WIRELESS PERSONAL AREA WIRELESS PERSONAL AREA NETWORKS (WPANs)NETWORKS (WPANs)

BLUETOOTH BLUETOOTH

Ian F. AkyildizIan F. AkyildizBroadband & Wireless Networking LaboratoryBroadband & Wireless Networking Laboratory

School of Electrical and Computer EngineeringSchool of Electrical and Computer Engineering

Georgia Institute of TechnologyGeorgia Institute of Technology

Tel: 404-894-5141; Fax: 404-894-7883 Tel: 404-894-5141; Fax: 404-894-7883

Email: ian@ece.gatech.eduEmail: ian@ece.gatech.edu

Web: http://www.ece.gatech.edu/research/labs/bwnWeb: http://www.ece.gatech.edu/research/labs/bwn

2IFA’2004

WPAN: WPAN: INTRODUCTIONINTRODUCTION

A WPAN (Wireless PAN) is a short-distance wireless A WPAN (Wireless PAN) is a short-distance wireless network specifically designed to support portable network specifically designed to support portable and mobile computing devices such as PCs, PDAs, and mobile computing devices such as PCs, PDAs, wireless printers and storage devices, cell phones, wireless printers and storage devices, cell phones, pagers, set-top boxes, and a variety of consumer pagers, set-top boxes, and a variety of consumer electronics equipment.electronics equipment.

Bluetooth is an example of a wireless PAN that Bluetooth is an example of a wireless PAN that

allows devices within close proximity to join allows devices within close proximity to join together in ad hoc wireless networks in order to together in ad hoc wireless networks in order to exchange information.exchange information.

Many cell phones have two radio interfaces-one for Many cell phones have two radio interfaces-one for

the cellular network and one for PAN connections.the cellular network and one for PAN connections.

3IFA’2004

WPANWPAN

WPANs such as Bluetooth provide the bandwidthWPANs such as Bluetooth provide the bandwidth and convenience to make data exchange practical and convenience to make data exchange practical for mobile devices such as palm computers. for mobile devices such as palm computers.

Bluetooth overcomes many of the complications Bluetooth overcomes many of the complications of other mobile data systems such as cellular of other mobile data systems such as cellular packet data systems...packet data systems...

The reach of a PAN is typically a few meters. The reach of a PAN is typically a few meters.

4IFA’2004

WPANWPAN

A Bluetooth PAN is also called a piconet, A Bluetooth PAN is also called a piconet, and is composed of up to 8 active devices and is composed of up to 8 active devices in a master-slave relationship (up to 255 in a master-slave relationship (up to 255 devices can be connected in 'parked' devices can be connected in 'parked' mode). mode).

The first Bluetooth device in the piconet The first Bluetooth device in the piconet is the master, and all other devices are is the master, and all other devices are slaves that communicate with the master. slaves that communicate with the master.

A piconet typically has a range of 10 A piconet typically has a range of 10 meters, although ranges of up to 100 meters, although ranges of up to 100 meters can be reached under ideal meters can be reached under ideal circumstances. circumstances.

5IFA’2004

WPANWPAN

A wireless PAN consists of a dynamic group of A wireless PAN consists of a dynamic group of less than 255 devices that communicate less than 255 devices that communicate within about a 33-foot range. within about a 33-foot range.

Unlike with wireless LANs, only devices within Unlike with wireless LANs, only devices within this limited area typically participate in the this limited area typically participate in the network, and no online connection with network, and no online connection with external devices is defined. external devices is defined.

One device is selected to assume the role of One device is selected to assume the role of the controller during wireless PAN the controller during wireless PAN initialization, and this controller device initialization, and this controller device mediates communication within the WPAN. mediates communication within the WPAN.

6IFA’2004

WPANWPAN

The controller broadcasts a beacon that lets all The controller broadcasts a beacon that lets all devices synchronize with each other and devices synchronize with each other and allocates time slots for the devices. allocates time slots for the devices.

Each device attempts to join the wireless PAN Each device attempts to join the wireless PAN by requesting a time slot from the controller.by requesting a time slot from the controller.

The controller authenticates the devices and The controller authenticates the devices and assigns time slots for each device to transmit assigns time slots for each device to transmit data. data.

The data may be sent to the entire wireless PAN The data may be sent to the entire wireless PAN using the wireless PAN destination address, or using the wireless PAN destination address, or it may be directed to a particular device.it may be directed to a particular device.

7IFA’2004

WPANWPAN

The 802.15 working group is defining The 802.15 working group is defining different versions for devices that have different versions for devices that have different requirements.different requirements.

802.15.3 focuses on high-bandwidth 802.15.3 focuses on high-bandwidth

(about 55M bit/sec), low-power MAC and (about 55M bit/sec), low-power MAC and physical layers, while 802.15.4 deals with physical layers, while 802.15.4 deals with low-bandwidth (about 250K bit/sec), low-bandwidth (about 250K bit/sec), extra-low power MAC and physical layers.extra-low power MAC and physical layers.

8IFA’2004

WPAN: HistoryWPAN: History

WPAN: smaller area of coverage, ad hoc only WPAN: smaller area of coverage, ad hoc only topology, plug and play architecture, support of topology, plug and play architecture, support of voice and data devices, and low-power voice and data devices, and low-power consumption.consumption.

– BodyLAN (DARPA, mid-1990s): inexpensive BodyLAN (DARPA, mid-1990s): inexpensive WPAN with modest bandwidth that could WPAN with modest bandwidth that could connect personal devices within a range of connect personal devices within a range of about 5 feet.about 5 feet.

– 802.11 project initiated a WPAN group in 1997.802.11 project initiated a WPAN group in 1997.In March 1998, the HomeRF group was formedIn March 1998, the HomeRF group was formedIn May 1998, a Bluetooth special group was formedIn May 1998, a Bluetooth special group was formedIn March 1999, 802.15 was approved as a separate In March 1999, 802.15 was approved as a separate

group to handle WPANgroup to handle WPAN

9IFA’2004

IEEE 802.15 WPANIEEE 802.15 WPAN

Development of standards for short distance Development of standards for short distance wireless networks used for networking of portable wireless networks used for networking of portable ad mobile computing devices.ad mobile computing devices.

The original functional requirement was published The original functional requirement was published in January 22, 1998, and specified devices with:in January 22, 1998, and specified devices with:– Power management: low current consumptionPower management: low current consumption– Range: 0 - 10 metersRange: 0 - 10 meters– Speed: 19.2 - 100 kbpsSpeed: 19.2 - 100 kbps– Small size: .5 cubic inches without antennaSmall size: .5 cubic inches without antenna– Low cost relative to target deviceLow cost relative to target device– Should allow overlap of multiple networks in the Should allow overlap of multiple networks in the

same areasame area– Networking support for a minimum of 16 devicesNetworking support for a minimum of 16 devices

10IFA’2004

IEEE 802.15 WPANIEEE 802.15 WPAN

The initial activities in the WPAN group included The initial activities in the WPAN group included HomeRF and Bluetooth group.HomeRF and Bluetooth group.

