Ad hoc Sensor Networks

Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework**

Consortium leader

PETER PAZMANY CATHOLIC UNIVERSITY

Consortium members

SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER

The Project has been realised with the support of the European Union and has been co-financed by the European Social Fund ***

**Molekuláris bionika és Infobionika Szakok tananyagának komplex fejlesztése konzorciumi keretben

***A projekt az Európai Unió támogatásával, az Európai Szociális Alap társfinanszírozásával valósul meg.

Ad hoc Sensor Networks

Standardized wireless systems

www.itk.ppke.hu

Érzékelő mobilhálózatok

Standardizált vezeték nélküli rendszerek

Dr. Oláh András

Lecture 7 review

• Network layer functions

• Routing algorithm requirements and strategies

• Network of networks: the Internet

• Routing in traditional networking technologies (Dijkstra, Belman- Ford routing algorithm)

• Routing in Mobile Ad Hoc Networks

• Routing as a quadratic optimization problem

Outline

• The IEEE 802 Family of Standards

• Cellular Systems (recall)

• Wireless LANs alias Wifi (recall)

• Bluetooth

• ZigBee

• Summary of

– 3G standards

– WLAN standards – WPAN standards

Standards

• Interacting systems require standardization

• Companies want their systems adopted as standard

– Alternatively try for de-facto standards

• Standards determined by TIA/CTIA in US

– IEEE standards often adopted

– Process fraught with inefficiencies and conflicts

• Worldwide standards determined by ITU-T

– In Europe, ETSI is equivalent of IEEE

Recall from Chapter 1

The IEEE 802 Family of Standards

• The Institute of Electrical and Electronics Engineers:

– A technical, professional, and student society.

– Publishes many journals and magazines.

– Also has developed a few technical standards.

• Working Groups

– 802.1 High Level Interface (HILI) Working Group (active)

– 802.2 Logical Link Control (LLC) Working Group (hibernating)

– 802.3 CSMA/CD Working Group (active) – Ethernet, standard for wired LAN’s

– 802.4 Token Bus Working Group (hibernating)

The IEEE 802 Family of Standards (cont’)

• Working Groups (cont’)

– 802.7 Broadband Technical Adv. Group (BBTAG) (hibernating)

– 802.9 Integrated Services LAN (ISLAN) Working Group (hibernating) – 802.10 Standard for Interoperable LAN Security (SILS) Working Group

(hibernating)

– 802.11 Wireless LAN (WLAN) Working Group (active) – 802.12 Demand Priority Working Group (hibernating)

– 802.14 Cable-TV Based Broadband Communication Network Working Group (disbanded, no publications)

– 802.15 Wireless Personal Area Network (WPAN) Working Group (active)

– 802.16 Broadband Wireless Access (BBWA) Working Group (active) – 802.17 Resilient Packet Ring (RPR) (active)

The IEEE 802 Family of Standards (cont’)

• Working Groups (cont’)

– 802.18 Radio Regulatory Technical Advisory Group (active) – 802.19 Coexistence Technical Advisory Group (active)

– 802.20 Mobile Wireless Access Working Group (active)

Cellular Systems (cont’)

• Typically require different access and routing strategies since data is bursty, whereas voice is continuous

• 3G features:

– 384 Kbps (802.11n has 100s of Mbps).

– Standard based on wideband CDMA

– Packet-based switching for both voice and data – 3G cellular popular in Asia and Europe

• Evolution of existing systems in US (2.5G++)

– GSM+EDGE, IS-95(CDMA)+HDR – 100 Kbps may be enough

– Dual phone (2/3G+Wifi) use growing (iPhone, Google)

• What means beyond 3G? Good question.

Recall from Chapter 1

Cellular Systems (cont’)

• 4G and Long Term Evolution (LTE) features:

– Ortgogonal Frequency Division Multiplexing/ Multiple Input Multiple Output technology (OFDM/MIMO)

– Much higher data rates (50-100 Mbps) – Greater spectral efficiency (bits/s/Hz)

– Flexible use of up to 100 MHz of spectrum – Low packet latency (<5ms).

