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An Overview to Course Contents |
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Practicalities |
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Table of course contents |
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Networking paradigms: Determining networking
trends |
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Network evolvement |
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Topology |
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divided |
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integrated |
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mobile |
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Telecommunication markets |
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Review of course contents in selected topics |
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The OSI-model |
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Networking approaches: PSTN, ISDN, Mobile,
Internet |
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Future trends |
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Lectures (Thursdays 14-16 in hall C) |
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Timo Korhonen (timo.korhonen@hut.fi) |
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Michael Hall (michael.hall@hut.fi) |
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Tutorials (Wednesdays 14-16 in S1) |
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Mika Nupponen (mika.nupponen@hut.fi), Yue Feng
(feng@cc.hut.fi) |
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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) |
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Reference: A.S. Tanenbaum: Computer Networks
(4th Ed., Prentice Hall) |
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Homepage: http://www.comlab.hut.fi/opetus/423 |
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Course grade consists of |
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Closed book Exam (max 5p, required) |
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Lecture Diary (max 5p, required at least 8
diaries to
return and grade, full compensation only if diaries of all lectures
returned, voluntary) |
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Tutorials (max 5p, voluntary) |
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Grade weights: E*0.95+D*0.2+T*0.15 |
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Example of lecture diary can be inspected at
homepage. |
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After the lecture send email to lectures@hut.fi
to specify: |
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Your name and student number |
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Web address where you store your lecture diaries
(all your diaries are accessible from a single page you set up) |
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Diaries graded by fellow students - grading
guide available at the course homepage |
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Introduction |
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Public Switched Telephone Network (PSTN) |
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Exchange techniques |
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Transmission |
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Integrate Services Digital Network (ISDN) |
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Functions |
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Interfaces |
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Automatic Transfer Mode (ATM) and Broadband-ISDN |
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X.25, Frame relay |
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Public land mobile networks |
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GSM |
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WCDMA |
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Signaling networks: SS7 |
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The Internet: Network topology, TCP/IP Suite,
Services |
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Trunk and access parts |
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Access part terminated by terminals |
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Network nodes and links are optimized for
certain assumed traffic patterns |
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This model applies for both data (packet) and
voice networks |
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Due to these network similarities network
analysis carriers common subtopics |
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User services and terminals (as IN services:
call last dialed...) |
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Standards (IETF, IEEE, ITU-T ...) |
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Routing and switching (unicast - multicast,
devices) |
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Transmission and links (as fibre, coax-cable..,
RSVP) |
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Access and transport (terminals, local-loop
techniques..) |
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Servers service (web,mail,ftp ...) |
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Signaling (SS7, X.25, Frame relay ...) |
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Network management (as OMAP of SS7...) |
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Interworking between networks (gateways, bridges
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Network planning |
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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 ... |
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Nodes and links with well defined (standardized)
interfaces |
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Network nodes and links that are optimized for
certain, assumed traffic |
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Traditional assumption: Voice and data services in different networks |
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UMTS supports wide range of applications that
posses different quality of service (QoS) requirements. |
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Applications and services can be divided in
different groups, depending on QoS requirements. Four traffic classes can
been identified: |
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Conversational class (very delay-sensitive
traffic) |
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Streaming class |
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Interactive class |
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Background class (the most delay insensitive) |
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Hence TCP (Connection-oriented transport-layer )
is not always applied - one may use also UDP (Connectionless
transport-layer protocol) - Why? |
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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 |
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Advanced networks have a tendency to carry intelligence
in terminals (and not in exchanges) |
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Reduces signaling traffic |
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Moves costs to end-users |
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IN (Intelligent Network) solutions developed
first for PSTN but a typical important part of most networks as in PLMNs |
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Enables service flexibility in exchanges (software
radio does the same in terminals) |
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IN services designed in cooperation with
terminal intelligence |
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Mobility is required practically for all
services in the very near future! |
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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 |
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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 |
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GPRS (General Packet Switched Data), |
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HSCSD (High Speed Circuit Switched Data) and |
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EDGE (Enhanced Data Rates for GSM Evolution) |
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Telecommunication network content and technology
producers, operators and consumers form an interoperable hierarchy |
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End-users (individuals and companies) |
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Information service providers (As a telephone
catalog services designed by a company, giving telephone numbers when you
give a name or an address) |
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Service brokers sell dedicated service packages
(as MySAP) |
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Network operators (as Elisa, Telia, or
Radiolinja) |
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Content providers (as Paramount Pictures) |
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OSI is seldom realized as
itself but several layers are
melted together into stratums |
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In this example X.25 packet
network operates on ATM
based SDH access stratums. |
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ATM forms an efficient
info pipe where no
address checking or
error correction is done
but it is left for
lower layers |
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Since ‘96 in Finland all the exchanges of PSTN
have been digital |
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However, there exists still analog phones |
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Natural connection to the modern PSTN is the
ISDN-interface |
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Networking requirements: What services require
from the network in respect of |
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Bandwidth, |
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Burstiness, |
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Symmetry (uplink /downlink rates), |
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Bit errors and blocking |
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Delay |
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Security |
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These define QOS (Quality of Service) |
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Different services (telecomm. traffic) require
different networking abilities |
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Most real-life sources produce bursty traffic |