HomeRF currently has its own website HomeRF currently has its own website [HomeRFweb][HomeRFweb]

IEEE 802.15 WPAN has four task groups:IEEE 802.15 WPAN has four task groups:– Task group 1: based on Bluetooth. Defines PHY Task group 1: based on Bluetooth. Defines PHY

and MAC for wireless connectivity with fixed, and MAC for wireless connectivity with fixed, portable, and moving devices within or entering portable, and moving devices within or entering a personal operating space.a personal operating space.

– Task group 2: focused on coexistence of WPAN Task group 2: focused on coexistence of WPAN and 802.11 WLANs.and 802.11 WLANs.

– Task group 3: PHY and MAC layers for high-rate Task group 3: PHY and MAC layers for high-rate WPANs (higher than 20 Mbps)WPANs (higher than 20 Mbps)

– Task group 4: ultra-low complexity, ultra-low Task group 4: ultra-low complexity, ultra-low power consuming, ultra-low cost PHY and MAC power consuming, ultra-low cost PHY and MAC layer for data rates of up to 200 kbps.layer for data rates of up to 200 kbps.

11IFA’2004

BluetoothBluetooth

IdeaIdea– Universal radio interface for ad-hoc wireless Universal radio interface for ad-hoc wireless

connectivityconnectivity– Interconnecting computer and peripherals, Interconnecting computer and peripherals,

handheld devices, PDAs, cell phones – handheld devices, PDAs, cell phones – replacement of IrDAreplacement of IrDA

– Embedded in other devices, goal: 5€/device Embedded in other devices, goal: 5€/device (2002: 50€/USB Bluetooth)(2002: 50€/USB Bluetooth)

– Short range (10 m), low power consumption, Short range (10 m), low power consumption, license-free 2.45 GHz ISMlicense-free 2.45 GHz ISM

– Voice and data transmission, approx. 1 Mbit/s Voice and data transmission, approx. 1 Mbit/s gross data rategross data rate

12IFA’2004

BluetoothBluetooth

One of the first modules (Ericsson).

13IFA’2004

History and hi-History and hi-tech…tech…

14IFA’2004

BluetoothBluetooth HistoryHistory

– 1994: Ericsson (Mattison/Haartsen), “MC-link” project1994: Ericsson (Mattison/Haartsen), “MC-link” project– Renaming of the project: Bluetooth according to Harald Renaming of the project: Bluetooth according to Harald

“Bl“Blåtand” åtand” Gormsen [son of Gorm], King of Denmark in the Gormsen [son of Gorm], King of Denmark in the 1010thth century century

– 1998: foundation of Bluetooth SIG, 1998: foundation of Bluetooth SIG, www.www.bluetoothbluetooth.org.org– 1999: erection of a rune stone at Ericsson/Lund1999: erection of a rune stone at Ericsson/Lund– 2001: first consumer products for mass market, spec. version 2001: first consumer products for mass market, spec. version

1.1 released1.1 released

Special Interest GroupSpecial Interest Group– Original founding members: Ericsson, Intel, IBM, Nokia, Original founding members: Ericsson, Intel, IBM, Nokia,

ToshibaToshiba– Added promoters: 3Com, Agere (was: Lucent), Microsoft, Added promoters: 3Com, Agere (was: Lucent), Microsoft,

MotorolaMotorola– > 2500 members> 2500 members– Common specification and certification of productsCommon specification and certification of products

15IFA’2004

……and the real stoneand the real stoneLocated in Jelling, Denmark,erected by King Harald “Blåtand”in memory of his parents.The stone has three sides – one sideshowing a picture of Christ.

This could be the “original” colors of the stone. Inscription:“auk tani karthi kristna” (and made the Danes Christians)

Inscription:"Harald king executes these sepulchral monuments after Gorm, his father and Thyra, his mother. The Harald who won the whole of Denmark and Norway and turned the Danes to Christianity." Btw: Blåtand means “of dark complexion”

(not having a blue tooth…)

16IFA’2004

CharacteristicsCharacteristics 2.4 GHz ISM band, 79 RF channels, 1 MHz carrier spacing2.4 GHz ISM band, 79 RF channels, 1 MHz carrier spacing

– Channel 0: 2402 MHz … channel 78: 2480 MHzChannel 0: 2402 MHz … channel 78: 2480 MHz– G-FSK modulation, 1-100 mW transmit powerG-FSK modulation, 1-100 mW transmit power

FHSS and TDDFHSS and TDD– Frequency hopping with 1600 hops/sFrequency hopping with 1600 hops/s– Hopping sequence in a pseudo random fashion, determined by a Hopping sequence in a pseudo random fashion, determined by a

mastermaster– Time division duplex for send/receive separationTime division duplex for send/receive separation

Voice link – SCO (Synchronous Connection Oriented)Voice link – SCO (Synchronous Connection Oriented)– FEC (forward error correction), no retransmission, 64 kbit/s duplex, FEC (forward error correction), no retransmission, 64 kbit/s duplex,

point-to-point, circuit switchedpoint-to-point, circuit switched Data link – ACL (Asynchronous ConnectionLess)Data link – ACL (Asynchronous ConnectionLess)

– Asynchronous, fast acknowledge, point-to-multipoint, up to 433.9 Asynchronous, fast acknowledge, point-to-multipoint, up to 433.9 kbit/s symmetric or 723.2/57.6 kbit/s asymmetric, packet switchedkbit/s symmetric or 723.2/57.6 kbit/s asymmetric, packet switched

TopologyTopology– Overlapping piconets (stars) forming a scatternetOverlapping piconets (stars) forming a scatternet

17IFA’2004

Bluetooth Protocol StackBluetooth Protocol Stack

Radio

Baseband

Link Manager

Control

HostControllerInterface

Logical Link Control and Adaptation Protocol (L2CAP)Audio

TCS BIN SDP

OBEX

vCal/vCard

IP

NW apps.

TCP/UDP

BNEP

RFCOMM (serial line interface)

AT modemcommands

telephony apps.audio apps. mgmnt. apps.

AT: attention sequenceOBEX: object exchangeTCS BIN: telephony control protocol specification – binaryBNEP: Bluetooth network encapsulation protocol

SDP: service discovery protocolRFCOMM: radio frequency comm.

