Wireless guide to wireless communications
This presentation is the property of its rightful owner.
Sponsored Links
1 / 69

Wireless# Guide to Wireless Communications PowerPoint PPT Presentation


  • 110 Views
  • Uploaded on
  • Presentation posted in: General

Wireless# Guide to Wireless Communications. Chapter 5 Low Rate Wireless Personal Area Networks. Objectives. Describe a wireless personal area network (WPAN) List the different WPAN standards and their applications Explain how IrDA, Bluetooth, and ZigBee work

Download Presentation

Wireless# Guide to Wireless Communications

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


Wireless guide to wireless communications

Wireless# Guide to Wireless Communications

Chapter 5

Low Rate Wireless Personal Area Networks


Objectives

Objectives

  • Describe a wireless personal area network (WPAN)

  • List the different WPAN standards and their applications

  • Explain how IrDA, Bluetooth, and ZigBee work

  • Describe the security features of low-rate WPAN technology

Wireless# Guide to Wireless Communications


What is a wpan

What is a WPAN?

  • Wireless personal area network (WPAN)

    • Group of technologies that are designed for short-range communications

    • Eliminates the need for wires or cables to interconnect multiple devices

  • Applications for WPAN technology include:

    • Synchronizing PDAs, cellular, and Smartphones

    • Home control systems (smarthome)

    • Cordless telephones

    • Portable device data exchange

Wireless# Guide to Wireless Communications


What is a wpan continued

What is a WPAN? (continued)

  • Applications for WPAN technology include (continued):

    • Industrial control systems

    • Location — smart tags used to locate people at home or at the office

    • Security systems

    • Interactive toys

    • Inventory tracking

  • Advantages

    • WPAN devices use very little power

    • Short range helps maintain security and privacy

Wireless# Guide to Wireless Communications


Existing and future standards

Existing and Future Standards

  • Institute of Electrical and Electronics Engineers (IEEE)

    • Currently developing various standards for WPANs

  • Interoperability

    • Interoperability is of utmost importance

    • Following the OSI protocol model

      • Allows manufacturers to ensure interoperability between their devices

Wireless# Guide to Wireless Communications


Existing and future standards continued

Existing and Future Standards (continued)

  • Interoperability (continued)

    • Open Systems Interconnect (OSI) model

      • Developed by the International Organization for Standardization (ISO)

    • Project 802

      • Started by the IEEE at about the same time ISO was creating OSI

      • Ensures interoperability among data networking products

      • Widely used standards: 802.3 (Ethernet) and 802.5 (Token Ring)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Existing and Future Standards (continued)

Wireless# Guide to Wireless Communications


Infrared wpans irda

Infrared WPANs (IrDA)

  • Most common infrared connection today

    • Based on the IrDA specifications

  • IrDA specifications

    • Define both physical devices and network protocols

  • IrDA devices’ characteristics

    • Provide walk-up connectivity

    • Provide a point-to-point method of data transfer

      • Between only two devices at a time

Wireless# Guide to Wireless Communications


Infrared wpans irda continued

Infrared WPANs (IrDA) (continued)

  • IrDA devices’ characteristics (continued)

    • Cover a broad range of computing and communicating devices

    • Inexpensively implemented

  • There are currently three published versions of the IrDA specifications

    • Plus a fourth currently under development

  • IrDA PHY layer

    • Light emitting diodes (LEDs) send signals

    • Photodiodes receive signals

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Infrared WPANs (IrDA) (continued)

Wireless# Guide to Wireless Communications


Infrared wpans irda continued1

Infrared WPANs (IrDA) (continued)

  • Serial Infrared (Version 1.0)

    • Designed to work like the standard serial port on a PC

    • Uses a UART (Universal Asynchronous Receiver/Transmitter)

      • Microchip that also controls a computer’s serial interface

    • Uses a clock that is 16 times faster than the data rate

    • Transmitting a 0 using 7-3-6

      • UART clock waits for seven clock cycles during the bit time (16 clock pulses)

      • Send an infrared pulse for three clock cycles

      • Then send nothing for six clock cycles

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Infrared WPANs (IrDA) (continued)

