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: [email protected]: [email protected]
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.