WiMax, Wimesh, Bluetooth, Zigbee, RFID, and other Wimesh, Bluetooth, Zigbee, RFID, and other wireless technologies EPL657 Panayiotis Kolios 1 Wireless broadband 2 + 802.20?? WMAN –

WiMax, Wimesh, Bluetooth,

Zigbee, RFID, and other

wireless technologies

EPL657

Panayiotis Kolios

1

Wireless broadband

2

+ 802.20??

WMAN – Wireless

Metropolitan Area

Network

802.16

WiMax

3

IEEE 802.16

Standard IEEE 802.16 (http://grouper.ieee.org/groups/802/16/) defines the

air interface, including the MAC layer and multiple PHY layer options,

for fixed Broadband Wireless Access (BWA) systems to be used in a

Wireless Metropolitan Area Network (WMAN) for residential and

enterprise use.

IEEE 802.16 is also often referred to as WiMax. The WiMax Forum strives to ensure

interoperability between different 802.16 implementations - a difficult task due to the

large number of options in the standard.

IEEE 802.16 cannot be used in a mobile environment. For this IEEE 802.16e is being

developed; expected to compete with IEEE 802.20 standard (base standard 2008 –now

in hibernation – lack of activity).

IEEE 802.20 http://grouper.ieee.org/groups/802/20/ or Mobile Broadband

Wireless Access (MBWA) is a proposed IEEE Standard to enable worldwide

deployment of multi-vendor interoperable mobile broadband wireless access

networks

4

WiMax Standards

802.16 802.16a 802.16-2004

802.16e-2005

Date Completed

December 2001

January 2003

June 2004

December 2005

Spectrum 10-66 GHz < 11 GHz < 11 GHz < 6 GHz

Operation LOS Non-LOS Non-LOS Non-LOS and Mobile

Bit Rate 32-134 Mbps Up to 75 Mbps

Up to 75 Mbps

Up to 15 Mbps

Cell Radius 1-3 miles 3-5 miles 3-5 miles 1-3 miles

5

802.16 Publications

6

IEEE 802.16 standardization

first version of IEEE 802.16 standard completed in 2001.

defined a single carrier (SC) physical layer for line-of-sight

(LOS) transmission in the 10-66 GHz range.

IEEE 802.16a defined three physical layer options (SC, OFDM,

and OFDMA) for the 2-11 GHz range.

IEEE 802.16c contained upgrades for the 10-66 GHz range.

IEEE 802.16d contained upgrades for the 2-11 GHz range.

In 2004, the original 802.16 standard, 16a, 16c and 16d were

combined into the massive IEEE 802.16-2004 standard.

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8

WiMax system

• Typically, a WiMAX system consists of two parts:

– A WiMAX Base Station (BS): Base station consists

of indoor electronics and a WiMAX tower. Typically, a base

station can cover up to 10 km radius (Theoretically, a base

station can cover up to 50 km radius or 30 miles, however

practical considerations limit it to about 10 km or 6 miles).

Any wireless node within the coverage area would be able to

access the Internet.

– A WiMAX receiver (Subscriber Station-SS) - The receiver

and antenna could be a stand-alone box or a PCMCIA card

that sits in your laptop or computer. Access to WiMAX base

station is similar to accessing a Wireless Access Point in a

WiFi network, but the coverage is further.

9

WiMax is well suited to offer both fixed

and mobile access

10

Application scenarios

11

WiMax Forum publication

Can_WiMAX_Address_Your_Applications_final.pdf

How WiMax Works

• WiMax can provide 2 forms of wireless service:

- Non-LOS, Wi-Fi sort of service, where a small antenna on a computer connects to the tower. Uses lower frequency range (2 to 11 GHz).

- LOS, where a fixed antenna points straight at the WiMax tower from a rooftop or pole. The LOS connection is stronger and more stable, so it is able to

send a lot of data with fewer errors. Uses higher frequencies, with ranges reaching a possible 66 GHz.

Through stronger LOS antennas, WiMax transmitting stations would send data to WiMax enabled computers or routers set up within 30 mile radius (3,600 square miles of coverage) .

12

WiMax Spectrum

• Broad Operating Range

• WiMax Forum is focusing on 3 spectrum bands for global deployment: – Unlicensed 5 GHz: Includes bands between 5.25 and

5.85 GHz. In the upper 5 GHz band (5.725 – 5.850 GHz) many countries allow higher power output (4 Watts) that makes it attractive for WiMax applications.

– Licensed 3.5 GHz: Bands between 3.4 and 3.6 GHz have been allocated for Broadband Wireless Access (BWA) in majority of countries.

