Docstoc

ZigBee Overview - Electrical _ Computer.ppt

Document Sample
ZigBee Overview - Electrical _ Computer.ppt Powered By Docstoc
					          ZigBee Overview

Modified from
-Adams 2003:
   -http://www.zigbee.org/resources/documents/Adams-
   Heile_SensorsExpo_AnaheimSept03_V1_000.ppt
-Adams 2004:
   -http://www.zigbee.org/resources/documents/IWAS_presenta
   tion_Mar04_Designing_with_802154_and_zigbee.ppt
-Karayanis (2003)
   -“Emerging Wireless Standards, Understanding the Role of
   IEEE 802.15.4 & ZigBee™ in AMR & Submetering,” AMRA
   2003 International Symposium.




                      Copyright 2002 The ZigBee Alliance, Inc.
        Low Data Rate Wireless Evolution

    First Stage                      Second Stage                        Third Stage
  ……… 2002             2003          2004      2005      2006         2007     2008      2009+

 Proprietary Dominates              Proprietary Fades                  Standards Dominate

 IEEE 802.15.4 Emerges              ZigBee Emerges                     IEEE 1451.5 Emerges

 System Integrator Focus            Semiconductor Focus                OEM Focus

 Leading Edge OEMs                  Early Adopter OEMs                 Wireless Ubiquitous

 $.1 - $1B Industry                 $1 - $10B Industry                 $10 - $100B+ Industry

 $1,000 - $100 Unit Cost            $100 - $10 Unit Cost               $10 - $1 Unit Cost


                              Mapping Your Future: From Data to Value
                                  AMRA 2003 International Symposium
   Wireless Networking Standards
Market Name GPRS/GSM            Wi-Fi™      Bluetooth™       ZigBee™
Standard    1xRTT/CDM          802.11b       802.15.1        802.15.4
                A
               Wide Area     Web,            Cable
Application                                                  Monitoring
               Voice &       Email,          Replaceme
Focus                                                        & Control
               Data          Video           nt
System                                                       4KB -
               16MB+          1MB+            250KB+
Resources                                                    32KB
Battery Life                                                 100 -
               1-7            .5 - 5          1-7
(days)                                                       1,000+
                                                             255 /
Network Size   1              32              7
                                                             65,000
Bandwidth
               64 - 128+      11,000+         720            20 - 250
(KB/s)
Transmission
Range          1,000+         1 - 100         1 - 10+        1 - 100+
(meters)
                 Mapping Your Future: From Data to Value
                                                Cost,        Reliability,
Success                     Speed,
               Reach,AMRA 2003 International Symposium
                                                Convenienc   Power,
Metrics        Quality      Flexibility
      Mission Statement


To enable reliable, cost-effective, low-
    power, wirelessly networked,
monitoring and control products based
    on an open global standard.




              Copyright 2002 The ZigBee Alliance, Inc.
  The ZigBee Alliance Solution
• Targeted at home and building automation and
  controls, consumer electronics, PC peripherals,
  medical monitoring, and toys
• Industry standard through application profiles
  running over IEEE 802.15.4 radios
• Primary drivers are simplicity, long battery life,
  networking capabilities, reliability, and cost
• Alliance provides interoperability and
  certification testing

                    Copyright 2002 The ZigBee Alliance, Inc.
IEEE 802.15.4 & ZigBee In Context
   Application                     Customer

         API                                          – “the software”
       Security                                       – Network, Security &
32- / 64- / 128-bit encryption     ZigBee
                                   Alliance             Application layers
      Network
                                                      – Brand management
Star / Mesh / Cluster-Tree

         MAC                                         IEEE 802.15.4
                                    IEEE
                                                      – “the hardware”
            PHY                    802.15.4
868MHz / 915MHz / 2.4GHz                              – Physical & Media Access
                                                        Control layers
  Silicon        Stack       App


                      Mapping Your Future: From Data to Value
                            AMRA 2003 International Symposium
                      History
                    Proposals Proposal ZigBee Alliance
Initial MRD RSI/TRD      v0.2 to IEEE      formed

                             ZigBee



                                                                IEEE 802.15.4

                                      PAR                            Reviews     Stand.
                                        Proposals                               Complete
1998      1999         2000                         2001               2002

                     Copyright 2002 The ZigBee Alliance, Inc.
        Working Groups
• Architecture
• Application Framework
• Network
• Security
• Interoperability
• Marketing



             Copyright 2002 The ZigBee Alliance, Inc.
                  The Wireless Market


          TEXT    GRAPHICS INTERNET    HI-FI         STREAMING            DIGITAL   MULTI-CHANNEL
                                       AUDIO           VIDEO               VIDEO        VIDEO
 LONG




                                                                                                    LAN
>




                                                               802.11b
< RANGE




                                                                      802.11a/HL2 & 802.11g


                                          Bluetooth 2
                 ZigBee                                                                             PAN
 SHORT




                                   Bluetooth1



                             LOW    < DATA RATE                  >     HIGH




                                      Copyright 2002 The ZigBee Alliance, Inc.
                             Applications
              security
               HVAC                                                                TV
                AMR                                                                VCR
      lighting control                                                             DVD/CD
        access control    BUILDING                                   CONSUMER      remote
                         AUTOMATION                                 ELECTRONICS

   patient
monitoring
                                          ZigBee                                             mouse
                                  Wireless Control that                                      keyboard
   fitness                           Simply Works                                  PC &      joystick
              PERSONAL
monitoring   HEALTH CARE                                                       PERIPHERALS


                                                                                security
                asset mgt
                                                                RESIDENTIAL/    HVAC
          process control                                          LIGHT        lighting control
           environmental    INDUSTRIAL                          COMMERCIAL
                             CONTROL                             CONTROL
                                                                                access control
              energy mgt
                                                                                lawn & garden irrigation


                                  Copyright 2002 The ZigBee Alliance, Inc.
Development of the Standard
                            • ZigBee Alliance
                               – 50+ companies: semiconductor
                                 mfrs, IP providers, OEMs, etc.
APPLICATION         Customer – Defining upper layers of

                                 protocol stack: from network to
ZIGBEE STACK                     application, including
                     ZigBee      application profiles
                     Alliance
  SILICON
               IEEE            – First profiles published mid
               802.15.4
                                 2003
                            • IEEE 802.15.4 Working Group
                               – Defining lower layers of
                                 protocol stack: MAC and PHY
                                 scheduled for release in April
                     Copyright 2002 The ZigBee Alliance, Inc.
  Frequencies and Data 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




                   Copyright 2002 The ZigBee Alliance, Inc.
              Stack Reference Model

       End developer applications,
 designed using application profiles         ZA1           ZA2             …   ZAn   IA1        IAn
Application interface designed using
                                                                   API                  UDP
                      general profile
     Topology management, MAC                                                              IP
   management, routing, discovery                         ZigBee NWK
    protocol, security management                                                     802.2 LLC
                                                                                     MAC (SSCS)
Channel access, PAN maintenance,
           reliable data transport                         IEEE 802.15.4 MAC (CPS)
  Transmission & reception on the
                                                                  IEEE 802.15.4 PHY
           physical radio channel