PPP

18IFA’2004

Frequency Selection During Frequency Selection During Data Transmission (TDMA/TDD)Data Transmission (TDMA/TDD)

S

fk

625 µs

fk+1 fk+2 fk+3 fk+4

fk+3 fk+4fk

fk

fk+5

fk+5

fk+1 fk+6

fk+6

fk+6

MM M M

M

M M

M M

t

t

t

S S

S S

S

symmetric

asymmetric

asymmetric

19IFA’2004

Overall Frame Overall Frame Format of Format of Bluetooth PacketsBluetooth Packets

The 48 bit address unique to every Bluetooth device is The 48 bit address unique to every Bluetooth device is used as the seed to derive the sequence for hopping used as the seed to derive the sequence for hopping frequencies of the devices.frequencies of the devices.

Four types of access codes:Four types of access codes:– Type 1: identifies a “M” terminal and its piconet addressType 1: identifies a “M” terminal and its piconet address– Type 2: identifies a “S” identity used to page a specific Type 2: identifies a “S” identity used to page a specific

“S”.“S”.– Type 3: Fixed access code reserved for the inquiry process Type 3: Fixed access code reserved for the inquiry process

(will be explained)(will be explained)– Type 4: dedicated access code reserved to identify specific Type 4: dedicated access code reserved to identify specific

set of devices such as fax machines, printers, or cell set of devices such as fax machines, printers, or cell phones.phones.

Header: 18 bits repeated 3 times with a 1/3 FEC codeHeader: 18 bits repeated 3 times with a 1/3 FEC code bitsaccess code packet header payload

72 54 0-2745 bits

S address type flow ARQN SEQN HEC3 4 1 1 1 8

preamble sync. (trailer)

4 64 (4)

20IFA’2004

Overall Frame Format of Overall Frame Format of Bluetooth PacketsBluetooth Packets

S-address allows addressing the 7 possible “S” terminals in a S-address allows addressing the 7 possible “S” terminals in a piconetpiconet

The 4-bit packet type allows for 16 choices of different grade The 4-bit packet type allows for 16 choices of different grade voice systems:voice systems:– 6 of this payload types are asynchronous connectionless 6 of this payload types are asynchronous connectionless

(ACL), primarily used for packet data communication(ACL), primarily used for packet data communication– 3 of the payload types are synchronous connection 3 of the payload types are synchronous connection

oriented (SCO), primarily used for voice communicationsoriented (SCO), primarily used for voice communications– 1 a integrated voice (SCO) and data (ACL) packet1 a integrated voice (SCO) and data (ACL) packet– 4 are control packets common for both SCO and ACL links4 are control packets common for both SCO and ACL links

bitsaccess code packet header payload72 54 0-2745 bits

S address type flow ARQN SEQN HEC3 4 1 1 1 8

preamble sync. (trailer)

4 64 (4)

21IFA’2004

Control PacketsControl Packets

Four types:Four types:– ID: occupies half of a slot, and it carries the access code ID: occupies half of a slot, and it carries the access code

with no data or even a packet type codewith no data or even a packet type code– NULL: used for ACK signaling, and there is no ACK for itNULL: used for ACK signaling, and there is no ACK for it– POLL: similar to the NULL, but is has an ACKPOLL: similar to the NULL, but is has an ACK

NULL and POLL: have the access code and the header, NULL and POLL: have the access code and the header, and so they have packet type codes and status report and so they have packet type codes and status report bitsbits

““M” terminals use the POLL packet to find the “S” M” terminals use the POLL packet to find the “S” terminals in their coverage area.terminals in their coverage area.

– FHS (Frequency Hop Synchronization): carries all the FHS (Frequency Hop Synchronization): carries all the information necessary to synchronize two devices in information necessary to synchronize two devices in terms of access code and hopping timing. This packet is terms of access code and hopping timing. This packet is used in the inquiry and paging process explained later.used in the inquiry and paging process explained later.

22IFA’2004

Polling-based Polling-based TransmissionTransmission

Polling-based TDD packet transmissionPolling-based TDD packet transmission– 625µs slots, master polls slaves625µs slots, master polls slaves

SCO (Synchronous Connection Oriented) – Voice SCO (Synchronous Connection Oriented) – Voice – Periodic single slot packet assignment, 64 kbit/s full-duplex, point-Periodic single slot packet assignment, 64 kbit/s full-duplex, point-

to-pointto-point ACL (Asynchronous ConnectionLess) – Data ACL (Asynchronous ConnectionLess) – Data

– Variable packet size (1,3,5 slots), asymmetric bandwidth, point-to-Variable packet size (1,3,5 slots), asymmetric bandwidth, point-to-multipointmultipoint

MASTER

SLAVE 1

SLAVE 2

f6f0

f1 f7

f12

f13 f19

f18

SCO SCO SCO SCOACL

f5 f21

f4 f20

ACLACLf8

f9

f17

f14

ACL

23IFA’2004

Connection Connection ManagementManagement

Standby: do nothingInquiry: search for other devicesPage: connect to a specific deviceConnected: participate in a piconet

• In the beginning of the formation of a piconet, all devices are in SB mode, then one of the devices starts with an inquiry and becomes the “M” terminal.

• During the inquiry process, “M” registers all the SB terminals that then become “S” terminals. After the inquiry process, identification and timing of all “S” terminals is sent to “M” using FHS packets.

• The “M” terminal starts a connection with a PAGE message including its timing and ID to the “S” terminal.

• When the connection is established, the communication takes place, and at the end, the terminal can be sent back to SB, Hold, park or Sniff states.

24IFA’2004

Connection Connection ManagementManagement

Park: release AMA, get PMA Sniff: listen periodically, not each slotHold: stop ACL, SCO still possible, possibly

participate in another piconet

• Hold, Park and Sniff are power-saving modes.

• The Hold mode is used when connecting several piconets or managing a low-power device.

• In the Hold mode, data transfer restarts as soon as the unit is out of this mode.

• In the Sniff mode, a slave listens to the piconet at reduced and programmable intervals according to the applications needs.

• In the Park mode a device gives up its MAC address but remains synchronized with the piconet.

• A Parked device does not participate in the traffic but occasionally listens to the traffic of “M” to resynchronize and check on broadcast messages.

