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Faculty of Computer Science Chair of Computer Networks, Wireless Sensor Networks, Dr. W. Dargie                           ...
Structure    Introduction    Concepts    Architecture    Implementation    Evaluation    Reference    TU Dresden,   ...
IntroductionTU Dresden,   ZigBee – Short range   slide 3 of 56
IntroductionWhat is ZigBee?• Specification of protocols for small, low-power radiosHistory• May 2003: IEEE 802.15.4 comple...
ZigBee Alliance - Members                      and many more....TU Dresden,    ZigBee – Short range   slide 5 of 56
ConceptsTU Dresden,   ZigBee – Short range   slide 6 of 56
Why do we need another WPAN standard?Decreasing• Power consumption   – ZigBee: 10mA <==> BT: 100mA• Production costs   – I...
Why do we need another WPAN standard?                                picture taken from [9]TU Dresden,   ZigBee – Short ra...
Why do we need another WPAN standard?Increasing• Sensitivity   – ZigBee: -92dbm(0,63pW) <==> BT: -82dbm(6,2pW)• flexibilit...
Usage Scenarios• Industrial & commercial• Consumer electronics• Toys & games• PC & periphals• Personal health care• home/b...
ZigBee Frequency BandsTU Dresden,   ZigBee – Short range   slide 11 of 56
ZigBee Protocol Stack        7Layer      Simplified 5Layer    ISO-OSI-Model    ISO-OSI-Model             IEEE 802 Model7  ...
Protocol Stack                                         picture taken from [10]TU Dresden,   ZigBee – Short range   slide 1...
ZigBee ProfilesProfiles:Definition of ZigBee-Profiles• describes a common language for exchanging data• defines the offere...
ArchitectureTU Dresden,   ZigBee – Short range   slide 15 of 56
ZigBee Node-TypesZigBee Coordinator (ZBC) (IEEE 802.15.4 FFD)• only one in a network• initiates network• stores informatio...
ZigBee Node-TypesZigBee Router (ZBR) (IEEE 802.15.4 FFD)• optional component• routes between nodes• extends network covera...
ZigBee Node-TypesZigBee End Device (ZBE) (IEEE 802.15.4 RFD)• optimized for low power consumption• cheapest device type• c...
Addressing/Discovering ZigBee NodesAddressing ZigBee Nodes:• optimized unique 64 bit address (IEEE 802.15.4)• 16 bit netwo...
Addressing/Binding ZigBee Endpoints                                       picture taken from [11]TU Dresden,     ZigBee – ...
Traffic-Types1. Data is periodic• application dictates rate2. Data is intermittent• application or stimulus dictates rate ...
Traffic-Modes1. Beacon mode:• beacon send  periodically• Coordinator and end  device can go to sleep• Lowest energy  consu...
Beacon-Mode                                            picture taken from [8]TU Dresden,   ZigBee – Short range   slide 23...
Traffic-Modes1. Non-Beacon mode:• coordinator/routers  have to stay awake  (robust power supply  needed)• heterogeneous  n...
Topologies   Mesh-Topologypicture taken from [7]           TU Dresden,   ZigBee – Short range   slide 25 of 56
Topologies   Tree-Topologypicture taken from [7]           TU Dresden,   ZigBee – Short range   slide 26 of 56
ImplementationTU Dresden,     ZigBee – Short range   slide 27 of 56
PHY layer2400MHz Band specs•   4 Bits per symbol•   DSSS with 32 Bit chips•   O-QPSK modulation•   Sine halfwave impulses ...
PHY layer868/915 MHz Band specs•   1 Bit per symbol•   Differential encoding•   DSSS with 15 Bit Chips•   BPSK modulation•...
PHY layerGeneral specs and services•   Error Vector Magnitude (EVM) < 35%•   -3dBm minimum transmit power (500µW)•   Recei...
PHY layerPHY Protocol Data Unit (PPDU) frame structure•   Frame to be sent via radio•   Preamble for chip and symbol synch...
MAC layerChannel access specification• Beacon/Nonbeacon• Define Superframe structure• Slotted/unslotted CSMA-CA   TU Dresd...
MAC layerManaging PANs•   Channel scanning (ED, active, passive, orphan)•   PAN ID conflict detection and resolution•   St...
