uke kurniawan usman - 2005 1 gsm fundamental by uke kurniawan usman

Uke Kurniawan Usman - 20051

GSM Fundamental

By

Uke Kurniawan Usman


Agenda

Network Architecture Functional Layer of GSM Air Interface System Capacity Anti Interference Technology Network Planning Numbering arrangement


MSC/VLR

HLR/AUC EIR SC/VM

OMC

BSC

BTSPSTNISDN

PSPDN

MS

BSS

MSS

Um

Abis

BIEA

F

C

H

MSC/VLR

E

GSM Network Structure


Equipment used by mobile service subscribers for access to services.

Mobile Station ( MS )

Mobile EquipmentSubscriber Identity Module (SIM)

Mobile stations are not fixed to one subscriber. A subscriber is identified with the SIM card.


Base Transceiver Station (BTS)

Wireless transmissionWireless diversityWireless channel encryptionConversion between wired and wireless signalsFrequency Hopping

BaseBand Unit: voice and data speed adapting and channel codingRF Unit: modulating/demodulating, transmitter and receiverCommon Control Unit: BTS operation and maintenance

GSM Network Entity Base Transceiver Station

( BTS )


Managing Wireless network-BSSMonitoring BTS

Controls:Wireless link distribution between MS and BTSCommunication connection and disconnectionMS location, handover and pagingVoice encoding, transecoding (TC), rate,

adaptation, The operation and maintenance functions of BSS.

Base Station Controller( BSC )

GSM Network Entity


holds all the switching functions

manages the necessary radio resources,

updating the location registration

carrying out the inter-BSC and inter-MSC tender

Inter-working with other networks (IWF).

GSM Network Entity

Mobile Service Switching Center( MSC )


Manages the mobile subscribers database

subscriber information

part of the mobile location information

3 identities essentialthe International Mobile subscriber Identity

the Mobile station ISDN Numberthe VLR address

GSM Network Entity

Home Location Register( HLR )


Visitor Location Register( VLR )

dynamically stores subscriber information needed to handle incoming/outgoing calls Mobile Station Roaming Number When a roaming mobile enters an MSC area. This MSC warns the associated VLR of this situation; the mobile enters a registration procedure through which it is assigned a mobile subscriber roaming number (MSRN)

Temporary Mobile Subscriber Identity, if applicableThe location area in which the mobile has been registeredData related to supplementary service parameters

GSM Network Entity


AUC/EIR

Authentication Center(s) (AUC)

Providing the authentication key used for authorizing the subscriber access to the associated GSM PLMN.

Equipment Identity Register(s) (EIR)

Handling Mobile Station Equipment Identity

GSM Network Entity


Agenda

Network Architecture Functional Layer of GSM Air Interface System Capacity Anti Interference Technology Network Planning Numbering arrangement


O AM

S ervice carrie r

CM

MM

RR

Subsc riber

Tran smissi on

Overview: Function Layers of GSM-1


CM

MM

RR

LAPDm

MS

RR

LAP Dm

Um

LAPD

BTSM

LAPD

Abis

RR

BTSM SCCP

MTP3

BS SAP

BTS BSC

MTP2

SCCP

MTP3

BS SAP

MTP2

CM

MM

MSC

A

Protocol Stack Structure of GSM


Agenda

Network ArchitectureFunctional Layer of GSMAir InterfaceSystem CapacityAnti Interference TechnologyNetwork Planning Numbering arrangement


Concept: channel is composed of a

series of timeslots of periodicity. Different signal energies are distributed into different timeslots. The adjacent channel interference is restricted by connection choosing from time to time. So the useful signal is passed only in the specified timeslot.

GSM adopts TDMA/FDMA mode channel width: 200KHz each channel has 8 timeslots

GSM adopts TDMA/FDMA mode channel width: 200KHz each channel has 8 timeslots

User 1

User 2

User 3

Frequency

time

TDMA


GSM Timeslot and Frame structure

time

Frequency

BP15/26ms

200KHz

interval


Frequency Resource

GSM900 :

up: 890~915MHz

down: 935~960MHz

duplex interval: 45MHz

bandwidth: 25MHz ，frequency interval: 200KHz

GSM1800 :up: 1710-1785MHz down: 1805-1880MHzduplex interval: 95MHz ， working bandwidth: 75MHz ，frequency interval: 200KHz

EGSM900 :

up: 880~890MHz

down: 925~935MHz

duplex interval: 45MHz

bandwidth: 10MHz ，frequency interval: 200KHz

GSM1900MHz:up:1850~1910MHzdown:1930~1990MHzduplex interval: 80MHz ， working bandwidth: 60MHz ，frequency interval: 200KHz


1800MHz

1900MHz

900MHzWhich one?