– Licensed 2.5 GHz: The bands between 2.5 and 2.6 GHz have been allocated in the US, Mexico, Brazil and in some SEA countries.

13

WiMax Uplink / downlink separation

IEEE 802.16 offers both TDD (Time Division Duplexing) and

FDD (Frequency Division Duplexing) alternatives.

Wireless devices should avoid transmitting and receiving at

the same time, since duplex filters increase the cost:

TDD: this problem is automatically avoided

FDD: IEEE 802.16 offers semi-duplex operation as an

option in Subscriber Stations.

(Note that expensive duplex filters are also the reason why

IEEE 802.11 WLAN technology is based on CSMA/CA

instead of CSMA/CD.)

14

IEEE 802.16 basic architecture

BS SS

SS

SS

Point-to-multipoint transmission AP

AP

802.11

WLAN BS = Base Station

SS = Subscriber Station

Fixed network

Subscriber line

replacement

15

ATM

transport

IP

transport

Service Specific Convergence

Sublayer (CS)

IEEE 802.16 protocol layering

MAC Common Part Sublayer

(MAC CPS)

Privacy sublayer

Physical Layer (PHY)

MA

C

Like IEEE 802.11, IEEE

802.16 specifies the Medium

Access Control (MAC) and

PHY layers of the wireless

transmission system.

The IEEE 802.16 MAC layer

consists of three sublayers.

16

ATM

transport

IP

transport


Sublayer (CS)



(MAC CPS)

Privacy sublayer


MA

C

CS maps data (ATM cells or IP

packets) to a certain

unidirectional connection

identified by the Connection

Identifier (CID) and associated

with a certain QoS.

CS adapts higher layer

protocols to MAC CPS.

May also offer payload header

suppression.

17

ATM

transport

IP

transport


Sublayer (CS)



(MAC CPS)

Privacy sublayer


MA

C

MAC CPS provides the core

MAC functionality:

• System access

• Bandwidth allocation

• Connection control

Note: QoS control is applied

dynamically to every

connection individually.

18

ATM

transport

IP

transport


Sublayer (CS)



(MAC CPS)

Privacy sublayer


MA

C

The privacy sublayer provides

authentication, key

management and encryption.

19

ATM

transport

IP

transport


Sublayer (CS)



(MAC CPS)

Privacy sublayer


MA

C

IEEE 802.16 offers three PHY

options for the 2-11 GHz band:

• WirelessMAN-SCa

• WirelessMAN-OFDM

• WirelessMAN-OFDMA

20

WiMAX

The WiMax (Worldwide

Interoperability for Microwave Access)

certification program of the WiMax

Forum addresses compatibility of IEEE

802.16 equipment

=>

WiMax ensures interoperability of

equipment from different vendors.

ATM

transport

IP

transport


Sublayer (CS)


(MAC CPS)

Privacy sublayer


WiMax

21

22

WiMAX (IEEE 802.16a) in a nutshell

Frequency Spectrum: 2 – 11GHz

Last mile technology (WAN)

Up to 30 miles of range with cell radius: 4-6 miles

Backhaul technology for wireless LANs (802.11)

Shared data rate up to 75 Mbps.

Support 50 customers with T1-rate wireless connections

ISP: http://www.towerstream.com/about.asp

Ref: http://www.intel.com/ebusiness/pdf/wireless/intel/80216_wimax.pdf

IEEE 802.16: WiMax in a nutshell

• The WiMAX wireless metropolitan network standard, IEEE 802.16,

– defines various high speed mechanisms that provide wireless last mile broadband access in Metropolitan Area Networks (MANs) at a cost much lower than traditional cable, DSL or T1 technologies.

• A typical scenario for the use of WiMAX is for it to provide broadband Internet access to various users in one or more buildings via rooftop antennae. – This emerging technology could had provided a very attractive

alternative to the 3G technology which is based on cellular networks. The low cost of WiFi deployment is obtained at the cost of much smaller coverage.

23


• WiMAX is part of a global standardization effort of the IEEE that involves not only the local WiFi networks (IEEE 802.11) but also regional networks (IEEE 802.22).

• IEEE 802.16 MAC protocol is mainly designed for point-to-multipoint access in wireless broadband applications.

• provides different levels of QoS to provide a multitude of transmission services including data, video and voice over IP.

24


• WIMAX Forum announced that 802.16 networks now

cover 430m people worldwide and are on a path to nearly

double to 800m pops by end of 2010. prediction!!

• based on almost 460 deployments in 135 countries,

• new roll-outs will be driven by auctions in India and Brazil,

among others.

