1. COMP1706: MOBILE AND NETWORK TECHNOLOGIES Bluetooth and ZigBee Dr. George Loukas University of Greenwich, 2014-2015

2.  Universal radio interface for ad-hoc wireless connectivity  Embedded in devices. Goal: 5€ /device  Short range (originally 10 m)  Low power consumption  2.45 GHz (unlicensed)  (originally) 1 Mbit/s Bluetooth: The idea

3. Bluetooth history 19941996200620141998200020022004200820122010 Ericsson “MC-link” project Foundation of Bluetooth Special Interest Group http://bluetooth.org named after 10 th century Danish king Harald “Bluetooth” Gormsen, who unified his country. Founding members: Ericsson, Intel, IBM, Nokia, Toshiba First consumer product, spec. v.1.1 Already 5 m chips sold per week Spec v.2 released Enhanced Data Rate 3 Mbps Spec v.3 adopted High Speed 24 Mbps Spec v.4 adopted Low Energy (2 Mbps) Spec v.4.2 released IEEE 802.15.1 Standard for wireless personal area networks

4. Bluetooth radio characteristics 79 channels Channel 0: 2402 MHz Channel 1: 2403 MHz Channel 2: 2404 MHz... Channel 78: 2480 MHz Frequency Hopping Spread Spectrum (FHSS) Pseudorandom. Determined my a master. 1600 hops/s Time division multiplexing

5. Piconet Bluetooth devices connected in an ad hoc fashion Master Active Slaves Parked Slaves One unit acts as master and the other as slaves for duration of piconet Master determines unique hopping pattern and slaves “hop together” (pattern depends on master’s globally unique ID) Participation in a piconet = hopping together with its master The master controls who transmits in each time slot No direct communication between slaves Max 1 master, 7 active slaves and over 200 parked

6. Scatternet Two or more piconets joined together by sharing of a common master or slaves A device can be a slave in one piconet and the master of another A device can be a slave in two piconets jumping back and forth between them. This is how two piconets communicate with each other

7. Bluetooth frequency hopping

8. Bluetooth transmission modes Synchronous connection oriented (SCO) mode: Voice link Reserved channel bandwidth (“circuit-switched”: periodic single- slot frame assignment) No retransmissions Forward Error Correction 64 Kbit/s duplex Asynchronous connectionless (ACL) mode: Data link Even time slots are for master transmissions and odd for slaves Retransmissions and Forward Error Correction Up to 433.9 Kbit/s symmetric or 723.2/57.6 kbit/s asymmetric

9. Bluetooth transmission modes Polling-based TDD packet transmission 625μs slots, master polls slaves SCO (Synchronous Connection Oriented) – Voice Periodic single slot packet assignment, 64 kbit/s full-duplex, point-to-point ACL (Asynchronous Connectionless) – Data Variable packet size (1, 3, 5 slots), asymm. bandwidth, point-to-multipoint

10. Bluetooth transmission modes Symmetric Vs. asymmetric

11. Bluetooth robustness Retransmission for ACLs Forward error correction for both ACL and SCO Slow frequency hopping Since v1.2, adaptive frequency hopping reassigns transmission to channels that have less interference (e.g. if WiFi interferes with some channels)

12. Bluetooth operation  Discovery: finding other devices  Connecting: setting up a communication path  Pairing: validating identity  Logical channels: adding communication paths for specific functions/services.

13. Bluetooth states AMA: Active member address PMA: Parked member address

14. Bluetooth security

15. Bluetooth profiles 1 Advanced Audio Distribution Profile (A2DP) 2 Attribute Profile (ATT) 3 Audio/Video Remote Control Profile (AVRCP) 4 Basic Imaging Profile (BIP) 5 Basic Printing Profile (BPP) 6 Common ISDN Access Profile (CIP) 7 Cordless Telephony Profile (CTP) 8 Device ID Profile (DIP) 9 Dial-up Networking Profile (DUN) 10 Fax Profile (FAX) 11 File Transfer Profile (FTP) 12 Generic Audio/Video Distr. Profile (GAVDP) 13 Generic Access Profile (GAP) 14 Generic Attribute Profile (GATT) 15 Generic Object Exchange Profile (GOEP) 16 Hard Copy Cable Replacement Profile (HCRP) 17 Health Device Profile (HDP) 18 Hands-Free Profile (HFP) 19 Human Interface Device Profile (HID) 20 Headset Profile (HSP) 21 Intercom Profile (ICP) 22 LAN Access Profile (LAP) 23 Message Access Profile (MAP) 24 OBject EXchange (OBEX) 25 Object Push Profile (OPP) 26 Personal Area Networking Profile (PAN) 27 Phone Book Access Profile (PBAP, PBA) 28 Proximity Profile (PXP) 29 Serial Port Profile (SPP) 30 Service Discovery Application Profile (SDAP) 31 SIM Access Profile (SAP, SIM, rSAP) 32 Synchronization Profile (SYNCH) 33 Synchronisation Mark-up Lang. Profile (SyncML) 34 Video Distribution Profile (VDP) 35 Wireless Application Protocol Bearer (WAPB) To stream music to phones and headsets To transfer images and remotely operate digital camera To operate hands-free devices in a car For Bluetooth keyboards, mice etc. Provides car access to driver’s contacts

16. Bluetooth profiles example

17. Bluetooth v.3 +HS HIGH SPEED Connections are established via Bluetooth But data transfer uses WiFi: Bluetooth 2.1 + EDR + IEEE 802.11a/g = 54 Mbit/s