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Modern networks can adapt into bursty service by
allocation capacity very rapidly for other users |
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Teletraffic can be forced to fixed rate or
bandwidth as speech in PSTN or ATM traffic |
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Real-time services for video and audio |
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Can not tolerate delays clearly observable by
human (in order 200 ms or larger) |
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Can tolerate relatively large error rates |
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Blocking probability depends on number of
customers in a service area |
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Fixed rate data services require much
non-reusable capacity: |
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Fixed delay |
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demanding error rate limit |
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High-latency data: |
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Large flexibility in delay |
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demanding error rate limit |
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Categories: |
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Symmetrical channel as in fixed line telephony |
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Asymmetrical channel |
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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) |
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Point-to-multipoint channel |
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TV and Fax are point-to-multipoint distributive
services |
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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 |
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Also Internet is used for point-to-multipoint
(multicast) services as in Webcasting (as in Web-broadcasting or in the
PointCast news service.) |
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Therefore developing Internet services set
stringent requirements for network infrastructure & planning! |
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Services require usually security & serrecy,
e. g. reliable, shielded transfer. Especially for |
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rescue services |
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police |
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defense force |
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some special applications as telesurgery |
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Networks can provide this by using: |
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fixed lines (PSTN, frame relay) |
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flexible routing (SS7) |
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scrambling or encryption (PLMNs) |
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coding or ciphering (in all modern telecom links & nets) |
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Often reassured in several network levels |
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The oldest (1876) bearer network (other: ISDN,
ATM, frame relay, The Internet) |
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After 1960 has got many renovations: data, fax,
processor exchanges, PCM, satellite communications, network intelligence |
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Primary characteristics |
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Analog access 300-3400 Hz |
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Circuit switched connection |
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Switched bandwidth 64 kbit/s (Digital exchanges) |
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Immobility (or limited mobility as in DECT=PABX
RF-interface) |
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Integrated nowadays especially with N-ISDN |
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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). |
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Support for data traffic "artificially
added" by |
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modems |
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ISDN (integrated into exchanges) |
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xDSL (x digital subscriber line) |
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However, PSTN is |
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Easily congested when subscriber services
(or behavior) changes unexpectedly (no graceful degradation as in
CDMA-PLMN): resource wasting |
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Vulnerable: network paralyzed easily in exchange
malfunctions (still parallel system(s) provided) |
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Network intelligence in exchanges and dummy
terminals |
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Poor adaptivity |
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However, an important backbone for other
networks! |
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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 |
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Modern day networks are constructed thus that
the required services can be supported: Thus |
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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. |
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Mobility enabled by DECT (Digital Enhanced
Cordless Telecommunications ) |
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Nowadays there exists many competitive
techniques for ISDN as |
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Cable modems, |
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ISM -band (Industry, Science, Medicine) LANs (as
HiperLAN I & II) |
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Digital satellite networking by DVB (SAS Astra®) |
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WCDMA |
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PSTN with 56 kbit/s (V.90) technology |
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Telecom nets require more and more processor
capacity: |
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More subscribers |
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Setting up connection is getting increasingly
complex |
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Number of supplementary services increasing |
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Thus the need to transmit signaling information
(=interactive network telematic communication) is increasing |
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The Internet carries “Everything over any
physical medium” but still the 'best effort' meaning no service quality
guaranteed |
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Internet topics: |
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TCP/IP: Frames and sessions |
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Routing: Backbone connected subnets |
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Network planning: Core - Regional nets - Access
nets - Users |
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Signaling: TCP client – server communications |
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Services: http, ftp, email, irc, news, telnet …. |
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Internetworking (!) for instance data over PSTN:
PPP, SLIP |
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The first Internet was ARPANET in 1969’s with
four nodes |
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Present TCP/IP version 4 has problems especially
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lacking of address capacity |
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security |
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In 1997 ipV6 was initiated - However not too
much used yet due to compatibility problems |
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TCP/IP does not have any general advance (except
that it is so widespread) when compared to IPX, AppleTalk, DECnet etc. |
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Essential high level network functions |
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routing management |
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name servers |
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network management protocols |
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Network consists of |
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hardware as workstations, networks, routers,
bridges |
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software as applications and protocols |
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TPC/IP tasks: end-to-end transmission, error
correction, maintain packet order |
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Internet is based on datagrams that address
subnets via routers |
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A simple routing could be accomplished by a
lookup table between target IP and subnet IP |
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PSTN used to transfer more and more data traffic |
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user PSTN rates increase up to several Mb/s |
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Also data networks (as Frame Relay) will be used
for voice and there is a strong tendency to put everything over IP |
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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)) |
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Inter(net)working between networks increases |
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Traditional voice service in PSTN transforms
using packets and moves to Internet |
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PLMNs and especially (RF)-LANs develop very fast |
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xDSL: www.adsl.com |
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3:rd generation PLMN: www.w3.org, www.3gpp.org |
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Telehallintokeskus: www.thk.fi |
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IEEE standards: www.ieee.org |
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Finnish standards:
www.thk.fi/tele/suomi/standard.htm |
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Network & terminal realization:
www.nokia.com |
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Have a look on link list at Kurose-Ross’s
homepage: open resources/references (!) |
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… and so many more! |
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Notes