Wireless# Guide to Wireless Communications


Infrared wpans irda continued2

Infrared WPANs (IrDA) (continued)

  • Fast Infrared (FIR) (Version 1.1)

    • Extends the data rate to 4 Mbps

    • When two IrDA devices first communicate

      • They both transmit using SIR

      • Then they shift to FIR speed

    • Uses 4-pulse position modulation (4-PPM)

      • Information is conveyed by the position of a pulse within a time slot

      • Two bits (or dibits) are transmitted for each pulse

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Infrared WPANs (IrDA) (continued)

Wireless# Guide to Wireless Communications


Protocols supported

Protocols Supported

  • IrDA Physical Layer Protocol (IrPHY)

    • Controls hardware that sends and receives IR pulses

  • IrDA Link Access Protocol (IrLAP)

    • Responsible for encapsulating the frames

    • Describes how the devices establish and close a connection

  • IrDA Link Management Protocol (IrLMP)

    • Detects the presence of devices offering a service

    • Checks the data flow

Wireless# Guide to Wireless Communications


Protocols supported continued

Protocols Supported (continued)

  • IrDA Transport Protocols (TinyTP)

    • Manages channels between devices

    • Performs error corrections

    • Divides data into packets

  • Optional extensions

    • IrWWW

    • IrTran-P (Infrared Transfer Picture)

    • Infrared printing (IrLPT)

    • Other extensions: IrFM, IrSimple, and IrOBEX

Wireless# Guide to Wireless Communications


Other irda considerations

Other IrDA Considerations

  • Factors to consider

    • Half-duplex transmission

    • Deflection angle

    • Ambient light

    • Ease of use

    • Security

    • Distance limitation

Wireless# Guide to Wireless Communications


Rf wpans

RF WPANs

  • Offer functionality beyond that of IR devices

  • Include

    • Bluetooth

    • 802.15.4 (ZigBee)

Wireless# Guide to Wireless Communications


Ieee 802 15 1 and bluetooth

IEEE 802.15.1 and Bluetooth

  • Industry specification

    • Bluetooth Special Interest Group (SIG)

  • Defines small-form-factor, low-cost wireless radio communications

  • IEEE licensed this wireless technology

    • To adapt and copy a portion of the specification as the base material for 802.15.1

  • 802.15.1 standard

    • Approved in March 2, 2002

    • Fully compatible with Bluetooth version 1.1

Wireless# Guide to Wireless Communications


Bluetooth protocol stack

Bluetooth Protocol Stack

  • 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

  • Radio module

    • A single radio transmitter/receiver (transceiver)

    • Only hardware required for Bluetooth to function

    • Bluetooth can transmit at a speed of up to 1 Mbps

    • Bluetooth version 2.0 transmits at 2 or 3 Mbps

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Bluetooth protocol stack continued

Bluetooth Protocol Stack (continued)

  • Modulation technique

    • Bluetooth uses a variation of frequency shift keying (FSK)

    • Two-level Gaussian frequency shift keying (2-GFSK)

      • Uses two different frequencies

        • To indicate whether a 1 or a 0 is being transmitted

    • Modulation index

      • Amount that the frequency varies

      • Between 280 KHz and 350 KHz

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Bluetooth protocol stack continued1

Bluetooth Protocol Stack (continued)

  • Bluetooth Baseband layer

    • Lies on top of the RF layer

    • Manages physical channels and links

    • Handles packets, and does paging and inquiry

      • To locate other Bluetooth devices in the area

  • Radio frequency

    • 2.4 GHz Industrial, Scientific, and Medical (ISM) band

    • Bluetooth divides frequency into 79 different channels

      • Spaced 1 MHz apart

    • Bluetooth uses FHSS

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Bluetooth protocol stack continued2

Bluetooth Protocol Stack (continued)

  • Radio frequency (continued)

    • Bluetooth uses the same frequency as IEEE 802.11b WLANs

    • Devices that use Bluetooth can interfere with 802.11b WLANs

    • Bluetooth version 1.2 adds a feature called adaptive frequency hopping (AFH)

      • Further improves compatibility with 802.11b

  • Network topologies

    • Piconet and scatternet

Wireless# Guide to Wireless Communications


Bluetooth protocol stack continued3

Bluetooth Protocol Stack (continued)

