systra training programme

SYSTRATraining

2 © Nokia Siemens Networks Presentation / Author / DateFor internal use

INTRODUCTION

&

EXPECTATIONS


TRAINING TIMING


09:30 To 11:00 – Training

11:00 To 11:15 – Break


13:00 To 14:00 – Lunch Break


15:30 To 15:45 – Break

15:45 To 17:00 - Training


Contents

Introduction to GSM Digital Communications Traffic Management Signalling Transmission Network Planning & Optimization Nokia Implementation Next Step


Introduction to GSM


Module ObjectivesAt the end of this module, you are able to:

• Fundamentals of Cellular Systems

• GSM evolution

• Advantages of GSM over analogue networks

• Interfaces of GSM networks


Basic concept - 1GSM vs. fixed network Telephony

Local Exchange

MobileSwitchingCentre

fixed medium

Mobile Station

fixed location

Variable Location

Diffuse Medium

Telephone

SONOFON

M N


Telephony Communication is a basic need in today’s world. Telephone has become part of life.

Fixed Line Telephony

Shortcomings

No Mobility

Long wait for new connections

Security problems.

Prone to Failures(Line disconnection etc)

Very little in the name of value added services

Telephone


Wireless Communications ModelDisplay

Acoustic coupler

Satellite dish Reciever

Transmitter

Source

Media of transmission is Radio Media of transmission is Radio FrequencyFrequency

Display

Reciever

Transmitter

Source

IBM PS/2

ASCII Printer


Types Of Wireless Communications

SimplexThe direction of transmission is in one direction only.e.g. Broadcast services?(AM/FM Radios,Television)Paging Services

In this type of communication there is a transmitter which transmits RF carrier ( modulated with information signal), this is received by the receiver which demodulates the information.


•Half Duplex The direction of transmission is alternate in both directions, e.g. Trunked Radios.

Direction of transmission is in both directions but it is not simultaneous, it is alternate.

Both the ends will have transmitter plus receiver so that at a time if one end transmits the other end will receive only and vice versa.

Push to talk radios are commonly used by police and military.


Duplex

The direction of transmission is simultaneous in both directions, e.g. Cordless Telephones, Mobile Phones, Microwave Radios.

In Duplex transmission both the terminals will transmit and receive simultaneously. This is the requirement in today’s world requiring advanced wireless mobile applications.

Definitely simultaneous communication is not possible on the same channel.


Wireless Communications BandsWireless Communications Bands

MF : 300KHz-3MHz(AM Radio)

HF : 3 MHz-30MHz

VHF : 30MHz-300MHz(FM Radio,

Paging services)

UHF : 300MHz-3GHz(Mobile Radios, Cordless

Phones)

SHF : 3GHz-30GHz(Microwave Band)

Selection of Band depends upon Application

Frequency Band is subdivided into Application Bands

Application Band is further divided into Technology Channels


GSM History19811981 analogue cellular introduced

Franco-German study of digital pan-european cellular system

19821982 Groupe Spécial Mobile (GSM) formed within CEPT

19861986 Permanent group to create standards for a digital system

19871987 MoU signed by over 18 countries

19891989 GSM was moved into the ETSI organisation

GSM name changed to Global System for Mobile communications.

The committees working on the system changed from GSM to SMG

19901990 DCS1800 (edited GSM900) specification developed

19921992 Australia was the first non-European country to join the MoU


GSM History Continued….

19941994 First GSM Network was launched in South Africa

By December 1994 there were 69 GSM networks in operation

19981998 HSCSD (High Speed Circuit Switched Data) trials in Singapore

19991999 First mobile data call using GPRS in a live network was made

20012001 MMS (Multimedia Messaging Service) has been standardized

20032003 UMTS Network operators in Europe..


GSM Evolutionary Steps


Scenarios across GSM in the World

USA: PCS1900

UK: GSM900DCS1800

Thailand: DCS1800

Canada:PCS 1900

Argentina,Brazil,Chile:DCS 1800 Malaysia:

DCS 1800

CIS, Denmark, Finland,France, Germany,Greece, Hungary,Poland, Norway, Sweden, Switzerland: GSM900DCS 1800

Singapore: DCS1800

Hong Kong:PCS 1900


StandardisationETSI

European Telecommunications Standards Institute• Financed by EU

• Co-operation of suppliers and operators

• Specification of European telecommunications standards

ETSI- standards :• Cellular GSM 900/1800 - GPRS - UMTS

• Cordless DECT

• Paging ERMES

• Trunked radio TETRA


GSM Standards

The GSM Standard is divided into phases (phase 1, phase 2 and phase 2+) all the phases has been finalized by ETSI.

Many of the GSM networks in operation today are currently using the phase 2+. However many of the GSM network operators are starting to implement UMTS (3G support).

The ETSI GSM standard specification is around 5500 pages, and are divided into12 series.


GSM Status

Specification start-up: 1980

First network in operation: Jan. 1992 (Radiolinja, Finland)

Forecast in 1995:

• At the ITU's Telecom '95 event, were stated that we will reach 100 million subscribers Worldwide before the year 2000.

September 1997: ~55 million subscribers.~1 new subscriber each second.~250 networks in 110 countries.

July 1998:

• More than15 months early then year 2000 the magic figure of 100 million subscribers was reached.

Today : Over 200 million subscribers. 369 networks in 137 countries.


NMS

NSSBSS

GSM Architecture & Interfaces

BSCHLR/AC/EIR

TCSM

MSC/VLR

BTS

AbisInterface

AterInterface

AInterface

AirInterface

TC

Ater’Interface

O&M Interface


GSM Architecture & Interfaces

BSC

HLR/AC/EIRTCSM

MSC/VLR

BTS

AbisInterface

AterInterface

AInterface

AirInterface

TC

Ater’Interface

Air interface OPEN• 13 kb/s traffic channels• 8 channels / TRX• some channels reserved for signalling• blocking

Ater interface PROPRIETARY• 16 kb/s traffic channels• up to 120 traffic channels / 2M frame• 64 kb/s CCS#7 signalling• 64 kb/s channels for X.25 NMS connection• blocking

Abis interface PROPRIETARY• 13 kb/s traffic channels• up to 96 traffic channels / 2M frame• one TRXSIG signalling channel / TRX• one BCFSIG signalling channel / BTS• 16, 32 or 64 kb/s signalling rates

A interface OPEN• 64 kb/s traffic channels• 30 traffic channels / 2M frame• 64 kb/s CCS#7 signalling• 64 kb/s channels for X.25 NMS connection


Interfaces in GSM

Um : MS - BTS (air or radio interface)A : MSC – BSCAbis : BSC – BTS (proprietary interface)Ater : BSC – TRAU (sometimes called Asub)

(proprietary interface)B : MSC – VLRC : MSC – HLRD : HLR – VLRE : MSC – MSCF : MSC – EIRG : VLR - VLR.


Advantages of GSM

•GSM uses radio frequencies efficiently, and due to the digital radio path, the system tolerates more intercell disturbances.

•The average speech quality is better than in analogue systems.

•Data transmission is supported throughout the GSM system.

•Speech is encrypted and subscriber information security is guaranteed.

•With ISDN compatibility, new services are offered.

•International roaming is technically possible within all countries using the GSM system.

•The large market increases competition and lowers the prices both for investments and usage.


GSM Specifications

One reason for the major success of GSM is, that it is very accurately standardised. The standard is open, i.e. it is available to everyone. The European Standards Telecommunications Institute (ETSI) is responsible for the GSM standards. The GSM technical specifications are grouped in this way:

01 General Description of a GSM PLMN02 Services03 Network Functions04 MS - BSS Interface05 Radio Path06 Speech Processing Functions07 Terminal Adaptation Functions08 BSS - MSC Interface09 Network Inter Working10 Service Inter Working

11 Type Approval Procedures12 Operation and Maintenance


Basic Idea of Digital Communication


Transmission Techniques


Transmission media

Transmission techniques

Transmission methods

Fibre

Coaxial cable

Copper cable

Microwave radioTerrestrial/satellite

PDH SDH

PCMISDN ATM

HDSL

CATV

Transmission Techniques


Transmission TechniquesMultiplexing

ITU- Standard:• 8000 samples per sec @ 8bit = 64 kbit/s

• 32 * 64 kbit/s = “2 Mbit/s” line

Lines can be de-/ multiplexed into lines of higher data rates• 8Mbit/s, 34 Mbit/s, 140Mbit/s etc...

....

32 * 64 kbit/s

MUX

2 Mbit/s MUX/deMUX

1 sec1 sec

8 Mbit/s2 Mbit/sMUX/

deMUX

1 sec

....

