S-72.423 Telecommunication Systems

An Overview to Course Contents

Topics today

Practicalities

Table of course contents

Networking paradigms: Determining networking trends

Network evolvement

Topology

divided

integrated

mobile

Telecommunication markets

Review of course contents in selected topics

The OSI-model

Networking approaches: PSTN, ISDN, Mobile, Internet

Future trends

Practicalities

Lectures (Thursdays 14-16 in hall C)

Timo Korhonen (timo.korhonen@hut.fi)

Michael Hall (michael.hall@hut.fi)

Tutorials (Wednesdays 14-16 in S1)

Mika Nupponen (mika.nupponen@hut.fi), Yue Feng (feng@cc.hut.fi)

Textbooks: Ericsson, Telia: Understanding Telecommunications, Part II, ISBN 91-44-00214-9 (Studentlitteratur), James F. Kurose, Keith W. Ross: Computer Networking (2nd Ed.,Addison Wesley)

Reference: A.S. Tanenbaum: Computer Networks (4th Ed., Prentice Hall)

Homepage: http://www.comlab.hut.fi/opetus/423

Grading

Course grade consists of

Closed book Exam (max 5p, required)

Lecture Diary (max 5p, required at least 8 diaries to
return and grade, full compensation only if diaries of all lectures returned, voluntary)

Tutorials (max 5p, voluntary)

Grade weights: E*0.95+D*0.2+T*0.15

Example of lecture diary can be inspected at homepage.

After the lecture send email to lectures@hut.fi to specify:

Your name and student number

Web address where you store your lecture diaries (all your diaries are accessible from a single page you set up)

Diaries graded by fellow students - grading guide available at the course homepage

Some topics from course contents

Introduction

Public Switched Telephone Network (PSTN)

Exchange techniques

Transmission

Integrate Services Digital Network (ISDN)

Functions

Interfaces

Automatic Transfer Mode (ATM) and Broadband-ISDN

X.25, Frame relay

Public land mobile networks

GSM

WCDMA

Signaling networks: SS7

The Internet: Network topology, TCP/IP Suite, Services

Telecommunication networks have
much in common

Trunk and access parts

Access part terminated by terminals

Network nodes and links are optimized for certain assumed traffic patterns

This model applies for both data (packet) and voice networks

Due to these network similarities network analysis carriers common subtopics

Course contents: Networking subtopics

User services and terminals (as IN services: call last dialed...)

Standards (IETF, IEEE, ITU-T ...)

Routing and switching (unicast - multicast, devices)

Transmission and links (as fibre, coax-cable.., RSVP)

Access and transport (terminals, local-loop techniques..)

Servers service (web,mail,ftp ...)

Signaling (SS7, X.25, Frame relay ...)

Network management (as OMAP of SS7...)

Interworking between networks (gateways, bridges ...)

Network planning

Paradigm shift

Network evolvement

Most people have observed that a telecommunications network is a system transmitting the messages (even SMS) … In this course we focus on analyzing that the networks
can be divide to ...

Data and voice networks

Nodes and links with well defined (standardized) interfaces

Network nodes and links that are optimized for certain, assumed traffic

Traditional assumption: Voice and data services in different networks

Integrated Services
Digital Network (ISDN)

UMTS and Differentiated Services

UMTS supports wide range of applications that posses different quality of service (QoS) requirements.

Applications and services can be divided in different groups, depending on QoS requirements. Four traffic classes can been identified:

Conversational class (very delay-sensitive traffic)

Streaming class

Interactive class

Background class (the most delay insensitive)

Hence TCP (Connection-oriented transport-layer ) is not always applied - one may use also UDP (Connectionless transport-layer protocol) - Why?