MAC layerTransfer handling• Transaction based (indirect transmission)   – Beacon indication   – Polling• Transmission, Rec...
MAC layerFrame security• Provided security features   – Access control   – Data encryption   – Frame integrity   – Sequent...
MAC layerHow far have we come?                               4                1                                           ...
NWK layerDistributed address assignment•   Tree structure or self managed by higher layer•   16Bit network space divided a...
NWK layerDistributed address assignment - Example• Cm=2 ; Rm=2 ; Lm=2                 Depth in network d   Offset Value   ...
NWK layerRouting cost•   Metric to compare „goodness“ of routes•   Base: Link cost between 2 neighbors•   Path cost = sum ...
NWK layerRoute discovery• Find or update route between specific source and  destination• Started if no active route presen...
NWK layerRoute discovery    RREQ    RREP                 1           2           3                 5               2      ...
NWK layerRouting• Check if routing table entry exists• Initiate route discovery if possible• Hierarchical routing as fallb...
Application Level                                     picture taken from [11]TU Dresden,   ZigBee – Short range           ...
Application Level                                     picture taken from [11]TU Dresden,   ZigBee – Short range           ...
Application LayerApplication Support Sub-layer (APS):• interface to NWK-layer (offers general set of functions)• Data tran...
Application Level                                     picture taken from [11]TU Dresden,   ZigBee – Short range           ...
Application LayerApplication Framework:• Specifies Datatypes• Devices describe themselves by ZigBee descriptor:   – freque...
Application LayerSupported Data-types                                        table taken from [1]   TU Dresden,   ZigBee –...
Application Level                                     picture taken from [11]TU Dresden,   ZigBee – Short range        sli...
Application LayerZigBee defined Objects (ZDO):• provides common function for applications• Initializes APS, NWK-Layer and ...
EvaluationTU Dresden,   ZigBee – Short range   slide 51 of 56
Pros and ConsPros                            Cons• good extension of             • Not many end devices  existing standard...
Gadget examplePantech & Curitel P1 phone• Only a prototype• control electrical  appliances• Check temperature &  humidity•...
ReferencesTU Dresden,   ZigBee – Short range   slide 54 of 56
References[1] ZigBee Specifications v1.0[2] “Designing with 802.15.4 and ZigBee”, Presentation Slides, available on ZigBee...
Thank you                    for              your attention!TU Dresden,    ZigBee – Short range   slide 56 of 56
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Transcript of "Zigbee1"

  1. 1. Faculty of Computer Science Chair of Computer Networks, Wireless Sensor Networks, Dr. W. Dargie ZigBee Jan Dohl Fabian Diehm Patrick GrosaDresden, 14.11.2006
  2. 2. Structure Introduction Concepts Architecture Implementation Evaluation Reference TU Dresden, ZigBee – Short range slide 2 of 56
  3. 3. IntroductionTU Dresden, ZigBee – Short range slide 3 of 56
  4. 4. IntroductionWhat is ZigBee?• Specification of protocols for small, low-power radiosHistory• May 2003: IEEE 802.15.4 completed• December 2004: ZigBee specification ratified• June 2005: public availabilityZigBee-Alliance• Companies developing and promoting the standard• 150+ members TU Dresden, ZigBee – Short range slide 4 of 56
  5. 5. ZigBee Alliance - Members and many more....TU Dresden, ZigBee – Short range slide 5 of 56
  6. 6. ConceptsTU Dresden, ZigBee – Short range slide 6 of 56
  7. 7. Why do we need another WPAN standard?Decreasing• Power consumption – ZigBee: 10mA <==> BT: 100mA• Production costs – In the beginning of 2005 – ZigBee: 1.1 $ <==> BT: 3 $• Development costs – Codesize ZB/codesize BT = ½• Bit-error-rate (BER) TU Dresden, ZigBee – Short range slide 7 of 56
  8. 8. Why do we need another WPAN standard? picture taken from [9]TU Dresden, ZigBee – Short range slide 8 of 56