32 * 64 kbit/s

MUX


Transmission TechniquesPDH

PDH (Plesiochronous Digital Hierarchy)• Voice spectrum ~ 4kHz

• Sampling rate 8 kHz

• 8 bits per sample

• Divided into 32 TS (TDM)USA : 24 timeslots

Higher Order PDH Bitrates

Europe : 2.048 Mb/sUSA : 1.554 Mb/s

M

U

XM

U

X

140 M

34 M

34 M

34 M

34 M

8 M8 M

8 M

8 MM

U

X

2 M

2 M

2 M

2 M


SDH (Synchronous Digital Hierarchy)• All network elements are synchronized to Primary Rate

Clock (PRC)

• Worldwide standard : interfacing to USA possible

Europe USA• STM- 1c (51.7 Mb/s) = STS-1

• STM- 1 (155.52 Mb/s) = STS-3

• STM- 4 (622.08 Mb/s) = STS-12

• STM-16(2488.32 Mb/s) = STS-48

• STM-64(9953.28 Mb/s) = STS-192STM-4

STM-1STM-1STM-1STM-1

Transmission TechniquesSDH


Leased Lines

Transmission lines rented from a “3rd party” operator

Leased line provider is usually also a competitor

Contra• High operating costs• Unpredictable lead times

(installation)• Difficult to deploy (may

include digging, groundwork..)

• No control over the physical route or the quality of the link

Pro• No implementation

effort for buyer• No extra

infrastructure to buy• Long distances are

uncritical

Analyse cost structure of Leased Line tariffs to decide

whether LL or microwave links are more economical


GENERAL RULE for TS allocation0 : Synchronization1 - 24 : TCH25 - 30 : TRX/BCF SIG31 : Loop control

Max 12 TRX per 2 Mbit frame

AbisInterface

AirInterface

BSCMSC

AInterface

Ater’Interface

TC SM

AterInterface

BTS2

BTS1

bits 1 2 3 4 5 6 7 8TS

0 Synchronisation1 BTS 12 TRX 13 BTS 14 TRX 25 BTS 16 TRX 37 BTS 28 TRX 19 BTS 210 TRX 211 BTS 212 TRX 313 BTS 314 TRX 115 BTS 316 TRX 217 BTS 318 TRX 319 BTS 320 TRX 421 BTS 322 TRX 523 BTS 324 TRX 625 BTS 1 TRX 1 SIG BTS 1 BCF SIG BTS 1 TRX 2 SIG

26 BTS 1 TRX 3 SIG BTS 2 TRX 1 SIG BTS 2 BCF SIG

27 BTS 2 TRX 2 SIG BTS 2 TRX 3 SIG

28 BTS 3 TRX 1 SIG BTS 3 BCF SIG BTS 3 TRX 2 SIG



31 Loop bits / LCB / MCB

BTS 11+1+1

BTS 21+1+1

BTS 32+2+2

Leased Lines2 Mbit Frame Allocation (Abis)


Modulation


Modulation is the process of encoding information from a message source in a manner suitable for transmission

Modulating signal = baseband signal Modulated signal = bandpass signal

Demodulation is the process of extracting the baseband message from the modulated carrier

Modulation TechnologiesBasics

Modulation

fc

bandpass

f0

baseband


Modulation TechnologiesModulation in GSM

GMSK Gaussian Minimum Shift Keying

• Simple binary digital phase modulation scheme

• Excellent power and bandwidth efficiencies

Constant envelope & continuous phase • Noise-resistant

• Limited bandwidth

Implementation of transmitters and receivers are easy and cheap


Channelization can be done by three methodsFDMA (Frequency Division Multiple Access)Each terminal (MS) has full time use of part of the spectral allocation. The FDMA technique divides the allocation in to a number of narrowband portions (channels). Each mobile station confines its signal energy within an allocated channel.

TDMA (Time Division Multiple Access )In TDMA each terminal has part time-use of part of the spectral allocation.TDMA technique breaks down the allocation in to a number of time slots (channels). Each mobile station confines its signal energy within an allocated time slot.

CDMA ( Code Division Multiple Access)In CDMA each terminal has full-time use of the entire spectral allocation and spreads its signal energy over the entire bandwidth. Base stations and terminals use codes unique to each signal to distinguish those signals coincident in time and frequency.


GSM band is divided in to 200 KHz channels.

All the mobile technologies do not need very large bandwidth for single user communication. Because of Duplex requirements a pair of channels is required for simultaneous communication.

Power

FDMAFrequency

Time

Channelization MethodsChannelization Methods

FDMA FDMA


FDMA / TDMA Grid

Frequency separation is 200 KHz in case of GSM and 30 KHz in case of IS-54

There are 8 time slots in case of GSM and 6 time slots in case of IS-54

Power

FDMA/TDMA Frequency

Ti me


Channelization Methods

Power

Time

CDMA Channels

Frequency Channel is divided in to code channels.Each 1.25 MHz FDMA channel is divided in to 64 code channels


Physical channel and TDMA frame

TDMA frame= 8 timeslots

01

23

45

76

01

23

45

76

01

23

45

200 kHz

Physcial channel, e.g. allocatedto one

subscriber with FR voice &no frequency hopping

frequencytim

e

TDMA frame

TDMA:

Is a method of sharing a resource (in this case a radio frequency) between multiple

Users by allocating a specific time (known as a time slot) for each user.

TDMA frame is defined as a grouping TSs that are numbered 0 to 7 as shown above.

Its has duration of 4.615ms ( 8 * 577us)


Power Budget


Installation Examples

Pole mounting for roof-top mounting

Tower mounting for directional antennas


Antennas Categories

Omnidirectional antennas• Radiation patterns is constant in the horizontal

plain

• Useful in flat rural areas

Directional antennas• Concentrate main energy into certain direction

• Larger communication range

• Useful in cities, urban areas, sectorised sites


Power BudgetBasics

Power budget is used to calculate the maximum allowed path loss

Main factors depend on equipment characteristics • BTS & MS TX power

• BTS & MS RX sensitivity

Other factors can be classified into 3 categories and have to be estimated

• Loss factors

• Gain factors

• Margins


path loss = 154 dB

combiner loss = 5 dB

Feeder Loss = 4 dB

Rx Sensitivity- 102 dBm

Tx Power45 dBm (30W)

AntennaGain = 16dBi

- 102 dBm

52 dBm

36 dBm

40 dBm

Power BudgetDownlink


path loss = 154 dBFeeder Loss = 4 dB

Tx Power33 dBm (2W)

AntennaGain = 16 dBi

DiversityGain = 4 dB

33 dBm

- 121 dBm

- 101 dBm

- 105 dBm

Rx Sensitivity -105 dB

Power BudgetUplink


~ 3 … 5 dB losses 50 … 70% of

signal power is lost before even

reaching the TX antenna

Power BudgetLoss Factors

At BS side• Connectors (UL/DL)

• Cables (UL/DL)

• Isolator (DL)

• Combiner (DL)

• Filter (UL/DL)

At MS side• MS Antenna

– Polarization (UL/DL)

– Connection (UL/DL)

• External cable

man

y m

ete

rs

cables &connectors

filter

combiner

BS output


Power BudgetGain Factors

At BS side

• Antenna gain (UL/DL)

– Main antenna parameter

– Slight difference between DL and UL

– The antenna models in use should be defined at the very beginning of the project

• Diversity gain (UL)

– Diversity can be implemented in many ways, with different gains

• LNA gain (UL)

• Booster or power amplifier gain (DL)

• Frequency hopping gain (UL/DL)

– FH improves average link quality, but it isn’t taken into account in power budget calculations

At MS side

• External antenna


Erlang


ErlangDefinition

Erlang is the unit of traffic• Definition

2 formulas• Erlang B: for systems that support no queuing

• Erlang C: for systems that support queuing

Seconds 3600

)()( Erlangs

timeonconversatiaveragehourpercallsx

Agner Krarup Erlang (1878-1929)


Traffic Management


Module ObjectivesAt the end of this module, you are able to:

• Subsystems of GSM

• Different network elements (generic architecture)

• Mobility concept (handover, location update, paging)

• Supplementary services offered by GSM networks


BTS

Network Architecture


System Overview

BaseStation

ControllerBSC

Public Switched

Telephone Network

BaseMobile Station

(MS)

MobileSwitching

CentreMSC

(PSTN)

StationSubsystem

(BSS)

