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WI-2Wireless Personal Area Networks (WPAN)

Wireless InternetProf. Antonio Capone

WPAN and IEEE 802.15 standards family

A. Capone: Wireless Internet 2


Personal Area

CellularOff-Campus Global

Coverage

WLANOn-campus: Office,

School, Airport, Hotel, Home

WPAN

Person Space: Office, Room, Briefcase, Pocket, Car

Short Range/Low Power

Voice AND Data

Low-cost

Small form factor

Many Co-located Nets

Universal Bridge


Personal Area

Personal Ad-hoc Connectivity

Cable Replacement

Landline

Data/Voice Access Points


IEEE 802.15Wireless Personal Area Networks

(WPANsTM)n Short rangen Low powern Low costn Small networksn Communication devices within a

“Personal Operating Space”o WG created by IEEE on a push of the

industrial world that was working on the specification of Bluetooth


IEEE 802.15 Wireless Personal Area Network (WPAN) Working Group

IEEE Wireless Standards

Task Group 1WPAN/Bluetooth™

Task Group 2Coexistence

Task Group 3WPAN High Rate

Task Group 3aWPAN Alt.

Higher Rate

Task Group 4WPAN Low Rate

IEEE 802.11WLAN Working Group

IEEE 802.16WMAN Working Group

IEEE 802.20Mobile BWA Working Group

IEEE 802.18Radio Regulatory TAG

IEEE 802.19Coexistence TAG

IEEE 802.22Wireless Regional Area

Networks


The 802.15 family

= Draft in process or complete

= Draft not defined e.g., CFP, etc.

1 Mb/s

2.4 GHzWPAN-Bluetooth

Bluetooth(TM)802.15.1

MAC Sublayer802.15.1

11 Mb/s22 Mb/s55 Mb/s

2.4 GHzWPAN-HRHigh Rate802.15.3

110 Mb/s? Mb/s

?WPAN-HR

Higher Rate802.15.3a


2 kb/s20 kb/s

868-868.6 MHzWPAN-LRLow Rate802.15.4

2 kb/s20 kb/s

902-928 MHzWPAN-LRLow Rate802.15.4

2 kb/s250 kb/s

2400-2483.5 GHzWPAN-LRLow Rate802.15.4


802.15

802.2 LLC

PhysicalLayer{

{{

= Other LLC

Service SpecificConvergence Sublayer

(SSCS)


Bluetooth


Bluetooth vs. 802.15.1

1. Bluetooth is an industrial specification for WPANs

2. The WG 802.15.1 adapted the industrial specifications of Bluetooth for the levels 1 and 2

3. ’96-’97: Ericsson internal project4. ’98: Bluetooth SIG created (Ericsson, IBM,

Intel, Toshiba, Nokia)5. ’99: new members join the SIG (3Com,

Lucent Technologies, Microsoft, Motorola)


BluetoothTM

o Radio technologyo Low costo Small range (10-20 m)o Low complexityo Small sizeo ISM 2.4 GHz bando Created by an industrial

consortiumo Only the first two levels

have then been standardized by IEEE 802.15.1

■ Danish King of medieval, Harald Blaatand II, aka Bluetooth (940-981)

■ He unified Denmark and Sweden


Application scenarios

o Headset



o Data synchronization



o Access point

Adsl, fiber, etc.

GPRS, UMTS, etc.