Network/service adaptivity

Services manifest themselves via various customer profiles (that may differ within a short time period), and thus efficient adaptivity should be supported by network configurations

Advanced networks have a tendency to carry intelligence in terminals (and not in exchanges)

Reduces signaling traffic

Moves costs to end-users

IN (Intelligent Network) solutions developed first for PSTN but a typical important part of most networks as in PLMNs

Enables service flexibility in exchanges (software radio does the same in terminals)

IN services designed in cooperation with terminal intelligence

Public Land Mobile Networks (PLMN)

Mobility is required practically for all services in the very near future!

In this course we will discuss especially the GSM (Global System for Mobile communications) (9.6 kbit/s++) and WCDMA (Wideband Code Division Multiple Access, or UMTS) networks

UMTS will be launched 2002-2003 yielding mobile data rates up to 2 Mb/s. However, the GSM network will be upgraded for higher rates thanks to

GPRS (General Packet Switched Data),

HSCSD (High Speed Circuit Switched Data) and

EDGE (Enhanced Data Rates for GSM Evolution)

Telecomm market players

Telecommunication network content and technology producers, operators and consumers form an interoperable hierarchy

Telecomm market players

End-users (individuals and companies)

Information service providers (As a telephone catalog services designed by a company, giving telephone numbers when you give a name or an address)

Service brokers sell dedicated service packages (as MySAP)

Network operators (as Elisa, Telia, or Radiolinja)

Content providers (as Paramount Pictures)

Telecom services categorized

The ISO-OSI Model

The OSI-functions

Practical networks usually melt OSI

Each OSI-layer has its standardized services

Practical network stratums

OSI is seldom realized as
itself but several layers are
melted together into stratums

In this example X.25 packet
network operates on ATM
based SDH access stratums.

ATM forms an efficient
info pipe where no
address checking or
error correction is done
but it is left for
lower layers

The PSTN hierarchy

Since ‘96 in Finland all the exchanges of PSTN have been digital

However, there exists still analog phones

Natural connection to the modern PSTN is the ISDN-interface

Example: PSTN Network operator in two towns

Telecommunications service requirements
from the physical level: QoS

Networking requirements: What services require from the network in respect of

Bandwidth,

Burstiness,

Symmetry (uplink /downlink rates),

Bit errors and blocking

Delay

Security

These define QOS (Quality of Service)

Different services require different rates

Burstiness: video, voice, data

Different services (telecomm. traffic) require different networking abilities

Most real-life sources produce bursty traffic

Modern networks can adapt into bursty service by allocation capacity very rapidly for other users

Speech and data communications

Teletraffic can be forced to fixed rate or bandwidth as speech in PSTN or ATM traffic

Bit errors and blocking

Real-time services for video and audio

Can not tolerate delays clearly observable by human (in order 200 ms or larger)

Can tolerate relatively large error rates

Blocking probability depends on number of customers in a service area

Fixed rate data services require much non-reusable capacity:

Fixed delay

demanding error rate limit

High-latency data:

Large flexibility in delay

demanding error rate limit

Symmetry

Categories:

Symmetrical channel as in fixed line telephony

Asymmetrical channel

Most technical Internet realizations (As xDSL-techniques or data over DVB, ADSL: 64 kb/s DL, 256 kb/s and up UL) are based on idea that downlink traffic is much larger that uplink traffic (in Welho^® (by HTV) connections 525 kb/s DL, 120 kb/s UL)

Point-to-multipoint channel

TV and Fax are point-to-multipoint distributive services

Note, however that some new (peer-to-peer) services in Internet (where your PC works as a server, using Gnutella network) might require symmetrical traffic channel

Also Internet is used for point-to-multipoint (multicast) services as in Webcasting (as in Web-broadcasting or in the PointCast news service.)

Therefore developing Internet services set stringent requirements for network infrastructure & planning!

