83180 Wireless LANs 9'3' 2005 LRWPAN LowRate Wireless Personal Area Networks

1
83180 Wireless LANs - 9.3. 2005LR-WPANLow-Rate
Wireless Personal Area Networks

• Toni Huovinen
• Coexistence Among Wireless Standards
• Lauri Anttila
• IEEE 802.15.4 Low-Rate WPAN - Overview
• Jarno Niemelä
• IEEE 802.15.4 MAC for LR-WPAN applications
• Tero Isotalo
• Low-Rate WPAN Examples, Trends and Products

2
Coexistence Among Wireless Standards

• Toni Huovinen
• Lauri Anttila
• Jarno Niemelä
• Tero Isotalo
• 9.3.2005

3
Introduction

• Both WLAN and WPAN operate in the same ISM band
• mutual interference between the systems
• severe performance degradations are possible
• Many factors effect the level of interference
• the distance between the WLAN and WPAN devices
• the amount of data traffic flowing over each of
  the two networks
• the power levels of the various devices
• the data rate of the WLAN
• types of information being sent over the wireless
  networks
• Performance degradations might discourage
  consumers to use more wireless devices

4
Introduction (contd)

• If nothing is done
• devices that transmit with relatively higher
  power or more interference resistant protocols
  get their data through
• where as the other devices suffers
• Coexistence is defined as ability of one system
  to operate in shared environment.
• Good coexistence policy is such that it do not
  increase an interference to other systems using
  the same wireless channel.

5
IEEE 802.15.2

• IEEE 802.15 working group released a recommended
  practice IEEE 802.15.2 Coexistence of Wireless
  Personal Area Networks with Other Wireless
  Devices Operating in Unlicensed Frequency Band
  in 2003.
• IEEE 802.15.2 defines coexistence methods for an
  IEEE 802.15 WPAN to operate in the presence of
  frequency static or slow-hopping WLAN devices
• Basically the scope of IEEE 802.15.2 is limited
  to coexistence of Bluetooth/IEEE 802.15.1 devices
  and IEEE 802.11b devices.
• It was expected that devices using these
  standards will have the largest market share
  among devices using 2.4 GHz ISM band
• Some of the proposed coexistence methods can be
  used also with other WPAN and WLAN standards.

6
IEEE 802.15.2 (contd)

• There are two categories of coexistence methods
• Collaborative methods
• Exchange information between WPAN and WLAN
  network.
• A wired communication link between system is
  needed.
• Applicable only if WPAN master and WLAN station
  are located in the same physical equipment (like
  laptop).
• Three different methods are defined.
• Non-collaborative methods
• Do not exchange information between two wireless
  networks.
• WPAN and WLAN devices do not have to be in the
  same equipment.
• Five different methods defined.
• It is possible to use several coexistence methods
  at the same time

7
Collaborative methods
8
Alternating wireless medium access (AWMA)

• AWMA is collaborative time division method.
• Recall that IEEE 802.11b station sends a beacon
  roughly periodically.
• In AWMA, part of each beacon period is allocated
  for WLAN traffic and rest for WPAN traffic.
• Lengths of these periods are included in the
  beacon.
• Synchronization between WPAN and WLAN devices is
  needed.
• One WLAN station and WPAN master need wired
  connection.
• WLAN station sends a synchronization signal to
  WPAN master via this connection.

9
Alternating wireless medium access (Contd)

• Recall that Bluetooth/IEEE 802.15.1 use either
  ACL or SCO connection.
• AWMA is suitable only for ACL connections.
• AWMA can prevent interference between WPAN
  devices in one piconet and all WLAN (IEEE
  802.11b) devices connected to same access point
  (AP) than the one which have physically
  co-located with WPAN master.
• Interference between WLAN devices that are
  connected to some other AP is prevented only if
  the APs are synchronized.
• AWMA is quite ineffective in the sense that
  transmissions of one system are not allowed
  during the empty time windows reserved for the
  other system.

