BLUETOOTH, RFID, DATA LINK LAYER

SWITCHINGBy Alisia Dunham & Chiana Grant

History of Bluetooth

1994: L.M. Ericsson company had an idea of connecting mobile phones to other devices without cable

1998: SIG (Special Interest Group) is formed, including four other companies, such as IBM, Nokia, Toshiba, and Intel.

This development became known as Bluetooth, after Harald Blaatand (Bluetooth) II Viking who unified Denmark and Norway without

cables (connections) First version of Bluetooth, Version 1.0, was

released in July of 1999

Bluetooth Today

All consumer electronic devices use Bluetooth, such as mobile phones, laptops, and navigation units

Protocols are included with Bluetooth Pairing: Allows the consumer electronic devices to

find and connect each other and securely transfer data

Protocols have evolved over the decade Bluetooth 2.0 (2004): higher data rates Bluetooth 3.0 (2009): device pairing with 802.11 for

high throughput data transfer Bluetooth 4.0 (Dec. 2009) low power operation;

saves battery use

Bluetooth Architecture

Basic Unit: piconet Master node and up to seven active slave nodes

within a distance of 10 meters Multiple piconets may exist in the same room and

can be connected through a bridge node Two or more piconets can be interconnected to

form a scatternet 205 parked nodes in the net. Master node determines which device gets to

communicate in which time slot All communication is between master and

slave

Scatternet Examplep.321

Bluetooth Applications

Bluetooth SIG Specifies particular apps to be supported and

provides different protocols stacks for each one 25 profiles

6 audio and video Hands-free telephony while driving car

Streaming stereo-quality audio and video Digital camera to TV

Human-Interface device profile Connects keyboards and mice to computers

Other profiles allow for a mobile phone to be used as a remote control.

Bluetooth Protocol Stack

Does not follow any other model Bottom Layer (Physical Radio Layer). Link Control. L2CAP (Logical Link Control Adaptation

Protocol). Top Layer.

Bluetooth Protocol Architecture

Bluetooth Radio Layer

Moves bits from master to slave, or vice versa

10 meter range on a low-power system operating on a 2.4 GHz ISM band

Frequency hopping spread spectrum is used so other networks can coexist on the ISM band

1600 hops/sec over slots with a dwell time of 625 picoseconds

Early revisions of bluetooth and 802.11 interfered enough to ruin each other’s transmissions.

Radio Layer, cont.

Three forms of modulation are used to send bits on a channel

Basic Scheme: frequency shift typing to send a 1- bit symbol every microsecond, which equals 1 Mbps

Enhanced Rates: phase shift keying to send 2-3 bits per symbol, which equals to 2-3 Mbps Only used in data portion of frames

Bluetooth Link Layers

Turns raw bit stream into frames and defines some key formats

Simplest forms. Frame length and other characteristics. Link manager

Pairing Procedure: old vs. new Upon Pairing Completion, the link

manager sets up 1 of 2 links SCO (Synchronous Connection Oriented). ACL (Asynchronous ConnectionLess.

Bluetooth Frame Structure

Access Code 54-bit header Frame sent in 2 rates

Basic rate: Enhanced rate:

Inside the header are 6 sub-categories: Address Type Flow Acknowledgement Sequence Checksum

Radio Frequency IdentificationR.F.I.D

Low end wireless devices that can be used to form computer networks

Technology that can be found in smartcards, implants for pets, passports, and library books to name a few

http://www.youtube.com/watch?v=yNPDgudPmXE&feature=youtu.be

Electronic Product Code (EPC)

Form of RFID that is a replacement for barcodes that stores larger amount of information

Capable of being read over 10 M in distance

Ability to communicate over distance makes it relevant

EPC 2nd Generation

2 key components: I. Tags II. Readers

Key Components of EPC

Tagssmall, inexpensive devices that have a 96-bit identifier and memory; memory is used to record location history; resembles a sticker and has an antenna printed on it; tiny dot in the middle = integrated circuit; “Class 1” is term used to define how tags gather power

Readers are the intelligence in the system; has its own power source; in charge of determining when tags send and receive messages; main job is to discover the identifiers of nearby tags

Key Components

Physical Layer of EPC Generation 2

This layer defines how bits are sent between RFID readers and tags. To spread a strong signal, limit interference, and satisfy regulatory requirement the reader performs frequency hopping at least every 400 msec.ASK or Amplitude Shift Keying is used to encode bitsThe reader is always transmitting a signal, regardless of whether it is the reader or tag communicating. Backscatter is used a low-energy way for tags to create weak signals of their own.

Identification Layer of EPC Generation 2

Readers need to receive a message from each tag that gives the identifier for the tag in order to inventory nearby tags. The reader tells tags the range of slots over which to randomize transmissions. However, tags randomly select slots in which to reply.

Data Link Layer Switching

Bridges: devices that connect LANs to a larger, faster network Commonly called switches Operated in data link layer Ability to handle IP packets

Uses of Bridges

3 reasons organizations use multiple LANs Connection. Cost. Load Accommodation.

To make these benefits available, bridges must be completely transparent

Two algorithms make this possible Backward learning Spanning tree algorithm

Learning Bridges

TWO LANS JOINED BY A BRIDGELANS WITH POINT-TO-POINT CABLES, INCLUDING ONE HUB, ARE JOINED.

Spanning Tree Bridge

Frame F0 is sent to B1

B1 sends 2 copies on each link to B2

B2 sends copies of F1 and F2 to all other ports

F3 and F4 are sent back to B1, and the cycle continues

Repeaters, Hubs, Bridges, Switches, Routers, and Gateways

Operates at different layersPhysical = repeater, hubData link = bridge, switchNetwork = routerTransport = transport gatewayApplication = application gateway

Repeaters, Hubs, Bridges, Switches, Routers, and Gateways

Repeaters do not understand frames, packets, or headers; only understand symbols that encode bits as volts. Hubs are physical layer devices that do not examine the link layer addresses or use them in any wayModern bridge has multiple ports, usually enough for 4 to 48 input lines of a specific type. Each port is isolated to be its own collision domain