Security and secrecy*

Services require usually security & serrecy, e. g. reliable, shielded transfer. Especially for

rescue services

police

defense force

some special applications as telesurgery

Networks can provide this by using:

fixed lines (PSTN, frame relay)

flexible routing (SS7)

scrambling or encryption (PLMNs)

coding or ciphering (in all modern telecom links & nets)

Often reassured in several network levels

Public switched telephone network (PSTN)

The oldest (1876) bearer network (other: ISDN, ATM, frame relay, The Internet)

After 1960 has got many renovations: data, fax, processor exchanges, PCM, satellite communications, network intelligence

Primary characteristics

Analog access 300-3400 Hz

Circuit switched connection

Switched bandwidth 64 kbit/s (Digital exchanges)

Immobility (or limited mobility as in DECT=PABX RF-interface)

Integrated nowadays especially with N-ISDN

The PSTN (cont.)

The PSTN is optimized for fixed speech service, statistically distributed, analog subscribers (by using the circuit switching technology that was made available beginning of this century).

Support for data traffic "artificially added" by

modems

ISDN (integrated into exchanges)

xDSL (x digital subscriber line)

However, PSTN is

Easily congested when subscriber services
(or behavior) changes unexpectedly (no graceful degradation as in CDMA-PLMN): resource wasting

The PSTN (cont.)

Vulnerable: network paralyzed easily in exchange malfunctions (still parallel system(s) provided)

Network intelligence in exchanges and dummy terminals

Poor adaptivity

However, an important backbone for other networks!

The PSTN will be there for a long time and it seems that it can be used for modern day networking also on quite high data rates by using various extension techniques

Modern day networks are constructed thus that the required services can be supported: Thus

Integrated Services Data Network (ISDN)

In N-ISDN (narrow band 2x64 kb/s +16 kb/s, extendable up to 30x64=1.92 Mb/s), B-ISDN (rates exceeding 100 Mb/s) and ATM (asynchronous transfer mode) networks all services are handled integrated, circuit switched way.

Mobility enabled by DECT (Digital Enhanced Cordless Telecommunications )

Nowadays there exists many competitive techniques for ISDN as

Cable modems,

ISM -band (Industry, Science, Medicine) LANs (as HiperLAN I & II)

Digital satellite networking by DVB (SAS Astra^®)

WCDMA

PSTN with 56 kbit/s (V.90) technology

Signaling networks

Telecom nets require more and more processor capacity:

More subscribers

Setting up connection is getting increasingly complex

Number of supplementary services increasing

Thus the need to transmit signaling information (=interactive network telematic communication) is increasing

The Internet(working)

The Internet carries “Everything over any physical medium” but still the 'best effort' meaning no service quality guaranteed

Internet topics:

TCP/IP: Frames and sessions

Routing: Backbone connected subnets

Network planning: Core - Regional nets - Access nets - Users

Signaling: TCP client – server communications

Services: http, ftp, email, irc, news, telnet ….

Internetworking (!) for instance data over PSTN: PPP, SLIP

TCP/IP: Transmission Control Protocol
Internet Protocol: a distributed triumph

The first Internet was ARPANET in 1969’s with four nodes

Present TCP/IP version 4 has problems especially in

lacking of address capacity

security

In 1997 ipV6 was initiated - However not too much used yet due to compatibility problems

TCP/IP does not have any general advance (except that it is so widespread) when compared to IPX, AppleTalk, DECnet etc.

Essential high level network functions

routing management

name servers

network management protocols

Network consists of

hardware as workstations, networks, routers, bridges

software as applications and protocols

TCP/IP Network transmission

TPC/IP tasks: end-to-end transmission, error correction, maintain packet order

Internet is based on datagrams that address subnets via routers

A simple routing could be accomplished by a lookup table between target IP and subnet IP

The playground of telecommunications markets

Future trends

PSTN used to transfer more and more data traffic

user PSTN rates increase up to several Mb/s

Also data networks (as Frame Relay) will be used for voice and there is a strong tendency to put everything over IP

The fax service in PSTN will diminish and the respective messages are transmitted by e-mail (that is transferred via a packet networks (usually by TCP/IP))

Inter(net)working between networks increases

Traditional voice service in PSTN transforms using packets and moves to Internet

PLMNs and especially (RF)-LANs develop very fast

Web resources

xDSL: www.adsl.com

3:rd generation PLMN: www.w3.org, www.3gpp.org

Telehallintokeskus: www.thk.fi

IEEE standards: www.ieee.org

Finnish standards: www.thk.fi/tele/suomi/standard.htm

Network & terminal realization: www.nokia.com

Have a look on link list at Kurose-Ross’s homepage: open resources/references (!)

