Transcript 1130 - Aalto

S-72.1130 Telecommunication
Systems
Overview
Practicalities
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Lectures (Tuesdays & Thursdays 14-16 in hall S4): Timo Korhonen (09 451
2351), Michael Hall (09 451 2322)
Tutorials (Wednesdays 14-16 in hall S3): Mika Nupponen (09 451 5416), Naser
Tarhuni (09 451 2362)
Exams:
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25.10.2005, 16-19, s1;s4
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21.12.2005, 9-12, s1; s4
Much of material in printed handouts, references:
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James F. Kurose, Keith W. Ross: Computer Networking, 2nd ed.
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A. Leon-Garcia, I. Widjaja: Communication Networks, 2nd ed.
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M. Duck, R. Read: Data Communications and Computer Networks, 2nd ed.
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W. Stallings: Data and Computer Communications, 7th ed.
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Ericsson, Telia: Understanding Telecommunications, Part I & Part II
Grading: Compulsory closed book exam and voluntary tutorials: e+t*0.15
Tutorials at: http://www.comlab.hut.fi/studies/1130/exercises/. First published
on 22.9 - return by 27.9, Return box in E-wing, 3rd floor.
Homepage: http://www.comlab.hut.fi/studies/1130
Course feedback: http://palaute.ee.hut.fi/
HUT Comms. Lab, Timo O. Korhonen
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Course Objectives
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To understand basic of Telecommunication Systems
 How & why systems operate the way they do?
What may happen in the future based on present state of
technology?
Role of abbreviations???
 Describe standardized protocols & systems
(=concepts)
 More important to understand the meaning of concept
that to remember the exact words where abbreviation
comes from
Role of interfaces
 Telecommunication systems are modular, what
happens in interfaces? This gives idea of internal
realization and function of modules
HUT Comms. Lab, Timo O. Korhonen
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Course Agenda
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Public Switched Telephone Network (PSTN)
Integrate Services Digital Network (ISDN) and SS7
Intelligent Network (IN)
Asynchronous Digital Subscriber Line (ADSL)
Wireless Local Area Networks (WLANs)
The Internet
 UDP
 SIP
 QoS: MPLS, diff. Serv.
 TCP/IP Suite
 Services
Telecommunications market
HUT Comms. Lab, Timo O. Korhonen
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Networking Subtopics
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User services as
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IN services: call last dialed, alternate billing services (as calling
card, collect call)
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Internet: web, email, ftp …
Terminals (modems and PSTN/ISDN phones), user interfaces
Standards (ITU-T, ITU-R, IETF, IEEE,...)
Routing and switching (unicast - multicast, devices & protocols
RSVP)
Transmission and links (fibre, coax-cable..)
Access and transport techniques (flow control, error control)
Signaling (SS7, X.25, Frame relay ...)
Network management (as OMAP of SS7...)
Interworking (gateways, bridges ...)
IN: Intelligent Network
Network planning
HUT Comms. Lab, Timo O. Korhonen
IETF: Internet Engineering Task Force
IEEE: the Institute of Electrical and Electronics Engineers, Inc
RSVP: Resource ReSerVation Protocol
ITU: International Telecommunications Union
SS7: Signaling System 7 (in ISDN)
OMAP: Operation and Maintenance Application Part
5
Information Society
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“Information and Communication Anytime, Anywhere, and
in Any Form”
Key development fields:
Services
Legislation
/Regulation
/Standardization
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Global
Market
Technology
To understand how networks/terminals/services evolve consider
especially services because all network costs are paid by service
users:
Services shape telecommunications’ evolution and
effect greatly on which technology is chosen!