Single Band Network General Priority

High

Low

Reason

For SubscriberFor Operator

Propagation Characteristic

New Operator

Frequency Resource


1800MHz

1900MHz

900MHz

Single Band Network

Single Band

Dual Band

Triple Band

In a sense, the network determines the handsets can be selected.But nowadays, most handsets support dual band.

Frequency Resource


Propagation characteristic

Cell coverage radius :

The higher the propagation frequency

The higher the propagation loss

The smaller the cell coverage radius.

900MHz

1800MHz

1900MHz

Single Band Network

Frequency Resource

We know


0 2045 2046 2047321 2044

3210 4947 48 50

0 24 251

1 super high frame = 2048 super frame = 2715648 TDMA frame

1 super frame = 1326 TDMA frame （ 6.12s ）

0 1 2524 504910

1 multiplex frame = 26 TDMA frames （ 120ms ）1 multiplex frame = 51 TDMA frame

0 1 765432

1 TDMA frame = 8 timeslot （ 120/26 = 4.615ms ）

BCCHCCCHSDCHSACCH/TCH

FACCH

Timeslot and Frame structure


0 1 765432

8 9 151413121110

16 17 232221201918

The physical channel adopts FDMA and TDMA techs.On the time domain, a specified channel occupies the same timeslots in each TDMA frame, so it can be identified by the timeslot number and frame number.

Physical Channel


channel

TCH

CCH

Voice CH

Data CH

FR Voice Traffic Channel (TCH/FS)

HR Traffic Channel (TCH/HS)

4.8Kbit/s HR TCH (TCH/H4.8)

9.6Kbit/s FR TCH(TCH/F9.6)

4.8Kbit/s FR TCH (TCH/F4.8)

BCH

FCCH (down)SCH (down)BCCH (down)

CCCHRACH (up)AGCH (down)

PCH (down)

DCCHSDCCHFACCHSACCH

14.4Kbit/s FR TCH (TCH/F14.4)

Enhanced FR Traffic Channel (TCH/EFR)

Channel Type-Summary


Channel Type

Traffic ChannelTransmit voice and data

Signaling Channeltransmit the signaling and synchronous data between BTS and MS.


Channel Type

BCH :

Frequency Correction CHannel （ FCCH）-- for MS error correction

Synchronous Channel （ SCH)

-- for MS frame synchronization and BTS recognization

Broadcasting Control CHannel （ BCCH）-- broadcasting information(cell selection information, etc..)


Channel Type

DCCH

Self-help Dedicated Control Channel （ SDCCH ）for channel distribution information transmission

Slow Associated Control Channel （ SACCH ）combined with one traffic channel or SDCCH, to transmit some specific information of user information

Fast Associated Control Channel （ FACCH ）combined with one traffic channel, taking the same signal as SDCCH. It occupies the service channel to transmit signaling information.


Structure of 51-frame Control CH

SF B C

R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R

51 Frame

SF C C SF C C SF C C I

R R R R R R R R R R

D0 D1 D2 D3 D4 D5 D6 D7 A0 A1 A2 A3

SF C C

R R R R R R R R R R

III

D0 D1 D2 D3 D4 D5 D6 D7 A4 A5 A6 A7 III

A1 A2 A3 III

A5 A6 A7 III

D0 D1 D2 D3 D4 D5 D6 D7 A0

D0 D1 D2 D3 D4 D5 D6 D7 A4

SF B C SF C C SF D0 D1 SF D2 D3 ISF A0 A1

SF B C SF C C SF D0 D1 SF D2 D3 ISF A2 A3

D3

D3

R R

R R

A2 A3

A0 A1

D2

D2

SF

SF

D0 D1

D0 D1

R R R R R R R R R R R R R R R R R R R R R R R

R R R R R R R R R R R R R R R R R R R R R R R

F：FCCH S：SCHB：BCCH C：CCCH(CCCH=PCH+AGCH+RACH)R：RACH D：SDCCHA：SACCH/C I： idle

BCCH+CCCH(Downlink)