• “In both emerging markets and mature countries,

companies and governments are deploying 4G WIMAX

networks to help bridge the digital divide,” said Intel’s

Maloney (Feb 2009).

• In early 2011 projections say that only about 5% of the

market will adopt 802.16!!!

25

Challenges to Overcome in WiMax

Deployment

• RF Interference: Disrupts a transmission and decreases performance. – Common forms are multi-path interference and attenuation.

Overlapping interference generate random noise.

• Infrastructure Placement: physical structure that houses or supports base station must be RF friendly. – Health and environmental concerns

– High RF activity in the area can cause interference.

– Obstacles such as trees and buildings can block signal paths.

– A metal farm silo, for example, may distort signals, or a tree swaying in the wind may change signal strength.

26

Solving the challenges in WiMax

Deployment

• Proper network design and infrastructure

placement are critical for solving the challenges.

- Subscriber Site Survey, Statistics Gathering, coordination

of RF use with neighbouring providers.

- Antennas (Type, Tilt Angles, Array Gain, Diversity Gain)

- Proper design and deployment of the provider’s NOC.

- Well deployed base station or cells with 24/7 access, RF

friendly structure, and shielding from weather elements.

27

WiMax Evolution Path Leads to Mobile

Access

28

IEEE802.20

29

MBWA: 802.20

• Mobile Broadband Wireless Access (MBWA)

aka Mobile-Fi

– IEEE Standard to enable worldwide deployment of

multi-vendor interoperable mobile broadband wireless

access network

– scope of working group consists of PHY, MAC, LLC

layers. The air interface will operate in bands below 3.5

GHz and with a peak data rate of over 80 Mbit/s.

– The goals of 802.20 and 802.16e, the so-called "mobile

WiMAX", are similar.

– New MAC and PHY with IP and adaptive antennas

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Wireless Mesh

Networks

33

Wireless Mesh Network solution

• ideal for WLAN coverage of large open areas, both indoor and outdoor,

• considered where Ethernet cabling is prohibitive to install or to minimize the requirement for leased backhaul.

• deployment scenarios that are often particularly well suited for Wireless Mesh Network include: – campus environments (enterprises and universities),

manufacturing, shopping centers,

– construction sites

– airports, sporting venues, special events

– military operations, disaster recovery, temporary installations, public safety

– municipalities, including downtown cores, residential areas, and parks

– carrier managed service in public areas or residential communities

34

WiMax Mesh Mode

35

• Presented in

(802.16d-2004) as

optional mode

• SS don’t have to

be within the range

of the BS

• Traffic is relayed

by parent nodes to

the BS

WMN deployment

36

Nortel approach

WMN deployment

37

Nortel approach

Comparison WLAN and WMN

38

Wireless Mesh networks example

39

The Wireless Mesh Network is well-suited for providing broadband

wireless access in areas that traditional WLAN systems are unable to cover.


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45


46

OTHER WIRELESS

TECHNOLOGIES

EPL657

Bluetooth

802.15 (zigbee)

Hiperlan – old stuff

47

Wireless Personal Area

Networks (WPAN)

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IEEE definition of WPAN

Wireless personal area networks (WPANs) are used to convey information over short distances among a private, intimate group of participant devices. connection made through a WPAN involves little or no infrastructure or direct connectivity to the world outside the link (ad-hoc). This allows small, power-efficient, inexpensive solutions to be implemented for a wide range of devices.

• less than 10 m diameter

• replacement for cables

(mouse, keyboard,

headphones)

• ad hoc: no infrastructure

• master/slaves:

– slaves request permission to

send (to master)

– master grants requests

• 802.15: evolved from

Bluetooth specification

– 2.4-2.5 GHz radio band

– up to 721 kbps

50

M radius of

coverage

S

S S

P

P

P

P

M

S

Master device

Slave device

Parked device (inactive) P

802.15: personal area network

Example of a Personal Area Network (PAN) as provided by

the Bluetooth standard.

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PAN example

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Bluetooth (IEEE 802.15.1)

Wireless Personal Area Network

Spread Spectrum: Frequency Hopping Spread Spectrum (FHSS)

Frequency Band: 2.4GHz

Very low power consumption

Short distance: < 10m

Relatively low rate: < 1M

Applications: Cellular phone

Peripheral device

Home appliance

Car

www.xilinx.com/esp/bluetooth/tutorials/intro.htm

53

Bluetooth ≈ IEEE 802.15.1

A widely used WPAN technology is known as Bluetooth (version 1.2 or version 2.0) The IEEE 802.15.1 standard specifies the architecture and operation of Bluetooth devices, but only as far as physical layer and medium access control (MAC) layer operation is concerned (the core system architecture). Higher protocol layers and applications defined in usage profiles are standardised by the Bluetooth SIG.