18. Bluetooth v.4 LOW ENERGY Designed specifically for small, battery- operated devices (Nike+, Fitbit, …) Not backward compatible Not voice-capable Also used for proximity detection based on signal strength (e.g. iBeacons)

19. INTERMISSION

20. ZigBee: The idea Designed for wireless sensor networks, interactive toys, home automation, robotics etc. Low rate Low power Battery lasts several months to years Low cost Range 10 - 100 m Named after a dance performed by honey bees to communicate with each other

21. ZigBee history 20042005201020142006200720082009201120132012 ZigBee Spec 1.0 released ZigBee PRO IEEE 802.15.4 20032015

22. ZigBee characteristics 2.4 GHz (unlicensed) – 16 channels Also, 30 channels in 915 MHz (USA) and 1 channel in 868 MHz (Europe) Delay 15 ms Data rates up to 250 kbit/s NOT intended to provide high bandwidth service (as WLAN does) NOT intended to provide moderate bandwidth wireless link over short range (as Bluetooth does)

24. ZigBee nodes  Full Function Device (FFD): can communicate with any node in the network and can be PAN coordinator (sink node), coordinator (router), or normal device or  Reduced Function Device (RFD): can only talk with a single FFD

25. Node roles  Coordinator  Always one and only one coordinator regardless of topology  Equivalent of access point in Wi-Fi or master in Bluetooth  The data sink in sensors networks  The node that issues commands in remote control applications  Selects the frequency channel with least detected activity to be used by the network  Allows other devices to join the network

26. Node roles  End devices  In the star topology, they are perimeter nodes  In the tree and mesh topology, they are leaf nodes  Cannot relay messages. Only send and receive  To conserve power, they usually sleep when not sending or receiving data

27. Node roles  Router  They relay messages  Not necessary in a star network (coordinator can be the router)  A router cannot sleep

28. Node roles  Each node maintains Neighbour, Routing and Binding Tables  Coordinator is responsible for initialising, maintaining and controlling the network.  An End device is said to ‘belong’ to a parent node  A parent node can be the coordinator or a router.  The End device polls to find a Parent node.  The parent node ‘discovers’ the end device by receiving these polls.  The parent node adds the end device to a Table

29. ZigBee protocol stack ZigBee extends IEEE 802.15.4 IEEE 802.15.4 defines the PHY and MAC layer ZigBee defines higher layers

30. Discovers new neighbours, incl. routers. Determines if a neighbouring device belongs to the network. Performs routing (AODV) Unlike Internet routing, here routing is reactive. A route to a destinaton is established on demand. A node broadcasts a route request to all of its neighbours. The neighbours forward the request to their neighbours until the destination is reached (‘flooding’ broadcast). Destination receives multiple copies and determines the shortest path taken. The route reply is unicast following the lowest cost path back to the source. The source then updates its routing table for the destination address with the next hop in the path and the path cost (number of hops). ZigBee Network (NWK) layer

31. AODV example 1 2 2 3a 3b 4 4 1.End Device has data to send to sink, passes message to its parent node. 2.Router broadcasts route request to its neighbours. 3.Neighbouring routers forward the route request (flood, steps 3a and 3b nearly simultaneous). 4.(Assuming that ‘3a’ message arrives first at the Coordinator) The route reply is sent back – using that route.

32. Deals with Addressing  64-bit IEEE address – fixed  16-bit Node ID – dynamically assigned  Devices within a node identified by Endpoint Identifier (1 – 240) Comprises components added by ZigBee spec (on top of IEEE 802.15.4 radio link spec), includes: ZigBee Device Object (ZDO) responsible for defining role of a device (Coordinator / End device) and for the discovery of new (one-hop) devices and the identification of their offered services. Application objects (application specific data objects). Application support sublayer (APS) offers a well-defined interface and control services. Serves as a bridge between the network layer and the other components of the application layer: manages binding tables – maps devices to the services offered by the discovered devices. ZigBee Application layer

33. Coexistence between Bluetooth and ZigBee Bluetooth is FHSS (frequency hopping spread spectrum). Its working frequency quickly hops 1600 times per second. Even if there are several kinds of 2.4GHz RF systems, the hopping system only interferes with other RF systems for a little time period. ZigBee is DSSS (direct sequence spread spectrum), so there is only one time channel overlap in 79 times. If a Bluetooth device transmits in a frequency that overlaps with the ZigBee channel, then the ZigBee device randomly backs off while the Bluetooth quickly hops to another frequency. So Bluetooth and ZigBee rarely disturb each other. They can coexist very well.

34. Coexistence between Wi-Fi and ZigBee Both are DSSS. The interference in Wi-Fi caused by ZigBee is smaller than the interference in ZigBee, caused by Wi-Fi, because ZigBee’s bandwidth (2MHz) is much smaller than Wi-Fi’s bandwidth (22MHz).

35. Transmission options  Each transmission can be sent secured or unsecured  Acknowledged: originator data is confirmed by recipient  Unacknowledged: no confirmation  Unicast: send to a specific recipient  Broadcast: send to all recipients  Multichannel: Originator attempts Tx using frequency re- acquisition mechanism  Single channel: Originator attempts Tx on the expected channel

36. ZigBee security  128-bit symmetric encryption is standard  A key is assigned to a network or a link

37. ZigBee product examples

38. Simulating ZigBee networks NS-2 http://www.ifn.et.tu- dresden.de/~marandin/ZigBee/Zi gBeeSimulationEnvironment.html OPNETOMNeT ++ with MiXim http://mixim.sourceforge.net Or just borrow ZigBee modules from the laboratory for real experiments