Physical layer

o ISM band at 2.4 GHzo 79 (23 in France and Japan) channels

spaced of 1 MHz (2402-2480 MHz)o Modulation G-FSK (1 Mb/s)o Device classes

Class Power(mW)

Power(dBm)

Range(approx)

Class 1 100 mW 20 dBm ~ 100 m

Class 2 2,5 mW 4 dBm ~ 10 m

Class 3 1 mW 0 dBm ~ 1 m


Physical layer

o Frequency Hopping (FH)o 1600 hops/s (625 µs per hop)o The FH sequence is pseudo random

and determined by the clock and the address of the ‘master’ device that regulates the access to the channel

o The other devices are ‘slaves’ and follows the sequence fk defined by the master


Physical layer

o The numbering of the slots is defined by the clock of the master

o The sequence is given by the master ID and a generation algorithm

master

slave

fk fk+1 fk+2 fk+3

625 µs


Physical layer

o It is possible to transmit packet with duration of 1, 3 or 5 intervals

master

slave

fk fk+3

625 µs

fk+4 fk+5 fk+6

3-slot packet


Physical layer

o It is possible to transmit packet with duration of 1, 3 or 5 intervals

master

slave

fk

625 µs

fk+5 fk+6

5-slot packet


Piconeto The simplest network architecture defined in

Bluetooth is called piconeto The piconet is an ad hoc network composed

of 2 or more deviceso A device acts as master and the other as

slaveso Communication can take place only between

master and slave and not directly between slaves

o Up to 7 slaves can be active in a piconeto The others can be in

n Stand-by (not part of the piconet)n Parked (part of the piconet but not active, up to a

maximum of 256 devices)


Piconet

o Addressesn MAC address of 48 bits n AMA (Active Member Address) 3 bitsn PMA (Parked Member Address) 8 bits

M

S

PSB

S

S

S S

S

S

P

P

SB

SB


Types of connectionso Bluetooth considers two types of connectionso SCO (Synchronous Connection Oriented)

n Fixed rate bi-directional connection (circuit)n FEC for improving qualityn Rate of 64 Kbit/s

o ACL (Asynchronous ConnectionLess)n Packet switched connection shared between

master and active slaves based on a polling access scheme

n Several options for packet formats and physical layer codes (1, 3, 5 slots)

n Rate up to 433.9 Kbit/s symmetric (using 5-slot packets in both directions) and 723.2/57.6 Kbit/s asymmetric (using 5-slot packets in one direction and 1-slot packets in the other)


Multiple AccessMaster

Slave 1

Slave 2

Slave 3

SCO (Synchronous Connection Oriented)

ACL (Asynchronous ConnectionLess)


Protocol Architectureo Original protocol

architecture not compliant with IEEE 802 structure

o Later adapted by IEEE for 802.15.1 specifications

o RF + Baseband equivalent to PHY + MAC

o Control plane for the network and connections creationRF

Baseband

AudioLink Manager

L2CAP

Other TCS RFCOMM

Data

SDP

Applications


Protocol Architecture


Packet format

o BT packet includes three parts:n The access code used for the synchronization

and the piconet identificationn The header used for the Link Control (LC) which

includes also the retransmission schemen The payload whose format depends on the type

of connection and the type of packet (number of slots, PHY protection, etc.)

Access code Header Payload

72 54 0-2745


Packet format

o Access code:n There are three types of access coden Channel Access Code (CAC): It defines the piconet,

the synchronization word is derived from the MAC address of the master

n Device Access Code (DAC): it is used to address a specific device during the page procedure, it also derives from the device MAC address

n Inquiry Access Code (IAC): it is used to discover all the device in range during the inquiry procedure

Synchronization word

4 64 4

Preamble Trailer


Packet format

o Header:n Active Member Address (AMA)n Type of packet: there are 16 types of packets

which differs based on length, type of physical layer protection, and connection

n Flow: flow controln ARQ: retransmissionn SQN: sequence numbern HEC: checksum

Type

3 4 8

AMA HECFlow ARQ SQN

1 1 1 X3FEC code1/3


Packet format

Access code Header FHS payload

72 54 240 (2/3 FEC)

FHS

Access code Header ACL payload

72 54 0-2744 ([1,2,3]/3 FEC)

ACL

Access code Header SCO payload

72 54 0-2744 ([1,2,3]/3 FEC)

SCO

Access code Header SCO payload

72 54 80

DV ACL payload

32-150 (2/3 FEC)


Link controller: ARQMaster

Slave A

Slave B

NACK

ACK

A1

MA1

B1

MB1

A1 B1

MB1


Link controller: stateso Stand-by: the devices is not active and the

radio is offo Connection: the device is connected with

other devices. This state includes other sub-states

o Inquiry: the device is looking for other devices in range

o Inquiry Scan: the device is listening for inquiry requests during small time intervals (low duty cycle).