54

Piconets

Bluetooth enabled electronic devices connect and communicate wirelessly through short-range, ad hoc networks known as piconets.

Piconets are established dynamically and automatically as Bluetooth enabled devices enter and leave radio proximity.

Up to 8 devices in one piconet (1 master and 7 slave devices). Max range 10 m.

ad hoc => no base station

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Piconet operation

The piconet master is a device in a piconet whose clock and device address are used to define the piconet physical channel characteristics. All other devices in the piconet are called piconet slaves. At any given time, data can be transferred between the master and one slave. The master switches rapidly from slave to slave in a round-robin fashion. Any device may switch the master/slave role at any time.

56

Power classes

Bluetooth products are available in one of three power classes:

Class

Class 1

Class 2

Class 3

Power

100 mW

2.5 mW

1 mW

Range

~100 m

~10 m

~10 cm

Industrial usage

Mobile devices

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Data rates

Channel data rates: Bluetooth version 1.2 offers a bit rate of 1 Mbit/s. Bluetooth version 2.0 offers 3 Mbit/s. Achievable user bit rates are much lower, (among others) due to the following reasons:

overhead resulting from various protocol headers

interference causes destroyed frequency bursts => information has to be retransmitted

IEEE 802.15.1 BLUETOOTH (I)

• Bluetooth technology aims at so-called ad hoc piconets, which are local area networks with a very limited coverage and without the need for an infrastructure.

• Needed to connect different small devices in close proximity without expensive wiring or the need for a wireless infrastructure.

• Represents a single-chip, low-cost, radio-based wireless network technology.

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BLUETOOTH (II)

• No standardization body has set up any specification

regarding Bluetooth.

• The primary goal of Bluetooth is not a complex

standard covering many aspects of wireless

networking, but a quick and very cheap solution

enabling ad hoc personal communication within a

short range in the license-free 2.4 GHz band.

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BLUETOOTH (III)

• Physical layer: – A frequency-hopping\time-division duplex scheme is used

for transmission with a fast hopping rate of 1,600 hops per second. The time between two hops is called a slot, which is an interval of 625μs, thus each slot uses a different frequency.

– On average, the frequency-hopping sequence ´visits´ each hop carrier with an equal probability.

– All devices using the same hopping sequence with the same phase form a Bluetooth piconet.

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BLUETOOTH (IV)

– With transmitting power of up to 100 mW, Bluetooth

devices have a range of up to 10m (or even up to 100m

with special transceivers).

– Having this power and relying on battery power, a

Bluetooth device cannot be in an active transmit mode all

the time.

– Bluetooth defines several low-power states for the device.

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BLUETOOTH (V)

– States of a possible Bluetooth device and possible

transitions:

• Standby mode: Every device which is currently not participating in

a piconet (and not switched off)

– In this mode, a device listens for paging messages.

• Connections can be initiated by any device which becomes the

master.

– This is done by sending page messages if the device already knows

the address of the receiver, or inquiry messages followed by a page

message if the receiver’s address is unknown.

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BLUETOOTH (VI)

• To save battery power, a Bluetooth device can go into one of three low power states if no data is ready to be sent:

– PARK state: The device has the lowest duty cycle, and thus the lowest power consumption. The device releases its MAC address, but remains synchronized with the piconet. The device occasionally listens to the traffic of the master device to resynchronize and check for broadcast messages.

– HOLD state: The power consumption of this state is a little higher. The device does not release its MAC address and can resume sending at once after transition out of the HOLD state.

– SNIFF state: It has the highest power consumption of the low-power states. The device listens to the piconet at a reduced rate.

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BLUETOOTH (VII)

64

STANDBY

inquiry page

connected transmit

PARK HOLD SNIFF

unconnected

connecting

active

low power

BLUETOOTH (VIII)

• MAC layer: – Several mechanisms control medium access in a Bluetooth

system.

– One device within a piconet acts as a master, all other devices (up to seven) act as slaves.

– The master determines the hopping sequence as well as the phase of the sequence.

– All Bluetooth devices have the same networking capabilities, i.e., they can be master or slave. The unit establishing the piconet automatically becomes the master and controls medium access; all other devices will be slaves.

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L2CAP layer

Host Controller Interface

L2CAP layer

Channel Manager

Resource Manager

L2CAP

Control Data Synchronous traffic

The Logical Link Control and Adaptation Protocol (L2CAP) layer handles the multiplexing of higher layer protocols and the segmentation and reassembly (SAR) of large packets. The L2CAP layer provides both connectionless and connection-oriented services.