… and so many more!


Practicalities
Table of course contents
Networking paradigms: Determining networking trends
Network evolvement
	Topology
		divided
		integrated
		mobile
	Telecommunication markets
Review of course contents in selected topics
	The OSI-model
	Networking approaches: PSTN, ISDN, Mobile, Internet
Future trends


	Lectures (Thursdays 14-16 in hall C)
		Timo Korhonen (timo.korhonen@hut.fi)
		Michael Hall (michael.hall@hut.fi)
	Tutorials (Wednesdays 14-16 in S1)
		Mika Nupponen (mika.nupponen@hut.fi), Yue Feng (feng@cc.hut.fi)
	Textbooks: Ericsson, Telia: Understanding Telecommunications, Part II, ISBN 91-44-00214-9 (Studentlitteratur), James F. Kurose, Keith W. Ross: Computer Networking (2nd Ed.,Addison Wesley)
	Reference: A.S. Tanenbaum: Computer Networks (4th Ed., Prentice Hall)
	Homepage: http://www.comlab.hut.fi/opetus/423


	Course grade consists of
		Closed book Exam (max 5p, required)
		Lecture Diary (max 5p, required at least 8 diaries to return and grade, full compensation only if diaries of all lectures returned, voluntary)
		Tutorials (max 5p, voluntary)
	Grade weights: E0.95+D0.2+T*0.15
	Example of lecture diary can be inspected at homepage.
	After the lecture send email to lectures@hut.fi to specify:
		Your name and student number
		Web address where you store your lecture diaries (all your diaries are accessible from a single page you set up)
	Diaries graded by fellow students - grading guide available at the course homepage


	Introduction
	Public Switched Telephone Network (PSTN)
		Exchange techniques
		Transmission
	Integrate Services Digital Network (ISDN)
		Functions
		Interfaces
	Automatic Transfer Mode (ATM) and Broadband-ISDN
	X.25, Frame relay
	Public land mobile networks
		GSM
		WCDMA
	Signaling networks: SS7
	The Internet: Network topology, TCP/IP Suite, Services


	Trunk and access parts
	Access part terminated by terminals
	Network nodes and links are optimized for certain assumed traffic patterns
	This model applies for both data (packet) and voice networks
	Due to these network similarities network analysis carriers common subtopics


	User services and terminals (as IN services: call last dialed...)
	Standards (IETF, IEEE, ITU-T ...)
	Routing and switching (unicast - multicast, devices)
	Transmission and links (as fibre, coax-cable.., RSVP)
	Access and transport (terminals, local-loop techniques..)
	Servers service (web,mail,ftp ...)
	Signaling (SS7, X.25, Frame relay ...)
	Network management (as OMAP of SS7...)
	Interworking between networks (gateways, bridges ...)
	Network planning


	Most people have observed that a telecommunications network is a system transmitting the messages (even SMS) … In this course we focus on analyzing that the networks can be divide to ...


	Nodes and links with well defined (standardized) interfaces
	Network nodes and links that are optimized for certain, assumed traffic
	Traditional assumption: Voice and data services in different networks


	UMTS supports wide range of applications that posses different quality of service (QoS) requirements.
	Applications and services can be divided in different groups, depending on QoS requirements. Four traffic classes can been identified:
		Conversational class (very delay-sensitive traffic)
		Streaming class
		Interactive class
		Background class (the most delay insensitive)
	Hence TCP (Connection-oriented transport-layer ) is not always applied - one may use also UDP (Connectionless transport-layer protocol) - Why?