HUT Comms. Lab, Timo O. Korhonen
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Paradigm Shift
Speech
Old view
Low-rate
data modems (V.90)
Current view
+ Other computers &
agent-programs (M2M)
SMS MMS
VoIP
http
HUT Comms. Lab, Timo O. Korhonen
DVB-H
ftp
smtp
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Evolving Telecommunication Services
PSTN-originated
services Call Holding/
International
Roaming
Call Waiting
Call Barring/
Call Forwarding
Data: 56 kb/s (V.90)
Pre-paid Services
Push-adds
Catalog Enquiry
Internet Access
Data: 9.6 Kb/s
… 380 kb/s
13 Kb/s Voice
Circuit/Packet
Switching: Mobility,
Data communication
*III Play=VoIP+DVB-H+Internet
HUT Comms. Lab, Timo O. Korhonen
Instant Messaging/Chat
Streaming: Video, Audio
WAP
Circuit Switching:
Voice services,
IN-services, limited data
Interactive Games
SMS
Voice Mail
Basic Voice
BW ~ 4 kHz
2.5G-3G
Services
2G Services
Data up to 2 Mb
Mobile Commerce
Push-to
Talk
10 Mb/s (HSDPA)
MMS
Rich Call: “See what I see!”
III Play*
Location Identification - Presence
All-IP: Location, mobility management, presence,
personalization, security
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Telecommunication Networks
Core Network
Node 1
Node 2
Access
Access
Node 3
Terminals
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Terminals
Internal structure can follow different
topologies: mesh/star/bus/ring
(see supplementary material)
Core and access parts
Access part terminated by terminals
Network nodes and links are optimized for certain assumed
traffic sources and transmission channels
Model applies for both data (packet) and voice networks
HUT Comms. Lab, Timo O. Korhonen
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Tasks of a Communication System
Entity 3
Entity 3
Entity 2
Entity 2
interface
Entity 1
Entity 1
Physical connection
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Initialization and release of link/across network
Synchronization RX & TX - carriers, start and end of packets
Information exchange protocols determine protocols for
communication in entities: CSMA, CDMA, … TCP/IP
Error control - corrective measures
Addressing and routing
Message formatting, source coding
Therefore, networks realized by following a layered structure
(as Open System Interconnections (OSI) )
HUT Comms. Lab, Timo O. Korhonen
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Access to OSI environment applications
2. Data Link
Independence of applications from differences
in data presentations(compression & encryption)
Establishing, managing and termination connections
(sessions~dialogues) between cooperating applications
Reliable, transparent data transfer for lower level
data segments or blocks(end-to-end flow & error cntr)
Routing & switching service for transport layer.
Layer of routers.
Sends data blocks with synchronization, error and flow
control for link layer connections. Layer of bridges.
1. Physical
Transmission of electrical signals in medium.
Layer or repeaters (multiplexing/bit transmission)
6. Presentation
5. Session
4. Transport
3. Network
HUT Comms. Lab, Timo O. Korhonen
LAN Layers
7. Application
Gateway Layers
Open System Interconnection (OSI) Layers
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Each OSI-layer has its Standardized Services
7. Application
NCP, FTP, Telnet, SMTP, SNMP, LAT, AFP, SMB...
6. Presentation
ACSE, ROSE, RTSE, ...
5. Session
NetBIOS, NetBEUI, DNS, ...
4. Transport
SPX, PEP, TCP, UDP, NSP...
3. Network
IPX, RIP, SAP, IDP, IP, ARP, RSVP, ICMP, X.25, RIP...
2. Data Link
IEEE 802.X, HDLC, ANSI X3T9.5, SMT,...
1. Physical
V.24, V.35, V.90, 10Base5, 10Base2, 10BaseT, FDDI,
SDH, G.703...
Good source for abbreviations:
http://www.mpirical.com/companion/mpirical_companion.html
HUT Comms. Lab, Timo O. Korhonen
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Example from mpirical - database
http://www.mpirical.com/companion/mpirical_companion.html
HUT Comms. Lab, Timo O. Korhonen
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ITU-T Standards
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G - Transmission Systems and media, digital systems and
networks
H - Audiovisual and multimedia systems
I - ISDN
Q - Switching and signalling
V - Data communications over PSTN
X- Data networks and open system communications
Other important standardization organizations:
- IEEE (Institute of Electrical and Electronics Engineers)
- IETF (The Internet Engineering Task Force)
- ISO (International Organization for Standardization)
- ETSI (European Telecommunications Standards Institute)
HUT Comms. Lab, Timo O. Korhonen
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Example: Retrieving a Document from the Web
Addressing
Step:
1.
TCP/IP connection
2.
3.
