Wireless Personal Area Networks

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Wireless Personal Area Networks based on Bluetooth, ZigBee, & Ultra-Wideband

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  • Device participating in both piconets can relay data between members of both ad hoc networks. However, the basic bluetooth protocol does not support this relaying - the host software of each device would need to manage it
  • Sdp – service discovery protocol
    TCS (Telephone Control protocol Specification
  • Mobilkommunikation
    SS 1998
  • HVAC (heating, ventilation, and air conditioning
    Automatic Meter Reading (AMR)
  • GTS – guaranteed time slots
  • Transmission from a Coordinator to a Device
    The coordinator has data to be transmitted to the device. It indicates this in the pending address fields of its beacon. Devices tracking the beacons, decode the pending address fields. If a device finds its address listed among the pending address fields, it realizes it has data to be received from the coordinator. It issues a Data-Request Command to the coordinator. The coordinator replies with an acknowledgement. If there is data to be sent to the device, it would transmit the data. If acknowledgements are not optional, the device would respond with an acknowledgement.
  • Wireless Personal Area Networks

    1. 1. Wireless Personal Area Networks CS5440 Wireless Access Networks Dilum Bandara Dilum.Bandara@uom.lk Some slides extracted from ZigBee by J. Dohl, F. Diehm, & P. Grosa and ZigBee by E. Ünal CSE 401 Special Topics In Computer Networks
    2. 2. Outline  Bluetooth  ZigBee  Ultra-Wideband 2
    3. 3. 3 OSI Stack Source: http://walkwidnetwork.blogspot.com/2013/04/physical-layer-osi-model.html
    4. 4. OSI vs. TCP/IP 4 Source: http://blog.anuesystems.com/category/span-and-taps/
    5. 5. Bluetooth – IEEE 802.15.1  Developed by Ericson  Now managed by Bluetooth Special Interest Group  2.4 – 2.48 GHz ISM band  Range – 10 m  Bandwidth – 2.1 Mbps (shared) (version 2.0)  Version 4.0  Includes Classic Bluetooth, Bluetooth high speed & Bluetooth low energy protocols  Bluetooth high-speed based on Wi-Fi  Classic Bluetooth based on legacy Bluetooth protocols  Low power consumption  Found in mobile phones, laptops, computer peripherals, printers, etc. 5
    6. 6. Bluetooth Applications  Cable replacement  Phone to PC connection  Connecting computing devices  Digital imaging  Smart car systems  Multiparty data exchange  Exchange business cards, calendar events  Share presentation material  Synchronize information between multiple terminals  Play multi-player games  Personal trusted device  Reliable e-commerce transactions  Local value added services  Locking & access control 6 Stick N Find
    7. 7. Bluetooth Piconet  Through master  No slave-to-slave communication  Up to 7 active slaves 255 parked slaves 7 Source: www.techrepublic.com/article/secure-your-bluetooth- wireless-networks-and-protect-your-data/6139987
    8. 8. Bluetooth Scatternet  By connecting 2+ piconets  No direct support at Baseband Layer 8 Source: www.techrepublic.com/article/secure-your-bluetooth- wireless-networks-and-protect-your-data/6139987
    9. 9. Bluetooth Protocol Stack 9 Source: http://withfriendship.com/user/sathvi/bluetooth-stack.php
    10. 10. Protocols & Usage Models 10 PPP RFCOMM TCP/IP Baseband L2CAP OBEX IrMC TCS-BIN Audio Sync Dial-up net. Usage Models File Transfer AT-commands Fax Headset LAN Access Cordless Phone SDP LMP
    11. 11. Bluetooth Protocol Stack (Cont.) 11
    12. 12. Bluetooth Applications/Profiles  Set of application protocols  Definitions of possible applications & specify general behaviors  Resides on top of Bluetooth core specification & (optionally) additional protocols  Example profiles  Hands-Free Profile (HFP)  Basic Printing Profile (BPP)  Audio/Video Remote Control Profile (AVRCP)  File Transfer Profile (FTP)  Human Interface Device Profile (HID)  Personal Area Networking Profile (PAN)  Generic Object Exchange Profile (GOEP)  OBEX 12