10
Packet traffic arbitration (PTA)

• This method can be used in case that coexisting
  WLAN device and WPAN device are in the same
  equipment.
• Both devices are connected to packet traffic
  arbitrator (PTA-block).
• Before a device can send a packet it must request
  a approval for transmission from PTA-block.
• If the transmission do not results in a
  collision, PTA-block grants the approval.
• If both devices send their requests (almost)
  simultaneously, the one with higher priority is
  approved to transmit and the other have to wait.

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PTA (Contd)

• Priorities can be selected deterministically
• IEEE 802.11b ACK packet (highest)
• IEEE 802.15.1 SCO packet
• IEEE 802.11b data packet
• IEEE 802.15.1 ACL packet (lowest)
• or in random manner or using some other fairness
  criteria.
• This method can be used also with SCO links.
• And it is also more efficient than previous
  method. (No need to wait own time window unless
  collisions are occurring.)

12
Deterministic interference suppression

• Recall, that Frequency hopping bandwidth of
  Bluetooth/IEEE 802.15.1 is roughly 1 MHz.
• Thus, it can be considered as a narrowband
  interference to IEEE 802.11b (or other frequency
  static or slow-hopping) WLAN devices.
• WLAN receiver can mitigate this narrowband
  interferer by programmable notch filter whose
  stop band of 1 MHz is hopping according to
  hopping process of WPAN device.
• WLAN device must have an integrated WPAN unit
  which provides frequency hopping information of
  interfering WPAN transmission.
• This method works purely on physical layer and
  mitigates only interference caused by WPAN
  devices to WLAN devices.

13
Non-collaborative methods
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Adaptive Interference Suppression

• This co-existence method is similar to
  Deterministic Interference Suppression
• However, now WLAN device do not need explicit
  knowledge of FH pattern nor timing of frequency
  hopping WPAN interferer
• WLAN transmitter uses adaptive signal processing
  methods to estimate the location of narrowband
  interference caused by WPAN and then filter out
  those frequencies.
• Also this method works purely on physical layer
  and mitigates only interference caused by WPAN
  devices to WLAN devices.

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Adaptive Interference Suppression (Contd)
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Adaptive packet selection

• Recall that Bluetooth/IEEE 802.15.1 defines
  various packet types for both ACL and SCL
  connections
• Packet types differ especially in the FEC code
  used and the amount of channel occupied
• The basic idea in Adaptive Packet Selection is
  to dynamically select packet types, given either
  an ACL or SCO link, such that maximal total
  network capacity is achieved.
• E.g. if WPAN connection is range limited (rather
  than interference limited), packet types with
  stronger FEC coding provide better throughput.
• SCO packet types are preferred in order HV1, HV2
  and HV3
• ACL packet types DM1, DM2, DM5 are preferred over
  DH1, DH2 and DH5

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Adaptive packet selection (Contd)

• In turn, if WPAN connection is interference
  limited, FEC coding does not help that much WPAN
  throughput, but cause more interference to WLAN.
• SCO packet types are preferred in order HV3, HV2
  and HV1.
• ACL packet types DH1, DH2, DH5 are preferred over
  DM1, DM2 and DM5.
• WPAN device can determine the limiting factor by
  monitoring RSSI (received signal strength
  indication) and BER (bit error rate)
• Low RSSI value (and BER) indicates range (noise)
  limited channel
• High RSSI value together with high BER indicates
  interference limited channel

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Packet scheduling for ACL links

• This method consists of two parts channel
  classification and master delay policy
• First, each Bluetooth/IEEE 802.15.1 device
  (adaptively) classify each of its FH channels to
  be good or bad (more on channel
  classification later on).
• Master device collects a table of channel
  conditions of all devices in piconet.
• Recall, that in ACL links all slave transmissions
  are always followed right after master
  transmission.
• Consequently, the master can check both the
  slave's receiving channel and its own receiving
  channel before choosing to transmit a packet in a
  given frequency hop.
• If one (or both) of the channels are marked as
  bad, master delays its own transmission until
  both channels are good.