4. –
6.
7. –
8.
HUT Comms. Lab, Timo O. Korhonen
Document
specifications
Document
response
Viewing the
document,
closing TCP/IP
The user clicks on a link to indicate which document
is to be retrieved. The browser must determine the
Internet address of the machine that contains the
document. To do so, the browser sends a query to
its local name server. DNS, UDP, HTTP, FTP, HTML
Once the address is known, the browser establishes
a connection to the server process in the specified
machine, usually a TCP connection. For the
connection to be successful, the specified machine
must be ready to accept TCP connections. TCP/IP
The browser runs a client version of HTTP, which
issues a request specifying both the name of the
document and the possible document formats it can
handle.
The machine that contains the requested document
runs a server version of HTTP. It reacts to the
HTTP request by sending an HTTP response which
contains the desired document in the appropriate
format. Document sent to the receiver.
The user may start to view the document. The TCP
connection is closed after a certain timeout period.
From Leon-Garzia, Widjaja: Communication Networks, 2th ed., Instructor’s Slide Set
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Different Services Require
Different Rates
Voice
Maximum Rates of some
Transmission Technologies
Telephony
Broadcasting
Video conferencing
Video
TV/HDTV
Video
GSM 14.4 kb/s
HSCSD 56 kb/s
POTS 56 kb/s
GPRS 114 kb/s
EDGE 384 kb/s
Frame Relay 1.54 Mb/s
T-1 1.54 Mb/s
ADSL 8 Mb/s
Cable modems 52 Mb/s
Ethernet 10 M, 100 M, 1G
FDDI 100 Mb/s
OC-256 13.3 Gb/s
Data
Inter-LAN/PBX communications
Fax
Streaming with MPEG, MP3
10k
HUT Comms. Lab, Timo O. Korhonen
1M
100M
Bit rate (b/s)
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Streaming Technologies
Major streaming video and streaming media technologies include
RealSystem G2 from RealNetwork, Microsoft Windows Media
Technologies (including its NetShow Services and Theater
Server), and VDO. Microsoft's approach uses the standard
MPEG compression algorithm for video. The other approaches
use proprietary algorithms. (The program that does the
compression and decompression is sometimes called the codec.)
Microsoft's technology offers streaming audio at up to 96 Kbps
and streaming video at up to 8 Mbps (for the NetShow Theater
Server). However, for most Web users, the streaming video will
be limited to the data rates of the connection (for example, up
to 128 Kbps with an ISDN connection). Microsoft's streaming
media files are in its Advanced Streaming Format (ASF).
Source: Searchnetworking.com
HUT Comms. Lab, Timo O. Korhonen
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Network Evolution
1995
2010
Single system support
Software
radio
Multi-system support
GSM, DECT
UMTS/4G
GPRS, EDGE, HSCSD
PSTN, ISDN
Voice, low rate data
Modest-rate
Push-to-talk,
VoIP
Internet
1992
HUT Comms. Lab, Timo O. Korhonen
2G: Data
compr.
2.5x
9.6 kb/s
1998
Radio
interface
Trunk
/Core
ATM, ISDN,
B-ISDN
TCP-IP/UDP
2G:
Fax/data/
SMS
9.6 kb/s
Terminal
Portable,
Multimedia,
global
virtual
Virtual
reality
reality
Services
2.5G:
HSCSD
28.8 kb/s
2.5G:
GPRS
92 kb/s
2.5G:
EDGE
384 kb/s
3G:
UMTS
2 Mb/s
3G:
HSDPA
10 Mb/s
2000
2001
2003
2004
2005
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Speech and Data Communications
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Speech
Data
Delays
Limited to ~200 ms
Depends on service
Errors
High tolerance
Very limited tolerance
Stream
Continuous: Circuit
switching
Bursty: Packet
switching
Teletraffic can be forced to fixed rate or bandwidth as
speech in PSTN or in ATM traffic
Waste of network resources follows if network resources
can not be reallocated on request (=statistical
multiplexing)
HUT Comms. Lab, Timo O. Korhonen
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Symmetry
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Categories:
 Asymmetrical channel
 based on idea that downlink traffic is much larger that
uplink traffic
 Traditionally in access networks (ADSL, Cable modems)
 Data over DVB
 Symmetrical channel as in fixed line telephony
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Some services (as P2P) require symmetrical traffic channel!
