Wireless personal area network
(WPAN)

  • designed for shortrange
    communications
  • eliminates the need for wires or cables to interconnect multiple devices

Applications for WPAN technology

Home control systems (smart home)

– Connecting audio and video devices to computers

– Connecting audio and video devices to computers

– Portable device data exchange

– Industrial control systems

Location services — smart tags used to locate people

Security systems

Interactive toys

Inventory tracking

Advantages

  • use very little power
  • Short range helps maintain security and privacy

Bluetooth

Bluetooth radio module
– A single radio transciever
– Only hardware required for Bluetooth to function
– Bluetooth 1.1, 1.2 can transmit at a speed of up to 1 Mbps
Bluetooth version 2.1 transmits at 2.1 or 3 Mbps – called
enhanced data rate (EDR)


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Bluetooth power classes and ranges
Power Class 1: 100mW, 330 feet (100m)
Power Class 2: 2.5mW, 33 feet (10m)
Power Class 3: 1mW, 3 feet (1m)


Radio frequency

  • uses the same frequency as IEEE
    802.11b/g/n WLANs
  • Bluetooth version 1.2 adds a feature called adaptive
    frequency hopping (AFH) - Further improves compatibility with 802.11 WLANs at
    2.4 GHz

Bluetooth RF layer
– Defines how the basic hardware that controls the radio
transmissions functions
– Data bits (0 and 1) are converted into radio signals and
transmitted
– Equivalent to OSI Physical layer

Modulation techniques

  • Bluetooth 1.x uses a variation of frequency shift keying
    (FSK)
  • This variation is called two-level Gaussian
    frequency shift keying (2-GFSK)
  • Uses two different frequencies
    To indicate whether a 1 or a 0 is being transmitted

Version 2.x Bluetooth

  • Added 2 modules -Pi/4~DQPSK (2 Mbps)


  • 8-DPSK (3 Mbps) : can only be used in ideal conditions

Network topologies

Version 3.0 Bluetooth

  • Added low power modes
  • 3.0+HS added an alternate MAC/PHY (AMP)
  • AMP uses separate radio module for 802.11-like
    transmissions

Version 4.0

  • introduced Bluetooth low energy (BLE)

Piconet

  • contains one master and at least one slave and that uses the same channel
  • Master, controls all of the wireless traffic – only 1
    • Slave, takes commands from the master – up to 7

Scatternet
Two or more linked piconets

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ZigBee

  • contains three different types of devices: a coordinator, routers, and end devices.
  • work with each to deliver messages and instructions from the central coordinator out to the individual end devices
  • select an appropriate channel by performing a channel scan and finding the most suitable one with the least amount of interference
  • assign a unique ID to the network, allocate a unique address to each device within the network
  • initiate and transfer the messages

How it Works

  • sends and receives radio waves in a band of 79 different frequencies (channels) centered on 2.45 GHz
  • Bluetooth devices automatically detect and connect to one another and up to eight of them can communicate at any one time.
  • To minimize the risks of interference from other electrical appliances (and also to improve security), pairs of devices constantly shift the frequency they're using
  • When a group of two or more Bluetooth devices are sharing information together, they form a kind of ad-hoc (piconet)