Link controller: stateso Page: the device is trying to create a piconet

connecting to another specific device with known address

o Page Scan: the device is listening to the channel for page requests for small internal of time


Link controller: states

Stand-by

Connection

Page InquiryPage scan

Inquiry scan

Master response

Slave response

Inquiry response


Page procedureo If a device wants to connect to another

device of which it knows the address, it runs the page procedure

o From the address, it calculate the Device Access Code (DAC)

o A stand-by device enters periodically into a page scan mode e starts listening for its DAC on the channels

o Due to ISM band usage rule, the page procedure cannot be executed on a fixed channel

o The device in page scan mode follows a pseudo random sequence on 32 channels (frequencies)


Page procedureo In order to limit the energy consumption, the

page scan is executed for 10 ms on a channel and then the device enters sleep mode for a period of the order of few seconds (from 1.28 to 3.85 s)

o At each new scan period, a new channel is selected according to the pseudo random sequence

o The device in page can calculate the sequence but it usually does not know the phase (clock)

o Therefore, it transmits the DAC sequentially on all channels


Page procedure

o In 10 ms the device in page can transmit on 16 out of 32 channels

o The transmission on the 16 channels is repeated until a reply is received

o If after a sleep period no reply is received, the other 16 channels are used for the sequential transmissions

fk fk+1 fk+2 fk+3

625 µs

FHS


Page procedureo The reply is actually the transmission of the DAC

itselfo In most of the cases the connection is established

within 2 sleep periodso A third packet is sent by the device in pageo It is the FHS packet which includes all the

information on the device, including the clocko The connection is now activeo The device that was paging takes the role of

master and the device that was scanning takes the role of Slave

o An AMA is assigned to the SlaveM S


Inquiry procedureo The inquiry procedure is used to discover

other devices in rangeo It is very similar to the page procedure, but

the access code used is a universal one named Inquiry Access Code (IAC)

o Also the inquiry scan sequence is pseudo random

o The reply to a inquiry request is a FHS packeto There may be a collision in the replyo If after an inquiry, a device goes to page

mode it can quickly calculate the page scan sequence and its phase for all the other devices. Therefore the connection delay is usually very short


Low power modes

o In the connection state, a slave device can enter into low power modes

o Hold: in this state the slave stops listening to the channel for a period of time negotiated with the master (the AMA is kept)

o Sniff: in this state the slave listens to the channel at regular internals (the AMA is kept)

o Park: in this state the AMA is released and a PMA is assigned. The slave device listens to the channel regularly (very low duty cycle) and it comes active again after receiving an unpark message from the master


Protocols: Link Management

o The link management protocol is in charge of connection setup messages, security and connection control

o Creation of ACL and SCO connectionso Management of security procedureso Adding and removal of slaves from a

piconeto LMP messages have priority over all

the others


Protocols: Security

41

Link key generationKLINK

PINRandom #

SRES’SRES ACO’ACO

Encryption key generation

SRES’

BD_ADDRB

CHECKSRES = SRES’

E1(SAFER+)

BD_ADDRBKLINKAU_RAND

E1(SAFER+)

BD_ADDRBKLINKAU_RAND

A (Verifier) B (Claimant)

AU_RAND

Protocols: Security

A. Capone: Wireless Internet

42

E0

BD_ADDRAclockA

KC’

Kcipher

Kcipher

Kcipher

dataA-B

dataB-A

E0

BD_ADDRAclockA

K’C’