                                Copyright 2002 The ZigBee Alliance, Inc.
       Protocol Stack Features
• Microcontroller utilized
• Full protocol stack <32 k                           APPLICATIONS                       Customer

                                           APPLICATION INTERFACE
• Simple node-only
                                                          SECURITY
  stack ~4k                                                                                     ZigBee
                                                   NETWORK LAYER
• Coordinators                                             Star/Cluster/Mesh
                                                                                                Alliance

  require extra RAM                                      MAC LAYER
                                                                                         IEEE
                                                         MAC LAYER
   – Node device database                                PHY LAYER
                                                                                     802.15.4

                                                    2.4 GHz      915MHz   868 MHz
   – Transaction table
                                                Application               ZigBee Stack          Silicon
   – Pairing table


                      Copyright 2002 The ZigBee Alliance, Inc.
          ZigBee and Bluetooth
Optimized for different applications
• ZigBee                 • Bluetooth
   – Smaller packets over   – Larger packets over small
     large network            network
   – Mostly Static          – Ad-hoc networks
     networks with many,    – File transfer
     infrequently used      – Screen graphics, pictures,
     devices                  hands-free audio, Mobile
   – Home automation,         phones, headsets, PDAs,
     toys, remote controls,   etc.
     etc.




                      Copyright 2002 The ZigBee Alliance, Inc.
      ZigBee and Bluetooth
Address Different Needs
                              • Bluetooth is a
                                cable replacement
                                for items like
                                Phones, Laptop
                                Computers,
                                Headsets
                              • Bluetooth expects
                                regular charging
                                       – Target is to use
                                         <10% of host
                                         power
               Copyright 2002 The ZigBee Alliance, Inc.
      ZigBee and Bluetooth
Address Different Needs

        • ZigBee is better for
          devices Where the
          battery is ‘rarely’
          replaced
          – Targets are :
             • Tiny fraction of host power
             • New opportunities where
               wireless not yet used



                 Copyright 2002 The ZigBee Alliance, Inc.
       ZigBee and Bluetooth
            Air interface
ZigBee                Bluetooth
• DSSS- 11 chips/       • FHSS
  symbol                • 1 M Symbol / second
• 62.5 K symbols/s      • Peak Information Rate
• 4 Bits/ symbol          ~720 Kbit / second
• Peak Information Rate
  ~128 Kbit/second




                Copyright 2002 The ZigBee Alliance, Inc.
            ZigBee and Bluetooth
                                                                             User Interface




                                                               Group Call
                                                                Cordless
                                                                Intercom
                                                                 Headset




                                                                                   vMessage
           Application




                                                                                              Networking
                                                                 vCard

                                                                 vNote
                                                                  vCal




                                                                                                Dial-up
                                                                                                            Fax    Service
   Application Interface                                                                                          Discovery
                                                               Telephony OBEX                                     Protocol




                                                       Voice
                                                                Control
          Network Layer                                         Protocol    RFCOMM
                                                                                  (Serial Port)

                                                                                   L2CAP
      Data Link Layer                                                       Host Control Interface

           MAC Layer                                                           Link Manager
           MAC Layer                                                         Link Controller
                                                                               Baseband
           PHY Layer
                                                                                   RF
              ZigBee                                                             Bluetooth
Silicon                  Application                             Silicon                                   Applications
               Stack                                                               Stack
            Zigbee                                                            Bluetooth
                               Protocol Stack Comparison
                                 Copyright 2002 The ZigBee Alliance, Inc.
      ZigBee and Bluetooth
Timing Considerations
      ZigBee:
      • Network join time = 30ms typically
      • Sleeping slave changing to active = 15ms typically
      • Active slave channel access time = 15ms typically
      Bluetooth:
      • Network join time = >3s
      • Sleeping slave changing to active = 3s typically
      • Active slave channel access time = 2ms typically
       ZigBee protocol is optimized for
         timing critical applications

                       Copyright 2002 The ZigBee Alliance, Inc.
        ZigBee and 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

                  Comparison Overview
                   Copyright 2002 The ZigBee Alliance, Inc.
     An Application Example
Battery Life & Latency in a Light Switch
        • Wireless Light switch –
          – Easy for Builders to Install
        • A Bluetooth Implementation
          would either :
          – keep a counter running so
            that it could predict which
            hop frequency the light
            would have reached or
          – use the inquiry procedure to
            find the light each time the
            switch was operated.
                Copyright 2002 The ZigBee Alliance, Inc.
 Light switch using Bluetooth
• Option 1: use counter to predict hop
  frequency reached by light
  – The two devices must stay within 60 us (~1/10 of
    a hop)
  – With 30ppm crystals, devices need to
    communicate once a second to track each other's
    clocks.
  – Assume this could be improved by a factor of 100
    then devices would need to communicate once
    every 100 seconds to maintain synchronization.
  – => 900 communications / day with no information
    transfer + perhaps 4 communications on demand
  – 99.5% Battery Power wasted

                  Copyright 2002 The ZigBee Alliance, Inc.
 Light switch using Bluetooth
• Option 2: Inquiry procedure to locate
  light each time switch is operated
   – Bluetooth 1.1 = up to 10 seconds typical
   – Bluetooth 1.2 = several seconds even if
     optimized




  – Unacceptable latency


                  Copyright 2002 The ZigBee Alliance, Inc.
  Light switch using ZigBee
• With DSSS interface, only need to
  perform CSMA before transmitting
  – Only 200 µs of latency
  – Highly efficient use of battery power

    ZigBee offers longer battery
    life and lower latency than a
         Bluetooth equivalent.



               Copyright 2002 The ZigBee Alliance, Inc.
      ZigBee and Bluetooth
              Conclusion
• ZigBee targets applications not
  addressable by Bluetooth or any other
  wireless standard

• ZigBee and Bluetooth complement for a
  broader solution




               Copyright 2002 The ZigBee Alliance, Inc.
                   Agenda
• What are IEEE 802.15.4 and ZigBee?
  – IEEE802.15.4 – Packet Radio made simple
  – ZigBee and the ZigBee Alliance
• Sensors and ZigBee, a natural pairing
  – What’s Important
     • Reliability and Robustness
     • Cost, Size and Extreme Battery Life
  – How it compares to other protocols
• Available Silicon and Platforms
  – Motorola’s 802.15.4/ZigBee Platform Combo
• Summary / Q&A

                   Copyright 2002 The ZigBee Alliance, Inc.
IEEE 802.15.4 Standard




       Copyright 2002 The ZigBee Alliance, Inc.
         IEEE 802.15.4 Basics
• 802.15.4 is a simple packet data protocol for lightweight
  wireless networks
   – Channel Access is via Carrier Sense Multiple Access with collision
     avoidance and optional time slotting
   – Message acknowledgement and an optional beacon structure
   – Multi-level security
   – Three bands, 27 channels specified
       • 2.4 GHz: 16 channels, 250 kbps
       • 868.3 MHz : 1 channel, 20 kbps
       • 902-928 MHz: 10 channels, 40 kbps
   – Works well for
       • Long battery life, selectable latency for controllers, sensors, remote
         monitoring and portable electronics
   – Configured for maximum battery life, has the potential to last as
     long as the shelf life of most batteries




