1130 - Aalto

Transcript 1130 - Aalto

S-72.1130 Telecommunication Systems

Overview

       

Practicalities

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:   25.10.2005, 16-19, s1;s4 21.12.2005, 9-12, s1; s4 Much of material in printed handouts, references:  James F. Kurose, Keith W. Ross: Computer Networking, 2nd ed.

   A. Leon-Garcia, I. Widjaja: Communication Networks, 2nd ed.

M. Duck, R. Read: Data Communications and Computer Networks, 2nd ed.

W. Stallings: Data and Computer Communications, 7th ed.

 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/ 2 HUT Comms. Lab, Timo O. Korhonen

Course Objectives

    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 3

Course Agenda

       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 4

Networking Subtopics

          User services as  IN services: call last dialed, alternate billing services (as calling card, collect call)  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 ...)

Network planning

IN: Intelligent Network 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 HUT Comms. Lab, Timo O. Korhonen 5

Information Society

  “

Information and Communication Anytime, Anywhere, and in Any Form

” Key development fields:

Services Global Market Legislation /Regulation /Standardization 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 6

Paradigm Shift

Old view Speech Low-rate data modems (V.90) Current view + Other computers & agent-programs (M2M) HUT Comms. Lab, Timo O. Korhonen SMS MMS http VoIP ftp DVB-H smtp 7

Evolving Telecommunication Services

PSTN-originated services Call Holding/ Call Waiting 2G Services International Roaming 2.5G-3G Services Interactive Games Instant Messaging/Chat Call Barring/ Call Forwarding SMS Streaming: Video, Audio Pre-paid Services Voice Mail Push-adds Basic Voice BW ~ 4 kHz Catalog Enquiry Internet Access Push-to Talk Data: 56 kb/s (V.90) Data: 9.6 Kb/s … 380 kb/s Data up to 2 Mb 10 Mb/s (HSDPA) Circuit Switching: Voice services, IN-services, limited data WAP 13 Kb/s Voice Circuit/Packet Switching: Mobility, Data communication Mobile Commerce MMS Rich Call: “See what I see!” III Play* Location Identification - Presence *III Play=VoIP+DVB-H+Internet HUT Comms. Lab, Timo O. Korhonen All-IP: Location, mobility management, presence, personalization, security 8

Telecommunication Networks Core Network Node 1 Node 2 Access Access Node 3 Terminals Terminals

    Core and access parts Access part terminated by terminals Internal structure can follow different topologies: mesh/star/bus/ring (see supplementary material) Network nodes and links are optimized for certain traffic sources and transmission channels assumed Model applies for both data (packet) and voice networks HUT Comms. Lab, Timo O. Korhonen 9

Tasks of a Communication System

Entity 3 Entity 3        Entity 2 Entity 2 interface Entity 1 Entity 1 Physical connection 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 10

Open System Interconnection (OSI) Layers 7. Application 6. Presentation 5. Session 4. Transport 3. Network 2. Data Link 1. Physical

Access to OSI environment applications 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 Layer of routers.

for transport layer. Sends data blocks with synchronization, error and flow control for link layer connections. Layer of bridges.

Transmission of electrical signals in medium .

Layer or repeaters (multiplexing/bit transmission) HUT Comms. Lab, Timo O. Korhonen 11

Each OSI-layer has its Standardized Services 7. Application 6. Presentation 5. Session 4. Transport

NCP, FTP, Telnet,

SMTP

, SNMP, LAT, AFP, SMB...

ACSE, ROSE, RTSE, ...

NetBIOS, NetBEUI,

DNS

, ...

SPX, PEP,

TCP

UDP

, NSP...

3. Network

IPX, RIP, SAP, IDP,

, 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 12

Example from mpirical - database

http://www.mpirical.com/companion/mpirical_companion.html

HUT Comms. Lab, Timo O. Korhonen 13

ITU-T Standards

      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 14

Example: Retrieving a Document from the Web Step:

Addressing 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

4. 6. 7. 8.

– – HUT Comms. Lab, Timo O. Korhonen TCP/IP connection 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

Document specifications 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.

Document response 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.

Viewing the document, closing TCP/IP 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 15

Different Services Require Different Rates

Telephony Broadcasting Video conferencing TV/HDTV Video Inter-LAN/PBX communications Fax Streaming with MPEG, MP3 10k HUT Comms. Lab, Timo O. Korhonen 1M 100M

Maximum Rates of some Transmission Technologies

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 Bit rate (b/s) 16

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

17 HUT Comms. Lab, Timo O. Korhonen

Network Evolution

1995 Single system support Multi-system support GSM, DECT GPRS, EDGE, HSCSD PSTN, ISDN Voice, low rate data TCP-IP/UDP Internet 2010 Software radio UMTS/4G ATM, ISDN, B-ISDN Terminal Radio interface Trunk /Core Services 2G: Fax/data/ SMS 9.6 kb/s 2G: Data compr.

2.5x

9.6 kb/s 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 1992 1998 2000 2001 2003 2004 2005 HUT Comms. Lab, Timo O. Korhonen 18

Speech and Data Communications

Delays Errors Stream Speech Limited to ~200 ms High tolerance Continuous: Circuit switching Data Depends on service Very limited tolerance 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 19

Symmetry

  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  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 HUT Comms. Lab, Timo O. Korhonen 20

Network Topology

Optical star-coupler Optical networks  Different topologies in different networks  BUS - Ethernet   Ring - FDDI Mesh - Internet; Number of connections required: 2  1) 

2 2   N : number of nodes Selection of topology effects for instance applicable MAC scheme & network reliability IEEE 802 (LAN) technology often applied 21 HUT Comms. Lab, Timo O. Korhonen

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

100 megabits

provides transmission speeds up 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

billion bits per second. provides up to 10 Source: Searchnetworking.com

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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

protocols.

FDDI-II

using other 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

Quality of Service (QoS)

     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 24

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

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Security and Secrecy*

   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:  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 • Others can’t do eavesdropping 26 HUT Comms. Lab, Timo O. Korhonen

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

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Network/Service Adaptivity

   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... )   IN (Intelligent Network, ITU-T Q.1200-series) solutions developed first for PSTN but typically an important part of most networks as in PLMNs  Enable service flexibility ( software radio does this in terminals)  Reduces signaling traffic Moves costs to end-users IN services designed in cooperation with terminal intelligence

PSTN WLANs PLMN

28 HUT Comms. Lab, Timo O. Korhonen

Development of Data and Voice Networks

Voice/modems in PSTN Leased lines 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-over whelming 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!

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Current Scenario

ISDN, V.90, Cable modem, ADSL etc.

Bluetooth Device WLAN Router

Modified from W. Stallings: Data and Computer Communications, 7th ed (home site lecture slides) HUT Comms. Lab, Timo O. Korhonen

MPLS

Example: Bluetooth Technology

Connecting devices in SOHO (Small Office/ Home Office) to your computer Realizing ad-hoc networking with Bluetooth See also http://www.bluetooth.com/ HUT Comms. Lab, Timo O. Korhonen Home networking 31

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 32

Example: 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 (IN), ADSL Primary characteristics     Circuit switched connections Analog access: bandwidth 300-3400 Hz Digital access for instance by   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 33

Network Stratums of PSTN

   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

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

 Telecommunication network content and technology producers, operators and consumers form an interoperable hierarchy HUT Comms. Lab, Timo O. Korhonen 35

    

Telecomm Market Players

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 36

Future Trends

     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-WLAN UMTS)

PLMN: Public Land Mobile Network, IP:Internet Protocol SLIP: Serial line IP

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Web Resources

          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

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