	Services manifest themselves via various customer profiles (that may differ within a short time period), and thus efficient adaptivity should be supported by network configurations
	Advanced networks have a tendency to carry intelligence in terminals (and not in exchanges)
		Reduces signaling traffic
		Moves costs to end-users
	IN (Intelligent Network) solutions developed first for PSTN but a typical important part of most networks as in PLMNs
		Enables service flexibility in exchanges (software radio does the same in terminals)
		IN services designed in cooperation with terminal intelligence


	Mobility is required practically for all services in the very near future!
	In this course we will discuss especially the GSM (Global System for Mobile communications) (9.6 kbit/s++) and WCDMA (Wideband Code Division Multiple Access, or UMTS) networks
	UMTS will be launched 2002-2003 yielding mobile data rates up to 2 Mb/s. However, the GSM network will be upgraded for higher rates thanks to
		GPRS (General Packet Switched Data),
		HSCSD (High Speed Circuit Switched Data) and
		EDGE (Enhanced Data Rates for GSM Evolution)


	Telecommunication network content and technology producers, operators and consumers form an interoperable hierarchy


	End-users (individuals and companies)
	Information service providers (As a telephone catalog services designed by a company, giving telephone numbers when you give a name or an address)
	Service brokers sell dedicated service packages (as MySAP)
	Network operators (as Elisa, Telia, or Radiolinja)
	Content providers (as Paramount Pictures)


	OSI is seldom realized as itself but several layers are melted together into stratums
	In this example X.25 packet network operates on ATM based SDH access stratums.
	ATM forms an efficient info pipe where no address checking or error correction is done but it is left for lower layers


	Since ‘96 in Finland all the exchanges of PSTN have been digital
	However, there exists still analog phones
	Natural connection to the modern PSTN is the ISDN-interface


	Networking requirements: What services require from the network in respect of
		Bandwidth,
		Burstiness,
		Symmetry (uplink /downlink rates),
		Bit errors and blocking
		Delay
		Security
	These define QOS (Quality of Service)


	Different services (telecomm. traffic) require different networking abilities
	Most real-life sources produce bursty traffic
	Modern networks can adapt into bursty service by allocation capacity very rapidly for other users


	Teletraffic can be forced to fixed rate or bandwidth as speech in PSTN or ATM traffic



	Real-time services for video and audio
		Can not tolerate delays clearly observable by human (in order 200 ms or larger)
		Can tolerate relatively large error rates
		Blocking probability depends on number of customers in a service area
	Fixed rate data services require much non-reusable capacity:
		Fixed delay
		demanding error rate limit
	High-latency data:
		Large flexibility in delay
		demanding error rate limit


Categories:
	Symmetrical channel as in fixed line telephony
	Asymmetrical channel
		Most technical Internet realizations (As xDSL-techniques or data over DVB, ADSL: 64 kb/s DL, 256 kb/s and up UL) are based on idea that downlink traffic is much larger that uplink traffic (in Welho^® (by HTV) connections 525 kb/s DL, 120 kb/s UL)
	Point-to-multipoint channel
		TV and Fax are point-to-multipoint distributive services
Note, however that some new (peer-to-peer) services in Internet (where your PC works as a server, using Gnutella network) might require symmetrical traffic channel
Also Internet is used for point-to-multipoint (multicast) services as in Webcasting (as in Web-broadcasting or in the PointCast news service.)
Therefore developing Internet services set stringent requirements for network infrastructure & planning!