    13. 13. Other Key Layers  Link Management Protocol (LMP)  Set-up & control of radio link between 2 devices  Logical Link Control & Adaptation Protocol (L2CAP)  Multiplex multiple logical connections between 2 devices using different higher-level protocols  Provides segmentation & reassembly of on-air packets  Service Discovery Protocol (SDP)  Allows a device to discover services offered by other devices, & their associated parameters  Baseband layer  Physical layer  Manages physical channels & links  Error correction, data whitening, hop selection, & security 13
    14. 14. Physical Channel  Required to use spread spectrum technology as it’s in ISM band  79 RF channels spaced 1 MHz apart  Channel – frequency range in which communication occurs  Frequency hoping  Channel represented by a pseudo-random hopping sequence hopping through 79 channels  Piconet – all devices use same channel  Hopping sequence is unique for the piconet & is determined by device address (BD_ADDR) of master 14
    15. 15. Physical Channel (Cont.)  Traffic controlled by master  Master clock used for all timing & scheduling activities  Master transmissions at even slots, slaves always at odd slots  Packet extended over up to 5 slots 15
    16. 16. Packets  Access code  Used for timing synchronization, offset compensation, paging & inquiry  Header  Contains information for packet acknowledgement, packet numbering for out-of-order packet reordering, flow control, slave address, & error check for header  Payload  Can contain either voice field, data field, or both 16
    17. 17. ZigBee  By ZigBee Alliance  Very low power consumption  long battery life  Low data rate  Low complexity circuits & small size  low cost 17
    18. 18. ZigBee Applications Telecom Services m-commerce info services object interaction (Internet of Things) ZigBee Wireless Control that Simply Works TV VCR DVD/CD remote security HVAC lighting control access control irrigation PC& Peripherals asset mgt process control environmental energy mgt Personal Health Care security HVAC AMR lighting control access control patient monitoring fitness monitoring 18 Source: http://zigbee.org/
    19. 19. ZigBee Protocol Stack  IEEE 802.15.4 covers physical layer & MAC layer of low-rate WPAN  ZigBee adds network construction, application services, & more on top of IEEE 802.15.4 19 Source: www.sena.com/products/industrial_zigbee/zigbee_summary.php
    20. 20. IEEE 802.15.4 Devıce Types  LR-WPAN devices defined by IEEE 802.15.4 1. Full Functional Device (FFD)  Can work as a PAN coordinator, as a coordinator, or as a simple device  Can communicate with either another FFD or a RFD 2. Reduced Functional Device (RFD)  For applications that don’t need to transmit large volumes of data & have to communicate only with a specific FFD 20
    21. 21. IEEE/ZigBee Topologies 21 Source: http://wireless.arcada.fi/MOBWI/material/PAN_5_2.html
    22. 22. ZigBee Topologies (Cont.) 1. Star Topology  Pros  Easy to synchronize  Low latency  Cons  Small scale 2. Mesh/P2P Topology  Pros  Robust multi-hop communication  Multi-path communication  Flexible network  Lower latency  Cons  Route discovery is costly  Needs to store routing table 22
    23. 23. ZigBee Topologies (Cont.) 3. Cluster Tree Topology  Pros  Low routing cost  Multi-hop communication  Scalable  Cons  Route reconstruction is costly  Latency may be quite long  Root node becomes a single point of failure 23
    24. 24. ZigBee Frequency Bands 24
    25. 25. PHY Protocol Data Unit (PPDU)  2 different services  Data service  Controls radio  Management service  Energy detection in the channel  Clear channel assesment before sending messages  Link Quality Indication (LQI) for received packets  Preamble for chip & symbol synchronization  Frame size 8-127 Octets 25