67

Higher protocol layers (1)

The operation of higher protocol layers is outside the scope of the IEEE 802.15.1 standard (but included in the Bluetooth SIG standards). The usage of these protocols depends on the specific Bluetooth profile in question. A large number of Bluetooth profiles have been defined.

L2CAP layer

RFCOMM

TCP/IP/PPP RS-232 emulation SDP TCS BIN OBEX

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The radio frequency communication protocol RFCOMM enables the replacement of serial port cables (carrying RS-232 control signals such as TxD, RxD, CTS, RTS, etc.) with wireless connections. Several tens of serial ports can be multiplexed into one Bluetooth device.

L2CAP layer

RFCOMM

TCP/IP/PPP SDP TCS BIN OBEX RS-232 emulation

69


TCP/IP based applications, for instance information transfer using the Wireless Application Protocol (WAP), can be extended to Bluetooth devices by using the Point-to-Point Protocol (PPP) on top of RFCOMM.

L2CAP layer

RFCOMM


70


The Object Exchange Protocol (OBEX) is a session-level protocol for the exchange of objects. This protocol can be used for example for phonebook, calendar or messaging synchronisation, or for file transfer between connected devices.

L2CAP layer

RFCOMM


71


The telephony control specification - binary (TCS BIN) protocol defines the call-control signalling for the establishment of speech and data calls between Bluetooth devices. In addition, it defines mobility management procedures for handling groups of Bluetooth devices.

L2CAP layer

RFCOMM


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The Service Discovery Protocol (SDP) can be used to access a specific device (such as a digital camera) and retrieve its capabilities, or to access a specific application (such as a print job) and find devices that support this application.

L2CAP layer

RFCOMM


73

Usage models

A number of usage models are defined in Bluetooth profile documents. A usage model is described by a set of protocols that implement a particular Bluetooth-based application. Some examples are shown on the following slides:

• File transfer

• LAN access

• Wireless headset

• Cordless (three-in-one) phone.

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File transfer application

Using the file transfer profile:

A Bluetooth device can browse the file system of another Bluetooth device, can manipulate objects (e.g. delete objects) on another Bluetooth device, or - as the name implies - files can be transferred between Bluetooth devices.

SDP

RFCOMM

OBEX

File transfer application

L2CAP

75

LAN access application

Using the LAN profile:

A Bluetooth device can access LAN services using (for instance) the TCP/IP protocol stack over Point-to-Point Protocol (PPP).

Once connected, the device functions as if it were directly connected (wired) to the LAN.

SDP

RFCOMM

PPP

LAN access application

L2CAP

TCP/IP (e.g.)

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Wireless headset application

Using the headset profile:

According to this usage model, the Bluetooth-capable headset can be connected wirelessly to a PC or mobile

SDP RFCOMM

Headset application

L2CAP

Audio

phone, offering a full-duplex audio input and output mechanism.

This usage model is known as the ultimate headset.

77

Cordless (three-in-one) phone

application

Using the cordless telephone profile:

A Bluetooth device using this profile can set up phone calls to users in the PSTN (e.g. behind a PC acting as voice base

SDP TCS BIN

Cordless phone application

L2CAP

Audio

station) or receive calls from the PSTN.

Bluetooth devices implementing this profile can also communicate directly with each other.

IEEE 802.15.4 LR-WPAN

(ZigBee)

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802.15.4 vs ZigBee - What's the

difference?

• The Wireless Sensor Network Research group (WSNRG)

has published an article titled 802.15.4 vs ZigBee which

helps people understand and distinguish between all the

communications technologies that are used in the WSN

field: 802.15.4, ZigBee, Mesh protocols, 2.4GHz, 868MHz

and 900MHz bands…

• This document compares both IEEE 802.15.4 and ZigBee

technologies while explaining the main characteristics of

each.

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See 802.15.4 vs Zigbee doc

http://www.sensor-networks.org/

http://www.sensor-networks.org/index.php?page=0823123150

zigbee vs ieee 802.15.4.docx

802.15.4 vs ZigBee - What's the

difference?

• To summarize 802.15.4 vs ZigBee:

– 802.15.4 is a protocol to get point to point and energy

efficient communications.

– ZigBee defines extra services (star topology routing,

encryption, application services) over 802.15.4.

– ZigBee creates semi-centralized networks where just

the end devices can sleep

– Different completely distributed mesh algorithms are

being used over 802.15.4.

80

See 802.15.4 vs Zigbee doc

zigbee vs ieee 802.15.4.docx

IEEE 802.15.4

• a standard which specifies the physical layer and

media access control (MAC) for low-rate wireless

personal area networks (LR-WPANs).