25IFA’2004

Interference Interference Between Bluetooth Between Bluetooth and 802.11and 802.11

The WLAN industry specified three levels of The WLAN industry specified three levels of overlapping: overlapping: – Interference:Interference: multiple wireless networks are said to multiple wireless networks are said to

interfere with one another if colocation causes interfere with one another if colocation causes significant performance degradationsignificant performance degradation

– Coexistence:Coexistence: multiple wireless networks are said to multiple wireless networks are said to coexist if they can be colocated without significant coexist if they can be colocated without significant impact on performance. It provides for the ability impact on performance. It provides for the ability of one system to perform a task in a shared of one system to perform a task in a shared frequency band with other systems that may or frequency band with other systems that may or may not be using the same rules for operationmay not be using the same rules for operation

– Interoperation:Interoperation: provides for an environment with provides for an environment with multiple wireless systems to perform a given task multiple wireless systems to perform a given task using a single set of rulesusing a single set of rules

26IFA’2004

PiconetPiconet

Collection of devices connected in an ad hoc fashion

One unit acts as master and the others as slaves for the lifetime of the piconet

Master determines hopping pattern, slaves have to synchronize

Each piconet has a unique hopping pattern

Participation in a piconet = synchronization to hopping sequence

Each piconet has one master and up to 7 simultaneous slaves (> 200 could be parked)

M=MasterS=Slave

P=ParkedSB=Standby

M

S

P

SB

S

S

P

P

SB

27IFA’2004

Forming a PiconetForming a Piconet

All devices in a piconet hop togetherAll devices in a piconet hop together– Master gives slaves its clock and device IDMaster gives slaves its clock and device ID

Hopping pattern: determined by device ID (48 bit, unique worldwide)Hopping pattern: determined by device ID (48 bit, unique worldwide) Phase in hopping pattern determined by clockPhase in hopping pattern determined by clock

AddressingAddressing– Active Member Address (AMA, 3 bit)Active Member Address (AMA, 3 bit)– Parked Member Address (PMA, 8 bit)Parked Member Address (PMA, 8 bit)

SBSB

SB

SB

SB

SB

SB

SB

SB

MS

P

SB

S

S

P

P

SB

28IFA’2004

ScatternetScatternet Linking of multiple co-located piconets through the Linking of multiple co-located piconets through the

sharing of common master or slave devicessharing of common master or slave devices– Devices can be slave in one piconet and master of Devices can be slave in one piconet and master of

anotheranother Communication between piconetsCommunication between piconets

– Devices jumping back and forth between the Devices jumping back and forth between the piconetspiconets

M=MasterS=SlaveP=ParkedSB=Standby

M

S

P

SB

S

S

P

P

SB

M

S

S

P

SB

Piconets(each with a capacity of < 1 Mbit/s)

29IFA’2004

WPAN: IEEE 802.15-1 WPAN: IEEE 802.15-1 – Bluetooth– Bluetooth

Data rateData rate– Synchronous, connection-oriented: Synchronous, connection-oriented:

64 kbit/s64 kbit/s– Asynchronous, connectionlessAsynchronous, connectionless

433.9 kbit/s symmetric433.9 kbit/s symmetric 723.2 / 57.6 kbit/s asymmetric723.2 / 57.6 kbit/s asymmetric

Transmission rangeTransmission range– POS (Personal Operating Space) POS (Personal Operating Space)

up to 10 mup to 10 m– with special transceivers up to 100 with special transceivers up to 100

mm FrequencyFrequency

– Free 2.4 GHz ISM-bandFree 2.4 GHz ISM-band SecuritySecurity

– Challenge/response (SAFER+), Challenge/response (SAFER+), hopping sequencehopping sequence

CostCost– 50€ adapter, drop to 5€ if 50€ adapter, drop to 5€ if

integratedintegrated AvailabilityAvailability

– Integrated into some products, Integrated into some products, several vendorsseveral vendors

Connection set-up timeConnection set-up time– Depends on power-modeDepends on power-mode– Max. 2.56s, avg. 0.64sMax. 2.56s, avg. 0.64s

Quality of ServiceQuality of Service– Guarantees, ARQ/FECGuarantees, ARQ/FEC

ManageabilityManageability– Public/private keys needed, key Public/private keys needed, key

management not specified, management not specified, simple system integrationsimple system integration

Special Special Advantages/DisadvantagesAdvantages/Disadvantages

– Advantage: already integrated Advantage: already integrated into several products, available into several products, available worldwide, free ISM-band, worldwide, free ISM-band, several vendors, simple system, several vendors, simple system, simple ad-hoc networking, peer simple ad-hoc networking, peer to peer, scatternetsto peer, scatternets

– Disadvantage: interference on Disadvantage: interference on ISM-band, limited range, max. 8 ISM-band, limited range, max. 8 devices/network&master, high devices/network&master, high set-up latencyset-up latency

30IFA’2004

WPAN: IEEE 802.15 – WPAN: IEEE 802.15 – future developments 1future developments 1

802.15-2: Coexistence802.15-2: Coexistence– Coexistence of Wireless Personal Area Networks Coexistence of Wireless Personal Area Networks

(802.15) and Wireless Local Area Networks (802.11), (802.15) and Wireless Local Area Networks (802.11), quantify the mutual interference quantify the mutual interference

802.15-3: High-Rate802.15-3: High-Rate– Standard for high-rate (20Mbit/s or greater) WPANs, Standard for high-rate (20Mbit/s or greater) WPANs,

while still low-power/low-cost while still low-power/low-cost – Data Rates: 11, 22, 33, 44, 55 Mbit/s Data Rates: 11, 22, 33, 44, 55 Mbit/s – Quality of Service isochronous protocol Quality of Service isochronous protocol – Ad hoc peer-to-peer networking Ad hoc peer-to-peer networking – Security Security – Low power consumption Low power consumption – Low cost Low cost – Designed to meet the demanding requirements of Designed to meet the demanding requirements of

portable consumer imaging and multimedia applicationsportable consumer imaging and multimedia applications

31IFA’2004

WPAN: IEEE 802.15 – future WPAN: IEEE 802.15 – future developments 2developments 2

802.15-4: Low-Rate, Very Low-Power802.15-4: Low-Rate, Very Low-Power– Low data rate solution with multi-month to multi-year battery life and Low data rate solution with multi-month to multi-year battery life and

very low complexityvery low complexity– Potential applications are sensors, interactive toys, smart badges, Potential applications are sensors, interactive toys, smart badges,

remote controls, and home automationremote controls, and home automation – Data rates of 20-250 kbit/s, latency down to 15 msData rates of 20-250 kbit/s, latency down to 15 ms – Master-Slave or Peer-to-Peer operationMaster-Slave or Peer-to-Peer operation– Support for critical latency devices, such as joysticksSupport for critical latency devices, such as joysticks – CSMA/CA channel access (data centric), slotted (beacon) or unslottedCSMA/CA channel access (data centric), slotted (beacon) or unslotted– Automatic network establishment by the PAN coordinatorAutomatic network establishment by the PAN coordinator – Dynamic device addressing,Dynamic device addressing, f flexible addressing formatlexible addressing format– Fully handshaked protocol for transfer reliabilityFully handshaked protocol for transfer reliability – Power management to ensure low power consumptionPower management to ensure low power consumption – 16 channels in the 2.4 GHz ISM band, 10 channels in the 915 MHz US 16 channels in the 2.4 GHz ISM band, 10 channels in the 915 MHz US