K’cipher

K’cipher

K’cipher

dataA-B

dataB-A

data

A B

Protocols: Security

A. Capone: Wireless Internet


Protocols: L2CAP

o Logical Link Control and Adaptation Protocol (L2CAP)

o Adaptation functions (segmentation and reassembly) and multiplexing

BasebandACL SCO

L2CAPLMP Voice

AudioSDP RFCOMM TCS


Profileso They are basic operation modes characteristic of

different applicationso They are used to guaranteed interoperability also

at application layero Object Push Profileo File Transfer Profileo Synchronization Profileo Advanced Audio Distributiono PANo Audio Video Remote Controlo Basic Printingo Basic Imagingo Extended Service Discoveryo Generic Audio Video Distributiono Hands Freeo Hardcopy Cable Replacement

o Generic Access Profileo Service Discovery

Application Profileo Cordless Telephony Profileo Intercom Profileo Serial Port Profileo Headset Profileo Dial-up Networking Profileo Fax Profileo LAN Access Profileo Generic Object Exchange

Profile


Scatternet

o A device can participate to more than one piconeto A device can be Master only in oneo Management of absence periods through hold and sniff

stateso Scatternet formation and routing out of the standard

M

S

S

S

S

S

S

S

M

SS

M


Scatternet (2)

o Scatternets allows, when necessary, to manage direct links among devices

M

S

S

M/S

S

S

Bluetooth v2.0

o v2.0 in 2004, v2.1 in 2007o Adaptive Frequency Hopping (AFH) –

v1.2o extended Synchronous Connections

(eSCO)o Multicast/Broadcasto Enhanced Data Rate (EDR) – rates up

to 3 Mb/s using Differential encoded Phase Shift Keying (DPSK) with 4 and 8 symbols (same band)


Bluetooth v3.0

o v3.0 in 2009o Rate up to 24 Mb/so … but using a different MAC/PHY,

which is actually WiFio BT is basically used only for the

negotiation of the connection parameters among the two devices


Bluetooth v4.0o v4.0 in 2010o New revised version of

n Classic BTn BT high speedn And new BT low energy (BLE)

o It’s a new stack that incorporates the work of the WiBree working group; New commercial name is Bluetooth Smart

o Low rate (260 kb/s), short range, low power for sensor and small devices

o Potential competitor of ZigBeeA. Capone: Wireless Internet 49


Zigbee


Low Rate - WPANo Most of the applications of wireless

networking require transmission rates from medium to high

o Most of the technical development resources from 90s have been devoted to this area: WLAN(IEEE 802.11), BlueTooth (IEEE 802.15), Wi-Max (IEEE 802.16)

o More recently the need for technologies able to manage networks for low transmission rates, short range and low power has emerged

o LR-WPANs are the response to this need


Data Rate

Pow

er C

onsu

mpt

ion

Com

plex

ity

802.15.4(Zigbee)

802.15.1(Bluetooth)

WPAN

802.11802.11b

802.11g

802.16(Wi-Max)

Low Rate - WPAN


Characteristics

o Low cost both of the hardware (< 2$) and the software

o Short range (single device: ~10m)o Low latency, when necessaryo And, above all, low power

consumption!


Applications

ZigBee

RESIDENTIAL/LIGHT

COMMERCIAL CONTROL

CONSUMER ELECTRONICS

TVVCRDVD/CDremote

securityHVAClighting controlaccess controllawn & garden irrigation

PC & PERIPHERALS

INDUSTRIALCONTROL

asset mgtprocess controlenvironmental

energy mgt

PERSONAL HEALTH CARE

BUILDING AUTOMATION

securityHVACAMR

lighting controlaccess control

mousekeyboardjoystick

patient monitoring

fitness monitoring


Towards Zigbee ...