• basis for the ZigBee, ISA100.11a, WirelessHART,

and MiWi specifications, which further extend

standard by developing the upper layers which

are not defined by 802.15.4.

• Alternatively, it can be used with 6LoWPAN and

standard Internet protocols to build a Wireless

Embedded Internet.

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82

IEEE 802.15.4 LR-WPAN (ZigBee

http://www.zigbee.org/)

ZigBee technology is simpler (and less expensive) than Bluetooth.

The main objectives of an LR-WPAN like ZigBee are ease of installation, reliable data transfer, short-range operation, extremely low cost, and a reasonable battery life, while maintaining a simple and flexible protocol.

The raw data rate will be high enough (maximum of 250 kbit/s @ 10 metres) to satisfy a set of simple needs such as interactive toys, etc..., but is also scalable down to the needs of sensor and automation needs (20 kbit/s or below) using wireless communications.

83

IEEE 802.15.4 LR-WPAN (ZigBee

http://www.zigbee.org/) Important features include:

• real-time suitability by reservation of guaranteed time slots,

• collision avoidance through CSMA/CA and integrated support for secure communications.

• Devices also include power management functions such as link quality and energy detection

• PHY manages the physical RF transceiver and performs channel selection and energy and signal management functions. Operates on unlicensed frequency bands:

• 868.0-868.6 MHz: Europe, allows 1 communication channel (2003, 2006) 902-928 MHz: North America, up to ten channels (2003), extended to 30 (2006) 2400-2483.5 MHz: worldwide use, up to 16 channels (2003, 2006)

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ZigBee http://www.zigbee.org/

ZigBee offers basically four kinds of different services:

• Extra Encryption services (application and network keys implement extra 128b AES encryption)

• Association and authentication (only valid nodes can join to the network).

• Routing protocol: AODV, a reactive ad hoc protocol.

• Application Services: An abstract concept called "cluster" is introduced. Each node belongs to a predefined cluster and can take a predefined number of actions. Example: the "house light system cluster" can perform two actions: "turn the lights on", and "turn the lights off".

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86


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88


Zigbee public profiles

89


Zigbee home control example

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LR-WPAN device types

Two different device types can participate in an LR-WPAN network:

Full-function devices (FFD) can operate in three modes serving as a personal area network (PAN) coordinator, a coordinator, or a device.

Reduced-function devices (RFD) are intended for applications that are extremely simple.

An FFD can talk to RFDs or other FFDs, while an RFD can talk only to an FFD.

91

Network topologies (1)

Two or more devices communicating on the same physical channel constitute a WPAN. The WPAN network must include at least one FFD that operates as the PAN coordinator. The PAN coordinator initiates, terminates, or routes communication around the network. The PAN coordinator is the primary controller of the PAN. The WPAN may operate in either of two topologies: the star topology or the peer-to-peer topology.

92


Star topology

PAN coordinator (always FFD) FFD RFD

In a star network, after an FFD is activated for the first time, it may establish its own network and become the PAN coordinator. The PAN coordinator can allow other devices to join its network.

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Peer-to-peer topology In a peer-to-peer network, each FFD is capable of communicating with any other FFD within its radio sphere of influence. One FFD will be nominated as the PAN coordinator.

A peer-to-peer network can be ad hoc, self-organizing and self-healing, and can combine devices using a mesh networking topology.

PAN coordinator (always FFD) FFD RFD

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ZigBee PHY and MAC parameters

Topology Ad hoc (central PAN coordinator)

RF band 2.4 GHz ISM frequency band

RF channels 16 channels with 5 MHz spacing

Spreading DSSS (32 chips / 4 bits)

Chip rate 2 Mchip/s

Modulation Offset QPSK

Access method CSMA/CA (or slotted CSMA/CA)

95

Comparison: Bluetooth radio and

baseband parameters

Topology Up to 7 simultaneous links

Modulation Gaussian filtered FSK

RF bandwidth 220 kHz (-3 dB), 1 MHz (-20 dB)

RF band 2.4 GHz ISM frequency band

RF carriers 79 (23 as reduced option)

Carrier spacing 1 MHz

Access method FHSS-TDD-TDMA

Freq. hop rate 1600 hops/s

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Beacon frames

The LR-WPAN standard allows the optional use of a superframe structure. The format of the superframe is defined by the coordinator. Superframe is bounded by network beacons, sent by the coordinator, and is divided into 16 equally sized slots. The beacon frame is transmitted in the first slot of each superframe. If a coordinator does not wish to use a superframe structure, it may turn off the beacon transmissions. The beacons are used to synchronize the attached devices, to identify the PAN, and to describe the superframe structure.

