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S Telecommunication Systems

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1 S-72.1130 Telecommunication Systems

2 HUT Comms. Lab, Timo O. Korhonen
Practicalities Lecturers: Timo Korhonen ( ), Michael Hall ( ) Tutorials: Mika Nupponen ( ), Naser Tarhuni ( ) Exam: Monday, , No need to buy any books, however, following references can be useful: 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: Closed book exam and voluntary tutorials: Round[ e (5 p) +t (5p) *0.15] Lecture handouts: Homepage: Course feedback: HUT Comms. Lab, Timo O. Korhonen

3 Lectures and tutorials
21.11 Overview to Telecommunication Systems 28.11 Public Switched Telephone Network 29.11 Transport and Signaling in the PSTN 5.12 Intelligent Network and Mobile Networks 12.12 Wireless Local Area Networks 13.12 Internet Tutorials: First tutorial session will be on , 12-14, S1 A self-study tutorial to be returned Check all tutorial info at: HUT Comms. Lab, Timo O. Korhonen

4 HUT Comms. Lab, Timo O. Korhonen
Course Topics Public Switched Telephone Network (PSTN) Integrate Services Digital Network (ISDN) and SS7 Wireless Local Area Networks (WLANs) The Internet, for instance… TCP/IP (Transmission Control Protocol/internet protocol) Suite UDP (User Datagram Protocol in transport layer) SIP (Session Initiation Protocol in application layer) QoS: MPLS (Multiprotocol Label Switching), Differentiated Services Services Telecommunications market HUT Comms. Lab, Timo O. Korhonen

5 HUT Comms. Lab, Timo O. Korhonen
Networking Subtopics User services as IN services: call last dialed, alternate billing services (as calling card, collect call) Internet: web, , ftp … Terminals modems and PSTN/ISDN phones, user interfaces… 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 Standards and recommendations: ITU-T, ITU-R, IETF, IEEE,... 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

6 HUT Comms. Lab, Timo O. Korhonen
Course Objectives Course discusses structure and properties of telecommunications networks Network topologies Protocols Interfaces Physical realizations Role of abbreviations – understanding concepts Abbreviations refer (define) concepts Abbreviations describe standardized protocols & parts of telecommunication systems More important to understand the meaning of concept than to remember the words building up abbreviations HUT Comms. Lab, Timo O. Korhonen

7 HUT Comms. Lab, Timo O. Korhonen
History 1844 Steinheil’s commercial telegraphy 1826 Ohm’s law 1800 1850 Volta:batteries; Fourier, Laplace, Cauchy: Mathematics Ampere, Faraday, Henry: Basic electronics Morse, Kelvin: Early telegraphy 1897 Marconi’s wireless telegraphy 1864 Maxwell’s electrodynamics 1887 Strowger’s automated switch 1850 1900 Bell, Edison: Telephony Heaviside, Pupin, Campbell: Theory of T. 1918 Armstrong’s heterodyne radio 1900 1937 Alec Reeves’ PCM 1950 TDMA telephony 1950 Lee De Forrest: Triode-tube; Transcontinental telephone. Communication’s electronic 1969 ARPANET 1998 Digital TV launched in USA 1972 Motorola’s cellular system 1950 2000 Commercial data services: DSP, channel coding trans-Pacific, trans-Atlantic optical cables Internet, Wide spread digital signal processing HUT Comms. Lab, Timo O. Korhonen

8 HUT Comms. Lab, Timo O. Korhonen
Information Society “Information and Communication Anytime, Anywhere, and in Any Form” Key development fields forming the business case: To understand how networks/terminals/services evolve consider especially services because all network costs are paid by service users: Services Global Market Legislation /Regulation /Standardization Technology Services shape telecommunications’ evolution and effect greatly on which technology is chosen! HUT Comms. Lab, Timo O. Korhonen

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

10 Components of Telecommunication Networks
Node 1 Node 2 Node 3 Access Core Network Terminals Internal structure can follow different topologies: mesh/star/bus/ring (see also supplementary material) Core and access sub-network Access part terminated by terminals Network nodes and links are optimized for certain assumed traffic (source statistics) and transmission channels (transfer function and noise) This model of telecommunication networks applies both to data and voice networks (packet and circuit switching) HUT Comms. Lab, Timo O. Korhonen

11 HUT Comms. Lab, Timo O. Korhonen
Network Topology Different topologies in different networks BUS - Ethernet Ring - FDDI Mesh - Internet; Number of connections required: N: number of nodes Selection of topology effects for instance applicable MAC scheme & network reliability Optical star-coupler Optical networks Example: FDDI: Token ring, Ethernet: CSMA/CD (an IEEE 802 technology) HUT Comms. Lab, Timo O. Korhonen

12 Tasks of a Telecommunication System
Input Output 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 frames/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) or TCP/IP stack ) NOTE: “Entities” refer to network elements as routers and bridges or different OSI-layers HUT Comms. Lab, Timo O. Korhonen

13 Example: Routers, hubs and bridges
Router is a device that extracts the destination of a packet it receives, selects the best path to that destination, and forwards data packets to the next device along this path.They connect networks together; a LAN to a WAN for example (link layer). Hub (for instance Ethernet hub, USB hub) A device that allows many USB devices to be connected to a single USB port Ethernet hub = multi-port repeater (concentrator) Works in physical level Network bridge connects multiple network segments at the data link layer Ref: Wikipedia HUT Comms. Lab, Timo O. Korhonen