    26. 26. MAC Layer  2 services  Data service  Tx & Rx MPDUs  Management service  If coordinator  Manages network beacons, PAN association & disassociation, frame validation, & acknowledgment  CSMA/CA for channel access  Support device security 26
    27. 27. Traffic-Modes – Device to PAN Coordinator  Beacon mode  Beacon send periodically  Coordinator & end device can go to sleep  Lowest energy consumption  Precise timing needed  Beacon period (ms-min) 27 Source: IEEE 802.15.4 Standard (2006)
    28. 28. Traffic-Modes – Device to PAN Coordinator (Cont.)  Non-Beacon mode  Coordinator/routers have to stay awake  Heterogeneous network  Asymmetric power 28 Source: IEEE 802.15.4 Standard (2006)
    29. 29. Data Transfer From PAN Coordınator 29 Source: IEEE 802.15.4 Standard (2006)
    30. 30. MAC Layer – Managing PANs  Channel scanning  Active, passive  PAN ID conflict detection & resolution  Starting a PAN  Sending beacons  Device discovery  Device association/disassociation  Synchronization (beacon/nonbeacon)  Orphaned device realignment 30
    31. 31. MAC Layer – Frame Security  Provided security features  Access control  Data encryption  Frame integrity  Sequential freshness  Available security modes  Unsecured mode  ACL mode  Secured mode  Available security suites  AES-CTR  AES-CCM  AES-CBC-MAC 31
    32. 32. Network Layer  Distributed address assignment  Tree structure or self managed by higher layer  16-bit network space divided among child routers  Child routers divide their space again for their children  Depends on  Maximum child count per parent  Maximum child-routers per parent  Maximum network depth 32
    33. 33. Network Layer (Cont.)  Route discovery  Find or update route between specific source & 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 33
    34. 34. Route Discovery RREQ RREP 1 2 3 4 2 1 5 34
    35. 35. Network Layer (Cont.)  Routing  Check if routing table entry exists  Initiate route discovery if possible  Hierarchical routing as fallback  Route 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 35
    36. 36. ZigBee Profiles  Describes a common language for exchanging data  Defines offered services  Device interoperability across different manufacturers  Standard profiles available from the ZigBee Alliance  Profiles contain device descriptions  Unique identifier (licensed by the ZigBee Alliance) 36
    37. 37. ZigBee vs. Bluetooth Feature(s) Bluetooth ZigBee Power Profile days years Complexity complex Simple Nodes/Master 7 64000 Latency 10 seconds 30 ms – 1s Range 10m 70m ~ 300m Extendibility no Yes Data Rate 1 Mbps 250 Kbps Security 64bit, 128bit 128bit AES & Application Layer 37
    38. 38. ZigBee vs. BluetoothSHORT<RANGE>LONG LOW < DATA RATE > HIGH PAN LAN Text Graphic s Internet Hi-fi Audio Streaming Video Digital Video Multi-channel Video 802.15.1 Bluetooth1 802.15.1 Bluetooth 2 802.15.4 ZigBee 802.11b 802.11a/HL2 & 802.11g 38
    39. 39. Ultra-Wideband  Short-range technology for high-speed WPANs  3.1 – 10.6 GHz, 15 MHz channels (up to 5)  10 m  Applications – Cell phones, HDTV, DVD players, audio players, etc. 39 Source: www.ice.rwth-aachen.de/index.php?id=630&tx_felogin_pi1[forgot]=1&tx_iceprojects_pi1[uid]=155
    40. 40. Ultra-Wideband (Cont.)  Emit large no of very-short pluses over a wide bandwidth  Few nanoseconds or less  Gains few 100s of Mbps  Channel capacity proportional to used bandwidth  No specific frequency allocation  Operate on frequency band allocated to other technologies  Secure  Like other spread spectrum technologies 40
    41. 41. Protocol Stack  Wireless USB, Wireless IP, Bluetooth over UWB, & IEEE1394 over UWB can be operated over a common radio platform 41 Source: http://research.nokia.com/page/244
    42. 42. Summary  Bluetooth  Spread Spectrum  Moderate rate, short-range (10 m)  ZigBee  Low rate, low power, short range (10 m – 100 m)  Ultra-Wideband  High rate, very-short range 42

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