o Starting in mid 90s, manufacturers design and develop proprietary solutions for wireless sensor networks

o Obviously this generates a lot of compatibility problems and high costs

o The need for a standardization arises: the Working Group 4 within the IEEE 802.15 (2001) is established

o The standard IEEE 802.15.4, that specifies as usual the physical and MAC layers, is published in May 2003

o The technology takes the commercial name of


Zigbee: protocol stack

PHY LAYER2.4 GHz 915MHz 868 MHz

MAC LAYERMAC LAYER

NETWORK LAYERStar/Cluster/Mesh

APPLICATION INTERFACE

APPLICATIONS

SiliconApplication ZigBee Stack

Customer

IEEE802.15.4

ZigBee Alliance

SECURITY


Zigbee: protocol stack

IEEE 802.15.4 PHY

IEEE 802.15.4 MAC (CPS)

ZigBee NWK

MAC (SSCS)802.2 LLC

IP

API UDP

ZA1 ZA2 … ZAn IA1 IAn

Transmission & reception on the physical radio channel

Channel access, PAN maintenance, reliable data transport

Topology management, MAC management, routing, discovery

protocol, security management

Application interface designed usinggeneral profile

End developer applications, designed using application profiles


Zigbee: frequencies and rates

BAND COVERAGE DATA RATE # OF CHANNEL(S)

2.4 GHz ISM Worldwide 250 kbps 16

868 MHz Europe 20 kbps 1

915 MHz ISM Americas 40 kbps 10

868MHz / 915MHz PHY

2.4 GHz

868.3 MHz

Channel 0 Channels 1-10

Channels 11-26

2.4835 GHz

928 MHz902 MHz

5 MHz

2 MHz

2.4 GHz PHY

Zigbee: frequencies and rates



ZigBeeo DSSS- 11 chips/

symbolo 62.5 K symbols/s o 4 Bits/ symbolo Peak Information Rate

~128 Kbit/second

Bluetootho FHSSo 1 M Symbol / secondo Peak Information Rate

~720 Kbit / second

ZigBee vs Bluetooth


ZigBee vs Bluetooth

Bluetooth:• Network join time = >3s• Sleeping slave changing to active = 3s typically• Active slave channel access time = 2ms typically

ZigBee:• Network join time = 30ms typically • Sleeping slave changing to active = 15ms typically• Active slave channel access time = 15ms typically


ZigBee vs Bluetooth

Bluetooth ZigBee

AIR INTERFACE FHSS DSSS

PROTOCOL STACK 250 kb 28 kb

BATTERY rechargeable non-rechargeable

DEVICES/NETWORK 8 255

LINK RATE 1 Mbps 250 kbps

RANGE ~10 meters (w/o pa) ~30 meters


Zigbee: devices

The standard defines two types of devices:o Full Function Device (FFD):

n Can transmit Beacon framesn Can communicate directly with other FFDn Can route trafficn Can act as PAN coordinatorn May be powered by external source

o Reduced Function Device (RFD):n Cannot route trafficn Cannot communicate directly with other RFDsn Can communicate only with one FFDn Is usually battery operatedn Can have advanced low power/sleep mode for

saving energy


Zigbee: topologyThere are three possible topologies:

1 - STAR TOPOLOGY

PAN Coordinator

Full Function Device

Reduced Function Device


2 - MESH TOPOLOGY

PAN Coordinator



Zigbee: topology


3 - CLUSTERED STARS

PAN Coordinator



Zigbee: topology

Physical layero Activation and deactivation of the radio

transceivero Energy detection (ED) within the current

channeln Detect energy level for each channel (used to

implement scanning functionalities)o Link quality indicator (LQI) for received

packetso Clear channel assessment (CCA)

n Used to implement the carrier sense multiple access with collision avoidance (CSMA-CA)

o Channel frequency selectiono Data transmission and reception



Physical layer: Overview

Transmission technique: Direct Sequence Spread Spectrum (DSSS)

Frequency Zone Bit-Rate # Channels

868 Mhz

915 Mhz

2.45 Ghz

Europa

USA

Ovunque

20 kbit/s

40 kbit/s

250 kbit/s

1

10

16

Physical layer

o 3 channels available in 868MHz bandso 30 channels available in the 915MHz bandso 16 channels available in the 2.4GHz bands