Point-to-multipoint channel (broadcasting)
 TV (DVB) and Fax are point-to-multipoint distributive
services
 Webcasting (PointCast news service)
Rapidly developing Internet services set stringent requirements
for network infrastructure & planning
 adaptivity
 service/system upgradability
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HUT Comms. Lab, Timo O. Korhonen
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Network Topology
Optical star-coupler
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Optical networks
Different topologies in
different networks
 BUS - Ethernet
 Ring - FDDI
 Mesh - Internet; Number
of connections required:
N ( N  1) N 2

2
2
N: number of nodes
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HUT Comms. Lab, Timo O. Korhonen
Selection of topology
effects for instance
applicable MAC scheme
& network reliability
IEEE 802 (LAN)
technology often applied
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What is Ethernet?
Ethernet is the most widely-installed local area network (LAN)
technology. Specified in a standard, IEEE 802.3, Ethernet was
originally developed by Xerox and then developed further by
Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial
cable or special grades of twisted pair wires. Ethernet is also
used in wireless LANs. The most commonly installed Ethernet
systems are called 10BASE-T (100 m / CAT 3 cables) and
provide transmission speeds up to 10 Mbps. Devices are
connected to the cable and compete for access using a Carrier
Sense Multiple Access with Collision Detection (CSMA/CD)
protocol.
Fast Ethernet or 100BASE-T provides transmission speeds up
to 100 megabits per second and is typically used for LAN
backbone systems, supporting workstations with 10BASE-T
cards. Gigabit Ethernet provides an even higher level of
backbone support at 1000 megabits per second (1 gigabit or 1
billion bits per second). 10-Gigabit Ethernet provides up to 10
billion bits per second.
Source: Searchnetworking.com
HUT Comms. Lab, Timo O. Korhonen
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What is FDDI?
FDDI (Fiber Distributed Data Interface) is a set of ANSI and ISO
standards for data transmission on fiber optic lines in a local area
network (LAN) that can extend in range up to 200 km (124 miles). The
FDDI protocol is based on the token ring protocol. In addition to being
large geographically, an FDDI local area network can support
thousands of users. FDDI is frequently used on the backbone for a
wide area network (WAN).
An FDDI network contains two token rings, one for possible backup in
case the primary ring fails. The primary ring offers up to 100 Mbps
capacity. If the secondary ring is not needed for backup, it can also
carry data, extending capacity to 200 Mbps. The single ring can extend
the maximum distance; a dual ring can extend 100 km (62 miles).
FDDI is a product of American National Standards Committee X3-T9
and conforms to the Open Systems Interconnection (OSI) model of
functional layering. It can be used to interconnect LANs using other
protocols. FDDI-II is a version of FDDI that adds the capability to add
circuit-switched service to the network so that voice signals can also
be handled. Work is underway to connect FDDI networks to the
developing Synchronous Optical Network (SONET).
HUT Comms. Lab, Timo O. Korhonen
Source: Searchnetworking.com
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Quality of Service (QoS)
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ATM, MPLS and UMTS support wide range of services that posses
different quality of service (QoS) requirements.
Transportation system differentiated into constant rate, real-time
and higher-latency services by Multi-Protocol Label Switching
(MPLS) or Differentiated Services (DiffServ)
User services can be divided to different groups, depending on QoS
requirements. Four traffic classes can been identified for ATM:
 Conversational class (very delay-sensitive traffic)
 Streaming class
 Interactive class
 Background class (the most delay insensitive)
Hence TCP (Connection-oriented transport-layer) is not a good
choice if errors can be tolerated
UDP (Connectionless transport-layer protocol) appropriate for
many streaming applications (error control in upper layers)
HUT Comms. Lab, Timo O. Korhonen
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Multiprotocol Label Switching (MPLS)
Multiprotocol Label Switching is a standards-approved
technology (IETF: RFC 3031) for speeding up network traffic
flow and making it easier to manage. MPLS involves setting up
a specific path for a given sequence of packets, identified by
a label put in each packet, thus saving the time needed for a
router to look up the address to the next node to forward the
packet to. MPLS is called multi-protocol because it works with
the Internet Protocol (IP), Asynchronous Transport Mode
(ATM), and frame relay network protocols. With reference to
the standard model for a network (the Open Systems
Interconnection, or OSI model), MPLS allows most packets to be
forwarded at the layer 2(switching) level rather than at the
layer 3(routing) level. In addition to moving traffic faster
overall, MPLS makes it easy to manage a network for quality of
service (QoS). Note: ATM header overhead always at least 10
%, for MPLS it is order of magnitude smaller.