A-Inter

A-bis

Um

2 Mbit/s PCMAir Interface

BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Equip. IdRegister

EIR

Authen.CentreAUC

VisitorLocationRegister

VLR

HomeLocationRegister

HLRMobile

SwitchingCentreMSC

MAPISUP / TUP

MAP

MAP MAP

ISUP / TUP

ISUP / TUP

MAP


GSM Network Interfaces

Rf Test Equipment

PSTN

SS#7SS#7LAP-DLAP-DmAbis Interface

1

24

57

8*

0

3

6

9

#

1

24

57

8*

0

3

6

9

#

1

24

57

8*

0

3

6

9

# BTS

BTS

BTS

BSC

BSC

BSC

MSC

MSC

MSC

Um Interface

Protocol Analyzers

Protocol Analyzers

Protocol Analyzers


System Building Blocks

HomeLocation Register

VisitorLocation Register

Mobile Switching Centre

BaseStation Controller

Base TransceiverStation

MSC BTSBSC

VLR

HLR

SONOFON

M N


HLR (Home Location register)

“Home Base” of information regarding customers subscribing to a particular operators GSM network

Keeps track of subscriber profile, conditions and whereabouts

MSC BTSBSC

VLR

HLR

SONOFON

M N


BTS

HLR contains

Subscriber information:

• IMSI (International Mobile Subscriber Identity)

• MSISDN (International Mobile Station ISDN Number)

• MS Category (e.g. payphone)

• Authentication vectors (RAND, SRES and Kc: AUC and SIM)

• Allowed services (subscription data)

Mobile location information:

• VLR number

• (MSRN - Mobile Station Roaming Number)


VLR (Visitor Location register)Database with information about mobile users present/active in the network segment served by the MSC

Handles true visitors as well as subscribers of the operator himself

MSC BTSBSC

VLR

HLR

SONOFON

M N


BTS

VLR contains.

Subscriber information:

• IMSI

• TMSI - Temporary Mobile Subscriber Identity

• MS category

• Authentication vectors

• Allowed services

Mobile location information:

• MSRN - Mobile Station Roaming Number

• LAI - Location Area Identity


BTS (Base Transceiver Station)

Contains the radio transmitters and receivers (transceivers) covering a certain geographical area of the GSM network

MSC BTSBSC

VLR

HLR

SONOFON

M N


BSC (Base Station Controller)

Controls a group of BTS’s in relation to power control and handover.

The combination of a BSC and its BTS’s is called a Base Station Subsystem (BSS).

The interface between the BTS & BSC and the is called the A-bis interface.

MSC BTSBSC

VLR

HLR

SONOFON

M N


MSC (Mobile Switching Centre)Serves a number of BSS’s (Base Station Subsystem) via the A-interface.

Responsible for call control (set-up, routing, control and termination of the calls)

Management of inter-MSC handover and supplementary services, and for collecting charging/accounting information.

Gateway to other GSM networks and public-switched networks)

MSC BTSBSC

VLR

HLR

SONOFON

M N


BTS

AUC - Authentication Centre

Contains the individual subscriber-identification key (also contained in the SIM), and provides the subscriber data to the HLR and VLR used for authentication and encryption of calls.

AUC

HLR


BTS

EIR - Equipment Identity Registration

Stores information about mobile stations in use and may block calls from a MS if the MS is stolen, not type-approved or has faults which may disturb the network.

Each MS is identified by a unique International Mobile Station Equipment Identity (IMEI)

MSC

EIR


BTS

TRAUTranscoder Rate Adaptation Unit


BTS

TRAU

TRAU - Transcoder / Rate Adaptation Unit Functions:

• Conversion of speech from 64 kbit/s on PCM (A-law) to 16 kbit/s on the GSM radio interface

• Intermediate rate adoption of data from V.110 frames to the special TRAU frames on the A-bis interface


Possible Locations of the TRAU

13Kbit/s speech channel

TRAU

BTS BSC MSC

BTS BSC MSC

BTS BSC MSC

TRAU

TRAU

Um A-bis A-Interface


BTS

GSM Speech Encoding

Bandwidth: 13 kbit/s

Encoding algorithm: Regular Pulse Excitation with Long Term Prediction (RPE LTP):

• Speech is sampled 8000 times per second

• Each sample is converted into a 13 bit digital value

• Every 20 ms a 260 bit segment is generated (13 kbit/s)

• The segment is divided by importance into 182 class 1 bits and 78 class 2 bits

• For protection, the 182 class 1 bits are mapped into 378 bits

• The resulting 456 bits (378 + 78) are divided into 8x57 bits

• The data are transmitted in 4 consecutive TDMA blocks

Resulting overall delay is 57.5 msec.


BTS

Control of TRAU

TRAU is controlled by BTS

In-band signalling used, if TRAU not at BTS

Control functions:

• Shift between speech and data

• Shift between full rate and half rate channels

• Timing of speech frames (BSS - MS)

• Comfort noise (Discontinuous Transmission)


BTS GSM Bands


GSM 900 Radio (Um) Interface Physical Channels

In GSM approx. 1000 radio channels has been assigned in the 900 MHz band. More precisely:

• 890 - 915 MHz “Uplink”

• 935 - 960 MHz “Downlink”

A combination of frequency and time division is used.

• 124 carriers

• Carrier spacing is 200 kHz

• 8 timeslots per carrier

BTS

Downlink

Uplink

Ch1 890

Ch124 915

Ch1 935

Ch124 960

SONOFON

M N


DCS-1800 Radio (Um) Interface Physical Channels

In GSM 1800 2992 radio channels has been assigned in the 1800 MHz band. More precisely:

• 1710 - 1785 MHz “Uplink”

• 1805 - 1880 MHz “Downlink”

A combination of frequency and time division is used.

• 374 carriers

• Carrier spacing is 200 kHz

• 8 timeslots per carrier

BTS

Downlink

Uplink

Ch1 1710

Ch374 1785

Ch1 1805

Ch374 1880

SONOFON

M N


GSM Bandwidth & Main Parameters900 MHz & 1800 MHz

GSM 900 :

GSM 1800 :

Channel spacing 200kHz

Usual bandwidth values (GSM900): 5 ..8 MHz per operator in one or more

sub-bands

1710 1785 1805 1880

duplex distance: 95 MHz

890 915 935 960


Operator A Operator B Op. BOp. Anot allocated


GSM 1900 :

2 x 60 MHz at channel spacing 200kHz ~300 channels

Band divided into sub-bands A..F

sub-bands A, B, C : 2 x 15 MHz spectrum

sub-bands D, E, F : 2 x 5 MHz

1850 1910 1930 1990


Operator A Operator DOp. B Op. EOperator C Op. F

GSM Bandwidth & Main Parameters 1900 MHz


GSM 900 GSM 1800• Frequency band 890 - 960 MHz 1710 - 1880

MHz

• Number of channels 124 (125) 372 (375)

• Channel spacing 200 kHz 200 kHz

• Multiplex technologies TDMA/FDMATDMA/FDMA

• Mobile power 0,8 / 2 / 5 W 0,25 / 1 W

There are no major differences between

GSM 900 and GSM 1800

GSM Bandwidth & Main Parameters

Summary


BTS Radio Channels


Same in GSM900 and GSM1800

FCH

Traffic Channels (TCH)

TCH/9.6FTCH/ 4.8F, HTCH/ 2.4F, H

Dedicated Channels

(DCH)

Broadcast Channel(BCH)

Control ChannelsCommon ControlChannel (CCCH)

SCH BCCH(Sys Info)

TCH/FAGCH RACH SDCCH FACCH/ Bm

FACCH/ Lm

TCH/HPCH

Common Channels (CCH)

Logical Channels

SACCH

Logical ChannelsOverview of Logical Channels


Common Channels


Logical ChannelsBroadcast Channels (BCH)

Frequency Correction Channel (FCCH)• Unmodulated carrier: like a flag for the MS which enables it to find the

frequency among several TRXs

Synchronisation Channel (SCH)• Contains the Base Station Identity Code (BSIC) and a reduced TDMA

frame number

Broadcast Control Channel (BCCH)• Contains detailed network and cell specific information as:

Frequencies, Frequency hopping sequence, Channel combination, Paging groups, Information on neighbour cells

• Careful frequency plan needed

• BCCH is not allowed to involve in Frequency Hopping


Logical ChannelsCommon Control Channels (CCCH)

Paging Channel (PCH)• It is broadcast by all the BTSs of a Location Area in the case of a

mobile terminated call

Random Access Channel (RACH)• It is used by the mobile station in order to initiate a transaction, or as a

response to a PCH

Access Grant Channel (AGCH)• Answer to the RACH. Used to assign a mobile a SDCCH


BTS

Radio (Um) Interface Common Control Channels

Broadcast: BCCH

• Carry system info intended for everybody, e.g. Location Area Identity

Paging: PCH

• To request a specific Mobile User to react/reply, e.g. when there is a call for him

Random Access: RACH

• Used by the Mobile Station to initiate contact with the network, e.g. when trying to start a call

Access Granted: AGCH

• Used to respond to the RACH to inform that the Mobile is now being allowed to access the network


GSM BCH

Broadcast ChannelBroadcast Channel

One BCH on all the time, in every cellBCH Information carried in Timeslot 0 other Timeslots can be used for TCH or filled with dummy data

Allows Mobile to Synchronize

Identifies Network Carries Paging and other Control Information


GSM RACH

Random Access ChannelRandom Access Channel

Used by the mobile to get attention

Mobile doesn't know path delay

So RACH has to be a special

SHORT BURSTSHORT BURST

Mobile sends normal burst after getting Timing Advance


Dedicated Channels


Logical ChannelsDedicated Channels (DCH)

Stand Alone Dedicated Control Channel (SDCCH)• System signalling: call set-up, authentication, location update,

assignment of traffic channels and transmission of SMS

Slow Associated Control Channel (SACCH)• Transmits measurement reports (UL)• Power control, time alignment, short messages (DL)

Fast Associated Control Channel (FACCH)• Mainly used for handover signalling• It is mapped onto a TCH and replaces 20 ms of speech

Traffic Channels (TCH)• Transfer user speech or data, which can be either in the form of Half

rate traffic (6.5 kbit/s) or Full rate traffic (13 kbit/s).