BCCH+CCCH(uplink)

8 SDCCH/8(Downlink)

8 SDCCH/8(uplink)

BCCH+CCCH+4SDCCH/4(Downlink)

BCCH+CCCH+4SDCCH/4

(uplink)

(a) FCCH+SCH+BCCH+CCCH

(b) SDCCH/8(0,...,7)+SACCH/C8(0,...,7)

(c) FCCH+SCH+CCCH+SDCCH/4(0,...,3)+SACCH/C4(0,...,3)


Channel Combination Type

Several logic channels combine together in some way to form some specific types of channel to transmit user data or signaling information. They are called combined channels. One combined channel can be mapped to a physical channel.

There are the following combined channels:a TCH/F + FACCH/F + SACCH/TFb TCH/H(0,1) + FACCH/H(0,1) + SACCH/TH(0,1)c TCH/H(0,0) + FACCH/H(0,1) + SACCH/TH(0,1) + TCH/H(1,1)d FCCH + SCH + BCCH + CCCHe FCCH + SCH + BCCH + CCCH + SDCCH/4(0...3) +

SACCH/C4(0...3)f BCCH + CCCHg SDCCH/8(0 ..7) + SACCH/C8(0 .. 7)

CCCH = PCH + RACH + AGCH


Small capacity cell with only 1 TRX

TN0: FCCH+SCH+CCCH+BCCH+SDCCH/4(0,_,3)+SACCH/C4(0,_,3);TN1-7: TCH/F+FACCH/F+SACCH/TF

The medium-size cell with 4 TRXs1TN0 group: FCCH+SCH+BCCH+CCCH;

2 SDCCH/8(0,_,7)+SACCH/C8(0,_,7);29 TCH/F+FACCH/F+SACCH/TF

Channel Assignment inside cells


Large-size cell with 12 TRXs1 TN0 group: FCCH+SCH+BCCH+CCCH;1 TN2 group, 1 TN4 group and 1 TN6 group: BCCH+CCCH;5 SDCCH/8(0,_,7)+SACCH/C8(0,_,7);87 TCH/F+FACCH/F+SACCH/TF

Channel Assignment inside cells


Agenda



Cell Mode Layout

O

Omni-directional cell

Adopt omni-directional antenna ，the overall directional propagation characteristic is the same.

Directional cell

In general, cell with multi-sector is in common use. Every directional cell adopts directional antenna.


Capacity

When the traffic is very low, and no possibility for quick increment, Omni-directional cell is used in common. Otherwise, we suggest to adopt the sector cell.

Note: TRX-transceiver,each TRX handles 1 frequency.

Coverage AreaSector cell is often used to enlarge the cell coverage radius because of the higher antenna gain.For special coverage ,such as road coverage, two-sector cell is adopted firstly.

BTS Mode


Erlang :

the traffic intensity of a totally occupied channel (i.e. the call hour of a unit hour or the call minute of a unit minute). For example, the traffic of a channel occupied for 30 minutes in an hour is 0.5 Erlang)

GOS:

defined as the probability of call blocking or the probability when the call delay time is longer than a given queuing time.

System capacity


Agenda



Reasons for Interference

The transmission path is very complex, ranging from the simple line-of-sight transmission to encountering such terrain as buildings, hills and trees. Wireless channels are extremely unpredictable.

Abrupt drop, or fading, of signal strength in the land mobile wireless channel is quite common. The fading feature of the mobile channel depends on the radio wave propagation environment.


Reasons for interference

Environmental factors:

• Terrain (mountains, hills, plains, water bodies, etc.);

• The quantity, heights, distribution and materials of buildings;

• The vegetation of the region;

• Weather conditions;

• Natural and artificial electromagnetic noises;

• Frequency;

• How MS is moved.


Co-Channel Interference

Conception: the interference among the signals of co-

channel cells is called co-channel interference.

Result from :Frequency reuse

Reduction method:co-channel cells must physically be

spaced at a minimum interval to ensure adequate isolation of transmissions.

Interference


Adjacent Channel InterferenceConception:

The signal interference from the frequency adjacent to that of the signal used is called adjacent channel interference.