ISM band and one channel in the European 868 MHz bandISM band and one channel in the European 868 MHz band

32IFA’2004

BluetoothBluetooth

A cable replacement technologyA cable replacement technology 1 Mb/s symbol rate1 Mb/s symbol rate Range 10+ metersRange 10+ meters Single chip radio + baseband Single chip radio + baseband

– at low power & low price point ($5)at low power & low price point ($5)

Why not use Wireless LANs?- power- cost

33IFA’2004

IEEE 802.11: Classical IEEE 802.11: Classical WLANsWLANs

Replacement for EthernetReplacement for Ethernet Supported data rates Supported data rates

– 11, 5.5, 2, 1 Mbps; and recently up to 20+Mbps @ 2.4 GHz11, 5.5, 2, 1 Mbps; and recently up to 20+Mbps @ 2.4 GHz– up to 54 Mbps in 5.7 GHz band (802.11 a)up to 54 Mbps in 5.7 GHz band (802.11 a)

Range Range – Indoor 20 - 25 metersIndoor 20 - 25 meters– Outdoor: 50 – 100 metersOutdoor: 50 – 100 meters

Transmit power up to 100 mWTransmit power up to 100 mW Cost: Cost:

– Chipsets $ 35 – 50Chipsets $ 35 – 50– AP $200 - $1000AP $200 - $1000– PCMCIA cards $100 - $150PCMCIA cards $100 - $150

34IFA’2004

Cordlessheadset

Emerging LandscapeEmerging Landscape

Which option is technically superior ?Which option is technically superior ? What market forces are at play ?What market forces are at play ? What can be said about the future ?What can be said about the future ?

IEEE 802.11

Bluetooth

LAN AP

802.11b for PDAs Bluetooth for LAN

access

New developments areblurring the distinction

35IFA’2004

Bluetooth Working Group HistoryBluetooth Working Group History

February 1998February 1998: The Bluetooth SIG is formed: The Bluetooth SIG is formed– promoter company group: promoter company group: Ericsson, IBM, Intel, Ericsson, IBM, Intel,

Nokia, ToshibaNokia, Toshiba May 1998May 1998: Public announcement of the Bluetooth SIG: Public announcement of the Bluetooth SIG July 1999July 1999: 1.0A spec (>1,500 pages) is published: 1.0A spec (>1,500 pages) is published December 1999December 1999: ver. 1.0B is released: ver. 1.0B is released December 1999December 1999: The promoter group increases to 9: The promoter group increases to 9

– 3Com, Lucent, Microsoft, Motorola3Com, Lucent, Microsoft, Motorola March 2001March 2001: ver. 1.1 is released: ver. 1.1 is released Aug 2001Aug 2001: There are 2,491+ adopter companies : There are 2,491+ adopter companies

36IFA’2004

New Applications

37IFA’2004

SynchronizationSynchronization

User benefitsUser benefits Automatic synchronization of calendars, address books, Automatic synchronization of calendars, address books,

business cardsbusiness cards Push button synchronizationPush button synchronization Proximity operationProximity operation

38IFA’2004

Cordless HeadsetCordless Headset

User benefitsUser benefits Multiple device access Multiple device access Cordless phone benefitsCordless phone benefits Hands free operationHands free operation

Cordlessheadset

39IFA’2004

Usage Scenarios ExamplesUsage Scenarios Examples

Data Access PointsData Access Points SynchronizationSynchronization HeadsetHeadset Conference TableConference Table Cordless ComputerCordless Computer Business Card ExchangeBusiness Card Exchange Instant PostcardInstant Postcard Computer SpeakerphoneComputer Speakerphone

40IFA’2004

Bluetooth Specifications

41IFA’2004

Bluetooth SpecificationsBluetooth Specifications

RF

Baseband

AudioLink Manager

L2CAP

Data

SDP RFCOMM

IP

Single chip with RS-232,USB, or PC card interface

A hardware/software/protocol descriptionA hardware/software/protocol description An application frameworkAn application framework

HC

I

Applications

42IFA’2004

Interoperability & ProfilesInteroperability & Profiles

Profiles

Pro

toco

ls

Applications Represents default Represents default solution for a usage solution for a usage modelmodel

Vertical slice Vertical slice through the through the protocol stackprotocol stack

Basis for Basis for interoperability and interoperability and logo requirementslogo requirements

Each Bluetooth Each Bluetooth device supports one device supports one or more profilesor more profiles

43IFA’2004

Bluetooth Profiles (in version Bluetooth Profiles (in version 1.2 release)1.2 release)

Generic AccessGeneric Access Service DiscoveryService Discovery Cordless TelephoneCordless Telephone IntercomIntercom Serial PortSerial Port HeadsetHeadset Dial-up NetworkingDial-up Networking FaxFax LAN AccessLAN Access Generic Object ExchangeGeneric Object Exchange Object PushObject Push File TransferFile Transfer SynchronizationSynchronization

44IFA’2004

TechnicalOverview

45IFA’2004

Bluetooth Radio SpecificationBluetooth Radio Specification

RF

Baseband

AudioLink Manager

L2CAP

Data Con

trolSDP RFCOMM

IP

Applications

48IFA’2004

Unlicensed Radio Unlicensed Radio SpectrumSpectrum

902 Mhz

928 Mhz

26 Mhz 83.5 Mhz 125 Mhz

2.4 Ghz

2.4835 Ghz5.725 Ghz

5.785 Ghz

cordless phonesbaby monitorsWireless LANs

802.11BluetoothMicrowave oven

802.11aHyperLan

33cm 12cm 5cm

49IFA’2004

Bluetooth Radio LinkBluetooth Radio Link

frequency hopping spread spectrumfrequency hopping spread spectrum– 2.402 GHz + k MHz, k=0, …, 782.402 GHz + k MHz, k=0, …, 78– 1,600 hops per second1,600 hops per second

GFSK modulationGFSK modulation– 1 Mb/s symbol rate1 Mb/s symbol rate

transmit powertransmit power– 0 dbm (up to 20dbm with power control)0 dbm (up to 20dbm with power control)

. . .