  • Network topologies (continued)

    • Bluetooth devices

      • Master, controls all of the wireless traffic

      • Slave, takes commands from the master

    • Piconet

      • Bluetooth network that contains one master and at least one slave and that uses the same channel

    • Each Bluetooth device is preconfigured with an address

      • Needed when participating or not participating in the piconet

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Bluetooth protocol stack continued4

Bluetooth Protocol Stack (continued)

  • Network topologies (continued)

    • All devices in a piconet must change frequencies both at the same time

      • And in the same sequence

    • Bluetooth connection steps

      • Inquiry procedure

      • Paging procedure

    • Multiple piconets can cover the same area

      • Each can contain up to seven slaves

    • Bluetooth device can be a member of two or more overlapping piconets

Wireless# Guide to Wireless Communications


Bluetooth protocol stack continued5

Bluetooth Protocol Stack (continued)

  • Network topologies (continued)

    • Scatternet

      • Group of piconets in which connections exist between different piconets

    • To communicate in each different piconet

      • Device must use the master device address and clock of that specific piconet

    • Bluetooth device can be a slave in several piconets

      • But can be a master in only one piconet

    • A master and slave can switch roles in a piconet

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Bluetooth protocol stack continued6

Bluetooth Protocol Stack (continued)

  • Bluetooth frames

    • Parts

      • Access code (72 bits) — Contains data used for timing synchronization, paging, and inquiry

      • Header (54 bits) — Contains information for packet acknowledgment, packet numbering, the slave address, the type of payload, and error checking

      • Payload (0-2745 bits) — Can contain data, voice, or both

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

Bluetooth Protocol Stack (continued)

Wireless# Guide to Wireless Communications


Bluetooth link manager layer

Bluetooth Link Manager Layer

  • Link between Bluetooth devices

    • Types of physical links

      • Synchronous connection-oriented (SCO) link

      • Asynchronous connectionless (ACL) link

Wireless# Guide to Wireless Communications


Bluetooth link manager layer continued

Bluetooth Link Manager Layer (continued)

Wireless# Guide to Wireless Communications


Bluetooth link manager layer continued1

Bluetooth Link Manager Layer (continued)

  • Link between Bluetooth devices (continued)

    • Error correction schemes

      • 1/3 rate Forward Error Correction (FEC)

      • 2/3 rate FEC

      • Automatic retransmission request (ARQ)

    • Bluetooth power usage

      • Bluetooth devices are designed to be mobile

      • Conserving power is essential

      • Power consumption varies depending on connection mode

Wireless# Guide to Wireless Communications


Bluetooth link manager layer continued2

Bluetooth Link Manager Layer (continued)

  • Link between Bluetooth devices (continued)

    • Bluetooth power usage (continued)

      • Power-saving modes

        • Active

        • Sniff

        • Hold

        • Park

Wireless# Guide to Wireless Communications


Other layers and functions

Other Layers and Functions

  • Logical Link Control Adaptation Protocol (L2CAP)

    • Logical Link Control layer

    • Responsible for segmenting and reassembling data packets

  • Radio Frequency Virtual Communications Port Emulation (RFCOMM) data protocol

    • Provides serial port emulation for Bluetooth data

  • LMP layer

    • Transmits control information

Wireless# Guide to Wireless Communications


Ieee 802 15 4 low rate wpans zigbee

IEEE 802.15.4-Low Rate WPANs (ZigBee)

  • ZigBee standard

    • Provides for the connectivity of simple fixed and mobile devices

      • That require only low data rates between 20 and 250 Kbps

      • Consume a minimum amount of power

      • Typically connect at distances of 33 feet (10 meters) to 150 feet (50 meters)

  • ZigBee Alliance

    • Formed in 2002

Wireless# Guide to Wireless Communications


Zigbee overview

ZigBee Overview

  • ZigBee specification

    • Based on the relatively low-level performance requirements of sensors and control systems

  • ZigBee devices are designed to remain quiescent for long periods of time

  • ZigBee transmissions are designed to be short in range

  • Some ZigBee devices have the ability to route packets to other devices

Wireless# Guide to Wireless Communications


Zigbee overview continued

ZigBee Overview (continued)