Source: Searchnetworking.com
HUT Comms. Lab, Timo O. Korhonen
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Security and Secrecy*
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Services require security & secrecy, e. g. reliable, shielded
transfer (Example WEP of Wi-Fi). Especially important for
 NGN-services that are ‘near to users’
 Vulnerable services:
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medical/health as tele-surgery
rescue, police, defense
Networks can provide this in several network levels
(problem: overheads);
 fixed lines (PSTN, frame relay)
 flexible routing (SS7)
 scrambling or encryption (PLMNs)
 coding or ciphering (in all modern telecom links &
nets)
Often used concept: AAA: Authentication, Authorization,
Accounting
• Message goes to the right receiver
*
HUT Comms. Lab, Timo O. Korhonen
• Others can’t do eavesdropping
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What is AAA?
Short for authentication, authorization and accounting, a system in IP-based
networking to control what computer resources users have access to and to
keep track of the activity of users over a network.
Authentication is the process of identifying an individual,
usually based on a username and password. Authentication is
based on the idea that each individual user will have unique
information that sets him or her apart from other users.
Authorization is the process of granting or denying a user
access to network resources once the user has been
authenticated through the username and password. The
amount of information and the amount of services the user has
access to depend on the user's authorization level.
Accounting is the process of keeping track of a user's activity
while accessing the network resources, including the amount of
time spent in the network, the services accessed while there
and the amount of data transferred during the session.
Accounting data is used for trend analysis, capacity
planning, billing, auditing and cost allocation.
AAA services often require a server that is dedicated to providing the three
services. RADIUS is an example of an AAA service.
Source: www.webopedia.com
HUT Comms. Lab, Timo O. Korhonen
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Network/Service Adaptivity
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Services manifest themselves via various service profiles (that may
differ within a short time period), and thus efficient adaptivity should
be supported by networks and terminals
Advanced networks have a tendency to carry intelligence in terminals
(and not in network nodes, exchanges, routers... )
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Reduces signaling traffic
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Moves costs to end-users
IN (Intelligent Network, ITU-T Q.1200-series) solutions developed first
for PSTN but typically an important part of most networks as in PLMNs
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Enable service flexibility (software radio does this in terminals)
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IN services designed in cooperation with terminal intelligence
PSTN
WLANs
HUT Comms. Lab, Timo O. Korhonen
PLMN
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Development of
Data and Voice Networks
Earlier Scenarios
Voice/modems in PSTN
Leased lines
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Frame Relay:
- applies virtual circuits
- example to connect LANs
- for high quality (links
have modest error
correction & flow control)
- rates: 2-50 Mb/s
Frame Flow Control:
(HDLC)
- service for a pair of
communicating entities
- reassures non-overwhelming
communications (packets
could suffocate receiver )
Nodes, links & layers with well-defined (standardized) interfaces
Network is optimized for certain, assumed traffic
Earlier Voice and data services in PSTN or data in dedicated
networks (X.25/Frame Relay)
Nowadays Internet carries both data and voice - QoS important!
HUT Comms. Lab, Timo O. Korhonen
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Current
Scenario
ISDN, V.90,
Cable modem,
ADSL etc.
MPLS
Bluetooth
Device
WLAN
Router
Modified from W. Stallings: Data and
Computer Communications, 7th ed
(home site lecture slides)
HUT Comms. Lab, Timo O. Korhonen
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Example: Bluetooth Technology
Connecting devices
in SOHO (Small Office/
Home Office) to
your computer
Realizing ad-hoc
networking with Bluetooth
Home
networking
See also http://www.bluetooth.com/
HUT Comms. Lab, Timo O. Korhonen
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What is Bluetooth?