19
Packet scheduling for SCO links

• A new SCO packet type, EV3, is proposed
• This packet is based on HV3 packet
• no FEC coding
• 240 bits payload
• one packet for every 6 slots.
• New features of EV3
• Slave transmissions are allowed only right after
  master transmission.
• Master can selected which two consecutive time
  slots of six (three options) are used.

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Packet scheduling for SCO links (Contd)

• Selection of time slots are again made according
  to channel classification tables such that both
  receiving channels (slaves and masters) are
  good if possible.

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Adaptive frequency hopping (AFH)

• This method is defined in IEEE 802.15.1
• This method dynamically changes the FH sequence
  of the Bluetooth/802.15.1 system in order to
  avoid the interference.
• Global channel classification is needed.
• Original FH pattern is mapped to subset of
  channels classified to be good.
• The mapping is such that also a new FH pattern
  becomes pseudorandom.

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AFH (Contd)

• To work properly, the method requires that there
  is enough good channels.
• In some countries (like USA), regulatory bodies
  have set a minimum number of FH channels.
• Small number of FH channels also affect on
  systems robustness.
• If number of good channels is too small, some
  bad channels can be included in hopping
  pattern.
• In this case QoS can be guaranteed, if SCO
  packets are preferred over ACL packets in
  allocation of good channels.

23
Channel classification

• Most of non-collaborative coexistence methods
  needs a channel classification information.
• In channel classification each Bluetooth/IEEE
  802.15.1 device classifies each FH channels to be
  either good or bad.
• The major concern of the quality should be
  interference caused by some other system.
• IEEE 802.15.2 do not define exactly how this
  classification should be implemented, but it
  suggests that classification can be based e.g. on
  RSSI, PER or carrier sensing.

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Channel classification (Contd)

• Since master device needs channel condition
  tables of its slaves, the tables can be exchanged
  using LMP messages.
• It is also possible to use implicit
  classification methods such as negative ACKs, in
  which cases the slave does not have to send any
  additional information to the master.
• Overall classification time can be reduced by
  grouping channels to blocks, which naturally
  reduce the accuracy.

25
Channel classification (Contd)

• In Adaptive Frequency Hopping method, global
  state of each FH channel is needed.
• The master obtains it by taking a weighted
  average of its own channel state and all the
  active slaves channel states.
• Finally, a global channel state for one
  sub-channel is obtained by threshold comparison
  of the average, which have value in 0,1.

26
Current Status of Coexistence Method Development

• Citation from IEEE 802.15.2 task groups web
  page
• The task group is now in hibernation until
  further notice.
• Several vendors are developing hardware and
  software coexistence solutions, which are based
  on IEEE 802.15.2 standard.
• New WPAN standards (like 802.15.3 and .4) deal
  also with coexistence issues particular to those
  systems

27
References

• IEEE 802.15.2-2003, IEEE Recommended Practice
  for Telecommunications and Information exchange
  between systems Local and metropolitan area
  networks Specific Requirements - Part 15.2
  Coexistence of Wireless Personal Area Networks
  with Other Wireless Devices Operating in
  Unlicensed Frequency Band, IEEE, 2003.
• T. Cooklev, Wireless Communication Standards, A
  Study of 802.11, 802.15, and 802.16,  IEEE
  Press, 2004.
• IEEE 802.15 Working Group for WPAN,
  http//ieee802.org/15/index.html

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IEEE 802.15.4 Low-Rate WPAN- Overview

• Toni Huovinen
• Lauri Anttila
• Jarno Niemelä
• Tero Isotalo

29
Outline

• Introduction
• Standardization
• Device Types and Functions
• Network Topologies
• Protocol Architecture
• Physical Layer
• Power Consumption Issues
• References

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802.15.4 Introduction

• WPAN Wireless Personal Area Network
• Motivation for 802.15.4
• A standard for WPANs with
• Short-range RF connectivity (typ. lt 10 m)
• Reliable transfer w/ low data rate (20-250 kb/s)
• Low power consumption (battery life gtgt 1 month)
• Very low cost
• Low complexity
• Applications sensors, meter reading, smart tags
  /badges, light switches, home automation,
  interactive toys etc.