Physical layer:Frame format

4 Byte 1 Byte 1 Byte Variabile

PREAMBOLO

STARTof

FRAMEDELIMITER

(SFD)

Synchronization Header (SHR)

FRAMELENGHT

(7bit)

Reserved(1 bit)

Protocol Header (PHR)

PSDU

Payload


MAC layer: Overview

o Two operational modes are defines:n Beacon Enabled (slotted CSMA/CA)

n Non Beacon Enabled (unslotted

CSMA/CA)


MAC layer: BEo Beacon Enabled (slotted CSMA/CA)

GTS GTS Inactive

Beacon Beacon

CAP CFP

0 1 2 3 4 5 6 7 8 9 10 11 12 13 1514

Superframe Duration(SD)=aBaseSuperframeDuration*2SO simboli

Beacon Interval (BI) = aBaseSuperframeDuration*2BO simboli

o Frame duration: from 15ms to 252sec (15.38ms*2n where 0 £ n £ 14)

o Guaranteed Time Slot assigned in the beacon frame


MAC layer:Slotted CSMA/CA

o The time unit is the backoff period (BP), whose default value is 20 symbol periods

o Three variables area defined:n NB, number of channel access attempt for a transmissionn CW, number of BPs after the end of the backoff period

before starting the transmissionn BE, exponent that defines the maximum number of BPs

necessary for starting the CCA (Clear Channel Assessment) procedure

o The transmission procedure (and the optional ACK) must be completed within the end of the CAP.

o In case this is not possible, MAC entity must suspend the random backoff counting and wait the start of the next CAP

o In case the macBattLifeExt bit is set to one, the backoff countdown can be performed only in the first six BPs after the beacon frame.

MAC layer:Slotted CSMA/CA

NB = 0, CW = 0

Battery lifeextension?

BE = macMinBE

BE = lesser of(2, macMinBE)

Locate backoffperiod boundary

Delay forrandom(2BE - 1) unit

backoff periods

Perform CCA onbackoff period

boundary

Channel idle?

CW = 2, NB = NB+1,BE = min(BE+1, aMaxBE)

CW = CW - 1

CW = 0?NB>

macMaxCSMABackoffs?

Failure Success

Slotted CSMA

Y

Y Y

Y

N

N

N

N



MAC layer:Unslotted CSMA/CA

oClassical CSMA/CA access mechanism (data - ACK) without synchronization

MAC layer:Unslotted CSMA/CA

NB = 0,BE = macMinBE

Delay forrandom(2BE - 1) unit

backoff periods

Perform CCA

Channel idle?

NB = NB+1,BE = min(BE+1, aMaxBE)

NB>macMaxCSMABackoffs

?

Failure Success

Un-slotted CSMA

Y

Y

N

N



MAC layer: Functions

o Beacon Management (Synchronization)o Channel access managemento Guaranteed Time Slot (GTS)

Managemento Associations e de-associationo Frame Acknowledgement


MAC layer: Frame format

2 Byte

FRAMECONTROL

1 Byte

SEQUENCENUMBER

2 Byte

FCS

Codice CRC

Variabile

Adressing fields

MAC Header

FRAMEPAYLOAD

MAC Payload

0/2 0/2/8 0/2 0/2/8

Destination

PANIdentifier

Destination

Address

SourcePAN

Identifier

SourceAddress

Identify type of frame, type of addressing, security

The address of a device can be long (48 bit, IEEE) or short (16 bit, assigned by the PAN coordinator)


MAC layer: Data Frame

o Up to 104 bytes payload


MAC layer: Ack Frame

o Transmitted right after data frame


MAC layer: Command Frame

o It allows the configuration and the control of remote devices (clients)

o It allows the implementations of simple network control and management procedures (based on a centralized architecture) in large scale networks