BTS

Radio (Um) Interface Dedicated Control Channels

Stand-alone Dedicated : SDCCH

• Used for settling practicalities such as roaming, authentication, encryption and call control before allocating the traffic channel

Slow Associated: SACCH

• Associated to a TCH

• Used together with the Traffic Channel to deal with control and measurement of radio signals

Fast Associated: FACCH

• Large bandwidth version of the SACCH

• Used for sudden control action such as handovers

• Implemented a robbed bits in a TCH


BTS

Radio (Um) Interface Logical Channels

Traffic channels (TCH):

• Carrying Voice/data

• Bm: 13 kbit/s user data

• Lm: Half rate (6,5 kbit/s)

Common control channels (CCCH):

• Channels that all Mobile Stations can share

Dedicated control channels (DCCH):

• Control channels for individual Mobile Stations


GSM SACCH

Slow Associated Control ChannelSlow Associated Control Channel

DOWNLINKDOWNLINKMobile Tx Power Commands Mobile Timing AdvanceCell's Channel Configuration

UPLINKUPLINKReceived signal quality report (RXQual)Received signal level report (RXLev)Adjacent BCH power measurements Mobile's status


GSM FACCH

Fast Associated Control ChannelFast Associated Control Channel

Used by BS and MS to send largeamounts of data FAST

Rapid message exchange for hand-offsControl Bits are either side of midamble:

Indicate if TCH or FACCH


GSM SDCCH

Stand Alone Dedicated Control ChannelStand Alone Dedicated Control Channel

Used during Call Setup

Used for Short Messaging Services (SMS)

Stepping Stone between BCH and TCH

Used for Authentication Etc.


FCCH

SCH

PCH

AGCH

BCCH

CCCH

Common Channels

Dedicated Channels

Logical ChannelsDownlink

SACCHFACCH

SDCCH

TCH/F

TCH/H

DCCH

TCH


RACH CCCHCommon Channels

SDCCHSACCH

FACCH

TCH/F

TCH/H

DCCH

TCH

Dedicated Channels

Logical ChannelsUplink


Search for frequency correction burst FCCHSearch for synchronisation sequence SCHRead system in formations BCCH

Listen for paging PCHSend access burst RACHWait for signalling channel allocation AGCHCall setup SDCCH

FACCHTraffic channel is assigned TCHConversation TCHCall release FACCH

idle mode

'off' state

dedicated mode

idle mode

Logical ChannelsUse


BTS

GSM Cell Structure


Cell Structure

R5xR

F1

F2

F3 F

4

F5

F6

F4

Omni-directional BTS

3-directional BTS

Safety distance

BTS

BTS

BTS

BTS To avoid interference between two cells using the same frequency, a safety distance of about 5 times the cell radius is required.A BTS may cover one cell (Omni-directional) or several cells (typical three directional cells).Each cell may be served by one or more TRXs depending on the required capacity.

Note: each TRX controls one carrier with eight TS.


Handovers

The Handover process is the situation where a Mobile Station changes from being served by one Antenna to another

Handovers take place during a call

Handover are done automatically

Crossing the boundary of two adjacent cells is the typical example of a Handover

BTS BTS


GSM Hand-Off

1

2

4

5

7

8

*

0

3

6

9

#

BCH

TCHMobile constantly monitorsreceived TCH quality (RxQual & RxLev)


BTS

Radio (Um) Interface Neighbour Cells

Mobile station in IDLE mode

• Besides listening to the BCCH and the PCH the mobile station is measuring for neighbour cells.

Mobile station in active mode

• In active mode the mobile station is using the time between the down and uplink TS (three TS 2ms) to do neighbour cell measuring.

The mobile station can measure up to 31 neighbour cells.

• In practice the mobile station measures up to 12 neighbour cells.

• Very often only three or four cells are measured.


HandoversMajor types of handovers

• Intra BSC

• Inter BSC

• Inter MSC

Purpose of handover

• Poor quality connection– Avoid loosing contact

to the mobile station

• Fault in the MS or BTS/BSC

• Network management

Intra BSC

Inter BSC

Inter MSC

BSC

MSC - A

MSC - B

BSC

BSC

BTS

BTS

BTSBTS

SONOFON

M N

SONOFON

M N

SONOFON

M N


BTS

GSMSignalling procedures


System Overview

BaseStation

ControllerBSC

Public Switched

Telephone Network

BaseMobile Station

(MS)

MobileSwitching

CentreMSC

(PSTN)

StationSubsystem

(BSS)

A-Inter

A-bis

Um

2 Mbit/s PCMAir Interface

BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Base Transceiver

Station BTS

Equip. IdRegister

EIR

Authen.CentreAUC

VisitorLocationRegister

VLR

HomeLocationRegister

HLRMobile

SwitchingCentreMSC

MAPISUP / TUP

MAP

MAP MAP

ISUP / TUP

ISUP / TUP

MAP


A functional model

Call Management (CM)

• Call Control (CC)

• SMS

• Non Call-related SS

Mobility Management (MM)

Radio Resource Management (RR)

CM

MM

RR

BTSBSC MSC

VLR

HLRSONOFON

M N


BTS

Call Management (CM)

Call Management takes care of the ordinary call-control procedure:

• Establishment and release of calls, as well as access to services and facilities.

CM is divided into:

• Call Control (CC), short messages services (SMS).

• Non-call-related supplementary services (SS).


BTS

Mobility Management (MM)

Mobility Management handles roaming and authentication procedure.


BTS

Radio Resource Management (RR)Radio Resource Management comprise:

• Paging.

• Radio-channel access.

• Ciphering.

• Handover.

• Radio-signal control

• Radio-signal measurement


BTS

Special signalling procedures for GSM

Call Management

• Ordinary Call Control (as usual)

Mobility Management

• Location Updating (Roaming)

• Authentication

Radio Resource Management

• Paging

• Network Access

• Encryption

• Radio Signal Control

• Radio Signal Measurements

• Handover


Area 1

Area 2

BTS BTS

BTS BTS

Location Updating (Roaming)

An MM procedure

Reasons for roaming:

• MS has detected that it has entered into a new location area (by listening to Broadcast system info)

Types of roaming:

• Inside same VLR area– The HLR does not need to know

• Another VLR area– In this case the HLR is informed

MSC

VLR

MSC

VLR

SONOFON

M N


BTS

Call Setup

A CM procedure

Distinguish two types

• Mobile Terminating Call – i.e. a call from the fixed network to a Mobile

Station

• Mobile Originating Call– i.e. a call from a Mobile Station to the fixed

network


BTS

Mobile Terminating Call

Problems and answers

• Where in the world is the Mobile Station – Look it up in the HLR

– (The HLR may have to ask the VLR)

• How to Make the Mobile Station Aware that a call is waiting

– Page it in the cell where it is located

• What does the MS do when being paged ?– Asks for a Radio channel

– Tells the system that it is ready

Now the usual setup flow follows


BTS

Mobile Originating CallProblems and Answers

• How the mobile gets in contact with the network– Switch the MS on

– Request a channel

– Tell the network what kind of service is wanted

• How does the network respond– Verifies the Mobile identity (authentication)

– Assigns a traffic channel

And then everything proceed as usual


BTSGSM Services


BTS

Services

Telephony

Data services (up to 9600 b/s)

Fax group 3 (special modem)

Short Message Service (SMS)

Supplementary services, e.g.

• Call Forwarding

• Call Barring

• Call Waiting

• Three Party Service

• Advice of Charge


BTS

GSM Features

Integrated voice/data (ISDN)

Improved performance

Improved security

• Digital encryption

• Authentication (IMSI)

• TMSI assignment

All types of Mobile Stations

Automatic roaming

Sophisticated radio functions

• Discontinuous transmission - DTX

• Frequency hopping


BTS

Services, phase 2 and 2+Half-rate and enhanced full-rate speech

New supplementary services:

• Display of called and calling user's number

• Multi-party conversations (up to 6 parties)

• Closed user groups / virtual private networks

• Call completion services (busy, no answer etc.)