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CSMA/CA operation (1)

Nonbeacon-enabled networks use an unslotted CSMA-CA channel access mechanism. Each time a device wishes to transmit data frames or MAC commands, it shall wait for a random period. If the channel is found to be idle, the device shall transmit its data. If the channel is found to be busy, following the device shall wait for the random backoff before trying to access the channel again.

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CSMA/CA operation (2)

Beacon-enabled networks use a slotted CSMA-CA channel access mechanism, where the backoff slots are aligned with the start of the beacon transmission.

Similar to the unslotted operation, however the device can begin transmitting on the next available slot boundary.

6LoWPAN

99

What is 6LoWPAN

• Low-power RF + IPv6 = 6LoWPAN

• Defined by IETF standards – RFC 4919, “IPv6 over Low-Power Wireless

Personal Area Networks (6LoWPANs): Overview, Assumptions, Problem Statement, and Goals”

– RFC 4944, “Transmission of IPv6 Packets over IEEE 802.15.4 Networks”

– draft-ietf-6lowpan-hc and –nd

100 Prepared by Zinon Zinonos

University of Cyprus 6LoWPAN

• simple, low-cost, wireless communication network for

constrained applications with limited power.

• is an adaption layer that allows efficient IPv6 communication

over IEEE 802.15.4.

• turns IEEE 802.15.4 into the next IP-enabled link

• offers wide-scale connectivity, open-system based interoperability,

and interoperability between low-power devices and IP devices

• Leverages well-known IP-based knowledge and practices

• Imports well-known capabilities of IPv6 to low-power devices.

uIPv6 101

Blip,and uIPv6 are implementations of

the 6LoWPAN stack for TinyOS 2.x

and CONTIKI

Why is needed?

102 Internet of Things

Benefits of using IP in 6LoWPAN

Technology

The benefits of 6LoWPAN include:

– Open, long-lived, reliable standards

– Transparent Internet integration

– Easy learning-curve

– Established network management tools

– Global scalability

– Established security

– End-to-end data flows

103

6LoWPAN architecture

104

IPv6

Application Protocols

UDP

IEEE 802.15.4 MAC

IEEE 802.15.4 PHY

6LowPan

IP

HTTP

UDP/TCP

Ethernet MAC

Ethernet PHY

IP Protocol Stack

6LowPAN protocol Stack

6LoWPAN characteristics

As IEEE 802.15.4: – Small MTU size of 127 bytes

– Low data rate of 250kbps

– Operates in 2.4 GHz band

– Short range communication

Efficient header compression

Network autoconfiguration using neighbor discovery

Unicast, multicast and broadcast support

Fragmentation – 1280 bytes IPv6 MTU -> 127 bytes 802.15.4 frames

Support for IP routing (e.g. IETF RPL)

Star and peer-to-peer (mesh) topologies

105

6LoWPAN routing

• RPL Routing

106

RPL 6LoWPAN routing protocol.pdf

RFID - RADIO-FREQUENCY

IDENTIFICATION

107

Radio-frequency identification (RFID)

• wireless non-contact system that uses radio-

frequency electromagnetic fields to transfer data

from a tag attached to an object, for the purposes

of automatic identification and tracking.

– Passive tags: require no battery and are powered by

the electromagnetic fields used to read them.

– Active tags: use a local power source and emit radio

waves (electromagnetic radiation at radio frequencies).

• RFID tag contains electronically stored information which

can be read from up to several metres away. Unlike a bar

code, the tag does not need to be within line of sight of the

reader and may be embedded in the tracked object.

108


• RFID tags are used in many industries: – track its progress through the assembly line of an

automobile

– Pharmaceuticals can be tracked through warehouses.

– Livestock and pets may have tags injected.

– identity cards can give employees access to locked

areas of a building

– RF transponders mounted in automobiles can be used

to bill motorists for access to toll roads or parking.

• Since RFID tags can be attached to

clothing, possessions, or even implanted

within people, the possibility of reading

personally-linked information without

consent has raised privacy concerns.

109


110

http://en.wikipedia.org/wiki/Radio-frequency_identification

5 D. Sen et al., RFID For Energy and Utility Industries, PennWell Corp., 2009 ISBN 978-1-595370-

105-5, pages 1-48

6 Stephen A. Weis, RFID (Radio Frequency Identification):Principles and Applications, MIT


• SEE SLIDES

• RFID: Cow Jewelry – or – Revolution slides

• By Travis Sparks

• http://www.cs.unc.edu/~sparkst

111

RFID SLIDES by Travis Sparks.ppt

http://www.cs.unc.edu/~sparkst

DASH 7 THE LOWEST POWER, LONGEST RANGE WIRELESS

NETWORKING TECHNOLOGY AVAILABLE ANYWHERE!!!!