                            Copyright 2002 The ZigBee Alliance, Inc.
     IEEE 802.15.4 standard
• Includes layers up to and including Link Layer Control
   – LLC is standardized in 802.1
• Supports multiple network topologies including Star,
  Cluster Tree and Mesh
• Features of the MAC:
  Association/dissociation, ACK,                                   ZigBee Application Framework
  frame delivery, channel access                                  Networking App Layer (NWK)
  mechanism, frame validation,
  guaranteed time slot management,                                 Data Link Controller (DLC)

  beacon management, channel scan                                 IEEE 802.15.4 LLC       IEEE 802.2
                                                                                         LLC, Type I
   • Low complexity: 26 primitives                                      IEEE 802.15.4 MAC
     versus 131 primitives for                                      IEEE 802.15.4      IEEE 802.15.4
     802.15.1 (Bluetooth)                                         868/915 MHz PHY     2400 MHz PHY




                       Copyright 2002 The ZigBee Alliance, Inc.
IEEE 802.15.4 MAC Overview
•   Employs 64-bit IEEE & 16-bit short addresses
     – Ultimate network size can reach 264 nodes (more than we’ll probably
       need…)
     – Using local addressing, simple networks of more than 65,000 (2^16) nodes
       can be configured, with reduced address overhead
•   Three devices specified
     – Network Coordinator
     – Full Function Device (FFD)
     – Reduced Function Device (RFD)
•   Simple frame structure
•   Reliable delivery of data
•   Association/disassociation
•   AES-128 security
•   CSMA-CA channel access
•   Optional superframe structure with beacons
•   GTS mechanism



                              Copyright 2002 The ZigBee Alliance, Inc.
 IEEE 802.15.4 Device Types
• Three device types
   – Network Coordinator
       • Maintains overall network knowledge; most sophisticated of the three
         types; most memory and computing power
   – Full Function Device
       • Carries full 802.15.4 functionality and all features specified by the
         standard
       • Additional memory, computing power make it ideal for a network
         router function
       • Could also be used in network edge devices (where the network
         touches the real world)
   – Reduced Function Device
       • Carriers limited (as specified by the standard) functionality to control
         cost and complexity
       • General usage will be in network edge devices
• All of these devices can be no more complicated than the
  transceiver, a simple 8-bit MCU and a pair of AAA batteries!




                             Copyright 2002 The ZigBee Alliance, Inc.
              Data Frame format




•   One of two most basic and important structures in 15.4
•   Provides up to 104 byte data payload capacity
•   Data sequence numbering to ensure that all packets are tracked
•   Robust frame structure improves reception in difficult conditions
•   Frame Check Sequence (FCS) ensures that packets received are
    without error


                            Copyright 2002 The ZigBee Alliance, Inc.
    Acknowledgement Frame
            Format




• The other most important structure for 15.4
• Provides active feedback from receiver to sender that
  packet was received without error
• Short packet that takes advantage of standards-
  specified “quiet time” immediately after data packet
  transmission

                     Copyright 2002 The ZigBee Alliance, Inc.
MAC Command Frame format




• Mechanism for remote control/configuration of
  client nodes
• Allows a centralized network manager to
  configure individual clients no matter how
  large the network

                 Copyright 2002 The ZigBee Alliance, Inc.
          Beacon Frame format




•   Beacons add a new level of functionality to a network
•   Client devices can wake up only when a beacon is to be broadcast,
    listen for their address, and if not heard, return to sleep
•   Beacons are important for mesh and cluster tree networks to keep all
    of the nodes synchronized without requiring nodes to consume
    precious battery energy listening for long periods of time


                           Copyright 2002 The ZigBee Alliance, Inc.
                   MAC Options
• Two channel access mechanisms
   – Non-beacon network
       • Standard ALOHA CSMA-CA communications
       • Positive acknowledgement for successfully received packets
   – Beacon-enabled network
       • Superframe structure
           – For dedicated bandwidth and low latency
           – Set up by network coordinator to transmit beacons at
             predetermined intervals
               » 15ms to 252sec (15.38ms*2n where 0  n  14)
               » 16 equal-width time slots between beacons
               » Channel access in each time slot is contention free
   – Three security levels specified
       • None
       • Access control lists
       • Symmetric key employing AES-128




                          Copyright 2002 The ZigBee Alliance, Inc.
        ISM Band Interference and
              Coexistence

• Potential for interference exists in every ISM band, not
  just 2.4GHz
• IEEE 802.11 and 802.15.2 committees are addressing
  coexistence issues
• ZigBee/802.15.4 Protocol is very robust
   – Clear channel checking before transmission
   – Backoff and retry if no acknowledgement received
   – Duty cycle of a ZigBee-compliant device is usually
     extremely low
   – It’s the “cockroach that survives the nuclear war”
       • Waits for an opening in otherwise busy RF spectrum
       • Waits for acknowledgements to verify packet reception at
         other end



                         Copyright 2002 The ZigBee Alliance, Inc.
    PHY Performance



802.15.4 has excellent
 performance in low
 SNR environments




                 Copyright 2002 The ZigBee Alliance, Inc.
   IEEE1451.5 Sensor Group
       Wireless Criteria
• A survey was conducted mid-2002 on the characteristics
  of a wireless sensor network most important to its users
• In order of importance, these characteristics are
   1.   Data Reliability
   2.   Battery Life
   3.   Cost
   4.   Transmission Range
   5.   Data Rate
   6.   Data Latency
   7.   Physical Size
   8.   Data Security
• How would you modify these requirements, if at all?



                        Copyright 2002 The ZigBee Alliance, Inc.
  Reliability and Robustness
throughout the stacks of IEEE
    802.15.4 and ZigBee




         Copyright 2002 The ZigBee Alliance, Inc.
            Reliability
• Consistently perform a given task
  to the desired result despite all
  changes of environmental behavior
• Without fail
• A necessary ingredient of trust
• “When the sensor measures its
  environment; the controller always
  knows that same value”

             Copyright 2002 The ZigBee Alliance, Inc.
             Reliability

• The wireless medium is not a
  protected environment like the
  wired medium, but rather, it is
  fraught with degradations,
  disruptions, and pitfalls such as
  dispersion, multipath, interference,
  frequency dependent fading,
  sleeping nodes, hidden nodes, and
  security issues.