  9. 9. Why do we need another WPAN standard?Increasing• Sensitivity – ZigBee: -92dbm(0,63pW) <==> BT: -82dbm(6,2pW)• flexibility – No. of supported nodes – ZigBee: 65536 (in a mesh) <==> BT: 7 (in a star)• Security – ZigBee: AES (128bit) <==> BT: SAFER (64/128bit)• Latency requirements – ZigBee: optional guaranteed time slot• Range – ZigBee: up to 75 m in LOS condition <==> BT: 10 m TU Dresden, ZigBee – Short range slide 9 of 56
  10. 10. Usage Scenarios• Industrial & commercial• Consumer electronics• Toys & games• PC & periphals• Personal health care• home/building automation Just everything you can imagine for wireless sensor nodes or in general short range communications TU Dresden, ZigBee – Short range slide 10 of 56
  11. 11. ZigBee Frequency BandsTU Dresden, ZigBee – Short range slide 11 of 56
  12. 12. ZigBee Protocol Stack 7Layer Simplified 5Layer ISO-OSI-Model ISO-OSI-Model IEEE 802 Model7 Application User Application < ZigBee <6 Presentation5 Session Application Profile Upper Layers4 Transport3 Network Network2 Data Link Data Link Logic Link Control (LLC) < 802.14.5 < Media Access Control (MAC)1 Physical Physical Physical TU Dresden, ZigBee – Short range slide 12 of 56
  13. 13. Protocol Stack picture taken from [10]TU Dresden, ZigBee – Short range slide 13 of 56
  14. 14. ZigBee ProfilesProfiles:Definition of ZigBee-Profiles• describes a common language for exchanging data• defines the offered services• device interoperatbility across different manufacturers• Standard profiles available from the ZigBee Alliance• profiles contain device descriptions• unique identifier (licensed by the ZigBee Alliance) TU Dresden, ZigBee – Short range slide 14 of 56
  15. 15. ArchitectureTU Dresden, ZigBee – Short range slide 15 of 56
  16. 16. ZigBee Node-TypesZigBee Coordinator (ZBC) (IEEE 802.15.4 FFD)• only one in a network• initiates network• stores information about the network• all devices communicate with the ZBC• routing functionality• bridge to other networks TU Dresden, ZigBee – Short range slide 16 of 56
  17. 17. ZigBee Node-TypesZigBee Router (ZBR) (IEEE 802.15.4 FFD)• optional component• routes between nodes• extends network coverage• manages local address allocation/de-allocation TU Dresden, ZigBee – Short range slide 17 of 56
  18. 18. ZigBee Node-TypesZigBee End Device (ZBE) (IEEE 802.15.4 RFD)• optimized for low power consumption• cheapest device type• communicates only with the coordinator• sensor would be deployed here TU Dresden, ZigBee – Short range slide 18 of 56
  19. 19. Addressing/Discovering ZigBee NodesAddressing ZigBee Nodes:• optimized unique 64 bit address (IEEE 802.15.4)• 16 bit network address (65536 devices)• 256 sub addresses for subunitsDevice Discovery• unicast (NWK id known), broadcast (NWK id unknown)• ZBC-/ZBR-Response: IEEE address + NWK address + all known network addressesBinding• creating logical links between 2 or more end devices TU Dresden, ZigBee – Short range slide 19 of 56
  20. 20. Addressing/Binding ZigBee Endpoints picture taken from [11]TU Dresden, ZigBee – Short range slide 20 of 56
  21. 21. Traffic-Types1. Data is periodic• application dictates rate2. Data is intermittent• application or stimulus dictates rate (optimun power savings)3. Data is repetitive (fixed rate a priori)• device gets guaranteed time slot TU Dresden, ZigBee – Short range slide 21 of 56
  22. 22. Traffic-Modes1. Beacon mode:• beacon send periodically• Coordinator and end device can go to sleep• Lowest energy consumption• Pricise timing needed picture taken from [1]• Beacon period (ms-m) TU Dresden, ZigBee – Short range slide 22 of 56
  23. 23. Beacon-Mode picture taken from [8]TU Dresden, ZigBee – Short range slide 23 of 56
  24. 24. Traffic-Modes1. Non-Beacon mode:• coordinator/routers have to stay awake (robust power supply needed)• heterogeneous network picture taken from [1]• asymmetric power TU Dresden, ZigBee – Short range slide 24 of 56
  25. 25. Topologies Mesh-Topologypicture taken from [7] TU Dresden, ZigBee – Short range slide 25 of 56