  • Basic classes of devices in a ZigBee network

    • Full-function device

    • PAN coordinator

    • Reduced-function device

  • ZigBee protocol stack

    • Based on the OSI seven-layer model

    • Defines only those layers that are relevant to achieving specific functionality

    • Total of 27 channels across different frequency bands

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

ZigBee Overview (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

ZigBee Overview (continued)

Wireless# Guide to Wireless Communications


Zigbee overview continued1

ZigBee Overview (continued)

  • ZigBee protocol stack (continued)

    • Since DSSS transmission is used

      • Carrier is modulated with a sequence of 15 chips

      • In both the 868 and 915 MHz bands

    • In the 2,450 MHz band, the technique employs 16 different 32-bit chip sequences

      • Modulated using offset quadrature phase shift keying (O-QPSK)

        • Uses two carrier waves that are exactly 90 degrees out of phase

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

ZigBee Overview (continued)

Wireless# Guide to Wireless Communications


Zigbee overview continued2

ZigBee Overview (continued)

  • IEEE 802.15.4 PHY frame format

  • 802.15.4 MAC layer

    • Handles all access from the upper layers to the physical radio channel

    • Access to the medium is contention based

      • Uses CSMA/CA

Wireless# Guide to Wireless Communications


Zigbee overview continued3

ZigBee Overview (continued)

  • 802.15.4 MAC layer (continued)

    • Superframe

      • Mechanism for managing transmission time in a piconet

    • Guaranteed time slots (GTS)

      • Reserved periods for critical devices to transmit priority data between two beacons

    • Beacons

      • Signal the beginning of a superframe

      • Contain info about the type and number of time slots

        • And the time synchronization frame for the network

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

ZigBee Overview (continued)

Wireless# Guide to Wireless Communications


Zigbee overview continued4

ZigBee Overview (continued)

  • 802.15.4 MAC layer (continued)

    • Beacon frames are not required for device-to-device communications

    • Procedures for associating with and joining a network, routing, and so on, are embedded in the hardware

    • ZigBee devices are engineered to automatically associate with and join the network

    • Device discovery

      • Devices query other devices to identify them

    • Service discovery

      • Identifies the capabilities of specific devices

Wireless# Guide to Wireless Communications


Zigbee overview continued5

ZigBee Overview (continued)

  • Coexistence with other standards

    • Relatively wideband interference, such as that generated by IEEE 802.11b networks

      • Appears like white noise to an IEEE 802.15.4 receiver

    • Impact of interference from Bluetooth (802.15.1) devices should be minimal

  • Network addressing

    • The ZigBee specification defines several different levels of addresses

      • For identifying devices within a PAN

Wireless# Guide to Wireless Communications


Zigbee overview continued6

ZigBee Overview (continued)

  • Network addressing (continued)

    • Levels of addresses

      • IEEE address

      • Network (PAN) address

      • Node address

      • Endpoint address

  • ZigBee network topologies

    • Basic topologies

      • Star, tree, and mesh

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

ZigBee Overview (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

ZigBee Overview (continued)

Wireless# Guide to Wireless Communications


Zigbee overview continued7

ZigBee Overview (continued)

  • ZigBee network topologies (continued)

    • In both tree and mesh topologies

      • Alternate paths may be available for packets

    • In cluster tree networks

      • Alternate paths are available

        • If another full-function device is within its radio range

    • In a star topology

      • Network is controlled by the PAN coordinator

    • Cluster tree topologies

      • Two or more tree topology networks that are interconnected by full-function devices

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

ZigBee Overview (continued)

Wireless# Guide to Wireless Communications


Wireless guide to wireless communications

ZigBee Overview (continued)

Wireless# Guide to Wireless Communications


Zigbee overview continued8

ZigBee Overview (continued)

  • Power management in ZigBee networks

    • Packet routing requires a lot of processing overhead

    • ZigBee devices are designed to be very small

      • Equipped with low-speed, power-efficient CPUs

    • In a cluster tree network, only the devices that interconnect each different cluster tree incur overhead