              Copyright 2002 The ZigBee Alliance, Inc.
             Reliability
• Each of these degradations and
  disruptions can be mitigated by
  various mechanisms within the ISO
  layers; but not all mechanisms are
  compatible with all other mechanisms
  or may negatively impact critical
  performance attributes
• The system must be optimized for
  the best performance in a realistic
  environment

              Copyright 2002 The ZigBee Alliance, Inc.
            Reliability
• In addition to the previous
  disruptions there is the case of
  sending messages to devices that
  are not receiving, e.g. they’re in
  the “sleep” mode. When this
  happens the message needs to be
  buffered by another device that is
  able to send the message when
  the sleeping device wakes up.

             Copyright 2002 The ZigBee Alliance, Inc.
                      Reliability
                                     Interferer




                                                                    Router


                                                                             Multipath
                  XX
              Sleeping Node                         Network
                                                    Coordinator


Hidden Node




                         Copyright 2002 The ZigBee Alliance, Inc.
            Reliability
• IEEE 802.15.4 has built upon the
  successes of previous IEEE 802
  standards by selecting those
  mechanisms proven to ensure
  good reliability without seriously
  degrading system and device
  performance.



              Copyright 2002 The ZigBee Alliance, Inc.
            Reliability
ISO Layers:
• PHY: Direct Sequence with
  Frequency Agility (DS/FA)
• MAC: ARQ, Coordinator buffering
• Network: Mesh Network (redundant
  routing)
• Application Support Layer: Security


             Copyright 2002 The ZigBee Alliance, Inc.
              Reliability
PHY Layers:
• Direct sequence: allows the radio to
  reject multipath and interference by use
  of a special “chip” sequence. The more
  chips per symbol, the higher its ability
  to reject multipath and interference.
• Frequency Agility: ability to change
  frequencies to avoid interference from a
  known interferer or other signal source.


               Copyright 2002 The ZigBee Alliance, Inc.
 IEEE 802 Direct Sequence
 IEEE   11        11b                        15.4       15.4
 802.                                        (900)      (2.4)
 Chips/ 11        11                         15         32
 Symbol

• As can be seen from above,
  IEEE802.15.4/ZigBee has more
  processing gain (chips/symbol)
  than its predecessors

             Copyright 2002 The ZigBee Alliance, Inc.
          Direct Sequence and
           Frequency Agility
               Interferer                  Desired Signal




Over the Air                                     After DS correlation


2.4 GHz
PHY                       Channels 11-26                        5 MHz



2.4 GHz                                                                 2.4835 GHz




                     Copyright 2002 The ZigBee Alliance, Inc.
              Reliability
MAC:
• ARQ (acknowledgement request) is
  where a successful transmission is
  verified by replying with an
  acknowledge (ACK). If the ACK is not
  received the transmission is sent again
• Coordinator buffering is where the
  network coordinator buffers messages
  for sleeping nodes until they wake
  again

               Copyright 2002 The ZigBee Alliance, Inc.
            Reliability
Network:
• Mesh Networking: allows various
  paths of routing data to the
  destination device. In this way if a
  device in the primary route is not
  able to pass the data, a different
  valid route is formed, transparent
  to the user.


              Copyright 2002 The ZigBee Alliance, Inc.
Reliability: Mesh Networking




   ZigBee Coordinator (FFD)

   ZigBee Router (FFD)

   ZigBee End Device (RFD or FFD)


   Mesh Link


   Star Link




                                    Copyright 2002 The ZigBee Alliance, Inc.
           Reliability
Application Support Sub-layer(APS):
• Security: supports reliability by
  keeping other devices from
  corrupting communications.
• The APS configures the security
  emplaced in the MAC layer and
  also adds some of its own.


             Copyright 2002 The ZigBee Alliance, Inc.
           Robustness
• Let’s define robustness as the
  ability to tolerate significant
  degrading phenomena in the
  physical medium
• Multipath and interference are
  probably the most significant
  degradations to the channel
  model.


              Copyright 2002 The ZigBee Alliance, Inc.
           Robustness
• Frequency hopping is a method that
  allows the radio to periodically
  change channels to over time
  minimize the effect of a “bad”
  channel. While this technique is
  very effective in some circumstances
  it creates other problems such as
  latency, network uncertainty for
  sleeping nodes, loss of the product
  bandwidth x time, etc.

             Copyright 2002 The ZigBee Alliance, Inc.
           Robustness
• Direct Sequence with Frequency
  Agility (DS/FA) combines the best
  features of DS and FH without
  most of the problems caused by
  frequency hopping because
  frequency changes aren’t
  necessary most of the time, rather
  they’re appropriate only on an
  exception basis.

             Copyright 2002 The ZigBee Alliance, Inc.
          Robustness
The 802.11 Working Group couldn’t
 agree upon which of the following
 PHYs was the best: FH, IR, or DS.
 So all three were standardized and
 left to the market to decide.
Of the three PHYs; DS was the clear
 market winner. DS provided
 sufficient robustness with higher
 overall performance.

             Copyright 2002 The ZigBee Alliance, Inc.
          Robustness
• Excess robustness does not
  achieve higher performance,
  rather it typically costs
  performance




             Copyright 2002 The ZigBee Alliance, Inc.
           Conclusion
• IEEE 802.15.4/ZigBee have
  addressed reliability throughout
  the ISO stack with proven
  mechanisms to minimize the
  uncertainty of the wireless medium




             Copyright 2002 The ZigBee Alliance, Inc.
Examples




Copyright 2002 The ZigBee Alliance, Inc.
    Transceiver Comparisons
• Instantaneous Power Consumption
   – 15.4 Transceivers are “similar” to Bluetooth Transceivers
       • 802.15.4
           – OQPSK with shaping
           – Max data rate 250kbps over the air
           – 2Mchips/s over the air Direct Sequence Spread Spectrum (62.5ksps*32
             spread)
           – -90 dBm sensitivity
           – 40ppm xtal
       • Bluetooth
           – FSK
           – Max data rate 720kbps over the air
           – 1Msps over the air Frequency Hop Spread Spectrum (79 channels @ 1600
             hps)
           – -85dBm sensitivity
           – 20ppm xtal
• Instantaneous power consumption will be similar for the raw
  transceivers without protocol
• Bluetooth’s frequency hop makes it extremely difficult to
  create extended networks without large synchronization cost


                            Copyright 2002 The ZigBee Alliance, Inc.
   Protocol Makes the Difference
• 15.4 Protocol was developed for very different reasons than
  Bluetooth
   – 802.15.4
       • Very low duty cycle, very long primary battery life applications
       • Static and dynamic star and mesh network structures with potentially a
         very large number (>>65534) of client units, low latency available but
         not necessary
       • Ability to remain quiescent for long periods of time without
         communicating to the network
   – Bluetooth
       • Moderate duty cycle, secondary battery operation where battery lasts
         about the same as master unit
       • Wire replacement for consumer devices that need moderate data rates
         with very high QoS and very low, guaranteed latency
       • Quasi-static star network structure with up to 7 clients (and ability to
         participate in more than one network simultaneously)
       • Generally used in applications where either power is cycled (headsets,
         cellphones) or mains-powered (printers, car kits)
• Protocol differences can lead to tremendous optimizations in
  power consumption

