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Networks

Wi-Fi, Bluetooth, VoIP and RFID

  • 3 things to know
  • A2 Unit 1

Overview

What happens when two Bluetooth devices are paired and stages a spoken word passes through in a VoIP call.

What you need to know

Answer each one before you reveal it.

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Key term

Wi-Fi uses collision avoidance rather than collision detection. Explain why.

Process

Describe the stages a spoken word passes through in a VoIP call.

Key term

Name the three components of an RFID system and state what each does.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is Wi-Fi?

    Model answer

    Wi-Fi is a family of wireless local area network standards that lets devices join a network over radio waves through an access point instead of a cable.

  2. 2

    Wi-Fi uses collision avoidance rather than collision detection. Explain why.

    Model answer

    A wireless transmitter cannot hear other stations while it is transmitting, and two stations may be in range of the access point but not of each other, so Wi-Fi tries to avoid clashes in advance by waiting a random period and, where needed, reserving the medium before sending.

  3. 3

    Name three factors that reduce the data rate actually achieved on a Wi-Fi link.

    Model answer

    Distance from the access point, solid obstructions such as thick walls, and interference from other networks or appliances sharing the same radio band all reduce the data rate achieved.

  4. 4

    What is Bluetooth used for?

    Model answer

    Bluetooth provides short-range, low-power wireless links between personal devices a few metres apart, such as a phone connected to headphones, a keyboard or a car audio system.

  5. 5

    Describe what happens when two Bluetooth devices are paired.

    Model answer

    Pairing makes the two devices exchange identities and agree a shared secret, usually confirmed by the user entering or approving a code, and each device then stores that secret so future connections are trusted and encrypted automatically.

  6. 6

    Compare Bluetooth with Wi-Fi in terms of range, data rate and power use.

    Model answer

    Bluetooth reaches only a few metres, carries far less data per second and draws very little power, while Wi-Fi covers a building, carries much more data and consumes considerably more power.

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