1Mhz

1 2 3 79

83.5 Mhz

50IFA’2004

Review of Basic Concepts

51IFA’2004

RF

Baseband

AudioLink Manager

L2CAP

Data Con

trol

BasebandBaseband

RFCOMMSDPIP

Applications

RF

Baseband

AudioLink Manager

L2CAP

Data Con

trolSDP RFCOMM

IP

Applications

52IFA’2004

Bluetooth Physical LinkBluetooth Physical Link

Point to point linkPoint to point link– master - slave relationshipmaster - slave relationship– radios can function as masters or slavesradios can function as masters or slaves m s

ss

m

s

PiconetPiconet– Master can connect to 7 slavesMaster can connect to 7 slaves– Each piconet has max capacity =1 MbpsEach piconet has max capacity =1 Mbps

– hopping pattern is determined by the masterhopping pattern is determined by the master

53IFA’2004

Connection SetupConnection Setup

Inquiry - scan protocolInquiry - scan protocol– to learn about the clock to learn about the clock

offset and device address offset and device address of other nodes in of other nodes in proximity proximity

54IFA’2004

Inquiry on Time AxisInquiry on Time Axis

Slave1

Slave2

Master

Inquiry hoppingsequence

f1 f2

55IFA’2004

Piconet FormationPiconet FormationMaster

Active Slave

Parked Slave

Standby

Page - scan protocolPage - scan protocol– to establish links to establish links

with nodes in with nodes in proximityproximity

56IFA’2004

AddressingAddressing

Bluetooth device address Bluetooth device address (BD_ADDR)(BD_ADDR)– 48 bit IEEE MAC address48 bit IEEE MAC address

Active Member address (AM_ADDR)Active Member address (AM_ADDR)– 3 bits active slave address3 bits active slave address– all zero broadcast addressall zero broadcast address

Parked Member address Parked Member address (PM_ADDR)(PM_ADDR)– 8 bit parked slave address8 bit parked slave address

57IFA’2004

Piconet ChannelPiconet Channel

m

s1

s2

625 sec

f1 f2 f3 f4

1600 hops/sec

f5 f6

FH/TDD

58IFA’2004

Multi Slot PacketsMulti Slot Packets

m

s1

s2

625 µsec

f1FH/TDD

Data rate depends on type of packet

f4 f5 f6

59IFA’2004

Physical Link TypesPhysical Link Types

m

s1

s2

SCO SCO SCO

Synchronous Connection Oriented (SCO) Link slot reservation at fixed intervals

Asynchronous Connection-less (ACL) LinkAsynchronous Connection-less (ACL) Link– Polling access methodPolling access method

SCO SCO SCOACL ACL ACLACL ACL ACL

60IFA’2004

Packet TypesPacket Types

Controlpackets

Data/voicepackets

ID*NullPollFHSDM1

Voice data

HV1HV2HV3DV

DM1DM3DM5

DH1DH3DH5

61IFA’2004

Packet FormatPacket Format72 bits 54 bits 0 - 2744 bitsAccess code

Header Payload

DataVoice CRC

No CRCNo retries

625 µs

master

slave

header

ARQ

FEC (optional) FEC (optional)

62IFA’2004

Access CodeAccess Code

SynchronizationSynchronization DC offset compensationDC offset compensation IdentificationIdentification SignalingSignaling

Access code

Header Payload

72 bits

Purpose

Channel Access Code (CAC) Device Access Code (DAC) Inquiry Access Code (IAC)

Types

X

63IFA’2004

Packet HeaderPacket Header

Addressing (3)Addressing (3) Packet type (4)Packet type (4) Flow control (1)Flow control (1) 1-bit ARQ (1)1-bit ARQ (1) Sequencing (1)Sequencing (1) HEC (8)HEC (8)

Access code

Header Payload

54 bits

Purpose

Encode with 1/3 FEC to get 54 bits

Broadcast packets are not ACKed

For filtering retransmitted packets

18 bitstotal

ss

m

s

16 packet types (some unused)

Max 7 active slaves

Verify header integrity

65IFA’2004

Data Packet TypesData Packet Types

DM1

DM3

DM5

DH1

DH3

DH5

2/3 FEC

No FEC

66IFA’2004

Inter Piconet Inter Piconet CommunicationCommunication

Cell phone Cordlessheadset

Cordless

headset

Cell phone

Cordlessheadset

Cell phone

mouse

67IFA’2004

ScatternetScatternet

68IFA’2004

Scatternet, Scenario 2Scatternet, Scenario 2How to schedule presence in two piconets?

Forwarding delay ?

Missed traffic?

69IFA’2004

Baseband: Baseband: SummarySummary

TDD, frequency hopping physical layerTDD, frequency hopping physical layer Device inquiry and pagingDevice inquiry and paging Two types of links: SCO and ACL linksTwo types of links: SCO and ACL links Multiple packet types (multiple data Multiple packet types (multiple data

rates with and without FEC)rates with and without FEC)

Baseband Baseband

L2CAPL2CAPLMPLMP

Physical

Data link

Device 2Device 1

70IFA’2004

Link Manager ProtocolLink Manager Protocol

Setup and management of Baseband connections

• Piconet Management• Link Configuration• Security

LMP

RF

Baseband

AudioLink Manager

L2CAP

Data Con

trolSDP RFCOMM

IP

Applications

71IFA’2004

Piconet Piconet ManagementManagement

Attach and detach slavesAttach and detach slaves Master-slave switchMaster-slave switch Establishing SCO linksEstablishing SCO links Handling of low power modes ( Sniff, Hold, Park)Handling of low power modes ( Sniff, Hold, Park)

req

response

Paging

Master

Slaves

s

m

s

72IFA’2004

Low Power Mode Low Power Mode (hold)(hold)

Slave

Hold duration

Hold offset

Master

73IFA’2004

Low Power Mode (Sniff)Low Power Mode (Sniff)

Master

Slave

Sniff period

Sniff offset

Sniff duration

Traffic reduced to periodic sniff Traffic reduced to periodic sniff slotsslots

74IFA’2004

Low Power Mode (Park)Low Power Mode (Park)

Master

Slave

Beacon interval

Beacon instant

Power saving + keep more than 7 slaves in a piconetPower saving + keep more than 7 slaves in a piconet Give up active member address, yet maintain Give up active member address, yet maintain

synchronizationsynchronization Communication via broadcast LMP messagesCommunication via broadcast LMP messages

75IFA’2004

Connection Establishment Connection Establishment & Security& Security

GoalsGoals– Authenticated accessAuthenticated access

Only accept connections from Only accept connections from trusted devicestrusted devices

– Privacy of communicationPrivacy of communication prevent eavesdroppingprevent eavesdropping