                            Copyright 2002 The ZigBee Alliance, Inc.
                       Applications
• Industrial Control/Monitoring Space
   – Asset Management
       • Basic identification
            – Device ID, Device PN/SN, Device source/destination, etc.
       • Asset “health”
            – Temperature, humidity, shock, fuel levels, etc.
            – Nearly any parameter can be monitored given an appropriate sensor
   – Asset Tracking
       • Location tracking through two-way communication
            – Simplest form is communication/identification when passes a checkpoint
                 » Same as other RFID tagging systems
            – More sophisticated “what other devices can it hear/communicate with?”
            – Other options include ranging (time of flight) and SNR measurement
                 » Has the potential for very precise location measurement
   – The wireless network uses protocol gateways to move
     command/monitor data between the end devices and the network
     data management center




                                Copyright 2002 The ZigBee Alliance, Inc.
                          Product Examples
Warehouses, Fleet management, Factory,                                Energy, diagnostics, e-Business
  Supermarkets, Office complexes                                         services
•     Gas/Water/Electric meter, HVAC
                                                                      •     Gateway or Field Service links to
•     Smoke, CO, H2O detector                                               sensors & equipment
•     Refrigeration case or appliance                                         –     Monitored to suggest PM, product updates,
•     Equipment management services & PM                                            status changes

•     Security services                                               •     Nodes link to PC for database storage
                                                                              –     PC Modem calls retailer, Service Provider, or
•     Lighting control                                                              Corp headquarters
•     Assembly line and work flow, Inventory                                  –     Corp headquarters remotely monitors assets,
•     Materials processing systems (heat, gas flow,                                 billing, energy management
      cooling, chemical)
                                                                                    Field Service
                                                                                      or mobile
                                                                                       worker




                 Temp.    Database
                 Sensor   Gateway                 Security
                                                   Sensor
                                                                                                    Back End
    Mfg Flow
                                                                     Telephone                       Server
                                                                     Cable line
                          Materials        HVAC
                                                                                                     Corp
                          handling
                                                                                     Service         Office           Retailer
                                         Copyright 2002 The ZigBee Alliance, Inc.    Provider
                 Home & Diagnostics
                     Examples
SOHO                                                     •      Mobile clients link to PC for database
                  Retailer
                   Dealer
                                                                storage
                                     Service                     – PC links to peripherals, interactive
                                                                    toys
                                     Provider
                                                                 – PC Modem calls retailer, SOHO,
                                                                    Service Provider
          Customers                                      •      Gateway links to security system,
                                                                temperature sensor, AC system,
   Back End                                                     entertainment, health.
    Server
     Server                                              •      Gateway links to field sales/service
                                                             PC &
          Telephone          Gateway(s)                    peripherals                     Entertainment
          Cable line

                                                                                         Temp.
     Field                                                                               Sensor
    Service
                                                              Body
                                                             monitor
AC or                                                                                             Security
 heat                                                                                              Sensor
Pump                                           Data Communication
                                                    Two way                              White goods


                                    Copyright 2002 The ZigBee Alliance, Inc.
     HID Scenario: Wireless
           Keyboard
• Scenario Parameters
  – Battery-operated keyboard
     • Part of a device group including a mouse or trackball,
       sketchpad, other human input devices
     • Each device has a unique ID
     • Device set includes a USB to wireless interface dongle
        – Dongle powered continuously from computer
     • Keyboard does not have ON/OFF switch
     • Power modes
        – Keyboard normally in lowest power mode
        – Upon first keystroke, wakes up and stays in a “more
          aware” state until 5 seconds of inactivity have passes,
          then transitions back to lowest power mode




                      Copyright 2002 The ZigBee Alliance, Inc.
         Keyboard Usage
• Typing Rates
  – 10, 25, 50, 75 and 100 words per
    minute
• Typing Pattern
  – Theoretical: Type continuously until
    battery is depleted
    • Measures total number of hours based
      upon available battery energy



               Copyright 2002 The ZigBee Alliance, Inc.
   Wireless Keyboard Using
           802.15.4
• 802.15.4 Operation Parameters
    • Star network
    • Non-beacon mode (CSMA-CA)
    • USB Dongle is a PAN Coordinator Full Functional
      Device (FFD)
    • Keyboard is a Reduced Function Device (RFD)
    • Power Modes
       – Quiescent Mode used for lowest power state
           » First keystroke latency is approx 25ms
       – Idle mode used for “more aware” state
           » Keystroke latency 8-12 ms latency




                   Copyright 2002 The ZigBee Alliance, Inc.
  Wireless Keyboard Using
          802.15.4
• 802.15.4 Chipset Parameters
    • Motorola 802.15.4 Transceiver and
      HCS08 MCU
    • Battery operating voltage 2.0 – 3.6 V
      – All required regulation internal to ICs
      – Nearly all available energy usable with end of
        life voltage at 2.0 volts




                 Copyright 2002 The ZigBee Alliance, Inc.
  Wireless Keyboard Using
         Bluetooth
• Bluetooth Operation Parameters
    • Piconet network
    • USB Dongle is piconet Master
    • Keyboard is a piconet Slave
    • Power Modes
      – Park mode used for lowest power state
         » 1.28 second park interval
         » First keystroke latency is 1.28s
      – Sniff mode used for “more aware” state
         » 15ms sniff interval
         » 15ms latency

                 Copyright 2002 The ZigBee Alliance, Inc.
   Wireless Keyboard Using
          Bluetooth
• Bluetooth Chipset Parameters
    • CSR BlueCore 2 –External + Flash + Regulator
    • Battery Operating Voltage 2.7 – 3.6 Vdc
       – Requires external regulator for best performance
       – Only 19 to 30 percent of available battery life
         usable with 2.7V cutoff voltage
    • Power Consumption (estimated)
       – Park Mode @ 1.28 s interval: 0.05mA avg
       – Sniff Mode @ 15ms interval: 8mA avg
       – NOTE: I do not assume a deep sleep mode since
         wake up time of 4 to 30 seconds seems
         unacceptable




                   Copyright 2002 The ZigBee Alliance, Inc.
BT vs. 15.4 Keyboard
    Comparison

                    Bad Hunt n’
                      Peck




                                                   802.15.4: Approx
                                                       38 days



                                                 BT: Approximately
                                                 5 operating days

                               By the way,
                            WirelessUSB looks
                               much like BT
      Copyright 2002 The ZigBee Alliance, Inc.
       Medical Sensor Scenario
            Assumptions
• Environment
   – Battery-operated sensor body-worn with either body-worn or
     facility-mounted coordinator
   – Sensor
       • Running 100% of time
       • Intelligent enough to output a digital waveform that at a minimum
         signals a detected heart beat
       • For the course of this study, assume that only the leading edge of this
         pulse contains information (I.e., heartbeat event occurred)
       • Power consumption is 10uA (WAG; immaterial to wireless connection
         but will consume wireless connection's battery)
   – Network Coordinator
       • Provides a regular RF beacon to which the sensor synchronizes
       • Expect to hear from the sensor during communications windows
         relative to beacon interval
       • Power Source
            – Battery-operated if body-worn cellphone or other network access device
            – Mains-powered if part of a hospital infrastructure




