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					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/
HUT Comms. Lab, Timo O. Korhonen                                                                    2
                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        Technology
                                          /Standardization



         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
                                                  Speech    Low-rate
                                                            data modems (V.90)
                                    Old view




                                   Current view




          + Other computers &
                                     SMS MMS
          agent-programs (M2M)                     DVB-H
                                          VoIP
                                                     smtp
                                      http     ftp
HUT Comms. Lab, Timo O. Korhonen                                                 7
                Evolving Telecommunication Services
                                                                     2G Services                      2.5G-3G
                               PSTN-originated
                                                                                                      Services
                               services Call Holding/
                                                                          International             Interactive Games
                                                   Call Waiting           Roaming
                                   Call Barring/                                             Instant Messaging/Chat
                                                                          SMS
                                   Call Forwarding
                                                                                           Streaming: Video, Audio
                                     Voice Mail                   Pre-paid Services
                                                                                           Push-adds
                                                        Catalog Enquiry                                        Push-to
                          Basic Voice                                                                          Talk
                          BW ~ 4 kHz                                            Internet Access
                                                        Data: 9.6 Kb/s
                      Data: 56 kb/s (V.90)              … 380 kb/s          Data up to 2 Mb          10 Mb/s (HSDPA)


                                                        WAP           Mobile Commerce              MMS
        Circuit Switching:                                                                                       III Play*
        Voice services,                                                   Rich Call: “See what I see!”
        IN-services, limited data
                                                    13 Kb/s Voice
                                       Circuit/Packet                    Location Identification - Presence
                                       Switching: Mobility,
                                       Data communication
                                                                          All-IP: Location, mobility management, presence,
     *III Play=VoIP+DVB-H+Internet                                        personalization, security

HUT Comms. Lab, Timo O. Korhonen                                                                                             8
                Telecommunication Networks
                                       Core Network

                                      Node 1      Node 2
                            Access                                  Access

                                            Node 3
         Terminals                                                             Terminals

                                                          Internal structure can follow different
                     Core and access parts               topologies: mesh/star/bus/ring
                                                          (see supplementary material)
                     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                                                                    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               Access to OSI environment applications




                                                                                            Gateway Layers
                                   Independence of applications from differences
      6. Presentation              in data presentations(compression & encryption)
                                   Establishing, managing and termination connections
      5. Session                   (sessions~dialogues) between cooperating applications
                                   Reliable, transparent data transfer for lower level
      4. Transport                 data segments or blocks(end-to-end flow & error cntr)
                                   Routing & switching service for transport layer.
      3. Network                   Layer of routers.




                                                                                            LAN Layers
                                   Sends data blocks with synchronization, error and flow
      2. Data Link                 control for link layer connections. Layer of bridges.
                                   Transmission of electrical signals in medium.
      1. Physical                  Layer or repeaters (multiplexing/bit transmission)


HUT Comms. Lab, Timo O. Korhonen                                                                         11
                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,...

                                   V.24, V.35, V.90, 10Base5, 10Base2, 10BaseT, FDDI,
      1. Physical                  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

                                   Addressing              The user clicks on a link to indicate which document
   Step:                                                   is to be retrieved. The browser must determine the
       1.                                                  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

                               TCP/IP connection           Once the address is known, the browser establishes
                                                           a connection to the server process in the specified
       2.                                                  machine, usually a TCP connection. For the
                                                           connection to be successful, the specified machine
                                   Document                must be ready to accept TCP connections. TCP/IP
                                   specifications          The browser runs a client version of HTTP, which
       3.
                                                           issues a request specifying both the name of the
                                                           document and the possible document formats it can
                                                           handle.
                                   Document
       4. –                        response                The machine that contains the requested document
                                                           runs a server version of HTTP. It reacts to the
       6.                                                  HTTP request by sending an HTTP response which
                                                           contains the desired document in the appropriate
                                                           format. Document sent to the receiver.
       7. –                          Viewing the
       8.                            document,           The user may start to view the document. The TCP
                                     closing TCP/IP      connection is closed after a certain timeout period.
                                                      From Leon-Garzia, Widjaja: Communication Networks, 2th ed., Instructor’s Slide Set
HUT Comms. Lab, Timo O. Korhonen                                                                                                           15
                Different Services Require
                Different Rates
                                                                    Maximum Rates of some
                                                                    Transmission Technologies

                                                                    GSM 14.4 kb/s
                                                                    HSCSD 56 kb/s
                          Telephony
 Voice