– Increased system capacity – Reduced cost-per-bit

– Support for multimedia

Recall from Chapter 1

• Wireless Multimedia (wireless HDTV, and gaming) everywhere

• Wifi features:

– Streaming video – Gbps data rates – High reliability

• WLANs connect “local” computers (100m range)

• Breaks data into packets

• Channel access is shared (random access)

• Backbone Internet provides best-effort service (no QoS)

– Poor performance in some apps (e.g. video)

Wireless LANs alias Wifi

Recall from Chapter 1

Wireless LANs alias Wifi (cont’)

• 802.11b (Old – 1990s)

– Standard for 2.4GHz ISM band (80 MHz) – Direct sequence spread spectrum (DSSS) – Speeds of 11 Mbps, approx. 120m range

• 802.11a/g (1999/2003 -)

– Standard for 5GHz

– OFDM in 20 MHz with adaptive rate/codes – Speeds of 54 Mbps, approx. 30-50m range

802.11n (2009 - )

– Standard in 2.4 GHz and 5 GHz band

– Adaptive OFDM /MIMO in 20/40 MHz (2-4 antennas)

Recall from Chapter 1

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2011.11.27. TÁMOP – 4.1.2-08/2/A/KMR-2009-0006 13

Bluetooth idea and features

• Cable replacement RF technology (low cost)

• Short range (10m, extendable to 100m)

• 2.4 GHz band (crowded)

• 1 Data (700 Kbps) and 3 voice channels, up to 3 Mbps

• Widely supported by telecommunications, PC, and consumer electronics companies

• Few applications beyond cable replacement

• Universal radio interface for ad-hoc wireless connectivity

• Embedded in other devices, goal: $5/device (2005: $40 bluetooth headset)

2001

2010

Bluetooth history

• History

– 1994: Ericsson (Mattison/Haartsen), “MC-link” project

– Renaming of the project: Bluetooth according to Harald “Blåtand” Gormsen [son of Gorm], King of Denmark in the 10th century

– 1998: foundation of Bluetooth SIG

– 1999: erection of a rune stone at Ercisson/Lund

– 2001: first consumer products for mass market, spec. version 1.1 released

– Nov. 8, 2004 (Overland Park, KS): Version 2.0 + EDR (Enhanced Data Rate) is announced. Up to 3 Mbps.

• Bluetooth Special Interest Group (SIG)

– Original founding members: Ericsson, Intel, IBM, Nokia, Toshiba – Added promoters: 3Com, Agere (was: Lucent), Microsoft, Motorola – > 2500 members

– Common specification and certification of products

• IEEE founded IEEE 802.15 for Wireless Personal Area Networks (WPAN) and

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2011.11.27. TÁMOP – 4.1.2-08/2/A/KMR-2009-0006 15

Bluetooth characteristics

• 2.4 GHz ISM band, 79 RF channels, 1 MHz carrier spacing

• Channel 0: 2402 MHz … channel 78: 2480 MHz

• GFSK modulation, 1-100 mW transmit power

• FHSS and TDD

• Frequency hopping with 1600 hops/s

• Hopping sequence in a pseudo random fashion, determined by a master

• Time division duplex for send/receive separation

• Two type of links:

• Voice link – SCO (Synchronous Connection Oriented): FEC (forward error correction), no retransmission, 64 kbit/s duplex, point-to-point, circuit switched

• Data link – ACL (Asynchronous Connectionless): Asynchronous, fast acknowledge, point-to-multipoint, up to 433.9 kbit/s symmetric or 723.2/57.6 kbit/s asymmetric, packet switched

Bluetooth characteristics (cont’)

• Topology: Overlapping piconets (stars) forming a scatternet

• Advantage:

– already integrated into several products, available worldwide, – free ISM-band, several vendors,

– simple system, simple ad-hoc networking, peer to peer, scatternets

• Disadvantage:

– interference on ISM-band, – limited range,

– max. 8 devices/network, – high set-up latency

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2011.11.27. TÁMOP – 4.1.2-08/2/A/KMR-2009-0006 17

Bluetooth protocol stack

Bluetooth network: piconet

• 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:

– Master gives slaves its clock and device ID Addressing (Active Member Address (AMA, 3 bit) and Parked Member Address (PMA, 8 bit)) – Phase in hopping pattern determined by clock

– Each piconet has a unique hopping pattern determined by device ID (48 bit, unique worldwide)

• Participation in a piconet = synchronization to hopping sequence:

• Each piconet has one master and up to 7 simultaneous slaves (>

200 could be parked).

