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Public Switched System

Public Switched System. Telecom Infrastructure. Edge Connection Terminal Equipment Phone Fax Modem DSL Subscriber Loop Core Switching Central office Switching hierarchy Circuit switching Packet switching Metro Area Network Long Haul Transmission Coax and microwave links

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Public Switched System

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  1. Public Switched System

  2. Telecom Infrastructure • Edge Connection • Terminal Equipment • Phone • Fax • Modem • DSL • Subscriber Loop • Core Switching • Central office • Switching hierarchy • Circuit switching • Packet switching • Metro Area Network • Long Haul Transmission • Coax and microwave links • Fiber optics Telephone Industry – The Economics Side of the Story http://elsa.berkeley.edu/~woroch/dance.pdf

  3. Phone • Electrical • Parts • Carbon microphone, electromagnet speaker, bell, dial • Signaling • DC • AC: 300-3400 Hz • Electronic • Dial tone and push button • DTMF http://en.wikipedia.org/wiki/DTMF

  4. Analog Signaling • Two Wires, Full Duplex • Ring, tip • Hybrid circuit, • Protection circuit • http://www.epanorama.net/circuits/teleinterface.html • On hook • DC: 48V • Ringing: 80V, 20 Hz • Off hook • DC: 23-80 mA, 5-10V • Dial tone: 350+440 Hz • Pulse or tone dialing • Ring tone 440+480Hz, or line busy 480+620 Hz • Connection Indication of line status by tones! http://www.telephonetribute.com/signal_and_circuit_conditions.htm

  5. Subscriber Loop • Twisted Wires • 22-26 gauge • Frequency dependent loss • Loading • Splice and repeater • A tour • http://www.epanorama.net/links/telephone.html • DSL • www.iol.unh.edu/services/testing/dsl/training/ADSL_Tutorial.pdf

  6. Central Office • Digitization • Switching • http://www.dmine.com/phworld/network/ • Multiplexing • Inter Office Trunk Line • Long Haul

  7. Hierarchy • Pre-Divestiture • Local Exchange Carrier • LATA • Interexchange Carrier • Long distance • Common Channel Signaling (SS7) http://www.pt.com/tutorials/ss7/ 585

  8. Digital Signaling • Bandpass • 4 kHz band limited filtering • Digitization • 8 kHz sampling • 256 A-law companding • 8-bit resolution • 64 kb/s DS0 • Time Division Multiplexing • x24 lines of 8 bits+1 bit; 1.544 Mb/s DS1 • DS2, 3; OC1, 3, 12, 48, 192, 768

  9. Switching • Space Switch • Historical electromechanical switch • Electronic switch http://en.wikipedia.org/wiki/List_of_telephone_switches

  10. Switching • Time Switch • Tim Slot Swapping • Memory

  11. Switching • TMS Switch • Switching Fabric • Contention • Queuing • Resource optimization http://www.ecs.umass.edu/ece/wolf/courses/ECE697J/slides/ECE697J-03-10-02.pdf http://www.cs.bham.ac.uk/~gkt/Teaching/SEM335/Queenie/program/BatcherBanyanApplet.html

  12. Circuit Switching • Pre-Arranged Switches to Establish a Path • Fixed bandwidth • Low variance in delay • Set up overhead • Idle time

  13. DATA data transmission circuit termination Data Flow Chart circuit establishment

  14. Header Data Trailer Packet Switching • Datagram • Multiple Routes to Send • Demo • http://www.pbs.org/opb/nerds2.0.1/geek_glossary/packet_switching_flash.html • Flexible, efficient • Variable delay, congestion • Buffer, sequencing • Virtual Circuit • Set up; data always in sequence • Systems • ATM, Frame Relay, X.25

  15. ISDN • Digital Telephony With Voice and Data • B Channel • Service at 64 kbs • D Channel • Control at 16 kbs • Speed • Basic: 144 kbs • Primary: 1.536 Mbps • B-ISDN: H channels • Introduction to ISDN • http://www.ralphb.net/ISDN/index.html

  16. Frame Relay • Characteristics • Resource sharing using packet switching • Dynamic bandwidth allocation supporting bursty data • Low latency, high throughput • WAN • Protocol • Synchronization • Flag Field • Destination • Address • Data link connection identifier – virtual connection • Flow Control • Forward explicit congestion notification • Backward explicit congestion notification • Discard eligibility • Information Field • Up to 16 kB • Error Handling • Frame check sequence http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/frame.pdf http://www.mfaforum.org/frame/tutorials/40142.shtml

  17. ATM • Characteristics • Asynchronous • Efficient • Near real time response • Support multiple services • Protocol • Header: 5 B • Generic Flow Control • Virtual Path Identifier • Virtual Channel Identifier • Payload Type Identifier • Cell Loss Priority • Header Error Control • Payload: 48 B http://www.uniforum.chi.il.us/slides/atmintro/ATM101.ppt.gz

  18. Voice Over Digital Networks • Digital Traffic >> Voice Traffic • Voice Support by Digital Networks • Conversion • Digitization • Compression • Prioritization • Fragmentation • Other Issues • Jitter • Silence suppression • Echo cancellation • Voice Over IP • http://www.solwise.co.uk/voiceoverip_intro.htm • Voice Over ATM, IP, and Frame Relay • http://www.protocols.com/papers/voe.htm

  19. SONET or SDH Transport • Synchronous • Scalable • Fiber friendly • http://www.cse.wustl.edu/~jain/cis777-99/ftp/g_9snt/sld001.htm

  20. STS-1 • Overhead and Payload • Transport • http://www.tek.com/Measurement/App_Notes/SONET/2RW_11407_2.pdf

  21. Characteristics of SONET • Synchronization • Accurate timing, no bit stuffing • Data Compatibility • Direct mux or demux • System Compatibility • Vendor, data rate • Service Compatibility • ATM, IP, video, etc. • Networking Capable

  22. More on SONET • Introduction • http://people.deas.harvard.edu/~jones/cscie129/nu_lectures/lecture12/sonet/sonet.html • Chips • http://www.lightreading.com/document.asp?doc_id=56058 • Future • http://www.fujitsu.com/downloads/TEL/fnc/whitepapers/futureofsonet-wp.pdf • http://img.lightreading.com/heavyreading/pdf/hr20031114_esum.pdf

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