Reduction method: accurate filtering and channel allocation

(maximizing channel intervals of the cell). Interval of frequency reuse inter-cell interference, such as C/I, C/A

Interference


FH technology

Dynamic power control (DPC)

Discontinuous Transceiving

(DTX)

Diversity receiving technique

Solution -Anti-interference


Reason: counteract Rayleigh Fading scatter interference among multiple calls

Types: Base band frequency hopping

keeps the transmission and receiving frequency of each carrier unit unchanged, but merely sends FU transmission data to different carrier units at different FN moments.

radio frequency hoppingcontrols the frequency synthesizer of each transceiver, making it hop according to different schemes in different time slots.

Frequency Hopping Technique


Discontinuous Speech Transmission (DTX)

TRAU BTS

BTS MS

Speech frame

480 ms

comfort noise frame

Two aims can be achieved by adopting DTX mode:

•lower the total interference electric level in the air

•save transmitter power.


The multi-path propagation of radio signals causesmagnitude fading and delay time.

Space Diversity (antenna diversity)

Polarization Diversityorthogonal polarization diversity. horizontal polarization and vertical polarization.

Frequency DiversityThe working principle of this technology is that such fading won’t take place on the frequency outside the coherence bandwidth of the channel.

Diversity Reception Technology


Agenda



“4 3” reuse mode: one group includes 3 sectors /site ,12 frequency which

are distributed to 4 sites. Every site owns 3 frequency.

Frequency Reuse

A3

D2B1

C3

B2D1

D3

A2C1

B3

C2A1

B3

C2A1

A3

A1B1

D1

D3D2

C3

B2A1

C3D2

C3

C1

D2B1C2A1

A2C1

D3


A3

C2B1

B3

A2C1

C3

B2A1

A3

C2B1

B3

A2C1

B3

A1C1

A1

A3A2

C3

B2A1

A3A3

C3

C1

B2A1B2A1

A2C1

B3

Frequency Reuse

“3 3” reuse mode: one group includes 3 sectors /site ,9 frequency which are

distributed to 3 sites. Every site owns 3 frequency.


Agenda



Numbering Arrangement

International Mobile Subscriber Identification number (IMSI)

International Mobile Subscriber Identification number (IMSI)

It identifies a unique international universal number of a mobile subscriber, which consists of MCC+MNC+MSIN.1) MCC: country code, 4602 ） MNC: network code, 00 or 013 ） MSIN: subscriber identification, H1H2H3H4 9XXXXXX, H1H2H3H4: subscriber registering place H1H2: assigned by the P&T Administrative Bureau (operator )to different provinces, to each province H3H4: assigned by each province/city

the IMSI of user will be written into the SIM card by specific device and software and be stored into the HLR with other user information.


It is the subscriber number commonly used. China uses the TDMA independent numbering plan:

CC+NDC+ H1H2H3H4 +ABC

CC: country code, 86NDC: network code, 135—139, 130H1H2H3H4: HLR identification code ABCD: mobile subscriber number inside each HLR

Mobile Subscriber ISDN Number （ MSISDN）Mobile Subscriber ISDN Number （ MSISDN）



International Mobile Equipment Identification code(IMEI)

International Mobile Equipment Identification code(IMEI)

It will uniquely identify a mobile station. It is a decimal number of 15 digits. Its structure is:

TAC+FAC+SNR+SP

TAC=model ratification code, 6 digitsFAC=factory assembling code, 2 digitsSNR=sequence code, 6 digitsSP=reserved, 1 digit



Mobile Subscriber Roaming Number (MSRN)

Mobile Subscriber Roaming Number (MSRN)

The MSRN is temporarily distributed to the subscriber by the VLR according to the request by the HLR when this subscriber is called. The MSRN is released and can be assigned to other subscriber later.

　　 CC + NDC + 00 + M1M2M3 + ABC　　 CC: country code, 86　　 NDC: mobile network code, 135—139, 130 　　 M1M2: same as the H2H3 of MSISDN　　 ABC: 000 -- 999



Temporarily Mobile Subscriber Identification Number (TMSI)

Temporarily Mobile Subscriber Identification Number (TMSI)

To insure the IMSI security, the VLR will assign an unique TMSI number for the accessed subscriber. It is used locally only and is a 4-byte TMSI number BCD code.


uke kurniawan usman - 2005 1 gsm fundamental by uke kurniawan usman

Documents