  26. 26. Topologies Tree-Topologypicture taken from [7] TU Dresden, ZigBee – Short range slide 26 of 56
  27. 27. ImplementationTU Dresden, ZigBee – Short range slide 27 of 56
  28. 28. PHY layer2400MHz Band specs• 4 Bits per symbol• DSSS with 32 Bit chips• O-QPSK modulation• Sine halfwave impulses Medium Binary Data Bit Symbol QPSK to to Mod. Symbol Chip picture taken from [4] TU Dresden, ZigBee – Short range slide 28 of 56
  29. 29. PHY layer868/915 MHz Band specs• 1 Bit per symbol• Differential encoding• DSSS with 15 Bit Chips• BPSK modulation• RC impulses (roll-off = 1) Medium Binary Data Bit Diff. BPSK to Encoder Mod. Chip TU Dresden, ZigBee – Short range slide 29 of 56
  30. 30. PHY layerGeneral specs and services• Error Vector Magnitude (EVM) < 35%• -3dBm minimum transmit power (500µW)• Receiver Energy Detection (ED)• Link Quality Indication (LQI)• Use ED & LQI to reduce TX-power• Clear Channel Assessment (CCA) with 3 modes 1. Energy above threshold 2. Carrier sense only 3. Carrier sense with energy above threshold TU Dresden, ZigBee – Short range slide 30 of 56
  31. 31. PHY layerPHY Protocol Data Unit (PPDU) frame structure• Frame to be sent via radio• Preamble for chip and symbol synchronization• Contains either data or data acknowlegement• Packet size 8-127 Octets• Contains MAC Protocol Data Unit (MPDU) table taken from [1] TU Dresden, ZigBee – Short range slide 31 of 56
  32. 32. MAC layerChannel access specification• Beacon/Nonbeacon• Define Superframe structure• Slotted/unslotted CSMA-CA TU Dresden, ZigBee – Short range slide 32 of 56
  33. 33. MAC layerManaging PANs• Channel scanning (ED, active, passive, orphan)• PAN ID conflict detection and resolution• Starting a PAN• Sending beacons• Device discovery• Device association/disassociation• Synchronization (beacon/nonbeacon)• Orphaned device realignment TU Dresden, ZigBee – Short range slide 33 of 56
  34. 34. MAC layerTransfer handling• Transaction based (indirect transmission) – Beacon indication – Polling• Transmission, Reception, Rejection, Retransmission – Acknowleded – Not acknowledged• GTS management – Allocation/deallocation – Usage – Reallocation• Promiscous mode TU Dresden, ZigBee – Short range slide 34 of 56
  35. 35. MAC layerFrame security• Provided security features – Access control – Data encryption – Frame integrity – Sequential freshness• Avaiable security modes – Unsecured mode – ACL mode – Secured mode• Avaiable security suites – AES-CTR – AES-CCM – AES-CBC-MAC TU Dresden, ZigBee – Short range slide 35 of 56
  36. 36. MAC layerHow far have we come? 4 1 6 0 5 2 7 3Problem: How do 6 and 7 talk to coordinator 0?Solution: Routing (NWK Layer) TU Dresden, ZigBee – Short range slide 36 of 56
  37. 37. NWK layerDistributed address assignment• Tree structure or self managed by higher layer• 16Bit network space divided among child routers• Child routers divide there space again for their children• Depends on: – Maximum child count per parent – Maximum child-routers per parent – Maximum network depth TU Dresden, ZigBee – Short range slide 37 of 56
  38. 38. NWK layerDistributed address assignment - Example• Cm=2 ; Rm=2 ; Lm=2 Depth in network d Offset Value 0 3 1 1 2 0 1 2 ? 0 6 4 5 TU Dresden, ZigBee – Short range slide 38 of 56
  39. 39. NWK layerRouting cost• Metric to compare „goodness“ of routes• Base: Link cost between 2 neighbors• Path cost = sum of link costs along the path• Link cost determination: – Link quality indication from PHY – Statistical measures TU Dresden, ZigBee – Short range slide 39 of 56
  40. 40. NWK layerRoute discovery• Find or update route between specific source and destination• Started if no active route present in routing table• Broadcast routing request (RREQ) packets• Generates routing table entries for hops to source• Endpoint router responds with Routing response (RREP) packet• Routes generated for hops to destination• Routing table entry generated in source device TU Dresden, ZigBee – Short range slide 40 of 56