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Introduction (contd)

• More 802.15.4 in a nutshell
• 802.15.4 defines Physical and MAC layers
• Uses the ISM bands 2.4 GHz, 915 MHz, and 868 MHz
  with data rates 250, 40, and 20 kb/s,
  respectively.
• Direct Sequence Spread Spectrum (DSSS)
• Access method is Carrier Sense Multiple Access
  with Collision Avoidance (CSMA-CA)
• Automatic network establishment by the network
  coordinator
• Supports star and peer-to-peer network topologies
• Network can accommodate up to 216 devices (cmpr
  to Bluetooth)
• 2 addressing modes 64-bit IEEE address or 16-bit
  short address
• Support for critical latency devices, such as
  joysticks
• Aims at a certain level of coexistence w/ other
  standards

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802.15.4 Standardization

• 802.15.4 is a recent standard, approved 12 May
  2003
• Original task group TG4 put to hibernation
• Currently two new task groups
• TG4a is developing an alternative PHY (Q2 2006 ?)
• High precision ranging/location capability (lt 1
  meter)
• Adding scalability to data rates
• Longer range (indoors 20-40 m, outdoors up to 1
  km)
• Even lower power consumption and cost
• TG4b is considering specific enhancements and
  clarifications to the original 802.15.4-2003
  standard
• Protocol layers above MAC are left to the
  manufacturers (the ZigBee Alliance)

33
802.15.4 Device Types and Functions

• Device can act in 3 modes a network coordinator,
  a coordinator or a network device
• A network device can initiate or terminate
  communications, a coordinator can also route
  messages
• Standard defines two device types
• Full-function device (FFD)
• Can be all of the above
• Reduced-function device (RFD)
• Can only be a network device
• No routing ability, and no communication between
  RFDs
• Extremely simple applications (light switch,
  passive sensor)
• Do not have to send large amounts of data
• Can be implemented with minimal resources
  memory
• Devices are battery (usually) or mains powered
• Devices can be fixed, portable and/or moving

34
802.15.4 Network Topologies
35
Network Topologies (contd)

• Two basic network topologies
• 1) Star topology
• One-hop communications, only between PAN
  coordinator and the network devices
• Typical applications are home automation, toys,
  games, PC peripherals
• 2) Peer-to-peer topology
• Any device can communicate with any other device
  as long as they are in range of one another
• Can be ad-hoc, self-organizing, and self-healing
• Enables more complex network topologies to be
  implemented, e.g. cluster-tree networks
• Multi-hop network formation is defined in the
  network layer, not part of 802.15.4
• Industrial control and monitoring, sensor
  networks, security

36
802.15.4 Protocol Architecture

• Standard defines PHY and MAC
• PHY includes the RF transceiver and its low-level
  control functions
• MAC provides access to the physical channel
• IEEE 802.2 Type 1 logical link control (LLC) can
  access the MAC sublayer through the service
  specific convergence sublayer (SSCS)
• The ZigBee Alliance is working on the upper
  layers (www.zigbee.org)

37
802.15.4 Physical Layer (PHY)

• PHY responsible for the following tasks
• Activation/Deactivation of the radio transceiver
• Energy Detection (ED) within the current channel
• Link Quality Indication (LQI) for received
  packets
• Clear Channel Assessment (CCA) for CSMA-CA
• Channel frequency adjustment
• Data transmission and reception
• PHY provides 2 services
• PHY data service
• PHY management service

38
PHY Frequency Bands and Data Rates
Table 1. Frequency bands and data rates
39
PHY Frequency Bands and Data Rates
40
PHY 2.4 GHz Mode

• Each symbol (i.e. 4 bits) is represented by one
  of 16 32-chip sequences
• First 8 sequences are cyclic shifts of one
  32-chip sequence, last 8 are cyclic shifts of
  another sequence (see next slide)