112

Dash7 low-power radio protocol

gains momentum …

• Yet another technology ???? • Goal: The lowest power, longest range wireless

networking technology available anywhere!!!

• DASH7 Alliance is the body responsible for overseeing the development of the

ISO 18000-7 standard for wireless sensor networking, as well as

interoperability certification of DASH7 devices and the licensing of DASH7

trademarks. The DASH7 Alliance is an industry consortium whereas "DASH7"

is the name of the technology.

• http://www.dash7.org/index.php?option=com_content&view=article&id=9&Itemid=11

• See IEEE spectrum article Wireless Networking Dashes in a New

Direction: The Dash7 low-power radio protocol gains momentum, Feb 2010.

113

Dash7

http://en.wikipedia.org/w/index.php?title=ISO_18000-7&action=edit&redlink=1



dash7-ieee-spectrum.pdf

• Range: Dynamically adjustable from 10 meters to 10 kilometers

• Power: <1 milliwatt power draw

• Data Rate: dynamically adjustable from 28kbps to 200kbps.

• Frequency: 433.92 MHz (available worldwide)

• Signal Propagation: Penetrates Walls, Concrete, Water

• Real-Time Locating Precision: within 4 meters

• Latency: Configurable, but worst case is less than two seconds

• P2P Messaging: Yes

• IPv6 Support: Yes

• Security: 128-bit AES, public key

• Application Profiles: None

• Standard: ISO/IEC 18000-7

114

Dash7 in a nutshell

especially appropriate for such things as radio-frequency

identification (RFID) tags

115

Dash7 in comparison

http://www.dash7.org/index.php?option=com_content&view=article&id=148&Itemid=203

116

Dash7 in comparison

SEE slides:

DASH7 Capabilities Overview for Seoul

Seoul Briefing of Dec 9th 2009 Slides

http://www.dash7.org/index.php?option=com_content&view

=article&id=192&Itemid=196

EPL657 DASH slides.ppt

WLAN technologies – summary

• The basic goals of all wireless LAN/WAN types (WLAN, WiMAX, WiMesh, BUETOOTH, ZigBee, etc…) are the provision of a much higher flexibility for nodes within a network.

• All WLANs suffer from limitations of the air interface and higher complexity compared to their wired counterparts but allow for a new degree of freedom for their users within rooms, buildings etc, leading to diverse applications, including the Internet-Of-Things

117

Extra slides

118

HIPERLAN –

High Performance LAN (I)

• The European Telecommunications Standards Institute (ETSI) standardized HIPERLAN as a WLAN allowing for node mobility and supporting ad hoc and infrastructure-based topologies.

• It is a wireless LAN supporting priorities and packet life time for data transfer at 23.5 Mbit/s, including forwarding mechanisms, topology discovery, user data encryption, network identification and power conservation mechanisms.

• HIPERLANs operate at 5.1 – 5.3 GHz with a range of 50m in buildings at 1 W transmit power.

119

HIPERLAN –

High Performance LAN (II)

• The service offered by a HIPERLAN is compatible

with the standard MAC services known from IEEE

802.x LANs.

• The HIPERLAN Channel Access Control mechanism

was specifically designed to provide channel access

with priorities.

• The CAC contains the access scheme EY-NPMA,

which is unique for HIPERLAN.

120

HIPERLAN –

High Performance LAN (III)

• Elimination-yield non-preemptive priority multiple access (EY-NPMA) – not only a complex acronym, but also the heart of the

channel access providing priorities and different access schemes.

– divides the medium access of different competing nodes into three phases:

• Prioritization: Determine the highest priority of a data packet ready to be sent on competing nodes

• Contention: Eliminate all but one of the contenders, if more than one sender has the highest current priority.

• Transmission: Finally, transmit the packet of the remaining node.

121

HIPERLAN –

High Performance LAN (IV)

– The contention phase is further subdivided into an elimination phase and a yield phase.

– The purpose of the elimination phase is to eliminate as many contending nodes as possible. The result is a more or less constant number of remaining nodes, almost independent of the initial number of competing nodes.

– The yield phase completes the work of the elimination phase with the goal of only one remaining node.

122

WiMax, Wimesh, Bluetooth, Zigbee, RFID, and other Wimesh, Bluetooth, Zigbee, RFID, and other wireless technologies EPL657 Panayiotis Kolios 1 Wireless broadband 2 + 802.20?? WMAN –

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