  41. 41. NWK layerRoute discovery RREQ RREP 1 2 3 5 2 1 4 TU Dresden, ZigBee – Short range slide 41 of 56
  42. 42. NWK layerRouting• Check if routing table entry exists• Initiate route discovery if possible• Hierarchical routing as fallbackRoute maintenance• Track failed deliveries to neighbors• Initiate route repair when threshold reached• Careful with network load!• In case of total connectivity loss: – Orphaning procedure – Re-association with network TU Dresden, ZigBee – Short range slide 42 of 56
  43. 43. Application Level picture taken from [11]TU Dresden, ZigBee – Short range slide 43 of 56
  44. 44. Application Level picture taken from [11]TU Dresden, ZigBee – Short range slide 44 of 56
  45. 45. Application LayerApplication Support Sub-layer (APS):• interface to NWK-layer (offers general set of functions)• Data transmission, binding and security management picture taken from [1] TU Dresden, ZigBee – Short range slide 45 of 56
  46. 46. Application Level picture taken from [11]TU Dresden, ZigBee – Short range slide 46 of 56
  47. 47. Application LayerApplication Framework:• Specifies Datatypes• Devices describe themselves by ZigBee descriptor: – frequency band – power description – application flags – application version – serial number – manufacturer – ... TU Dresden, ZigBee – Short range slide 47 of 56
  48. 48. Application LayerSupported Data-types table taken from [1] TU Dresden, ZigBee – Short range slide 48 of 56
  49. 49. Application Level picture taken from [11]TU Dresden, ZigBee – Short range slide 49 of 56
  50. 50. Application LayerZigBee defined Objects (ZDO):• provides common function for applications• Initializes APS, NWK-Layer and Security Service Specification• offers services like device-/service-descovery, binding and security management• assembles information about the network• for ZBC/ZBR -> e.g. binding table picture taken from [1] TU Dresden, ZigBee – Short range slide 50 of 56
  51. 51. EvaluationTU Dresden, ZigBee – Short range slide 51 of 56
  52. 52. Pros and ConsPros Cons• good extension of • Not many end devices existing standards available yet• supported by many • Single point of failure companies (centralized architecture)• low power consumption• low cost• easy implemented (Designer concentrates on end application)• flexible network structure TU Dresden, ZigBee – Short range slide 52 of 56
  53. 53. Gadget examplePantech & Curitel P1 phone• Only a prototype• control electrical appliances• Check temperature & humidity• Sending messages in case of trespass picture taken from [9] TU Dresden, ZigBee – Short range slide 53 of 56
  54. 54. ReferencesTU Dresden, ZigBee – Short range slide 54 of 56
  55. 55. References[1] ZigBee Specifications v1.0[2] “Designing with 802.15.4 and ZigBee”, Presentation Slides, available on ZigBee.org[3] “ZigBee Tutorial”, http://www.tutorial-reports.com/wireless/zigbee[4] IEEE 802.15.4 Specification[5] “Network Layer Overview”, Presentation Slides, Ian Marsden, Embedded Systems Show,Birmingham, October 12th, 2006, 064513r00ZB_MG_Network_Layer_Overview.pdf, availableon ZigBee.org[6] “Designing a ZigBee Network”, Presentation Slides, David Egan, Ember Corporation, ESS2006, Birmingham, 064516r00ZG_MG_Network_Design.pdf, available on ZigBee.org[7] “ZigBee Architecture Overview”, Presentation Slides, Oslo, Norway June 2005,ZigBee_Architecture_and_Specifications_Overview.pdf, available on ZigBee.org[8] “Low Power Consumption Features of the IEEE 802.15.4/ZigBee LR-WPAN Standard”,http://www.cens.ucla.edu/sensys03/sensys03-callaway.pdf[9] “ZigBee Home Automation Mobile from Pantech”, http://www.i4u.com/article2561.html[10] “Basic Lecture - ZigBee” http://www.korwin.net/eng/infor/info_zb_01.asp[11] “Introduction to the ZigBee Application Framework”, Presentation Slides, ZigBee OpenHouse, San Jose, June 15th, 2006, 053340r06ZB_AFG-Overview-ZigBee-Open-House.pdf,available on ZigBee.org TU Dresden, ZigBee – Short range slide 55 of 56
  56. 56. Thank you for your attention!TU Dresden, ZigBee – Short range slide 56 of 56
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