• Intelligent network services (CAMEL)

• Roaming between GSM and DCS 1800 (PCS 1900)

High speed data services:

• High Speed Circuit Switched Data (HSCSD)

• General Packet Radio Service (GPRS)


Frequency Hopping


What is Frequency Hopping?

• Changing the carrier frequency in the radio link between mobile station and base station during the connection.


FHBasics

Frequency Hopping is a sequential change of carrier frequency on the radio link between BS and MS• It averages the interference (interference diversity) and

• Minimizes the impact of fading (frequency diversity)

It is a standardised feature it is supported by all mobilesFrequency

Time

F1

F2

F3


BRTSL 0 1 2 3 4 5 6 7

TRX-1

TRX-2

TRX-3

TRX-4

f1 B = BCCH timeslot. It does not hop.

f2

f3

f4

Time slot 0 of TRX-2,-3,-4 hop over f2,f3,f4.

Time slots 1...7 of all TRXshop over (f1,f2,f3,f4).

The TRXs operate at fixed frequencies: consecutive bursts in each time slot are switched through different TRXs

The 1st time slot of the BCCH TRX is not allowed to hop

The number of frequencies to hop over is determined by the number of TRXs (biggest limitation!)

FHBase-Band Frequency Hopping


BTRX-1

Non-BCCH TRXs are hopping overthe MA-list (f1,f2,f3,...,fn) attached to the cell.

TRX-2

B = BCCH timeslot. TRX does not hop.

f1,f2,f3,fn

f1,f2,f3,fn

. . . .

All the TRXs except the BCCH TRX change their frequency for every TDMA frame

Thus the BCCH TRX doesn’t hop at allThe number of frequencies to hop over is limited to 63, which is the maximum length of the Mobile Allocation (MA) list

FHSynthesised Frequency Hopping

BB-FH is feasible with large configurations

RF-FH is viable with smaller configurations


Frequency hopping

RTSL 0 1 2 3 4 5 6 7

TRX-1 f1

TRX-2 f2

TRX-3 f3

TRX-4 f4

• Synthesized Hopping:

• Base Band Hopping:

TRX-1

TRX-2

f1,f2,f3,f4,

f1,f2,f3,f4,

.....

B

B

B = BCCH timeslot. It does not hop.

Time slots 1...7 of all TRXshop over MA(f1, f2, f3, f4).This hopping group uses HSN-2.

MAIOs have to be different between

same RTSLs in same hopping group.

0 0 0 0 0 0 0

1 1 1 1 1 1 1

2 2 2 2 2 2 2

3 3 3 3 3 3 3

0

1

2

Time slot 0 of TRX-2,-3,-4 hop over MA (f2, f3, f4).This hopping group uses HSN-1.

B = BCCH timeslot. TRX does not hop.

Non - BCCH TRXs are hopping overthe MA -list (f1,f2,f3,...,fn) attached to the cell.

fa

(fb)

(fc)

MAIOs have to be different between

same RTSLs in same hopping group.

Only one hopping group. Only HSN-1 is meaningful.

TRX-3

0 0 0 0 0 0 0 0

1 1 1 1 1 1 1 1


Network Planning & Optimization


Network planning team

• data acquisition• site survey and selection• field measurement evaluation• NW design and analysis• transmission planning

Network design• number and configuration of BS• antenna systems specifications • BSS topology• dimensioning of transmission lines• frequency plan• network evolution strategy

Network performance• grade of service (blocking)• outage calculations• interference probabilities• quality observation

Customer requirements• coverage requirements• quality of service• recommended sites• subscriber forecasts

External information sources• topo- & morphological data• population data• bandwidth available• frequency co-ordination• constraints

Interactions with• external subcontractors• site hunting teams• measurement teams• Operator• switch planning engineers

Network Planning Scope


CoveragePlanning andSite Selection

ParameterPlanning

PropagationmeasurementsCoverageprediction

SiteacquisitionCoverageoptimization

External Interference Analysis

NetworkConfigurationand

Dimensioning

PRE-PLANNING

DETAILED PLANNING

Traffic distributionService distributionAllowed blocking/queuingSystem features

IdentificationAdaptation

Area / Cellspecific

Handoverstrategies

Maximumnetworkloading

Other RRM

NetworkOptimization

POST-PLANNING

Surveymeasurements

Statistical performance analysis

Quality Efficiency Availability

Capacity Requirements

Requirementsand strategyfor coverage,quality and

capacity,per service

Network Planning Process General


Network Optimisation

“Improving network quality from a subscribers point of view”

“Improving network quality from an operators point of view”


Optimisation needed to...

Maximise/Maintain network Quality• Radio Network has to follow city developements

Achieve Quality Criteria set by• Operator:

• Key Performance Indicators balance investment versus achieved quality

• Subscriber:• 110% coverage propability everywhere


Optimisation Flow Chart

Tools

KPI

Documentati

on

Analyzation

N

Case closed

YSolution worked ?

Solution

More info

needed ?

Y

N

HW change

Parameter change

Performance Analysis

O&MFT CC DB


Optimisation Inputs and Tools

Operation & Maintenance• Statistics

• Alarms

• Parameters (NMS/BSS)

Field Tests (TOM/NEMO, TEMS)• Drive tests

• CW measurements

Customer Complaints

Database consistancy checks (NetAct)• Planning tool <-> BSS/NMS


Optimisation Solutions

• Parameter changes• Frequency changes• Neighbour changes etc...

• Hardware changes• Antenna tilt• Antenna orientation• Antenna changes• HW check• Adding/deleting cell• Adding/deleting site• Adding/deleting TRX


NOKIA Implementation


DX 200 Platform


Nokia Implementation of GSM Network


DX200 Platform Common Features

Distributed processing architecture

meeting the cost-effective capacity

requirement

Modularity (Plug-In Unit, PIU) enabling

HW/SW upgrade and maintenance

w/o traffic disturbance

Fault Tolerant Computing Platform

Cartridge mechanics


NOKIA i-series NE CabinetNOKIA i-series NE Cabinet


DX 200 Platform

Signalling towards subscribers

Collecting dialled numbers

Collecting the charging data

Hunting for a free circuit

Making speech path connections

Signalling towards other exchanges

Analyzing and subscriber data

Supervising the processes running

Collecting statistical data


Exchange

Computer Units

Message bus

Signalling towards

Subscribers

Collecting dialled

numbers

Collecting Charging

data

Making Speech path

connections

Signalling towards

other exchanges

Collecting statistical data

Supervising the processes

running

Hunting for a free circuit

Distributed Processing of DX200Distributed Processing of DX200


SWITCHING

CONTROL

MANAGEMENT

SYNCHRONISATION AND TIMING

TRUNK NETWORK INTERFACE

ET

INTERFACE FOR

MOBILE ACCESS

ET

DX 200 Network Element

Basic Principles of DX200Basic Principles of DX200


BCSU BSC Signaling Unit

BTS Base Transceiver

Station

CLS Clock & Sync. Unit

ET Exchange Terminal

GSWB Bit Group Switch

MB Message Bus

MCMU Marker and CellularManagement Unit

MSC Mobile Services

Switching Center

OMU Operation &

Maintenance Unit

BCSU BSC Signaling Unit

BTS Base Transceiver

Station

CLS Clock & Sync. Unit

ET Exchange Terminal

GSWB Bit Group Switch

MB Message Bus

MCMU Marker and CellularManagement Unit

MSC Mobile Services

Switching Center

OMU Operation &

Maintenance Unit

BSC Functional UnitsBSC Functional Units


GSW

ET

ET

ET

ET

CLS

Message Bus

M OMUSignaling Unit

CM

TopologyFile Edit LocateView Help

Mount431 74371950 79%/

NetworkTraff ic Help

I/O

Additional Unit

DX200 ArchitectureDX200 Architecture


Base Station Controller (BSC)Base Station Controller (BSC)

ET

GSW

PCU

BCSU

AS7

MSC/TCSM2

SGSN

BTS

MCMU

TCH (Circuit Switched) TCH (Circuit Switched)

Data (Packet Switched)Data (Packet Switched)

Signalling (CCS7)Signalling (LAPD)