	Services require usually security & serrecy, e. g. reliable, shielded transfer. Especially for
		rescue services
		police
		defense force
		some special applications as telesurgery
	Networks can provide this by using:
		fixed lines (PSTN, frame relay)
		flexible routing (SS7)
		scrambling or encryption (PLMNs)
		coding or ciphering (in all modern telecom links & nets)
	Often reassured in several network levels


	The oldest (1876) bearer network (other: ISDN, ATM, frame relay, The Internet)
	After 1960 has got many renovations: data, fax, processor exchanges, PCM, satellite communications, network intelligence
	Primary characteristics
		Analog access 300-3400 Hz
		Circuit switched connection
		Switched bandwidth 64 kbit/s (Digital exchanges)
		Immobility (or limited mobility as in DECT=PABX RF-interface)
		Integrated nowadays especially with N-ISDN


	The PSTN is optimized for fixed speech service, statistically distributed, analog subscribers (by using the circuit switching technology that was made available beginning of this century).
	Support for data traffic "artificially added" by
		modems
		ISDN (integrated into exchanges)
		xDSL (x digital subscriber line)
	However, PSTN is
		Easily congested when subscriber services (or behavior) changes unexpectedly (no graceful degradation as in CDMA-PLMN): resource wasting


		Vulnerable: network paralyzed easily in exchange malfunctions (still parallel system(s) provided)
		Network intelligence in exchanges and dummy terminals
		Poor adaptivity
		However, an important backbone for other networks!
	The PSTN will be there for a long time and it seems that it can be used for modern day networking also on quite high data rates by using various extension techniques
	Modern day networks are constructed thus that the required services can be supported: Thus


	In N-ISDN (narrow band 2x64 kb/s +16 kb/s, extendable up to 30x64=1.92 Mb/s), B-ISDN (rates exceeding 100 Mb/s) and ATM (asynchronous transfer mode) networks all services are handled integrated, circuit switched way.
	Mobility enabled by DECT (Digital Enhanced Cordless Telecommunications )
	Nowadays there exists many competitive techniques for ISDN as
		Cable modems,
		ISM -band (Industry, Science, Medicine) LANs (as HiperLAN I & II)
		Digital satellite networking by DVB (SAS Astra^®)
		WCDMA
		PSTN with 56 kbit/s (V.90) technology


	Telecom nets require more and more processor capacity:
		More subscribers
		Setting up connection is getting increasingly complex
		Number of supplementary services increasing
	Thus the need to transmit signaling information (=interactive network telematic communication) is increasing


	The Internet carries “Everything over any physical medium” but still the 'best effort' meaning no service quality guaranteed
	Internet topics:
		TCP/IP: Frames and sessions
		Routing: Backbone connected subnets
		Network planning: Core - Regional nets - Access nets - Users
		Signaling: TCP client – server communications
		Services: http, ftp, email, irc, news, telnet ….
		Internetworking (!) for instance data over PSTN: PPP, SLIP


	The first Internet was ARPANET in 1969’s with four nodes
	Present TCP/IP version 4 has problems especially in
		lacking of address capacity
		security
	In 1997 ipV6 was initiated - However not too much used yet due to compatibility problems
	TCP/IP does not have any general advance (except that it is so widespread) when compared to IPX, AppleTalk, DECnet etc.
	Essential high level network functions
		routing management
		name servers
		network management protocols
	Network consists of
		hardware as workstations, networks, routers, bridges
		software as applications and protocols


	TPC/IP tasks: end-to-end transmission, error correction, maintain packet order
	Internet is based on datagrams that address subnets via routers
	A simple routing could be accomplished by a lookup table between target IP and subnet IP


	PSTN used to transfer more and more data traffic
	user PSTN rates increase up to several Mb/s
	Also data networks (as Frame Relay) will be used for voice and there is a strong tendency to put everything over IP
	The fax service in PSTN will diminish and the respective messages are transmitted by e-mail (that is transferred via a packet networks (usually by TCP/IP))
	Inter(net)working between networks increases
	Traditional voice service in PSTN transforms using packets and moves to Internet
	PLMNs and especially (RF)-LANs develop very fast