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Introduction to Networking: Data Communication Systems

Learn about the elements of data communication systems, communication devices (wired and wireless), basic data transmission concepts, common transmission flaws affecting data signals, rules of communications, and signal transmission.

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Introduction to Networking: Data Communication Systems

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  1. TOPIC 1.2 INTRODUCTION TO NETWORKING

  2. OBJECTIVES • By the end of the topic, students should be able to: • List the elements of data communication systems. • Describe the communication devices: • Wired • Wireless • Describe basic data transmission concepts • Define common transmission flaws affecting data signals. • Define rules of communications • Explain the signal transmission

  3. DATA COMMUNICATION SYSTEM ELEMENTS • Data Elements • Communication Devices • Electronic Communication Methods • Transmission Media

  4. DATA ELEMENTS • Message • Sender • Receiver • Medium • Protocol

  5. COMMUNICATION DEVICES • A hardware component that enables a computer to send and receive data, instructions and information and from one or more computers. • Type of communication devices: • Wired (Data Terminal Equipment (DTE)) • Wireless (3G,GPRS, laptop, mobile phones)

  6. COMMUNICATION DEVICES • Wired • Serial Wires are used for high end connectivity between different devices and widely used on layer 3. • DTE ( data terminal equipment) and DCE (data circuit-terminating equipment / data communications equipment). • Ethernet Cables (UTP) • How many types of Ethernet?

  7. COMMUNICATION DEVICES • Wireless Devices

  8. COMMUNICATION DEVICES • REPEATER ~ increasing the signals energy • HUB / SWITCH • Centralizing connection for all network devices • Sending packets using MAC address • BRIDGE ~ Connecting two or more different networks for communication • ROUTER ~ Forwarding packets in the network using MAC and IP address • GATEWAYS ~ a device that acts as a “MAIN PATH” for all network traffics

  9. Electronic communication methods • Email • Instant Messaging

  10. Transmission media • Guided Media • Twisted-Pair Cable • Coaxial Cable • Fiber Optic Cable • Unguided Media: Wireless • Transport electromagnetic waves without using a physical conductor

  11. Transmission media • Twisted-Pair Cable • Color-coded pairs of insulated copper wires twisted around each other and encased in plastic coating • Twists in wire help reduce effects ofcrosstalk • Number of twists per meter or foot known as twist ratio • Alien Crosstalk • When signals from adjacent cables interfere with another cable’s transmission

  12. Shielded Twisted-Pair (STP) • STP cable consists of twisted wire pairs that are individually insulated and surrounded by shielding made of metallic substance

  13. Unshielded Twisted-Pair • Consists of one or more insulated wire pairs encased in a plastic sheath • Does not contain additional shielding • To manage network cabling, it is necessary to be familiar with standards used on modern networks, particularly Category 3 (CAT3) and Category 5 (CAT5)

  14. Comparing STP and UTP • Throughput • Both can transmit up to 100 Mbps • Cost • Typically, STP is more expensive • Connector • Both use RJ-45 connectors (see Figure 4-27) and data jacks • Noise immunity • STP is more noise-resistant • Size and scalability • Maximum segment length for both is 100 meters

  15. Fiber-Optic Cable • Contains one or several glass fibers at its core • Surrounding the fibers is a layer of glass called cladding

  16. Single-mode fiber • Carries light pulses along single path • Multimode fiber • Many pulses of light generated by LED travel at different angles

  17. Unguided Media: Wireless • Infrared transmission • Infrared networks use infrared light signals to transmit data through space • Direct infrared transmission depends on transmitter and receiver remaining within line of sight • In indirect infrared transmission, signals can bounce off of walls, ceilings, and any other objects in their path

  18. RF transmission • Radio frequency (RF) transmission relies on signals broadcast over specific frequencies • Two most common RF technologies: • Narrowband • Spread spectrum

  19. DATA TRANSMISSION CONCEPTS • Analog and digital signaling • Data modulation • Simple, half-duplex and full-duplex • Multiplexing • Point-to-point transmission • Broadcast transmission • Bluetooth, 3G • Throughput • Bandwidth

  20. TRANSMISSION FLAWS • Noise • Occurred when devices act as a sending antenna and the transmission medium act as the receiving antenna. • Attenuation • Loss of signal strength as transmission travels away from source • Analog signals pass through an amplifier, which increases not only voltage of a signal but also noise accumulated An analog signal distorted by noise, and then amplified

  21. TRANSMISSION FLAWS • Latency • Latency is the delay between requesting data and the receipt of a response, or in the case of one-way communication, between the actual moment of a signal's broadcast and the time it is received at its destination • Electromagnetic interference (EMI) • Interference that may be caused by motors, power lines, television, copiers, fluorescent lights, or other sources of electrical activity • Radiofrequency interference (RFI) • Interference that may be generated by motors, power lines, televisions, copiers, fluorescent lights, or broadcast signals from radio or TV towers

  22. TRANSMISSION FLAWS • Distortion • Signal changes its form or shape. • Made of different frequencies. • Regeneration • Process of retransmitting a digital signal • Repeater • Device used to regenerate a signal A digital signal distorted by noise, and then repeated

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