ET ET


Rack Layouts of the DX 200 BSC2iBCB BCE R2A1-SCC1

9V

BSC2i

27

27

27

CLSCLAC

O1

O1

O1

O1

PSA20_2 PSA20_3

PSFP2 PSFP3

PSA20_0 PSA20_1

PSFP0 PSFP1

BCSU 3MC1C

BCSU 4MC1C

BCSU 6MC1

CBCSU 7MC1C

BCMSU 8 MC1C

OMUMC1C

MCMU 1MC1C

MCMU 0MC1C

2701

O1

GSWB 0

SW1C0

GSWB 1

SW1C1

CLSCLOC

BCSU 5MC1C

O1

O1

27

27

27

BCSU 1MC1C

BCSU 2MC1C

BCSU 0MC1C

ET5C0

19

37CBD

8

002

120

088

058

030

152

ET5C8

ET5C7

ET5C1

01

13

ET5C3

ET5C4

ET5C2

ET5C6

ET5C5

SD3C-S

01

13


BSC3i Cabinet and unit configuration

PDFU 0PDFU-A

GSWB 0SW1C-C

CL

S 0

,1C

LOC

-B

GSWB 1SW1C-C

ET4C 0ET4C-B

(32*ET2E/A)

ET4C 1ET4C-B

(30*ET2E/A)

FTRB 0 FTRB 1

FTRB 2 FTRB 3

CPRJ45 CPGOCPGO

PDFU 1PDFU-A

PDFU 2PDFU-A

PDFU 3PDFU-A

OMUCM2C-A

BCSU 1CC3C-A

BCSU 0CC3C-A

BCSU 2CC3C-A

BCSU 4CC3C-A

BCSU 3CC3C-A

BCSU 5CC3C-A

BCSU 6CC3C-A

CC4C-ACC4C-AMCMU 1MCMU 0


Group Switch GSWB

2 3 4 5 6

SW

64B

SW

64B

SW

64B

PS

C1

SW

64B

SWBUS4


Switching functionality

Group Switch (GSW/GSWB)

Purpose: The GSW is the switching matrix. The basic function is to switch dynamic connections, each input is capable of being switched to any output. Internal semipermanent connections are established with MML. GSWB of BSC is capable of bitwise switching. Belonging to the M-GSW switching entity, GSW is a subunit of Marker M.

Type: Functional unit

Redundancy: 2N


Operation & Maintenance Unit for BSC3i

•1 •2 •4 •5 •6 •7•3 •8 •9 •10

•AP

•DBG

•RST

•J7

•J6

•WO

•RUN•LF•OL

•TE

•AP•DRAM

•SB

•CPSI

•SCSI•ETx0•ERx0

•OPR•OPR

•AP•AP

•OPR

•ON

•OFF

• PS

C6

-A

• MB

IF-B

0

• MB

IF-B

1

• CP

U

• AS

7-B

2 /

AC

25

-A

• AS

7-B

1 /

AC

25

-A

• AS

7-B

0

• SE

RO

-A

• HW

AT

-A

•ETx1•ERx1

• OD

PU

-A +

M0

91

• HD

PU

-A +

WD

W18

-S

• HD

PU

-A +

WD

W18

-S

•12 •13 •14

•SW0

•SW1

•RST


Management functionality

Operation and Maintenance Unit (OMU)

Purpose: The OMU is the unit controlling the automatic self-repair functions of the network element, it monitors the exchange continuously and starts recovery procedures if errors occur. The OMU contains the user interface for the operating personal to do the normal operation and maintenance tasks. The OMU contains the interfaces for I/O system.

Type: Computer unit

Redundancy: 2N or no redundncy


MCMU for BSC3i

1 2 4 5 6 73

DBG

RST

J7

J6

WO

RUN

LF

OL

TE

AP

DRAM

SB

CPSI

SCSI

ETx0

ERx0

OPROPROPR

ON

OFF

PS

C6

-A

MB

IF-B

0

MB

IF-B

1

CP

U

SW

CO

P-A

ETx1

ERx1

ES

B2

0

J5

OPR

RST

ES

B2

0

J5

OPR

RST

ET

H1

ET

H2

ET

H1

ET

H2


Control functionality

Marker (M)Purpose: The Marker controls and supervises the GSW.Type: Computer unit with subunitsRedundancy: 2N

Central Memory (CM) Purpose: The CM is one of the most important units in the network element. It is the central RAM of the exchange, which holds all the system software and also keeps a copy of all exchange specific software data. It is responsible for loading and updating data automatically to system's hard disks.Type: Computer unit with no subunitsRedundancy: 2NIn the BSC the common units Marker and Central Memory are integrated into the same functional unit called Marker and Cellular Management Unit (MCMU).


External interfaces

Exchange Terminal (ET)

Purpose: The ET is the unit which handles the external 2 Mbit/s PCM circuits through electrical synchronisation and adaptation of external 2Mbit/s.


Redundancy: none


Synchronisation and timing

Clock and Synchronisation Unit (CLSU)

Purpose: The CLSU is responsible for generating the synchronisation signals for different units.


Redundancy: 2N


BSC Signalling Unit BCSU for BSC3i

1 2 4 5 6 73 8 9 10

AP

DBG

RST

J7

J6

WO

RUNLF

OL

TE

APDRAM

SB

CPSI

SCSI

ETx0

ERx0

OPROPR

APAP

OPR

ON

OFF

PS

C6-

A

MB

IF-B

0

MB

IF-B

1

CP

U

AS

7-B

2

AS

7-B

1

AS

7-B

0

PC

U-B

3

PC

U-B

4ETx1

ERx1

RUN0

RUN1

RUN0

RUN1


Net element specific Control and Signalling units in BSC

Base Station Controller Signalling Unit (BCSU)

Purpose: The BCSU takes care of signalling towards the BSC and the MSC as well and controlling theBTS.

Type: Computer unit

Redundancy: N+1


DX200 Software StructureDX200 Software Structure

System block

Service block

Program block


Software StructureSoftware Structure

A fundamental part of the DX200 system software is the real-time operating system kernel, DMXRTE, implemented in each Control Computer. The operating system is a platform for other system level software and all the application software.

The most significant functions of the operating system are:▪ Scheduling of processor time

▪ Synchronisation of processes

▪ Exchange of messages between processes located in one computer or separate computers

▪ Time supervision

▪ Creation and deletion of processes

▪ Memory allocation and protection

▪ Observation of message traffic and processor load

▪ Initialisation of the operating system.


Nokia NMS


Functional units in the NMS/2000


NOKIA NMS 2000

The standard Nokia NMS 2000 consists of servers and operator positions that can be either application workstations or X terminals. These components are connected to a Local Area network. Servers are also provided and consist of a communications server, a database server and a standby server or combinations of these. A router is provided to allow communications to the various elements in the GSM network, which is connected to a Data Communication Network (DCN)


Network ElementsOMC (NMS)

Operation and Maintenance Center

(Network Management System)• Fault monitoring

• Alarm handling

• Performance measurements

• OMC is connected to GSM network e.g. via X.25 link

• Supervises all network elements

• Collects measurement data

• Remote handling of network elements

necessary tool for network optimisation


Nokia BTS


Network ElementsTasks of BTS

Base Transceiver Station• Maintain synchronisation to MS

• RF signal processing (combining, filtering, coupling...)

• Diversity reception

• Radio interface timing

• Detect access attempts of mobiles

• De-/ encryption on radio path

• Channel de-/ coding & interleaving

• Perform frequency hopping

• Forward measurement data to BSC

typically 1 - 4 TRX / sectortypically 1 - 3 sectorsavg. 7,5 traffic channels per TRX


Network Elements Talk-family Base Station

Key Functionality

Nokia Intratalk (indoors) and Citytalk (outdoors) are base stations that can accommodate up to 12 TRX in omni or sectored configurations in two cabinets. Nokia Flexitalk Base Station is a compact Base Station with flexible configuration from 1 boosted TRX to 2 TRX omni configuration. The modular architecture and various antenna combinations help to achieve the best coverage and capacity solution. Nokia Talk-family base stations support GSM data evolution with the capabilty to support high speed circuit switched data (HSCSD) and GPRS.Key Benefits

• Flexible configurations and solutions from initial coverage building to large capacity sites • Smooth evolution path to 3G services with co-siting solutions • Protected investment through future-proofed expandability • Field-proven technology with high reliability


Network Elements MetroSite

• The Nokia MetroSite GSM BTS is a complete, all-climate microcellular base transceiver station.

• It can be used in GSM 900, GSM 1800, GSM 1900 systems, or as a GSM 900/GSM 1800 dual band BTS.

• Both omni and sectored configurations are supported.

• The small-sized Nokia MetroSite GSM BTScabinet accommodates up to four transceiver units (TRXs).

• In order to ensure high quality of calls, the Nokia MetroSite GSM BTS supports versatile features, such as frequency hopping.


MetroSite Concept

Nokia MetroSiteBase Station

Connected to FXC RRI orFC RRI indoor unit.

Connected to FXC RRI orFC RRI indoor unit.