                              Copyright 2002 The ZigBee Alliance, Inc.
    802.15.4/ZigBee Operation
              Mode
•   802.15.4/ZigBee Mode
     – Network environment using Guaranteed Time Slot (GTS)
     – Network beacons occurring either every
         • 960ms or 61.44s (closest values to 1 and 60 s)
         • Guaranteed time slot occurs at some predetermined point in the beacon interval
•   Sensor has two ongoing processes
     – Heartbeat time logging
     – Transmit heartrate and other information (8 bytes total)
         • Instantaneous heartrate (1/timeinterval between last two pulses,1ms precision)
         • Running average heartrate (1/time interval between last twenty pulses, 1ms
           precision)
         • Sensor average temperature (0.1C precision)
         • Sensor average battery state (0.1V precision)



                    heartbeat
                        GTS

                     Beacon

                                                     time


                                 Copyright 2002 The ZigBee Alliance, Inc.
     Medical Sensor Scenario
• Low Power, Low Latency
   – RF XCVR IC is essentially off (leakage currents
     predominating) in normal state
   – MCU is capable of responding immediately to an interrupt
      • MCU onboard 32kHz time clock is running
      • Heartbeat sensor is capable of generating an interrupt signal
        for MCU
• System is in a multisensor environment where all
  sensors are assigned guaranteed timeslots (GTS) for
  communications
• Scenario 1
   – Beacon interval is 960ms (15ms*2^6)
• Scenario 2
   – Beacon interval is 61.44s (15ms*2^12)
• Assume that retries are not necessary due to GTS
   – Reasonable if we assume RF environment is well-controlled

                        Copyright 2002 The ZigBee Alliance, Inc.
General Schematic

    Vcc                                                              Vcc
                                                                                                    3Vdc
 802.15.4   SPI                                         SPI
                                   4
  XCVR
                                                                  MCU
           IRQ/                                         INT
                                                                                  IRQ
          RESET                                               OSC1         OSC2


                  Plus about 10-12 small value
16.000MHz         capacitors, resistors excluding any          32.768kHz
                  special components for heartbeat
                  sensor)
                                                                                        Heartbeat
                                                                                         Sensor




                       Copyright 2002 The ZigBee Alliance, Inc.
     Sensor Battery Type
• Lithium coin primary battery
  – Tadiran Lithium type TL-2186
    • http://www.tadiran.com/pdf/tl-2186.pdf
  – 400 mAh nominal capacity (0.5mA
    constant to 2.0V)
  – 3.6V BOL, 2.0V EOL




               Copyright 2002 The ZigBee Alliance, Inc.
                 Two Processes
• Process 1
   – Each heartbeat forces the MCU to respond to the sensor interrupt
   – From MCU interrupt to completion of processing
       • Approximately 980 microseconds
       • Approximately 3E-8 mAh consumed per heartbeat
• Process 2
   – Each 960ms or 61.44s the system synchronizes to network and
     transmits the information
   – From MCU beacon wakeup to completion of transmission
       • Approximately 56ms (varies depending on beacon interval and
         assigned guaranteed time slot)
       • Approximately 3E-4 mAh consumed per transmission event
• Constant Idle Currents
   – 10 microamp sensor
   – Leakage currents in RF XCVR IC and MCU oscillator/Time base
     reference (~ microamps)




                          Copyright 2002 The ZigBee Alliance, Inc.
802.15.4/ZigBee vs Bluetooth
                             Li-Coin Cell Battery Life
                       (Beacon Interval vs Heartrate vs Days)
         900                                            At beacon interval ~60s,
                                                        15.4/ZigBee battery life
         800
                                                            approx 750 days
         700

         600                   802.15.4/ZigBee superior
                                at all beacon intervals                                                                       60
         500                     greater than 0.246s                                                                          72
  Days




                                                                                                                              86
      400                                                                                                                     104
                                                                                         At beacon interval ~1s,
   Bluetooth 33 days                                                                                            124
      300                                                                                15.4/ZigBee battery life
 (park mode @ 1.28s)                                                                                            149
                                                                                             nearly 136 days
                                                                                                                              179
         200
                                                                                                                              BT@72bps
         100

           0
               0.015

                       0.031

                                0.062

                                        0.123

                                                0.246

                                                         0.492

                                                                 0.984

                                                                         1.969

                                                                                 3.937

                                                                                           7.875

                                                                                                   15.749

                                                                                                            31.498

                                                                                                                     62.996

                                                                                                                              125.993

                                                                                                                                        251.986
                                                          Beacon Interval (sec)




                                                Copyright 2002 The ZigBee Alliance, Inc.
                  Conclusion
• Bluetooth and 802.15.4 transceiver physical
  characteristics are very similar
• Protocols are substantially different and designed for
  different purposes
• 802.15.4 designed for low to very low duty cycle static
  and dynamic environments with many active nodes
• Bluetooth designed for high QoS, variety of duty cycles,
  moderate data rates in fairly static simple networks with
  limited active nodes
• Bluetooth costs and system performance are in line with
  3rd and 4th generation products hitting market while 1st
  generation 15.4 products will be appearing only late this
  year




                      Copyright 2002 The ZigBee Alliance, Inc.
             More Information
• ZigBee Alliance web site
   – http://www.ZigBee.org


• IEEE 802.15.4 web site
   – http://www.ieee802.org/15/pub/TG4.html


• Articles
   – “Meet the ZigBee Standard”, Sensors Mag June 2003
     http://www.sensorsmag.com/articles/0603/14/
   – “ZigBee Vital in Industrial Applications”, EETimes, 29
     July 2003
     http://www.eetimes.com/story/OEG20030727S0002



                     Copyright 2002 The ZigBee Alliance, Inc.
Motorola 802.15.4/ZigBee™
Platform for Low Data Rate
         Wireless Jon Adams
                                   Director,
                                   Architecture
                                   and Systems
                                                  Motorola
                                    American Association of
                                                  Wireless and
                                                         Railroads
                                                  Broadband
                                           Automatic Equipment
                                Identification Conference
                                                  Systems Group
                                        Pittsburgh, PA 17 June
                                   jta @
         Copyright 2002 The ZigBee Alliance, Inc.
 System Simplicity and
      Flexibility




Motorola RF Packet Radio             Motorola 8-Bit MCU



                  Copyright 2002 The ZigBee Alliance, Inc.
Motorola 802.15.4 / ZigBee™
          solution
• Features
   – 2.4 GHz Band, -90 dBm RX sensitivity at 1% PER
       • IEEE spec is –85 dBm
   – Power supply 2.0-3.6 V w/ on-chip regulator, logic interface 1.7 to
     3.3
       • Runs off a single Li or 2 alkaline cells
   – Complete RF transceiver data modem – antenna in, fully
     packetized data out
   – Data and control interface via standard SPI at 4 to 8 MHz
   – 802.15.4 MAC
   – A large number of Motorola’s substantial line of HC08 MCUs will
     interoperate with the data modem chip
       • Often 802.15.4 functionality can be added to existing systems simply
         by including the modem chip and reprogramming an existing MCU that
         may already be in the application
   – HC08 RAM/FLASH configurations from 384B/4kB to 2kB/60kB
     depending upon application SW needs




