Chapter 9
Download
1 / 38

Communication Circuits - PowerPoint PPT Presentation


  • 173 Views
  • Updated On :

Chapter 9. Communication Circuits. Agenda. Definition Types Media Ownership Error conditions, prevention, and correction. Definitions. Telecommunication circuit Link Data link Channel Data circuit Forward channel (high speed for data) Reverse channel (low speed for control) Node.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Communication Circuits' - tirzah


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Chapter 9 l.jpg

Chapter 9

Communication Circuits


Agenda l.jpg
Agenda

  • Definition

  • Types

  • Media

  • Ownership

  • Error conditions, prevention, and correction


Definitions l.jpg
Definitions

  • Telecommunication circuit

  • Link

  • Data link

  • Channel

  • Data circuit

    • Forward channel (high speed for data)

    • Reverse channel (low speed for control)

  • Node


Type of circuits l.jpg
Type of Circuits

  • Point-to-point circuits

  • Multipoint circuits or multidrop circuits

  • Two-wire circuits and four-wire circuits

  • Analog

  • Digital circuits

  • ISDN

  • T-carrier systems


Point to point circuits l.jpg
Point-to-Point Circuits

  • Only two points or nodes

  • Between two telephones or terminal to computer

  • More expense

  • Necessary & high volume of traffic


Multipoint circuits l.jpg
Multipoint circuits

  • Multidrop circuit or a network

  • Low volume of traffic

  • Less expensive


Two wire and four wire circuits l.jpg
Two-wire and Four-wire circuits

  • Two-wire circuits

    • Half-duplex circuits

    • Frequency division multiplexing for full-duplex data flow

    • Standard dial-up telephone

    • Less expensive

  • Four-wire circuits

    • Full-duplex circuits

    • Leased lines

    • More expensive


Analog circuits l.jpg
Analog Circuits

  • Voice grade circuits

    • Low speed but up to 56,00bps

    • Noise

    • Error

  • Low-speed circuits or subvoice-grade circuits

    • Subdivide voice grade circuit to 12 or 24 circuits

    • Speed ranges between 45 to 200 bps

    • Burglar alarm, fire alarm, telegraph, & Teletypewriter usage

  • Use Amplifier for long distance


Digital circuits l.jpg
Digital Circuits

  • Low error rate, noise, & high speed

  • Data service unit/channel service unit (DSU/CSU)

    • Shape and time the pulses

    • Less complicated

    • Less expensive

  • Need repeater for long distance


Integrated services digital network isdn i l.jpg
Integrated Services Digital Network (ISDN) - I

  • Types of channels

    • B (bearer) channel: 64kbps data

    • D (delta) channel: 16kbps signal

    • Broadband ISDN (BISDN): a full-duplex circuit or two asymmetrical simplex channel for high speed

  • Access methods

    • Basic rate interface: 2B+D

    • Primary rate interface: 23B+D

    • Broadband ISDN (B-ISDN)


Integrated services digital network isdn ii l.jpg
Integrated Services Digital Network (ISDN) - II

  • Benefits

    • Efficient

    • Integrated voice and data

    • Programmable to meet user’s need

    • Robust signaling channel for network management

    • International defined open system interface

  • Problems in US

    • Difficulty in agreeing on precise standards

    • High cost

    • Not active marketed service


T carrier systems l.jpg
T-carrier Systems

  • T1, T2, T3, T4

  • T2 and T4 for carriers

  • T1 and T3 for carriers and customers

  • T1 Line

    • Repeater for every mile

    • 24 circuits of 64,000 bps

    • Pulse Code Modulation (PCM) or Adaptive Differential Pulse Code Modulation (ADPCM)

    • Multiplexing equipment needed

    • Flexible to reconfiguration, low cost for high quality and volume

  • Fractional T1 (any multiple of 64kbps)


Switched multimegabit data service smds l.jpg
Switched Multimegabit Data Service (SMDS)

  • High-speed switched digital service from carrier

  • Two speeds

    • T1 speed (1.544 Mbps)

    • T3 speed (44.736 Mbps)

  • Configuration

    • Lease line from organization to central office

    • Normal, shared communication facilities between central offices

  • Benefit: less expensive


Digital subscriber line dsl i l.jpg
Digital Subscriber Line (DSL) - I

  • Deliver digitized signals over telephone lines

  • Higher data communication speed for Internet usage

  • xDSL for dedicated, point-to-point, public network access over twisted pair copper wire

    • More bandwidth downstream than upstream

    • More for individual customer than business organization


Digital subscriber line dsl ii l.jpg
Digital Subscriber Line (DSL) - II

  • Asymmetric digital subscriber line (ADSL)

    • Standard voice band

    • Medium speed upstream band

    • High speed downstream band

  • New offerings

    • G.Lite ADSL: lower bandwidths for less cost

    • SDSL (symmetric digital subscriber line): equal speed in both direction

    • VDSL (very-high-rate digital subscriber line): high speed over short twisted pair telephone lines up to 1,000 feet


Circuit media l.jpg
Circuit Media

  • Conducted or guided media

    • Twisted pair or unshielded twisted pair (UTP)

    • Shield twisted pair

    • Coaxial cable

    • Optical fiber

  • Radiated or unguided media (wireless)

    • Microwave radio

    • Satellite

    • Infrared


Twisted pair l.jpg
Twisted Pair

  • 22, 24, 26 gauge

  • Twisted pair or unshielded twisted pair (UTP)

  • Electrical noise & other interference

  • Electrical Industries Association (EIA): Category 1, 2, 3, 4, 5,5E (extended), 6, and 7 (data grade starting Cat 3)