Constraints Processing and memory

limitations $10 headsets, joysticks

Cannot rely on PKI Simple user experience

LMP_host_conn_req

LMP Accepted

Security procedure

Paging

Master

Slave

LMP_setup_complete

LMP_setup_complete

76IFA’2004

AuthenticationAuthentication

Authentication is based on link key (128 bit Authentication is based on link key (128 bit shared secret between two devices)shared secret between two devices)

How can link keys be distributed securely ?How can link keys be distributed securely ?Verifier

Claimant

challenge

response

accepted

Link key Link key

77IFA’2004

Pairing (Key Distribution)Pairing (Key Distribution)

Pairing is a process of establishing a trusted secret Pairing is a process of establishing a trusted secret channel between two devices (construction of initialization channel between two devices (construction of initialization key Kkey Kinitinit))

KKinitinit is then used to distribute unit keys or combination keys is then used to distribute unit keys or combination keys

Random number

Kinit

PIN + Claimant address

Randomnumber

PIN + Claimantaddress

Randomnumber

Verifier Claimant

Kinit

challenge

response

accepted

78IFA’2004

Link Manager Protocol Link Manager Protocol SummarySummary

Piconet managementPiconet management Link configurationLink configuration

– Low power modesLow power modes– QoSQoS– Packet type selectionPacket type selection

Security: authentication and encryptionSecurity: authentication and encryption

Baseband Baseband

L2CAPL2CAPLMPLMP

Physical

Data link

Device 2Device 1

79IFA’2004

L2CAPL2CAP

Logical Link Control andAdaptation Protocol

L2CAP provides• Protocol multiplexing• Segmentation and Re-assembly• Quality of service negotiation

RF

Baseband

AudioLink Manager

L2CAP

Data

SDP RFCOMM

IP

Applications

80IFA’2004

L2CAPL2CAP

Logical Link Control andAdaptation Protocol

L2CAP provides• Protocol multiplexing• Segmentation and Re-assembly• Quality of service negotiation

RF

Baseband

AudioLink Manager

L2CAP

Data

SDP RFCOMM

IP

Applications

81IFA’2004

Why baseband isn’t sufficient?Why baseband isn’t sufficient?

Baseband

• Baseband packet size is very small (17min, 339 max) • No protocol-id field in the baseband header

IP RFCOMM IP RFCOMM

reliable*, flow controlled

MultiplexingdemultiplexingMTU

in-sequence, asynchronous link

82IFA’2004

IP RFCOMM

Need a Multiprotocol Encapsulation Need a Multiprotocol Encapsulation LayerLayer

IP RFCOMM

reliable*, in-order, flow controlled, ACL link

Desired features• Protocol multiplexing• Segmentation and re-assembly• Quality of service

What about• Reliability?• Connection oriented or connectionless?• integrity checks?

unreliable, no integrity

83IFA’2004

Segmentation and Segmentation and ReassemblyReassembly

Length Payload

Basebandpackets

start ofL2CAP

continuationof L2CAP

continuationof L2CAP

CRC CRC CRC

• cannot cope with re-ordering or loss• mixing of multiple L2CAP fragments not allowed• If the start of L2CAP packet is not acked, the rest should be discarded

min MTU = 48672 default

91IFA’2004

Serial Port Emulation using Serial Port Emulation using RFCOMMRFCOMM

Serial Port emulation on top of a packet oriented link• Similar to HDLC• For supporting legacy apps

RF

Baseband

AudioLink Manager

L2CAP

Data

SDP RFCOMM

IP

Applications

92IFA’2004

Serial Line Emulation over Serial Line Emulation over Packet based MACPacket based MAC

L2CAP

Design considerationsDesign considerations– framingframing: assemble bit stream into bytes and, : assemble bit stream into bytes and,

subsequently, into packetssubsequently, into packets– transporttransport: in-sequence, reliable delivery of : in-sequence, reliable delivery of

serial streamserial stream– control signalscontrol signals: RTS, CTS, DTR: RTS, CTS, DTR

RFCOMM

L2CAP

RFCOMM

93IFA’2004

GOALS

IP over Bluetooth V 1.0IP over Bluetooth V 1.0

Internet access using cell Internet access using cell phonesphones

Connect PDA devices & laptop Connect PDA devices & laptop computers to the Internet via computers to the Internet via LAN access pointsLAN access points

RF

Baseband

AudioLink Manager

L2CAP

Data

SDP RFCOMM

IP

Applications

94IFA’2004

LAN Access Point ProfileLAN Access Point Profile

SecurityAuthenticationAccess control

Efficiencyheader and data compression

Auto-configurationLower barrier for deployment

Why use PPP?

Access Point

Baseband

L2CAP

RFCOMM

PPP

IP

95IFA’2004

Inefficiency of LayeringInefficiency of Layering

Emulation of RS-232 over the Bluetooth radio Emulation of RS-232 over the Bluetooth radio link could be eliminatedlink could be eliminated

L2CAP

RFCOMM

rfc 1662

PPP

IP

L2CAP

RFCOMM

rfc 1662

PPP

IP

Palmtop LAN access point

packet oriented

packet oriented

byte oriented

96IFA’2004

Terminate PPP at LAN Terminate PPP at LAN Access PointAccess Point

PPP server function at each access pointPPP server function at each access point– management of user name/password is management of user name/password is

an issuean issue– roaming is not seamlessroaming is not seamless

Bluetooth

RFCOMM

PPP

IP

Bluetooth

RFCOMM

PPP

IP

ethernet

Palmtop Access Point

97IFA’2004

L2TP TunnelingL2TP Tunneling

Tunneling PPP traffic from access points to the PPP serverTunneling PPP traffic from access points to the PPP server– 1) centralized management of user name/password1) centralized management of user name/password– 2) reduction of processing and state maintenance at 2) reduction of processing and state maintenance at

each access pointeach access point– 3) seamless roaming3) seamless roaming

Bluetooth

RFCOMM

PPP

IP

Palmtop Access Point

Bluetooth

RFCOMM

PPP

IP

ethernet

IP

UDP

ethernet

IP

UDP

PPP server

98IFA’2004

Seamless Roaming with Seamless Roaming with PPPPPP

AP1

Server

AP2

MAC level registration MAC level handoff

REQ1

RPL2 REQ

3

RPL4

CLR5

palmtopPPP PPP

PPP

100

IFA’2004

BluetoothCurrent Market

Outlook

101

IFA’2004

Market Forecasts for Year 2005Market Forecasts for Year 2005

Units sold annually Revenue Chip price

1.4 bn

$ 5.4 bn

$ 3.6 995 m

$ 4.4 bn

$ 4.4

$ 2.02

$ 4.3 bn

$ 2.2 bn

2.1 bn

1.5 bn

Cahners In-stat (2000 forcast)

revised (2001 forcast)

Merrill Lynch (2000 forcast)

revised (2001 forcast)

103

IFA’2004

Value to Carriers: Synchronization Value to Carriers: Synchronization and Pushand Push

More bits over the airMore bits over the air Utilization of unused capacity Utilization of unused capacity

during non-busy periodsduring non-busy periods Higher barrier for switching Higher barrier for switching

service providersservice providers

104

IFA’2004

Value to Carriers: Cell Value to Carriers: Cell phone as an IP Gatewayphone as an IP Gateway

More bits over the airMore bits over the air Enhanced user experienceEnhanced user experience

– Palmpilot has a better UI than a cell Palmpilot has a better UI than a cell phonephone

Growth into other vertical marketsGrowth into other vertical markets

Will Pilot and cell phone eventually merge?