                             Copyright 2002 The ZigBee Alliance, Inc.
  Motorola’s RF Data Modem
       Transceiver (1)
• Designed for the IEEE 802.15.4 and ZigBee™ standards
   – Operates in the 2.4 GHz ISM band available worldwide
   – Cost effective CMOS design
   – Low external components, no T/R switch required
   – On-chip low noise amplifier
   – 0dBm (1.0 mW) PA, step adjustable to –30dBm
   – Integrated VCO, no external components
   – Full spread-spectrum encoding and decoding compatible
     with 802.15.4
   – RX sensitivity of –90 dBm at 1% PER, better than
     specification
   – Engineered to support 250 kBit/s O-QPSK data in 5.0 MHz
     channels, per the IEEE 802.15.4 specification
   – No line-of-sight limitations as with infrared (IR)


                      Copyright 2002 The ZigBee Alliance, Inc.
   Motorola’s RF Data Modem
        Transceiver (2)
• Designed to run DIRECTLY off two alkaline AA or AAA cells, or
  one Lithium cell
   – 2.0 to 3.6 V with on-chip voltage regulator
   – Can use the full capacity of the battery (to end of life ~1.0V per
     cell)
• Buffered transmit and receive data packets for simplified use
  with low-end microcontrollers
• SPI data and control interface, operates up to 8MHz
• Designed to support peer to peer and star topologies
• On-board timers to support optional Superframe/Guaranteed
  Time Slots for low latency transfer
• Will support optional Zigbee™ Network layer software
• Application-configurable power-saving modes that take best
  advantage of battery operation
   – RX/TX > Idle > Doze > Hibernate > Off


                          Copyright 2002 The ZigBee Alliance, Inc.
Scalability to Address Specific Needs
802.15.4 is a guest in existing microcontrollers

 802.15.4 PHY Compliant Transceiver                                                           Application-
      RF Transceiver IC                                                                    specific interfaces
                                                        Zigbee NWK
                                           SPI                               Application
        RF Receiver         Digital                    15.4 FFD MAC
                          Processing




                                                                                                             System Complexity and Cost
       RF Transmitter                                      >32kB FLASH 8-Bit
                                                             Microcontroller


      RF Transceiver IC                                         Application
                                           SPI          Zigbee NWK
        RF Receiver         Digital                    15.4 RFD MAC
       RF Transmitter     Processing                        32kB FLASH 8-Bit
                                                             Microcontroller


      RF Transceiver IC
                                                                Application
                                           SPI
        RF Receiver         Digital                    15.4 RFD MAC
       RF Transmitter     Processing                        12kB FLASH 8-Bit
                                                             Microcontroller


      RF Transceiver IC
                                           SPI                  Application
        RF Receiver         Digital
                                                       Direct SPI Calls
       RF Transmitter     Processing                     3kB FLASH (min) 8-Bit
                                                             Microcontroller


                                  Copyright 2002 The ZigBee Alliance, Inc.
Motorola’s 802.15.4 Platform
        Advantages
•   Total System Solution
     – Single source for platform solution
          • Integrated Circuits, Reference Designs, Modules, Stack Software, Development
            Systems
•   Key technology enhancements provide for a superior solution
     – Adjacent channel rejection
          • Improvements in noisy environment
     – High Sensitivity Radio Solution
          • 5 dBm beyond spec – longer range
     – Extended Temperature Operating Range
          • -40°C to +85°C for industrial and automotive applications
     – Operating voltage range optimized for alkaline or lithium primary cells
          • 2.0 Vdc to 3.6 Vdc, disposable
     – Adjustable TX Output power
          • Improved coexistence for short range applications, improved battery life
•   IEEE and ZigBee™ Alliance membership
     – Technology and standards driver
     – Early access to new technology




                                  Copyright 2002 The ZigBee Alliance, Inc.
Home/Light Commercial
       Spaces




       Copyright 2002 The ZigBee Alliance, Inc.
                  Industrial/Commercial
                          Spaces                              Energy, diagnostics, e-Business
     •     Warehouses, Fleet management,                         services
           Factory, Supermarkets, Office                      •      Gateway or Field Service links to
           complexes                                                 sensors & equipment
                                                                       –      Monitored to suggest PM, product updates,
     •     Gas/Water/Electric meter, HVAC                                     status changes
     •     Smoke, CO, H2O detector                            •      Nodes link to PC for database storage
     •     Refrigeration case or appliance                             –      PC Modem calls retailer, Service Provider, or
                                                                              Corp headquarters
     •     Equipment management services &                             –      Corp headquarters remotely monitors assets,
           Preventative maintenance                                           billing, energy management
     •     Security services
     •     Lighting control
     •     Assembly line and work flow,                                       Field Service
           Inventory                                                            or mobile
                                                                                 worker
     •     Materials processing systems (heat,
           gas flow, cooling, chemical)
              Temp.    Database
              Sensor   Gateway              Security
                                             Sensor
                                                                                              Back End
Mfg Flow
                                                               Telephone                       Server
                                                               Cable line
                       Materials     HVAC
                                                                                                Corp
                       handling
                                                                               Service          Office           Retailer
                                   Copyright 2002 The ZigBee Alliance, Inc.    Provider
        Peel-n’-Stick Security
               Sensors
• Battery Operation
   – 2 AA Alkaline or 1 Li-AA
     cell
• 802.15.4/ZigBee Mode
   – Non-beacon network
     environment                                        Vcc     SPI
                                                                          4
                                                                                 SPI    Vcc
                                                                                              3Vdc


• Sensor process                                     802.15.4
                                                      XCVR CLK                   OSC1   MCU

   – RC Oscillator waking up                                    IRQ

     MCU and doing network
     check-in at some interval                                        Security
                                                    16.000MHz
      • Many security systems                                          Sensor

        have between ~10
        second and ~15 minute
        requirement
   – On a sensor event,
     device immediately
     awakens and reports in
     to network


                       Copyright 2002 The ZigBee Alliance, Inc.
      Security Sensor Timing
                                 Battery-Powered                            Mains-Powered
                                      Sensor                                    Router

                                    Interval timer
                                  expires: Wake Up

                         256µs           CCAx2

                         192µs           RX>TX

                        ~650µs              TX                                    RX

                         192µs           TX>RX                                  RX>TX

Check-in only           ~350µs                                                  ACK TX
                                        ACK RX
    ~1640µs                                                                 OPT: Pending ON
   Event and Get Data
             ~2300µs    ~650µs          RX Data                                 TX Data

