1. Bluetooth By Christian Doyle

2. Overview What is Bluetooth? What’s with the name? Establishing a connection Multiplexing Piconets Scatternets Architecture Routing Sources

3. What is Bluetooth? First version released in 1999 Short range radio ISM (industrial – scientific – medical) 2.4GHz 79 channels at 1MHz each 1Mbps data rate Originally created as a replacement for cables Inexpensive chips Create mobile ad hoc networks of many different types of devices

4. More on Bluetooth Frequency hopping physical layer Multiple channels, each defined by frequency hopping sequence  802.11 uses a single channel broadcast Channels are shared using polling to allocate time slots to slaves Devices must be on same frequency in order to communicate Link layer uses ARQ and FEC

5. What’s with the name? Named after the 10 th century Danish King Harald Blatand or Harold Bluetooth in English Harold united warring factions in what is now Norway, Sweden, and Denmark Similarly Bluetooth technology is supposed to unite different types of devices such as PDAs, laptops and mobile phones

6. Establishing a connection Asymmetric processes, involve two types of nodes: senders and receivers Nodes broadcast on predetermined frequency Inquiry phase  Senders discover and collect neighborhood info about receivers Paging phase  Senders connect to receivers that were discovered during the inquiry phase

7. TDD Time division duplexing Single slave communication  Master sends on even numbered slots  Slave sends on odd numbered slots Multiple slave communication  Master sends on even numbered slots  Slave only sends if the last even numbered slot was addressed to it (polling)

8. Piconet One “hop” network All nodes must be on same hopping frequency One master Any number of slaves There may only be seven active slaves at any given time In order to talk to other slaves, master must “park” one of them

9. Piconet Master Slave

10. Scatternet Connection of piconets is called a scatternet Nodes can only be active in one piconet Nodes must change hopping frequency in order to be active in another piconet Nodes can not communicate unless they are in the same piconet, even if they can physically receive each other’s messages

11. Scatternet A “bridge” node connects two piconets Bridge nodes can be a slave in one piconet and a master in another Nodes can only be a master in one piconet

12. Scatternet Master Slave

13. Architecture Goal is to form fully connected scatternets Switching frequency creates performance problem “Bluetree”  One “Blueroot”  Every master only has at most two slaves Other options  Bridge may only connect two piconets  Minimize number of piconets  Connected  Two piconets should share only one bridge

14. Bluetree Master Slave

15. Other architectures Master Slave

16. Routing Because devices are mobile an optimal path may not be optimal in a few moments Routing is very reliant on the application and architecture Reactive routes: created when needed Random IPs

17. Sources Bluetrees – Scatternet Formation to Enable Bluetooth- Based Ad Hoc Networks  Zaruba et al Distributed Topology Construction of Bluetooth Personal Area Networks  Salonidis et al Performance Aspects of Bluetooth Scatternet Formation  Miklos et al Bluetooth – an Enabler for Personal Area Networking  Kazantzidis et al Data Communication and Networking  Forouzan, Behrouz www.Bluetooth.org