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2011.11.27. TÁMOP – 4.1.2-08/2/A/KMR-2009-0006 19

Bluetooth network: piconet (cont’)

Bluetooth network: scatternet

• Linking of multiple co-located piconets through the sharing of common master or slave devices

• Devices can be slave in one piconet and master of another: as soon as a master leaves a piconnet, all traffic within this piconet is suspended until the master returns.

• Communication between piconets

• Devices jumping back and forth between the piconets

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2011.11.27. TÁMOP – 4.1.2-08/2/A/KMR-2009-0006 21

Operational state of a Bluetooth device

IEEE 802.15.4 / ZigBee Radios

• Low-Rate WPAN

• Data rates of 20, 40, 250 Kbps

• Support for large mesh networking or star clusters

• Support for low latency devices

• CSMA-CA channel access

• Very low power consumption

• Frequency of operation in ISM bands (2.4GHz)

• Focus is primarily on low power wireless sensor networks

Recall from Chapter 1

IEEE 802.15.4 / ZigBee Radios (cont’)

• ZigBee Aliance

– „the software”

– Network, Security & Application layers – Brand management

• IEEE 802.15.4

– “the hardware”

– Physical & Media Access Control layers

• What does ZigBee do?

– Designed for wireless controls and sensors

– Operates in Personal Area Networks (PAN’s) and device-to-device networks – Connectivity between small packet

devices

– Control of lights, switches, thermostats, appliances, etc.

ZigBee Mesh Networking

• Topology

– Star

– Cluster Tree – Mesh

• Network coordinator, routers, end devices

• States of operation

– Active – Sleep

• Devices

– Full Function Devices (FFD’s)

– Reduced Function Devices (RFD’s)

• Modes of operation

Summary of current wireless systems

3G standars cdma2000 W-CDMA

Subclass ^{1X 1XEV-D0 1xEV-DV 3X UMTS FOMA J-Phone}

Bandwidth (MHz) ^{1.25 3.75 5}

Chip Rate (Mchips/s) ^{1.2288 3.6864 3.84}

Max. data rate (Mbps) ^{0.144 2.4 4.8 5-8} 2.4 (8-10 with HSDPA)

Modulaton QPSK (Down link), BPSK (Up link)

Coding Convolutional (low rate), Turbo coding (high rate)

Chapter 1

Summary of current wireless systems (cont’)

WLAN standards 802.11 802.11a 802.11b 802.11g

Bandwidth (MHz) ^83.5

Frequency ^{2.4 GHz 5.2GHz 2.4GHz 2.4GHz}

Number of Channels ^{3 12 3 3}

Modulation ^{BPSK, QPSK}

DSSS, FHSS

BPSK, QPSK MQAM, OFDM

BPSK, QPSK DSSS

BPSK, QPSK MQAM, OFDM

Coding Convolutional Convolutional

Max. data rate (Mbps)

1.2 54 11 54

Range ^{27-30 75-100 30}

Recall from Chapter 1

Summary of current wireless systems (cont’)

WPAN standards ZigBee (802.15.4)

Bluetooth (802.15.1)

UWB

(802.15.3) Frequency Range (GHz) 2.4 -2.4835 2.4 -2.4835 3.1-10.6

Max. Data Rate (Mbps) ^{0.25 1 100}

Range (m) ^{30 10 10}

Modulation BPSK, OQPSK

DSSS

GFSK FHSS

BPSK, QPSK OFDM or DSSS

Power Consumption (mW) ^{5-20 40-100 80-150}

Access ^CSMA/CS Time Division Undefined

Networking Mesh/Star/Tree Subnet Clusters Undefined

Recall from Chapter 1

Summary

• The Institute of Electrical and Electronics Engineers (IEEE) is the most important technical society which publishes many journals and magazines and it also has developed a few technical standards.

• The cellular mobile networks are developing constantly.

• Wifi is also developing and capable of offering higher data speed to a larger number of users.

• Bluetooth has completed its mission: it ensures small range, small size, integrated and cheap wireless networks

• ZigBee is a protocol stack built on IEEE 802.15.4 physical and MAC layer.

• Next lecture: Communication protocols for wireless sensor

networks