                                   Set Interval timer

                                          Sleep




                                 Copyright 2002 The ZigBee Alliance, Inc.
802.15.4 Security Sensor
                                       Any check-in interval
                                     exceeding ~14 sec allows
                                     sensor to surpass alkaline
                                         battery shelf life




                                                              Only at 15-min interval
                                                              does BT reach battery
                                                                     shelf life




        Copyright 2002 The ZigBee Alliance, Inc.
    Body-Worn Medical Sensors
• Heartbeat Sensor
   – Battery-operated using                              heartbeat
     CR2032 Li-Coin cell                                       GTS
• 802.15.4/ZigBee Mode                                    Beacon
   – Network environment using
     Guaranteed Time Slot                                                    time

     (GTS)
   – Network beacons occurring
     either every
       • 960ms or 61.44s (closest
         values to 1 and 60 s)                           Vcc                            Vcc

• Sensor has two ongoing
                                                                                                                   3Vdc
                                                                 SPI       SPI
                                                      802.15.4
  processes
                                                                       4            MCU
                                                       XCVR
                                                                IRQ/       INT
   – Heartbeat time logging                                    RESET             OSC1         OSC2
                                                                                                     IRQ


   – Transmit heartrate and
     other information (8 bytes                                                                            Heartbeat

     total)
                                                     16.000MHz                    32.768kHz                 Sensor

       • Instantaneous and average
         heart rate
       • Body temperature and
         battery voltage


                          Copyright 2002 The ZigBee Alliance, Inc.
  Tracking Global Shipments
          Securely 1
• High value consumer electronics shipment from
  Singapore to Chicago (sea leg)
   – Container loaded with high-value electronics in Singapore,
     container’s transponder reads all the traditionally RFID-
     tagged material inside the container
   – Loaded on ship at harbor, crane/ship communicates with
     container’s transponder confirming loading, contents and
     security and providing it information on ship’s network
   – As ship proceeds across Pacific, environmental and
     security data regularly collected from container’s
     transponder, ensuring the safety of the contents and
     providing ability for shipper/contents owner to proactively
     respond to container malfunction/security breach
   – Offloading at Long Beach, container transponder
     communicates with crane to validate contents/point of
     origin/container security and provides it information on
     train’s network


                       Copyright 2002 The ZigBee Alliance, Inc.
  Tracking Global Shipments
          Securely 2
• High value consumer electronics shipment from
  Singapore to Chicago (rail leg)
   – Transloaded onto COFC train at Los Angeles harbor, crane
     verifies contents, container ID and car number location
     match to train manifest and provides it information on
     train’s network
   – Conveying flatcar establishes link with loaded container,
     communicates “loaded” status forward to locomotive
     computer
   – Train leaves for Chicago; along way, locomotive continues
     to request and receive regular updates from container and
     relay entire train status to Ops
      • Railroad provides the just-in-time information via internet to
        the shipper/receiver
   – Train arrives Chicago, container offloaded at yard, crane
     communicates with container and verifies contents,
     source, and security and provides it information on truck’s
     network

                         Copyright 2002 The ZigBee Alliance, Inc.
  Tracking Global Shipments
          Securely 3
• High value consumer electronics shipment from
  Singapore to Chicago (road leg)
   – Road tractor/trailer combo moving container to final
     destination has transponder that communicates with
     container, and verifies contents, source, destination, and
     security
   – Container arrives at destination (big box retail store
     distribution) where employees verify for the final time the
     contents, source, destination and container security before
     signing off on delivery
• Shipment protected at all times on journey
• Mishandling, smuggling, homeland security issues all
  contained with this simple yet very sophisticated system



                       Copyright 2002 The ZigBee Alliance, Inc.
  What security issues are
 there and how will they be
          solved?
• Security and data integrity
  – Key benefits of the ZigBee technology
  – ZigBee leverages the security model
    of the IEEE 802.15.4 RF standard
    • Extends this capability with robust
      encryption options
    • Can be tailored to the specific needs of
      the networked device




                Copyright 2002 The ZigBee Alliance, Inc.
   How is ZigBee related to
      IEEE 802.15.4?
• ZigBee takes full advantage of
  – A powerful physical radio specified by IEEE
    802.15.4
• ZigBee adds
  – Logical network and application software
• ZigBee is based on the IEEE 802.15.4
  RF standard, and the Alliance is working
  closely with the IEEE to ensure an
  integrated and complete solution for the
  market

                 Copyright 2002 The ZigBee Alliance, Inc.
       Non-Beacon vs Beacon
              Modes
• Non-Beacon Mode
   – A simple, traditional multiple access system used in simple peer
     and near-peer networks
   – Think of it like a two-way radio network, where each client is
     autonomous and can initiate a conversation at will, but could
     interfere with others unintentionally
   – However, the recipient may not hear the call or the channel might
     already be in use
• Beacon Mode
   – A very powerful mechanism for controlling power consumption in
     extended networks like cluster tree or mesh
   – Allows all clients in a local piece of the network the ability to know
     when to communicate with each other
   – Here, the two-way radio network has a central dispatcher who
     manages the channel and arranges the calls
• As you’ll see, the primary value will be in system power
  consumption



                           Copyright 2002 The ZigBee Alliance, Inc.
     Example of Non-Beacon
           Network
• Commercial or home security
   – Client units (intrusion sensors, motion detectors, glass break
     detectors, standing water sensors, loud sound detectors, etc)
       • Sleep 99.999% of the time
       • Wake up on a regular yet random basis to announce their continued
         presence in the network (“12 o’clock and all’s well”)
       • When an event occurs, the sensor wakes up instantly and transmits the
         alert (“Somebody’s on the front porch”)
   – The ZigBee Coordinator, mains powered, has its receiver on all
     the time and so can wait to hear from each of these stations
       • Since ZigBee Coordinator has “infinite” source of power it can allow
         clients to sleep for unlimited periods of time to allow them to save
         power




                            Copyright 2002 The ZigBee Alliance, Inc.
 Example of Beacon Network
• Now make the ZigBee Coordinator battery-operated also
   – All units in system are now battery-operated
   – Client registration to the network
       • Client unit when first powered up listens for the ZigBee Coordinator’s
         network beacon (interval between 0.015 and 252 seconds)
       • Register with the coordinator and look for any messages directed to it
       • Return to sleep, awaking on a schedule specified by the ZigBee
         Coordinator
       • Once client communications are completed, ZigBee coordinator also
         returns to sleep
   – This timing requirement potentially impacts the cost of the timing
     circuit in each end device
            – Longer intervals of sleep mean that the timer must be more accurate or
            – Turn on earlier to make sure that the beacon is heard, increasing receiver
              power consumption, or
            – Improve the quality of the timing oscillator circuit (increase cost) or
            – Control the maximum period of time between beacons to not exceed 252
              seconds, keeping oscillator circuit costs low




                              Copyright 2002 The ZigBee Alliance, Inc.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:53
posted:6/1/2012
language:
pages:104
yan198555 yan198555
About