    • 802.15.4 standard favors battery-powered devices

      • Does not prevent devices from being connected to another power source

    • ZigBee must maintain certain parameter values

      • In case of a power failure

Wireless# Guide to Wireless Communications


Low rate wpan security

Low Rate WPAN Security

  • Security should be of little concern with WPANs

  • One of the most serious concerns is social engineering

  • Designing security in WPANs

    • Much more difficult task than in other networking technologies

  • Public key infrastructure (PKI)

    • Unique security code, or key, provided by a certificate authority

  • Certificate authority

    • Private company that verifies the authenticity of users

Wireless# Guide to Wireless Communications


Security in infrared wpans

Security in Infrared WPANs

  • Limited to the line-of-sight characteristic of this type of connection

  • IrDA specification makes no provision for encrypting data or protecting the connection

    • Users may encrypt a file before exchanging it

  • IrDA devices support open access

    • So that anyone can transmit files without first notifying the device’s owner

  • Open access can be a major security concern

Wireless# Guide to Wireless Communications


Security in bluetooth wpans

Security in Bluetooth WPANs

  • Bluetooth provides security at the LMP layer

    • Using authentication

  • Authentication is based on identifying the device itself

  • Authentication scheme is a challenge-response strategy

  • Encryption is the process of encoding communications

    • And ensures that the transmissions cannot be easily intercepted and decoded

Wireless# Guide to Wireless Communications


Security in bluetooth wpans continued

Security in Bluetooth WPANs (continued)

  • Encryption modes

    • Encryption Mode 1 — Nothing is encrypted

    • Encryption Mode 2 — Traffic from the master to one slave is encrypted

      • But traffic from the master to multiple slaves is not encrypted

    • Encryption Mode 3 — All traffic is encrypted

  • Levels of Bluetooth security

    • Level 1 — No security

    • Level 2 — Service-level security

    • Level 3 — Link-level security

Wireless# Guide to Wireless Communications


Security in zigbee and ieee 802 15 4 wpans

Security in ZigBee and IEEE 802.15.4 WPANs

  • ZigBee WPANs use symmetric keys for authentication and encryption

  • IEEE 802.15.4 standard provides in addition:

    • Frame integrity, access control, and sequential freshness security services

  • Frame integrity uses a message integrity code (MIC)

  • Access control is based on access control list (ACL)

  • Sequential freshness

    • Security service used by the receiving device

    • Ensures that the same frames will not be transmitted more than once

Wireless# Guide to Wireless Communications


Security in zigbee and ieee 802 15 4 wpans continued

Security in ZigBee and IEEE 802.15.4 WPANs (continued)

  • Security modes in the 802.15.4 standard

    • Unsecured mode

    • ACL mode (which uses access control)

    • Secured mode (which uses full authentication and encryption)

Wireless# Guide to Wireless Communications


Summary

Summary

  • Network protocol is the set of rules for messages exchanged between communication devices

  • The most common infrared connection today is based on the IrDA standard

    • IrDA devices cannot send and receive at the same time

    • IrDA is easy to use

  • Bluetooth is a wireless technology that uses short-range radio frequency (RF) transmissions

    • Supported by over 2,500 hardware and software vendors

Wireless# Guide to Wireless Communications


Summary continued

Summary (continued)

  • Bluetooth uses two-level Gaussian frequency shift keying (2-GFSK) modulation

  • Error correction schemes used in Bluetooth

    • 1/3 rate Forward Error Correction (FEC), 2/3 rate FEC, and the automatic retransmission request (ARQ)

  • ZigBee is a specification for low rate WPANs created by the ZigBee alliance

    • Includes full mesh networking capability

  • ZigBee network topologies: star, tree, and mesh

Wireless# Guide to Wireless Communications


Summary continued1

Summary (continued)

  • IEEE 802.15.4 standard frequency bands: 868 MHz,915 MHz, and the 2.4 GHz-ISM band

  • 802.15.4 is designed to coexist easily with other WPAN and WLAN technologies

  • Security in Bluetooth supports only device authentication and limited encryption

  • ZigBee supports message integrity at the MAC layer

    • Can also check for the freshness of the message

Wireless# Guide to Wireless Communications


  • Login