41
PHY 2.4 GHz Mode


42
PHY 2.4 GHz Mode

• Chip modulation is offset-QPSK, in which the
  Q-branch signal is delayed by one chip period
  (Tc) with respect to the I-branch signal
• Pulse shape is half-sine with period 2Tc
• The result is a constant-envelope signal!
  (actually, it is equivalent to MSK)
• Good in terms of Power Amplifier (PA) efficiency,
  and thus important for low power consumption

43
PHY 2.4 GHz Mode
Offset-QPSK with half-sine pulse shaping
44
PHY 868/915 MHz Mode

• Raw bits are differentially encoded
• XOR between current bit and the previous encoded
  bit
• Each coded bit mapped to a 15-chip PN sequence
• Zero to 1 1 1 1 0 1 0 1 1 0 0 1 0 0 0
• One to 0 0 0 0 1 0 1 0 0 1 1 0 1 1 1 (zeros
  complement)
• BPSK modulation with raised cosine pulse shaping
  with roll-off 1.0 (100 excess bandwidth)

45
PHY Power levels, PSD masks, sensitivity
Transmit PSD masks 2.4 GHz

• Tramsmit power is greater than -3 dBm
• Maximum defined by local authorities (Europe 100
  mW, U.S. 1 W !)
• Maximum received power -20 dBm
• Sensitivity -85 dBm (2.4 GHz) or -92 dBm
  (868/915 MHz)

868 / 915 MHz
46
PHY Packet Structure

• PHY Packet Fields (both PHYs)
• Preamble (32 bits) Symbol synchronization
• Start of Packet Delimiter (8 bits) Frame
  synchronization
• PHY Header (8 bits) Specifies PSDU length
• PSDU (up to 127 bytes) Data field

47
Power Consumption Issues

• 802.15.4 standard developed for low power
  consumption
• Low complexity protocols and physical
  implementation
• Additional power management techniques can be
  used in the physical implementation
• Area of manufacturer differentiation
• Battery-powered devices will use duty-cycling
• Most of the time in sleep-mode (up to 99 )
• However, they must listen to network beacons, and
  stay synchronized to the network
• ? balance between power consumption and message
  latency

48
References

• T. Cooklev, Wireless Communications Standards, A
  Study of 802.11, 802.15, and 802.16, IEEE Press,
  2004.
• http//standards.ieee.org/getieee802
• J. Zheng, M.J. Lee, Will IEEE 802.15.4 Make
  Ubiguitos Networking a Reality? A Discussion on
  a Potential Low Power, Low Bit Rate Standard,
  IEEE Comm. Magazine, June 2004.

49
IEEE 802.15.4 MAC for LR-WPAN applications

• Toni Huovinen
• Lauri Anttila
• Jarno Niemelä
• Tero Isotalo

50
Outline

• Overview of MAC for IEEE 802.15.4
• Functionalities
• Frame types and structures
• Data transfer
• Security

51
IEEE 802.15.4 MAC objectives

• Extremely low cost
• Easy implementation
• Reliable data transfer
• Short range operation
• Very low power consumption
• Certain level of security

52
Device classes

• Full Function Device (FFD)
• Functions in any topology
• Able to talk to RFDs or other FFDs
• Operate in three modes (PAN coordinator,
  coordinator, and device)
• Reduced Function Device (RFD)
• Limited to star topology
• Can only talk to an FFD (coordinator)
• Cannot become a coordinator
• Unnecessary to send large amounts of data
• Extremely simple
• Can be implemented using minimal resources and
  memory capacity

53
An example network
54
MAC functionalities

• Beacon management
• Channel access mechanism
• Dynamic channel selection (GTS management)
• Frame reception and acknowledgments
• (Dis)association
• Security

Data link
PHY
55
Beacon management

• Beacon enabled mode
• Slotted CSMA/CA
• Beacon disabled mode
• CSMA/CA (similar to one in IEEE 802.11)
• Generation of beacons if a device is a
  coordinator
• Either broadcasting or unicasting of beacons
• Synchronization performed using beacons