105

IFA’2004

Value to Carriers: Value to Carriers: Call HandoffCall Handoff

More attractive calling plansMore attractive calling plans Alleviate system load during peak periodsAlleviate system load during peak periods Serve more users with fewer resourcesServe more users with fewer resources

Threat or opportunity?

Cordless base

106

IFA’2004

Biggest Challenges Biggest Challenges facing Bluetoothfacing Bluetooth

InteroperabilityInteroperability– Always a challenge for any new technologyAlways a challenge for any new technology

Hyped up expectationsHyped up expectations Out of the box ease of use Out of the box ease of use Cost target $5Cost target $5 Critical massCritical mass RF in siliconRF in silicon Conflicting interests – business and engineeringConflicting interests – business and engineering

107

IFA’2004

ReferencesReferences

[1] IEEE 802.11, “Wireless LAN MAC and Physical [1] IEEE 802.11, “Wireless LAN MAC and Physical Layer Specification,” June 1997.Layer Specification,” June 1997.

[2] Hirt, W.; Hassner, M.; Heise, N. “IrDA–VFIr (16 [2] Hirt, W.; Hassner, M.; Heise, N. “IrDA–VFIr (16 Mb/s): modulation code and system design.” IEEE Mb/s): modulation code and system design.” IEEE Personal Communications, vol.8, (no.1), IEEE, Personal Communications, vol.8, (no.1), IEEE, Feb. 2001.Feb. 2001.

[3] Lansford, J.; Bahl, P. “The design and [3] Lansford, J.; Bahl, P. “The design and implementation of HomeRF: a radio frequency implementation of HomeRF: a radio frequency wireless networking standard for the connected wireless networking standard for the connected home.” Proceedings of the IEEE, IEEE, Oct. 2000.home.” Proceedings of the IEEE, IEEE, Oct. 2000.

[4] Specification of Bluetooth System, ver. 1.0, [4] Specification of Bluetooth System, ver. 1.0, July 1999July 1999

108

IFA’2004

References (cnt)References (cnt)

[5] Haartsen, J.C. “The Bluetooth radio system.”, IEEE [5] Haartsen, J.C. “The Bluetooth radio system.”, IEEE Personal Communications, IEEE, Feb. 2000. Personal Communications, IEEE, Feb. 2000.

[6] Haartsen, J.C. ‘Bluetooth towards ubiquitous [6] Haartsen, J.C. ‘Bluetooth towards ubiquitous wireless connectivity.’, Revue HF, Soc. wireless connectivity.’, Revue HF, Soc. Belge Ing. Belge Ing. Telecommun. & Electron, 2000. p.8–16.Telecommun. & Electron, 2000. p.8–16.

[7] Rathi, S. “Bluetooth protocol architecture.” [7] Rathi, S. “Bluetooth protocol architecture.” Dedicated Systems Magazine, Dedicated Systems Dedicated Systems Magazine, Dedicated Systems Experts, Oct.–Dec. 2000. Experts, Oct.–Dec. 2000.

[8] Haartsen, J.C.; Mattisson, S. “Bluetooth–a new low–[8] Haartsen, J.C.; Mattisson, S. “Bluetooth–a new low–power radio interface providing short–range power radio interface providing short–range connectivity.” Proceedings of the IEEE, IEEE, Oct. 2000.connectivity.” Proceedings of the IEEE, IEEE, Oct. 2000.

[9] Gilb, J.P.K “Bluetooth radio architectures.” 2000 IEEE [9] Gilb, J.P.K “Bluetooth radio architectures.” 2000 IEEE Radio Frequency IntegratedRadio Frequency Integrated Circuits (RFIC) Symposium Circuits (RFIC) Symposium Digest of Papers, Boston, MA, USA, 11–13 June 2000.Digest of Papers, Boston, MA, USA, 11–13 June 2000.

109

IFA’2004

References (cnt)References (cnt)

[10] N. Benvenuto, G. Cherubini, “Algoritmi e circuiti per le [10] N. Benvenuto, G. Cherubini, “Algoritmi e circuiti per le telecomunicazioni”, Ed. telecomunicazioni”, Ed. Libreria Progetto.Libreria Progetto.

[11] The Bluetooth Special Interest Group, Documentation [11] The Bluetooth Special Interest Group, Documentation available at available at http://www.http://www.bluetoothbluetooth.com/.com/

[12] IEEE 802.15 Working Group for WPANs™; [12] IEEE 802.15 Working Group for WPANs™; http://www.manta.http://www.manta.ieeeieee.org/groups/802/15/.org/groups/802/15/

[13] Barker, P.; Boucouvalas, A.C.; Vitsas, V. “Performance [13] Barker, P.; Boucouvalas, A.C.; Vitsas, V. “Performance modelling of the IrDA infrared wireless communications modelling of the IrDA infrared wireless communications protocol.” International Journal of Communication Systems, protocol.” International Journal of Communication Systems, vol.13, Wiley, Nov.–Dec. 2000. vol.13, Wiley, Nov.–Dec. 2000.

[14] Tokarz[14] Tokarz, , K.; Zielinski, B. “Performance evaluation of IrDA K.; Zielinski, B. “Performance evaluation of IrDA wireless transmission.” 7th Conference on Computer Networks, wireless transmission.” 7th Conference on Computer Networks, Zakopane, Poland, 14–16 June 2000.Zakopane, Poland, 14–16 June 2000.

[15] ETSI RES, “Digital European Cordless Telecommunications [15] ETSI RES, “Digital European Cordless Telecommunications (DECT), Common interface Part 1: Overview,” ETS 300 175–1, (DECT), Common interface Part 1: Overview,” ETS 300 175–1, 1996.1996.