toolkit
Toolkit

GSM
GSM
DATA
DATA
W
@
P

WAP
WAP

Circuit Switched technology

Packet Switched technology

F
o
n
e

Internet

Mobile Network

Time

W@P Service

W@P Gateway

98

99

Technology for Applications

2000

2001

Coverage or Traffic Limitations

TRAFFICLIMITED
AREA
(10000
subscribers
per km2)

COVERAGELIMITED
AREA
(-75 dBm
at cell edge)

COVERAGELIMITED
AREA
(-70 dBm
at cell edge)

Erlang Concept
Erlang is the unit of statistical resource
use

Average number of busy channels

during the period of observation
(usually, the peak hour).
Erlang B
At any time, more than 1 user may request the same resource simultaneously. The use of such a
resource is associated with a blocking rate.
Erlang C
When more than 1 user request at the same time, instead of rejecting the extra calls, there is a
queuing system.

Different Types of Cells

EXTENDED-CELL:
macro cell with system coverage
extension ( 120 km) for coasts...

CONCENTRIC-CELL:
macro cell with system coverage
limitation inside another macro
MACRO-CELL:
antenna radiating above roofs
---> Wide Coverage ( 35 km)

High sensitivity to
interference
Requires "secured"
Frequency reuse pattern

PICO-CELL:
Antenna inside building
---> Very small coverage

MICRO-CELL:
Antenna below the roofs
---> small coverage

High isolation from

interferences
A few Frequencies
intensively reused

Cell Patterns

Cell Sectorization

TRI

OMNI

BI

Omnidirectional Site Antennas

Bi and Trisectorial Site Antennas

Link Budgeting

Calculation of the maximum coverage range of each cell in a specific environment.

Definition of planning tools parameters.
Based on the path loss calculation between the MS and the BS in both ways.
This calculation considers:

RF parameters of MS and BS,

system parameters (diversity gains...),
propagation parameters (shadowing),
physical installation parameters (antenna height),
environment classification.

- What is the maximum EIRP?

- What are the losses in
transmission and reception?
- Is diversity used?

EIRP:Equivalent Isotropic Radiated Power

- Beyond which distance the

communication will cut off?
- Is indoor coverage guaranteed?
- Is frequency hopping used?

- What is the minimum

equivalent sensitivity?
- What is the maximum
equivalent output power?
- What are the body losses?

Link Budget Parameters

Overview
Propagation Parameters:
- Incar, Indoor penetration factors
- Frequency 900, 1800, 1900 MHz
- Antenna Height
- Environment

Standard conf. DLNA conf.

Antenna Gain

Rx Sensitivity

Design Parameters:
Overlapping margin

Radio Link

Common cable Losses

Rx Sensitivity

Specific Tx Cable
Losses
Antenna Gain

Combiner losses

Rx Sensitivity

Tx PA Output
Power

Tx PA Output Power

MS

Rx Diversity Gain

Base Station
Duplexer
Combiner
Power Amplifier

Other factors for MS

Body Losses
Common cable losses

DLNA:Diversity Low Noise Amplifier

Link Budget Parameters

BTS TX Power Amplifier

2.5W PA

GSM 900 S2000L

DCS 1800 S2000L

PCS 1900 S2000L

25W PA

35W PA

20W PA

S2000E
S4000 Indoor S4000 Indoor S2000H
S4000 Outdoor

S4000 Indoor

30W PA
S8000 Indoor
S8000 Outdoor

S2000E
S2000H
S4000 Outdoor

S4000 Indoor
S8000 Indoor
S8000 Outdoor

S2000E
S2000H
S4000 Indoor
S4000 Outdoor

S8000 Outdoor

Link Budget Parameters

Combiners

H2D

4.5
4.5dB
dBLoss
Loss

4.9
4.9dB
dBLoss
Loss
C

Hy/2

TX

TX

2-Way
2-WayHybrid
HybridCombiner
Combinerwith
withDuplexer
Duplexer
allows Synthesized Frequency Hopping

TX TX TX TX

4-Way
4-WayCavity
CavityCombiner
Combinerwith
with
Duplexer
Duplexer
allows Baseband Frequency Hopping

Link Budget Parameters

Cable Losses

At the BS, for a 7/8 foam dielectric coaxial cable:

4 dB/100 m (900 MHz),
6 dB/100 m (1800 MHz),
Common cable losses for 40 meters: 2.5 dB (900 MHz) and 3.5 dB (1800 MHz).
Jumpers (up and down the feeder)
0.5 dB (800 MHz),
1 dB (1800 MHz).

Link Budget Parameters

BTS Antenna Gain

Omnidirectional antenna
Default 6.5 V with 11 dBi gain
Directional antenna for trisectorial site
Default 65 H / 6.5 V with 18 dBi gain

Link Budget Parameters

Mobile Station Parameters

900 MHz

1800/1900 MHz

TX PA Output
Power

33 dBm (2W)

30 dBm (1W)

RX Sensitivity

-102 dBm

-100 dBm

Antenna Gain

-2 dBi for Handheld

2 dBi for Car Kit

Common Cable
Loss

0 dB for Handheld
2 dB for Car Kit

Body Loss

3 dB for Handheld
0 dB for Car Kit

Link Budget Presentation

Parameters
Antenna Gain (65 )
18 dBi

Frequency
Base Height
Mobile Height
Environment

Jumper Loss
0.5 dB
Feeder Loss
3 dB

Penetration Factor 15 dB

Sensitivity
-110 dBm
Coupling system
Tx loss
4.5 dB

RXm

Body Loss 3 dB

Outdoor Minimum Field

95%: -80 dBm
Coverage Range
95%: 810 m

Cable Loss
0 dB

Antenna Gain
-2 dB

RX

TX

Output Power
30 dBm

RXd

Sensitivity
Max TX Output Power
44.8 dBm
Base Station

1800 MHz
40.0 m
1.5 m
Urban

-100 dBm

Options
Rx Diversity Gain: 5 dB
Overlapping Margin: 0 dB

Mobile

Link Budget Calculation

Exercise 1: S8000 INDOOR: OPERATING FREQUENCY 1800 MHz
BTS

MS

TX OUTPUT
POWER

30.00 W (44.8
dBm)

1.00 W (30.0
dBm)

COMBINER
LOSSES

5.0 dB

None

-110.0 dBm

-102.0 dBm

RX SENSITIVITY
RX SENSITIVITY
+
DIVERSITY
COMMON
CABLE
LOSSES
ANTENNA GAIN

-115.0 dBm

None

3.0 dB

0.0 dB

18.0 dBm

-2.0 dBm

BODY LOSSES

3.0 dB

OVERLAPPING
MARGIN

0.0 dB

INDOOR
PENETRATION
FACTOR

18.0 dB

Fading
Example of Field Strength Variation for GSM 1800
-10

Zoom on
Short Term Fading

-20
Measurement
Free Space

Field Strength (dBm)

-30

/2

-40

2m
-50
-60

Long Term Fading

-70
-80
-90
0

-100

500

1000

1500

2000

2500

3000

Distance (m)

3500

4000

4500

5000

Clutters

Thank you