  • Punchdown block


Shielded twisted pair l.jpg
Shielded Twisted Pair

  • Pros:

    • Less interference

    • Faster speed

  • Cons:

    • More expensive

    • Physically larger and difficult to connect to a terminating block


Coaxial cable l.jpg
Coaxial Cable

  • Pros:

    • Large bandwidth (400 - 600 MHz)

    • High capacity

    • Less interference

    • Good for noise environment

  • Cons:

    • Tapped easy (security problem)

    • Bulky to install


Optical fiber i l.jpg
Optical Fiber - I

  • Types:

    • Single mode: more expensive & high capacity

    • Multimode: less expensive and less capacity

    • Inexpensive plastic

    • Expensive glass

  • Standard

    • Synchronous optical network (SONET) in US


Optical fiber ii l.jpg
Optical Fiber - II

  • Pros:

    • High bandwidth

    • No interference

    • No crosstalk

    • Small physical size and light weight for installation

    • Very secure

  • Cons:

    • Repeater for long distance

    • Expansive


Microwave radio i l.jpg
Microwave Radio - I

  • Characteristics

    • Long distance

    • Straight line transmission

    • 20-30 miles between transmission towers

    • Radio license by FCC

  • Private microwave links connecting office in a city


Microwave radio ii l.jpg
Microwave Radio - II

  • Pros:

    • Analog or digital signals

    • For voice, data and television signals

    • Long distance

  • Cons:

    • Interference by heavy rain

    • Straight line transmission

    • Security

  • Vendors

    • Motorola

    • Rockwell Communication Systems


Satellite i l.jpg
Satellite - I

  • Characteristics:

    • Geosynchronous orbit

    • Microwave radio transmission

    • Uplink and downlink

  • Types

    • Geosynchronous satellites (22,300 m)

    • Medium earth orbit (MEO) satellites (6,000 m)

    • Low earth orbit (LEO) satellite (300 – 1,000 m)

  • Usages

    • Direct broadcast satellite (DBS) system for TV broadcasting

    • Digital satellite service (DSS) for high speed Internet receive-only access

    • Global telephone systems


Satellite ii l.jpg
Satellite - II

  • Pros:

    • Analog or digital signals

    • For voice, data and television signals

    • Long distance

  • Cons:

    • Security and encryption

    • Propagation delay


Infrared l.jpg
Infrared

  • Light waves

  • Line of sight

  • Wireless communication between nearby equipment


Circuit ownership l.jpg
Circuit Ownership

  • Private circuits

  • Leased circuits

  • Bypass

  • Switched (dial-up) circuits

  • Selection criteria

    • Cost, speed, availability, reliability, maintenance, users’ requirements

    • Others?


Circuit identification l.jpg
Circuit Identification

  • Blue prints and document circuit and equipment

  • Circuit number to each circuit for identification


Multiplexing and concentrating l.jpg
Multiplexing and Concentrating

  • Time division multiplexing (TDM)

    • Bit, character, or entire message

  • Statistical time division multiplexing (STDM) using address field

  • Frequency division multiplexing (FDM)

  • Concentrator using buffering and intelligence

    • Circuit multiplexer

    • Concentration

    • Inverse concentration


Circuit error conditions l.jpg
Circuit Error Conditions

  • Background noise (electrical phenomenon)

  • Impulse Noise (spike)

  • Attenuation

  • Attenuation distortion

  • Envelope delay distortion (different propagation delay)

  • Phase jitter (by carrier signal)

  • Echo

  • Crosstalk

  • Dropouts


Error prevention l.jpg
Error Prevention

  • Line conditioning for leased lines reduce

    • Attenuation (class C)

    • Envelope delay distortion (class C)

    • Noise (class D)

    • Distortion (class D)

  • Methods

    • Shielding

    • Improving connection for cables and connectors

    • Electronic versus mechanical equipment

      • Quality

      • Trouble-free


Error detection l.jpg
Error Detection

  • Echo checking every character

  • Vertical redundancy checking (VRC) or parity checking

  • Longitudinal redundancy checking (LRC) or block check character (BCC)

  • Cyclic redundancy checking (CRC-16) of polynomial error checking


Parity check example l.jpg
Parity Check Example

  • Parity BCC

  • 1 1 1 1 1 1 0

  • 0 0 0 0 0 0 0

  • 1 0 1 0 1 1 0

  • 0 0 0 1 0 1 0

  • 0 0 0 0 1 0 1

  • 0 0 1 0 0 0 1

  • 0 1 0 1 0 1 1

  • 0 0 1 1 1 0 1 VRC


Error correction l.jpg
Error Correction

  • Equipment and circuit requirement

    • Buffer

    • Reverse channel or channel turn around

  • Retransmission - automatic repeat request (ARQ)

  • Methods

    • Stop and wait ARQ - ACK and NAK: long data block , low error rate, & having a reverse channel

    • Continuous ARQ: long propagation time

    • Forward error correction (FEC): simplex transmission

      • using Hamming code, Hagelbarger code, Bose-Chaudhuri code

      • High cost (extra bits & codes)


Guidelines for wiring l.jpg
Guidelines for Wiring

  • 25% more capacity

  • Internet usage

  • Two Cat 5 at each desk

  • Fiber optic cable for backbone

  • Good wiring contractor

  • Others?


Future l.jpg
Future

  • High-speed digital service

  • Bandwidth-on-demand


Points to remember l.jpg
Points to Remember

  • Definition

  • Types

  • Media

  • Ownership

  • Error conditions, prevention, and correction


Discussion l.jpg
Discussion

  • Design the communications circuits needs for a bank and state you reasons to insure the security and accuracy


ad