MAC layer: Beacon Frame format

o It allows the frame synchronization and the assignment of GTS


Network formation

o A FFD device looks for an available channel and selects a PANid (Channel Scanning). Then it starts transmitting Beacon frames

o A device that wants to connect to the network starts scanning channel looking for beacon frames

o Once scanning phase is over, device selects the network and sets the corresponding parameters according to the values indicated in the beacon frame; it then transmits an Associate Request Command to PAN Coordinator

o The PAN Coordinator replies with an Association Response Command

Network formation: Scanning

o Active Scanning (only for FFDs): n a beacon request message is sent out to trigger beacon

transmission

n Upon termination of the scanning procedure a PAN ID is chosen

o Passive Scanning (for FFDs and RMDs): similar to Active Scanning but without explicit Beacon Request messages

Beacon request

BeaconBeaconBeacon

Set to channel1

Set to channel2

aBaseSuperframeDuration*(2n + 1)symbols, where n = ScanDuration

Beacon request

BeaconBeaconBeacon


Network formation: Association



Network layer: Frame format

2 Byte 2 Byte 2 Byte 1 Byte 1 Byte Variabile

Routing fields

FRAMEPAYLOAD

NWK PayloadNWK Header

FRAMECONTROL

DestinationAddress

SourceAddress

BroadcastRadius

BroadcastSequenceNumber

Includes frame type, version, route-discovery information

Maximum number of hops that a message can cross

(like TTL in IP)

Network address must be the sameof the hort MAC address


Zigbee Routing: overview

o Defined in Zigbee Specification, by Zigbee Alliance (7/2005)

o Three types of devices:n ZB Coordinator (FFD)n ZB Router (FFD)n ZB End-Device (RFD o FFD)

o Routing is oriented to Zigbee (it is adapted from ad hoc routing protocols and considers the device types of zigbee)

o The algorithm integrates two mechanisms:n Ad-hoc On-demand Distance Vector (AODV)n Cluster Tree Algorithm


Ad-hoc On-demand Distance Vector

o Simple protocol for ad hoc networks based on the on-demand/reactive paradigm

o We’ll later in the ad hoc network slideset how it works


Cluster Tree Algorithm

o The procedure is initiated by a FFD that can become the network coordinator

o The FFD asks to the MAC entity to identify available channels, assigns a PANidentifier to the network and the Network Address 0 to itself (Coordinator)

o Then the network association procedure continues according to MAC layer rules. Each new device is also associated to network layer becoming ZB Router (FFD) or ZB End-Device

o The ZB Router can allow other devices to connect to the network

o The addresses are assigned a hierarchical and completely distributed mode


Cluster Tree Algorithm

max

Dep

th (L

m)

nwkMaxRouters (Rm)

nwkMaxChildren (Cm)

Depth=0

Depth = d-1

Depth = d

o The size A(d) of the range of addresses assigned to a router node at depth d < Lm is defined by:

o Nodes at depth Lm and end-devices are assigned a single address.

o Simple Assignment Rule: o A mote at level d is assigned addresses in range [x,x

+ A(d)-1]o It will assign

n [x+(i-1)A(d+1)+1,x+iA(d+1)] to its i-th router child (1£i£Rm)

n x+RmA(d+1)+j to its jth end-device child (1 £j £Dm).

Address Assignment Rule


An Exampleo Address allocations

for Rm = 2, Dm = 2 and Lm= 3.n A(2)=2+2+1=5n A(1)=1+2+2A(2)=1

3n A(0)=1+2+2A(1)=2

9n PAN Coordinator can

assign addresses in the range [0,28]


Tree-Based Routing: Principles

o Routing Along the Tree:n If destination address is

one of children end devices: o route directly

n Else if destination address belongs to one of children routers’ adresses set: o send to corresponding

children routern Else

o Send to parent node

Dest

Routing dev

Dest

Routing dev

Dest

Routing dev


Routing Along the Tree: Shortcomings

o Routing may be not optimizedn Route always along the treeen Routing is “quality-agnostic”n E.g.: A wants to send to B