14 Development of Data and Voice Networks
Frame Relay: - applies virtual circuits - example to connect LANs - for high quality (links have modest error correction & flow control) - rates: 2-50 Mb/s Development of Data and Voice Networks Voice/modems in PSTN Frame Flow Control: (HDLC*) - service for a pair of communicating entities - reassures non-over- whelming communications (packets could suffocate receiver ) Earlier Scenarios Leased lines *High-Level Data Link Control 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

15 HUT Comms. Lab, Timo O. Korhonen
Current Scenario * ISDN, V.90, Cable modem, ADSL etc. FireWire Device 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 *Synchronous Optical Networking

16 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

17 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

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

19 Speech and Data Communications
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

20 Different Services Require Different Transmission Rates
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 Mb/s ADSL 8 Mb/s Cable modems 52 Mb/s Ethernet 10 M, 100 M, 1G FDDI 100 Mb/s OC Gb/s Telephony Voice Broadcasting Video conferencing TV/HDTV Video Video Inter-LAN/PBX communications Data Fax Streaming with MPEG, MP3 10k 1M 100M Bit rate (b/s) HUT Comms. Lab, Timo O. Korhonen

21 HUT Comms. Lab, Timo O. Korhonen
7 Application Layer Type of communications: , file transfer, client/server TCP/IP Suite works with 5 layers only 6 Presentation Layer Encryption, data conversion: ASCII to EBCDIC, BCD to binary ... 5 Session Layer Starts, stops session maintains order OSI Layers 4 Transport Layer Ensures delivery of entire file or message 3 Network Layer Routes data to different LANs and WANs based on network address 2 Data Link (MAC) Layer Transmits packets form node to node based on station address RTP: Real-time Transport Protocol (for internet telephony applications) ICMP: Internet Control Message Protocol (errors/IP package processing) ARP: Address Resolution Protocol (data link address determination) RARP: Reverse ARP (for instance DHCP host can ask its IP address) 1 Physical Layer Electrical signals and cabling BCD: Binary Coded Decimal (four bits present each decimal digit) EBCDIC - Extended Binary Coded Decimal Interchange Code (256 characters by 8 bits) HUT Comms. Lab, Timo O. Korhonen

22 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 Understanding abbreviations: Wikipedia or Mpirical ( HUT Comms. Lab, Timo O. Korhonen

23 HUT Comms. Lab, Timo O. Korhonen
Protocols in Practice: Retrieving a Document from the Web 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 Addressing Step: 1. 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 2. 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. 3. 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. 4. – 6. 7. – 8. Viewing the document, closing TCP/IP The user may start to view the document. The TCP connection is closed after a certain timeout period. HUT Comms. Lab, Timo O. Korhonen From Leon-Garzia, Widjaja: Communication Networks, 2th ed., Instructor’s Slide Set

24 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) Note that ITU-T standards nowadays available free-of-charge at ITU-T site HUT Comms. Lab, Timo O. Korhonen

25 Future Perspectives - PLMN
1995 2010 Terminals Single system support Software radio Multi-system support UMTS/4G WLANs WiMAX Radio interfaces GSM, DECT GPRS, EDGE, HSCSD, HSDPA Trunk /Core PSTN, ISDN ATM, ISDN, B-ISDN TCP-IP/UDP Services Voice, low rate data Modest-rate Internet Portable, global virtual reality Multimedia, Virtual reality Push-to-talk, VoIP 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

26 HUT Comms. Lab, Timo O. Korhonen
Future Perspectives PLMNs and especially wireless LANs develop very fast in home & office networks Increasing data rates QoS very important Traffic gets more symmetrical (P2P) PSTN: 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 HUT Comms. Lab, Timo O. Korhonen

27 Future Perspectives – Special Topics
Sensor networking Autonomous, self-organizing Low power consumption Flexible topology High number of intelligent nodes Complex MAC-protocols Usage of sensor networks Monitoring Body area networks (BANs) Cross-layer design Wire-replacement technologies Bluetooth Zigbee FireWire HUT Comms. Lab, Timo O. Korhonen

28 HUT Comms. Lab, Timo O. Korhonen
Web Resources Tutorials, links, abbreviations : Mpirical bank of abbreviations: companion/mpirical_companion.html Wikipedia: 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: Finish Spectral Regulation: IEEE standards: ITU standards: xDSL development: HUT Comms. Lab, Timo O. Korhonen

29 HUT Comms. Lab, Timo O. Korhonen
Review Questions What does the concept of information society means? Describe implications to technology/service development. What are the basic components and tasks of generalized telecommunication network? Give an example how telecommunication services have evolved? What were the enabling changes in technology? What are the OSI layers? Give examples of their tasks. Summarize the expected development of mobile telecommunication networks in terminals, radio interface core network and in services HUT Comms. Lab, Timo O. Korhonen

30 S-72.1130 Telecommunication Systems - Annex
What is … (Some important concepts)

31 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 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: HUT Comms. Lab, Timo O. Korhonen

32 HUT Comms. Lab, Timo O. Korhonen
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:

33 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: HUT Comms. Lab, Timo O. Korhonen

34 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 follow Advanced Streaming Format (ASF). Source: HUT Comms. Lab, Timo O. Korhonen

35 HUT Comms. Lab, Timo O. Korhonen
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 HUT Comms. Lab, Timo O. Korhonen

36 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. HUT Comms. Lab, Timo O. Korhonen Source:

37 HUT Comms. Lab, Timo O. Korhonen
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 that specifies its radio interface by using frequency hopping. HUT Comms. Lab, Timo O. Korhonen

38 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

39 Example from mpirical - database
HUT Comms. Lab, Timo O. Korhonen

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