Nokia MetroHopper

Radio

Nokia MetroHubTransmission Node

Nokia FlexiHopperMicrowave Radio

Nokia MetroSiteBattery Backup

Nokia MetroSite Antennas


New MetroSite Family Members

Nokia MetroSite WCDMA Base Station

Nokia FlexiHopper Microwave Radio (PDH)

Nokia MetroHopper Radio

Nokia UltraHopper Microwave Radio (SDH)

High-power Nokia MetroSite GSM Base Station

Nokia MetroSite GSM Base Station

Nokia MetroHub Transmission Node

Nokia MetroSiteBattery Backup Unit


Nokia MetroSite Base Station Antennas

Directional 130 degrees: 6 dBi Omnidirectional: 2 dBi

Dual band 2 port antennas

• GSM 900 / GSM 900

• GSM 900 / GSM 1800

• GSM 1800 / GSM 1800

1 feeder per TRX

No internal combiners needed

RX diversity

External 2 to 1 combiner available for special cases


Network Elements PrimeSite

• Nokia PrimeSite is a complete 1 TRX Base Transceiver Station for both indoor and outdoor use in 900 MHz (GSM 900), 1.8 GHz (GSM 1800), and 1.9 GHz(GSM 1900) systems.

• The product has been optimized for one carrier.

• The number of TRXs can be increased by chaining several Nokia PrimeSites with a single clock synchronization cable between each unit.

• Nokia PrimeSite conforms to both GSM Phase I and Phase II requirements.

• The product is in link balance with 2WMS for GSM 900, and 1WMS for GSM 1800 and GSM 1900.


Network Elements InSite

Key Functionality Nokia InSite Base Station is a compact, one-transceiver picocellular base station (BTS) for a variety of indoor coverage and capacity solutions. This tiny GSM/GPRS BTS is available in 900 and 1800 and 1900 MHz. Weighing just 2.4 kg and no bigger in area than a sheet of A4 paper, it can be installed virtually anywhere. Compact and integrated system elements, highly automated configuration and flexible transmission, means this base station can be installed in about one-tenth the time of other base stations giving fast return on investment. Rollout can cost a fraction of that of conventional indoor networks.

Key Benefits Dedicated indoor solution at a fraction of the conventional cost, means less capital expenditure • Single TRX picocellular base station for smooth growth of your indoor network • Highly automated and integrated system speeds up implementation and enables faster return on investment • Compatibility with future technology developments helps ensure cost-effective network upgrades • Network integration typically achieved during one site visit by one person


SMS


Short Message Services (SMS)

Extremely popular service, similar to the peer-to-peer instant messaging services in the Internet

Allows exchange of alphanumeric messages up to 160 characters

Two types of services:

• Broadcast

• Peer to peer

Uses the same infrastructure as GSM

SMS has instant delivery service as well as store-and-forward service


Operations

SMS makes use of the GSM infrastructure, protocols, and the physical layer to manage the delivery of messagesEach message is treated individually, and is maintained and transmitted by the SMS center (SMSC)Short messages (160 char mapped into 140 bytes) are transmitted through the GSM infrastructure using SS-7Short messages are transmitted in time slots that are freed up in the control channels


Reference Architecture

HLR VLR

SMS-GMSCSMS-IWMSC

MSC

MS

SMSC


Cases of Short Messages

SM originating from an MS

• Goes to MSC for processing

• SMS-interworking MSC (SMS-IWMSC forwards the SM to the SMSC

Mobile terminated short message

• SM is forwarded by the SMSC to the SMS-gateway MSC (SMS-GMSC)

• Either the HLR or VLR is queried

• SM is either delivered to the BSC or forwarded to another MSC


NEXT STEP


Evolution of GSM


HSCSDBasics

High Speed Circuit Switched Data• Data rate up to 57.6 kbit/s

• Multiple set of basic resources (TCH) is reserved for one high speed data call

• Data rate and number of reserved timeslots can be defined by the user application

• S7 implementation of the feature is for up to 4 channels (each channel corresponds to 9.6/14.4 kbit/s)

. . .

PSTNISDNPDN

IWF

MSCBSC/TRAUBTS


New Applications & Uses Feasible

GPRSBasics

General Packet Radio Service

End User (compared to 9.6 data & HSCSD): • Service differentiation opportunities

• Always connected

• Pay per bit transferred

• Higher speeds

• Faster session set up

Operator:• Service differentiation opportunities

• Catch Corporate business (including speech)

• Additional revenue for content

• Get more use out of network investment

• Path to 3rd Generation


Introduction

GPRS (General Packet Radio Service)

• Reuse the existing GSM infrastructure

• Introduce packet-switched routing functionality– Better data transfer rates

– Low cost and connectivity-oriented

• Migration Path to 3G Networks


GPRS - Overview

GPRS is an overlay on top of the GSM physical layer and network entities

Extends data capabilities of GSM

Provides connections to external packet data networks through the GSM infrastructure with short access time to the network for independent short packets (500-1000 bytes)

No hardware changes required for Base Station

Scalable, high throughput (21.4 kbps), support for voice and data


GPRSCircuit Switched vs. Packet Switched

Circuit Switched

Packet Switched


Packet-switched techniquevs. circuit-switchedIn circuit-switching, resources (e.g. a channel) are allocated to user for duration of connection

• Inefficient use of resources

• User pays for the whole connection

• High QoS: channel maintains real-time connection

In packet-switching, resources are allocated to user only for the time it takes to send each packet

• A channel can serve many users

• User pays by the packet

• Ideal for bursty data connections


Comparison

Packet-switched

• High bit rates (up to 170kbit/s)

• Shared bandwidth

• Variable access times

• Friendly bill (based on volume)

• Robust application support– Frequent transmission of small

volumes

– Infrequent transmission of small or medium volumes

Circuit-switched

• Low bit rates (14.4kbit/s)

• Reserved bandwidth

• Fixed access time

• Unfriendly bill (based on duration)

• Limited application support– Large volumes


13 ©NOKIA CTXX 3218_3.0en.PPT / 14.09.2001

Telephone networks

Packet switched

Datanetworks

• End-to-end connection (call) establishment needed

• Dedicated resources (e.g. PCM-tsl) for one user are reserved during call establishment

• Only 30 - 40% of resources are effectively used for speech transfer

• Speech is transferred in real time

• Speech does not accept delays

• Errors in transmission are not so critical for speech

• Charging is usually based on time

• No connection needed

• Resources are shared between different user sessions, not dedicated

• Resources are requested on demand, more efficient use

• Packets are not sent in real time buffering and delay

• Error correction and detection possible

• Charging is usually based on volume number of packets

Circuit switched


14 ©NOKIA CTXX 3218_3.0en.PPT / 14.09.2001

Telephone networks

Packet switched

Datanetworks

Physical circuitPCM-tsl(CONS)

• End-to-end connection (call) establishment needed

• Dedicated resources (e.g. PCM-tsl) for one user are reserved during call establishment

• Only 30 - 40% of resources are effectively used for speech transfer

• Speech is transferred in real time• Speech does not accept delays• Errors in transmission are not so critical

for speech• Charging is usually based on time

Virtual circuit (VC) No VCX.25 IP

(CONS) (CLNS)

• No connection needed• Resources are shared between different

user sessions, not dedicated• Resources are requested on demand, more

efficient use• Packets are not sent in real time

buffering and delay• Error correction and detection possible• Charging is usually based on volume

number of packets

Circuit switched


GPRS Architecture


MSC

SS7 signalingNetwork

PSTN

ISDN

BSCBTS

IP networksInternet

Packet Core

IP BackboneFirewall

Gateway GPRSSupport Node

Serving GPRS

Support Node

HLR

GGSN

SGSN

GPRSNetwork Overview


GPRS Architecture - Components

New components introduced for GPRS services:

• SGSN (Serving GPRS Support Node)

• GGSN (Gateway GPRS Support Node)

• IP-based backbone network

Old components in GSM upgraded for GPRS services:

• HLR

• MSC/VLR

• Mobile Station


Reference Architecture

Refer to handout

Uses GSM architecture

GPRS support nodes (GSN): responsible for delivery and routing of data packets between the MS and the external network

Serving GPRS support node (SGSN)

• Controls access to MSs that are attached to a group of BSCs (routing area (RA) of SGSN)

Gateway GPRS support node (GGSN)

• Logical interface to the Internet

GPRS Register (GR)

• Colocated with HLR and stores routing information


GPRS ArchitectureSGSN – Serving GPRS Support Node

At the same hierarchical level as the MSC.

Transfers data packets between mobile stations and GGSNs.

Keeps track of the individual MSs’ location and performs security functions and access control.

Detects and registers new GPRS mobile stations located in its service area

Participates into routing, as well as mobility management functions.