A B


ZigBee Application Profileso Needs:

n A common language for exchanging datan A well defined set of processing actionsn Device interoperability across different manufacturersn Simplicity and reliability for the end users

o Profile Definition (9 Profile Libraries Currently Specified)n A set of devices required in the application arean A set of clusters to implement the functionality

o A set of attributes to represent device stateo A set of commands to enable the communication

n Specification of which clusters are required by which devices

n Specific functional description for each device


Profile Componentso E.g.: Personal Health Care

Profileo Data Collection Unit

n The Data Collection Unit (DCU) gathers the data from the different on-body medical and non-medical devices and delivers it to a gateway.

o Electrocardiographn This is a device that records and

measures the electrical activity of the heart over time.

o Pulse Monitorn A pulse monitor measures a

proxy value for the heart rate. o Sphygmomanometer

n A sphygmomanometer (blood pressure meter) is a device that measures the blood pressure.

Heart rate monitor

Blood pressure monitor

Nurses station

Data collection unit


Profiles Snapshot

securityHVACAMR


ZigBee

TVVCR

DVD/CDremote

securityHVAC


lawn & garden irrigation

asset mgtprocess controlenvironmental

energy mgt

mousekeyboardjoystick

patient monitoring

fitness monitoring

mobile gaming, location-based services, secure mobile payments, mobile advertising, billing,

3D vision Support

Smart energy mgtA. Capone: Wireless Internet 97


High Rate PAN (IEEE 802.15.3)

Short notes only


Short notes on IEEE 802.15.3

IEEE 802.15.3 (High Rate WPAN)o IEEE 802.15.3-2003 is the standard (MAC and PHY) for

high rate WPANs (11 to 55 Mb/s).o – 3a (WPAN High Rate Alternative PHY)

n IEEE 802.15.3a was an attempt to improve the physical layer of IEEE 802.15.3 using Ultra Wide Band (UWB) for multimedia applications

n The result of IEEE 802.15.3a WG was that of putting together the 23 proposals into 2:o Multi-Band Orthogonal Frequency Division Multiplexing (MB-

OFDM) UWB, WiMedia Allianceo Direct Sequence - UWB (DS-UWB), UWB Forum.

n In January 2006 IEEE 802.15.3a members decided to suspend work due to the lack of agreement among the two proposals


Short notes on IEEE 802.15.3

o – 3b (MAC Amendment)n IEEE 802.15.3b proposed some improvements to

802.15.3 for interoperability at MAC layer.o – 3c (WPAN Millimeter Wave Alternative PHY)

n IEEE 802.15.3c WG was started on March 2005 for working a physical layer based on millimeter waves.

n The mmWave WPAN will work on non-licenced 57-64 GHz bands.

n The goal is that of reaching very high rates (2-10 Gb/s) for supporting multimedia broadband applications like HDTV, home theater, real time streaming, etc.


Other wireless high rate initiatives

o Wireless USBn Based on the WiMedia Alliance's Ultra-WideBand (UWB)n 480 Mbit/s at distances up to 3 metres and 110 Mbit/s at

up to 10 metresn Designed to operate in the 3.1 to 10.6 GHz frequency

rangeo WirelessHD (WiHD)

n Based on a 7 GHz channel in the 60 GHz Extremely High Frequency radio band

n First-generation rate of 4 Gbit/s, new versions up to 25 Gbit/s

o Wireless Gigabit initiative (WiGig)n WiGig tri-band devices operate in the 2.4, 5 and 60 GHz

bands and deliver data rates up to 7 Gbit/so Wireless Home Digital Interface (WHDI)

n is a consumer electronic standard for a wireless HDTV n 3Gbit/s (allowing 1080p - HD video) in a 40 MHz

channel, and data rates of up to 1.5Gbit/s (allowing 1080i and 720p - HD video) in a single 20 MHz channel of the 5 GHz unlicensed band

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