                                                                    POTS 56 kb/s
                                                                    GPRS 114 kb/s
                                         Broadcasting               EDGE 384 kb/s
                                                                    Frame Relay 1.54 Mb/s
                                                                    T-1 1.54 Mb/s
                                     Video conferencing             ADSL 8 Mb/s
                                                                    Cable modems 52 Mb/s
                                                  TV/HDTV
 Video




                                                                    Ethernet 10 M, 100 M, 1G
                                                                    FDDI 100 Mb/s
                                               Video                OC-256 13.3 Gb/s


                                   Inter-LAN/PBX communications
 Data




                               Fax
                    Streaming with MPEG, MP3

                       10k                      1M                100M         Bit rate (b/s)
HUT Comms. Lab, Timo O. Korhonen                                                                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
HUT Comms. Lab, Timo O. Korhonen                                                           17
                 Network Evolution

         1995                                                                 2010



         Single system support                                                                    Terminal
                                                                             Software
                                   Multi-system support                      radio

         GSM, DECT                                                                                  Radio
                                                                             UMTS/4G
                                       GPRS, EDGE, HSCSD                                          interface

                                                                                                     Trunk
          PSTN, ISDN                                                       ATM, ISDN,
                                            TCP-IP/UDP                                               /Core
                                                                           B-ISDN

         Voice, low rate data                                                                     Services
                                             Modest-rate                   Multimedia,
                                                                       Portable, global
                                          Push-to-talk, VoIP
                                             Internet                      Virtual reality
                                                                       virtual reality




                                       2G:         2G: Data    2.5G:        2.5G:            2.5G:       3G:      3G:
                                       Fax/data/   compr.      HSCSD        GPRS             EDGE        UMTS     HSDPA
                                       SMS         2.5x        28.8 kb/s    92 kb/s          384 kb/s    2 Mb/s   10 Mb/s
                                       9.6 kb/s    9.6 kb/s


                                         1992        1998       2000         2001             2003       2004      2005

HUT Comms. Lab, Timo O. Korhonen                                                                                            18
                Speech and Data Communications

                                             Speech                  Data

                             Delays    Limited to ~200 ms    Depends on service

                              Errors     High tolerance      Very limited tolerance

                                       Continuous: Circuit      Bursty: Packet
                             Stream
                                            switching             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                     Different topologies in
                                                                             different networks
                                                                               BUS - Ethernet

                                                                               Ring - FDDI
                                                          Optical networks
                                                                               Mesh - Internet; Number

                                                                                 of connections required:
                                                                                    N ( N  1) N 2
                                                                                              
                                                                                        2       2
                                                                                  N: number of nodes
                                                                                 Selection of topology
                                                                                  effects for instance
                                                                                  applicable MAC scheme
                                                                                  & network reliability
                                                                                 IEEE 802 (LAN)
                                                                                  technology often applied
HUT Comms. Lab, Timo O. Korhonen                                                                             21
                   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                                                             22
                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   23
                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
HUT Comms. Lab, Timo O. Korhonen                                                        25
                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                                                                      26
                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                                                                       27
                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... )
                           Reduces signaling traffic
                           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
                           Enable service flexibility (software radio does this in terminals)
                           IN services designed in cooperation with terminal intelligence



                                                  PSTN
                                                          PLMN
                                                WLANs

HUT Comms. Lab, Timo O. Korhonen                                                                  28
                                                                              Frame Relay:
                              Development of                                  - applies virtual circuits
                              Data and Voice Networks                         - example to connect LANs
                                                                              - for high quality (links
                                                                              have modest error
                                             Voice/modems in PSTN               correction & flow control)
                                                                              - rates: 2-50 Mb/s
                                                                              Frame Flow Control:
          Earlier Scenarios


                                                                              (HDLC)
                                                                              - service for a pair of
                                                                                communicating entities
                                                                              - reassures non-over-
                                               Leased lines                      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!
HUT Comms. Lab, Timo O. Korhonen                                                                           29
                Current
                Scenario

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




                     Bluetooth
                     Device
                                                           MPLS

                                   WLAN
                                   Router




Modified from W. Stallings: Data and
Computer Communications, 7th ed
(home site lecture slides)

HUT Comms. Lab, Timo O. Korhonen                                  30
                Example: Bluetooth Technology



                       Connecting devices
                       in SOHO (Small Office/
                       Home Office) to
                       your computer




                Realizing ad-hoc                  Home
                networking with Bluetooth         networking




             See also http://www.bluetooth.com/

HUT Comms. Lab, Timo O. Korhonen                               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

                                              Wi-Fi (802.11b,g)
              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                                  34
                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
HUT Comms. Lab, Timo O. Korhonen                                                               37
                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




HUT Comms. Lab, Timo O. Korhonen                                                              38

				
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