GPRS ArchitectureGGSN – Gateway GPRS Support Node

Provides inter-working between PLMN and external packet-switched networks.

Converts the GPRS packets from SGSN into the appropriate packet data protocol format (e.g., IP or X.25) and sends out on the corresponding packet data network.

Participates into the mobility management.

Maintains the location information of the mobile stations that are using the data protocols provided by that GGSN.

Collects charging information for billing purpose.


GPRS ArchitectureBackbone Network

Tunnels of data and signaling messages between GPRS support nodes.

Protocol architecture based on the Internet Protocol (IP).

GTP (GPRS Tunneling Protocol) used to tunnel user data and signaling between GPRS Support Nodes. All PDP (Packet Data Protocol) PDUs (Protocol Data Units) shall be encapsulated by GTP.


GPRS ArchitectureBackbone Network (cont.)

Two kinds of GPRS backbone Network:

• Intra-PLMN backbone network: The IP network interconnecting GSNs within the same PLMN.

• Inter-PLMN backbone network: The IP network interconnecting GSNs and intra-PLMN backbone networks in different PLMNs.

Two intra-PLMN backbone networks are connected via the Gp interface using Border Gateways and an inter-PLMN backbone network.

Border Gateway handles the packet transfer between GPRS PLMNs.


SW Upgrade in MSC/VLR and HLR

GPRS capable MS

NMS Upgrade to T12

MSC

ISDN/PSTN

NetworkEIR

HLR/AuC

SMSC

BSC

BTS

Um

HW and SW Upgrade in BSC (S9+PCU)

SW Upgrade in BTS

Internet or

Corporate LAN

GPRS Core

Network

GPRS Core Network Elements

New Services (APNs, WAP)

GPRSHW & SW Upgrades from GSM


GPRS ArchitectureInterfaces

TE MT BSS SGSN GGSN PDN TE

MSC/VLR HLR

SGSNCGF

EIR

BillingSystem

Other PLMN

GGSN

R Um

AGs

DGr

Gc

Gb Gn Gi

Gn Gp

Gf

GaGa

• CGF(Charging Gateway)


Packet transfer

Intra-PLMN backbone

PLMN


Packet Transfer

A laptop connects with a GPRS-capable handset.

The handset communicates with GSM base station.

Base station sends the GPRS packets to SGSN.

SGSN encapsulates packets

Handset location information is updated in other GSM components, such as HLR.

SGSN sends encaps. packets to GGSN.

GGSN decapsulates and sends to PDNs.


What is Traffic Management?

Traffic Management Procedure is subdivided into 2 areas:

1. What is Mobility Management?• Procedures that take care of the mobility of the user, such as the

GPRS attach, are called GPRS Mobility Management (GMM).

– The GMM procedures are similar to the mobility management for circuit switched users.

– Examples: GPRS Attach, GPRS Detach, Cell Update, Intra-SGSN Routing Area Update

2. What is Session Management?• Procedures that handle the GPRS MS connection management

to the external data networks are called Session Management (SM).

– Examples: PDP Context Activation


What sort of procedures are needed?

• MS switches on for the first time.

• MS indicates that it is switched on and ready. (GPRS Attach)

• MS indicates that it is switched off. (GPRS Detach)

• MS indicates that it wants to transmit data. (PDP Context Activation)

• MS indicates to stop data transmission. (PDP Context Deactivation)• • MS moves from one part to another of a service area. (Cell Update

and RA Update procedure)

• MS may roam into another networks service area. (Roaming)

• etc.


Types of subscriber information Subscriber Identity

—How do we uniquely identify a subscriber?– IMSI, TMSI, IP Address

—Where will this information be maintained?

Subscriber Location —How do we know the location of the subscriber?

– Location Area (LA) and Routing Area (RA)


Subscriber Services —What sort of services is a subscriber allowed to access?—Where will this information be maintained?

Subscriber Authentication —What information is needed to authenticate the subscriber?

– Ki Algorithms, Triplets



Type of info What info Where

Identity IMSI

TMSI

IP address

SIM, HLR, VLR,SGSN, GGSN

VLR, SGSN

MS, SGSN, GGSN

Location VLR-address

Location Area

Serving SGSN

Routing Area

HLR

SGSN, VLR

HLR, VLR

SGSN

Services Basic services,supplementary services,circuit switched bearerservices, GPRS serviceinformation

Basic services,supplementary services,CS bearer services

GPRS service information

HLR

VLR

SGSN

Authenticationdata

Ki, algorithms

Triplets

SIM, AC

VLR, SGSN


21 ©NOKIA CTXX 3218_3.0en.PPT / 14.09.2001

What are the advantages of GPRS to operators?• More revenue

• Huge potential market for data services—Data traffic rising faster than voice

• Fast roll-out and continuous network expansion—Operators can start small and develop GPRS capacity as traffic and

revenue start to increase

• GPRS uses excessive voice capacity for data (see next slide)

• Smooth path to 3G services (Covered in Evolution from 2G to 3G module)


EDGEBasics

Enhanced Data rate for Gsm Evolution (EDGE)• Update of the GSM standard towards 3G networks/mobiles

• Operators who do not get/want 3G-license (UMTS/WCDMA) can provide 3G-services anyway

• Enhancement results from introduction of new modulation (8-PSK) + channel coding schemes

• ECSD (Enhanced Circuit Switched Data): circuit switched channels/services. Updates HSCSD for 8-PSK modulation

• EGPRS (Enhanced GPRS): packet switched channels/services. Updates GPRS for 8-PSK modulation


EDGEEDGE in GSM/GPRS Networks

EDGE 8-PSK coverage

EDGE capable TRX, GSM compatible

EDGE GMSK coverage

A-bisBTS

BTS

MSC

Gn

GGSN

EDGE capable terminal,

GSM compatible

More capacity in interfaces to support higher data usage

GbBSC

A

SGSN

EDGE functionality in the network elements


EDGE

The fundamentals difference between GSM/GPRS and EDGE is that EDGE uses 8 PSK modulation, which encodes 3 bits per modulated symbol, compared with 1bit per symbol GMSK that is used for GSM and GPRS network.

EDGE will enable data rates of upto 473 Kbits/s per TRX for Enhanced GPRS (E-GPRS), with slightly reduced coverage.

Ability to handle Wireless multimedia services, Internet / Intranet, Videoconferencing and fast electronic mail transfer.


UMTSStandardisation


UMTSNetwork Architecture

Core NetworkRAN

Air

Air

Air

Iupacket

Iucircuit

Iur

Iur

RNC

RNC

RNC

Iub

Iub

Iub

BS

BS

BS

BS

BSBS

BSMSC

Serving GPRSSupport Node(SGSN type U)

IWUTC

IuIu

Circuit Domain

Packet Domain


UMTS UL(FDD)

60 MHz

UMTS(TDD)

20 MHz

1920

1900 2000 2100 2200

UMTS DL(FDD)

60 MHz

1980 2110 2170

UMTS(TDD)

15 MHz

20102025

UMTSAllocated Bandwidth


5 MHz

3.84 MHz

f

Guard Bands

UMTSWCDMA Carrier


Frequency

Pow

er

den

sity

(W

att

s/H

z)

Unspread narrowband signal

Spread wideband signal

W

R

UMTSSpreading / Despreading

A narrowband signal is spread to a wideband signal


High bit rates

Spectral efficiency

Different qualityrequirements

Efficient packet data

Downlink capacity

WCDMA GSMCarrier spacing 5 MHz 200 kHz

Frequency reuse factor 1 1–18Power control frequency 1500 Hz 2 Hz or lower

Quality control Radio resource management algorithms

Network planning (frequency planning)

Frequency diversity 5 MHz bandwidth gives multipath diversity with

Rake receiverFrequency hopping

Packet data Load-based packet scheduling

Time slot based scheduling with GPRS

Downlink transmit diversity

Supported for improving downlink capacity

Not supported by the standard, but can be

applied

UMTSDifferences with GSM


3rd Generation Mobile Systems

A Summary of the main objectives for the IMT – 2000 air interface is shown below

Full coverage and mobility for 144Kbits/s, preferably 384Kbits/s

Limited coverage and mobility for 2 Mbits/s

Efficient use of the radio spectrum compared with existing systems

Flexible architecture to allow

the introduction of new

services


Combined GSM and WCDMA Network


WCDMA Network


W-CDMA (Wideband CDMA)

For the 3rd Generation mobile systems, a high bit rate is required for multimedia data. Therefore, the spreading code must be of a higher bit rate.

IS 95 CDMA uses a bandwidth of 1.25MHz, but

W-CDMA systems for UMTS will occupy a bandwidth of 5MHz.

In the W-CDMA system the spreading codes are used to spread out the data signal to cover the whole wideband spectrum that is allocated for the data transfer.


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