Bluetooth is an industrial specification for wireless personal area networks (PANs).
Bluetooth provides a way to connect and exchange information between devices like personal
digital assistants (PDAs), mobile phones, laptops, PCs, printers and digital cameras via a
secure, low-cost, globally available ISM short range radio frequency.
Bluetooth lets these devices talk to each other when they come in range, even if they are not in
the same room, as long as they are within up to 100 metres (328 feet) of each other, dependent
on the power class of the product. Products are available in one of three power classes:
Class 3 (1 mW) is the rarest and allows transmission of 10 centimetres (3.9
inches), with a maximum of 1 metre (3.2 feet)
Class 2 (2.5 mW) is most common and allows a quoted transmission distance
of 10 metres (32 ft)
Class 1 (100 mW) has the longest range at up to 100 metres.
The specification was first developed by Ericsson, and was later formalized by the Bluetooth
Special Interest Group (SIG). SIG was established by Sony Ericsson, IBM, Intel, Toshiba and
Nokia, and later joined by many other companies as Associate or Adopter members. Bluetooth
is also IEEE 802.15.1 that specifies its radio interface by using frequency hopping.
HUT Comms. Lab, Timo O. Korhonen
http://en.wikipedia.org/wiki/Bluetooth
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Example: Public Switched
Telephone Network (PSTN)
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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 (IN), ADSL
Primary characteristics
 Circuit switched connections
 Analog access: bandwidth 300-3400 Hz
 Digital access for instance by

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ISDN (2x64 kbit/s + 16 kbits/s)
ADSL - Supports also packet switched connections
Limited mobility (DECT=PABX RF-interface)
HUT Comms. Lab, Timo O. Korhonen
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Network Stratums of PSTN
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In practical PSTN different
networks form ‘stratums’
In this example X.25 packet
network operates on ATM
based SDH access stratums.
ATM forms an efficient
info pipe (virtual circuits)
where no address checking
or error correction is done
but it is left for
higher layers
HUT Comms. Lab, Timo O. Korhonen
Wi-Fi (802.11b,g)
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Telecommunications Market
End-Users
Content and Service Providers
Service operators/
Telecommunications Networking Solutions
Physical Telecommunication Network
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Telecommunication network content and technology
producers, operators and consumers form an
interoperable hierarchy
HUT Comms. Lab, Timo O. Korhonen
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Telecomm Market Players
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End-users (individuals , companies, machine-to-machine
communications)
Information service providers (Telephone catalog services
designed by a company, giving telephone numbers when you
give a name or an address… Eniro)
Service brokers sell dedicated service packages (...MySAP)
Network operators (...Elisa, Telia, or Radiolinja)
Content providers (...Paramount Pictures)
HUT Comms. Lab, Timo O. Korhonen
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Future Trends
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PLMNs and especially wireless LANs develop very
fast in home & office networks
Increasing data rates
QoS very important
Traffic gets more symmetrical (P2P)
PSTN:
 Is used to transfer more and more data traffic
 Voice services of PSTN use IP (VoIP) and move
to Internet
Need of seamless communication of NGN means
that different networks must link efficiently ->
Inter(net)working between different kind of
networks important (example: Bluetooth-WLANUMTS)
HUT Comms. Lab, Timo O. Korhonen
PLMN: Public Land Mobile Network, IP:Internet Protocol
SLIP: Serial line IP
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Web Resources
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Tutorials, links, abbreviations :
http://searchnetworking.techtarget.com/
Mpirical bank of abbreviations: http://www.mpirical.com/
companion/mpirical_companion.html
Wikipedia: http://en.wikipedia.org
Note: Many standards available online in the Library (as for instance
ITU-standards )
Have a look on course reference books homepages!
3:rd generation PLMN: www.w3.org, www.3gpp.org
Finish Spectral Regulation: www.ficora.fi
IEEE standards: www.ieee.org
ITU standards: www.iti.org
xDSL development: www.adsl.com
HUT Comms. Lab, Timo O. Korhonen
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