56
Association and disassociation

• Support for WPAN self-configuration (ubiquotous
  networks)
• Enables a star to be setup automatically
• Allows also the creation of self-configuring,
  peer-to-peer (p2p) network
• Orphaning offers a way to detect link and/or node
  failures
• A realignment procedure can take place

57
MAC frame formats
MAX. 127 bytes
2
2
1
0-20
Variable
DATA FRAME
Frame control
Sequence number
Address info
Frame check sequence
Payload
ACKNOWLEGDMENT FRAME
MAC sub layer
Frame control
Sequence number
Frame check sequence
MAC COMMAND FRAME
Frame control
Sequence number
Address info
Command payload
Frame check sequence
BEACON FRAME
Frame control
Sequence number
Address info
Beacon payload
Frame check sequence
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A superframe structure
GTS 2
GTS 1
Contention Access Period (CAP)
Total 16 slots
Contention Free Period (CFP)
15ms 2n where 0 ? n ? 14
Transmitted by network coordinator. Contains
network information, frame structure and
notification of pending device messages.
Network beacon
Contention period
Access by any device using slotted CSMA-CA
Guaranteed Time Slot
Reserved for devices requiring guaranteed
bandwidth n 0.
up to 7 GTSs
59
A superframe with an inactive part
60
Network forming

• WPAN has to be initiated by a FFD
• Active or passive scan
• Selection of suitable PAN identifier
• An FDD becomes a coordinator

61
Data transfer/transactions

• (1) From a device to a coordinator
• (2) From a coordinator to a device
• (3) From one peer to another in a peer-to-peer
  multihop network
• OR
• (1) Direct data transmission
• (2) Indirect data transmission
• (3) GTS (guarantee time slot) data transmission

62
Communication from device to coordinator
BEACON ENABLED MODE
BEACON DISABLED MODE
Slotted CSMA/CA
unslotted CSMA/CA
63
Communication from coordinator to device
BEACON ENABLED MODE
BEACON DISABLED MODE
unslotted CSMA-CA
slotted CSMA-CA
Indirect transmission
Indirect transmission
64
Traffic types/examples

• Periodic data
• Application defined data rate (e.g., sensors)
• Intermittent data (generated )
• Application / external stimulus defined data rate
  (e.g., ligth switch)
• Repetitive low latency data
• GTS
• Allocation of time slots (e.g., mouse)

65
MAC QoS

• QoS can be provided by upper layers
• Different traffic types
• Priority in queuing during CAP (high or normal
  priority)
• In beacon enabled networks, contention free
  period provides QoS

66
802.15.4 security overview

• Access control
• Prevents unauthorized access
• Message integrity
• Authentication and integrity provided using
  message integrity code (MIC)
• Message confidentiality
• Encryption applied
• Replay protection
• Packet numbering
• IEEE 802.15.4 security is provided by MAC

67
MAC security modes

• Unsecured mode
• Mandatory for all devices
• However, does not provide any security
• ACL (access control list) mode
• Optional
• No cryptographical methods applied
• Secured mode
• Optional
• Advanced Encryption Standard (AES)

68
Security suites

• Set of operations for ensuring security
• Indicates
• the symmetric cryptographic algorithm
• mode
• integrity code bit length
• Integrity done using AES

69
Security suites (contd)

• AES-CTR
• Access control
• Encryption
• Sequential freshness
• AES-CBC-MAC (cipher block chaining, CBC)
• Access control
• Authentication
• AES-CCM
• Mixture of CTR and CBC-MAC modes (CCM)
• Provides all four security services

70
References

• IEEE 802.15.4 Specifications Wireless Medium
  Access Control (MAC) and Physical Layer (PHY)
  Specifications for Low-Rate Wireless Personal
  Area Networks (LR-WPANs), available online
  http//standards.ieee.org/getieee802/download/802.
  15.4-2003.pdf
• T. Cooklev, Wireless Communications Standards, A
  Study of 802.11, 802.15, and 802.16,  IEEE Press,
  2004.
• N. Satyr, D. Wagner, Security considerations for
  IEEE 802.15.4 networks, Wise 2004, USA.
• S. Ergen, Zigbee/IEEE 802.15.4 Summary,
  available online http//www.eecs.berkeley.edu/cs
  inem/academic/publications/zigbee.pdf
• J. Zheng, M. Lee, Will IEEE 802.15.4 make
  ubiquitous networking a reality? A discussion on
  a potential low power, low bit rate standard,
  IEEE Communications Magazine, vol. 42, no. 6, Jun
  2004 pp. 140-146

71
Low-Rate WPANExamples, Trends and Products

• Toni Huovinen
• Lauri Anttila
• Jarno Niemelä
• Tero Isotalo

9.3. 2005 - 83180 Wireless LANs
72
Contents

• Overview
• Zigbee
• Comparison to other 802.15 standards
• Other techniques
• RFID
• BodyLan
• FAN (Fabric area networks)

73
Overview

• Need for lower power consuming and cheaper
  equipment standard compared to 802.11 and 802.15
• WLAN/BT widely in use, but they are too
  expensive, consume too much battery and have too
  complicated protocol stack to be used in
  sensor-networks and in different wireless
  controlling
• Ready products using 802.15.4 not yet in the
  market
• However, 802.15.4/Zigbee compatible chipsets and
  plug-in units are already available
• Planned areas wireless automated monitoring and
  control of facilities, home-appliance networks,
  home healthcare, etc.
• Zigbee using 802.11.4, similar systems Bodylan,
  Wireless USB, ...

74
Zigbee

• Bases on 802.11.4 MAC/PHY, sometimes used also as
  a nickname for 802.11.4
• Ultra-low complexity, ultra-low cost, ultra-low
  power consumption, and low data rate (20-250
  kb/s) wireless connectivity among inexpensive
  devices
• 64k (216) network nodes

75
Zigbee Alliance

• Non-profit industry consortium defining a global
  specification for reliable, cost-effective, low
  power wireless applications based on the IEEE
  802.15.4 standard.
• Six promoters (Honeywell, Invensys, Mitsubishi,
  Motorola, Philips, and Samsung) and more than 100
  participants
• Performs marketing and compliance certification
  for 15.4
• Not officially associated with the IEEE
• Wireless Control that Simply Works
• www.zigbee.org

76
Uses of Zigbee
77
Zigbee / IEEE 802.15.4Protocol Stack

• Divided Responsibility
• Lower (MAC/PHY) stacks IEEE 802.15.4
• Upper stacks Zigbee Alliance
• IEEE 802 compatible LLC protocol can be used

Application Layer
Zigbee Alliance
IEEE 802.15.4
78
Zigbee Protocol Stack

• There are ready programmed protocol stacks
  available in the market
• Some chip manufactors have specific stacks for
  their own chips, and some companies, i.e., Ember,
  Figure8, Helicomm, provide common stacks

79
Zigbee Network Model (1)

• Star, mesh, or combined Star/Mesh type network

80
Zigbee Network Model (2)

• Flexible topology of Zigbee network consists of
  reduced function nodes, and full function nodes
• Reduced function nodes can not communicate with
  each others
• Communication goes through full function nodes,
  and requires also network coordinator
• Full function nodes can work as a coordinator
• gt Star topology

81
Zigbee Network Model (3)

• Network can consist also only of full function
  nodes
• In such case, all equipment are equal and can
  communicate with each others
• gt Mesh topology
• Wider networks form from combined star and mesh
  topology networks

82
Zigbee Network Model (4)

• 16/64 bit addressing
• Large amount of network nodes, even up to 64k
  (16-bit) nodes (cf. 7 nodes in bluetooth)
• Can be used in wide automation networks that do
  not require large bandwidth

83
Zigbee Module
Micro-controller
RF Rx/Tx Chip
Analog / Digital I/O
User Application
Antenna Connector / PCB antenna
Zigbee-protocols
802.15.4 MAC
802.15.4 PHY
DC Mains Voltage
84
Business Trends

• Multiple of manufactors are developing Zigbee
  chips
• Compelete chips (PHYMAC) Motorola/Freescale,
  Chipcon, Atmel, Panasonic,...
• RF chips (PHY) ZMD, CompXS, ...
• Chips already available on the market
• Chip sizes beginning from 20x15x1.8 mm
• First applications expected soon

85
Commercial ExampleiBean Product Family (1)
86
Commercial ExampleiBean Product Family (2)

• 802.15.4 and
• Zigbee compatible
• Also non-compatible products using other
  frequency bands
• More information
• www.millennial.net

87
Competitors for ZigBee

• In addition to other 802. techniques, there is
  some technique very similar to Zigbee competing
  from same applications
• Typically working at 2.4G ISM frequency
• i.e. Cypress, and finnish Espotel ERF

88
Comparison to other standards (1)
89
Comparison to other standard (2)
90
Comparison to other standards (2)
Cost Comparison
Data Rate Comparison
91
Competitors for ZigBee Cypress

• Called WirelessUSB (different from Wireless USB)
• low memory consumption protocol stack (4kB vs
  32kB in Zigbee)
• Star-topology network
• 50m range, low power consumption
• automatic interference regognition
• Used for PC mice/keyboards, but looking for new
  areas

92
Competitors for ZigBeeEspotel ERF

• Designed to replace Bluetooth in industry
  automation sensors and embedded systems
• Lighter protocol stack compared to bluetooth
• Can use Zigbee chips, but does not fit into the
  standard
• Energy consumption at the same level with Zigbee
• Lower total cost due to missing standardization
  reguirements
• Missing standard makes it easier to fit customers
  need, but lack of compatibility may cause problems

93
On-Body-Networking

• Provide connectivity between different sensors
  and other equipments in wearable electronics
• Sports, Medicine, Police, Fireman, Astronauts ...
• BodyLan, FAN (Fabric Area Network)

94
BodyLan Consept
95
Comparison of Different BodyLan Techniques
96
Future..?

• Although present and close future world looks
  like totally networked, more is coming
• Independent sensors of size of 1c coin are
  already reality, but consept called smart dust
  is under development.
• Target is to have sensors size of a dust
  particle, and they would be everywhere around,
  and they would work with e.g. solar power
• Ability to form networs automatically
• Such projects are going on in many universities,
  also in TUT/TKT

97
References

• 1 Roy L. Ashok Dharma P.Agrawal,
  Next-Generation Wearable Networks, Computing
  Practices, IEEE Computer Society, 2003
• 2 Philip Kuryloski and Sameer Pai, Our
  Crossbow Sensor Equipment and Zigbee,
  wisl.ece.cornell.edu/presentations/MICAz.pdf,
• 3 Zigbee Alliance, Wireless Control That
  Simply Works www.zigbee.org
• 4 Krister Wikström, Zigbee tuotteistuu,
  Prosessori 1/2005
• 5 Shigeru Fukunaga, Tadamichi Tagawa, Kiyoshi
  Fukui, Koichi Tanimoto, Hideaki Kanno,
  Development of Ubiquitous Sensor Network, Oki
  Technical Review, October 2004/Issue 200 Vol.71
  No.4

98
Q What is the origin of theZigBee name?

• The domestic honeybee, a colonial insect, lives
  in a hive that contains a queen, a few male
  drones, and thousands of worker bees. The
  survival, success, and future of the colony is
  dependent upon continuous communication of vital
  information between every member of the colony.
  The technique that honey bees use to communicate
  new-found food sources to other members of the
  colony is referred to as the ZigBee Principle.
  Using this silent, but powerful communication
  system, whereby the bee dances in a zig-zag
  pattern, she is able to share information such as
  the location, distance, and direction of a newly
  discovered food source to her fellow colony
  members. Instinctively implementing the ZigBee
  Principle, bees around the world industriously
  sustain productive hives and foster future
  generations of colony members. 3