Modeling & Simulation of Bluetooth MAC protocol

1. Modeling & Simulation of Bluetooth MAC protocol COE543 Term Project Spring 2003 Submitted by: H.M.Asif (ID# 230457)

2. Outlines: • Bluetooth overview • The Bluetooth Stack • Bluetooth MAC protocol • Simulation design and Assumption • Results • Future work • Conclusion

3. Bluetooth overview: • What is Bluetooth? • Why Bluetooth? • Bluetooth History • Bluetooth Network Topology

4. What is Bluetooth? • Cable replacement technology primarily • Bluetooth wireless technology is an open specification for a low-cost, low-power, short-range radio technology for ad-hoc wireless communication of voice and dataanywhere in the world.

5. Cont’d: • Bluetooth uses a frequency-hopping scheme in the unlicensed Industrial Scientific-Medical (ISM) band at 2.4 GHz. • The major goal with the Bluetooth wireless technology is to allow relatively cheap electronic devices to communicate directly in an ad-hoc fashion, Moreover, the Bluetooth equipped devices can also form networks– such a network of personal devices is often referred to as a personal area network (PAN).

6. Why Bluetooth? • Cable replacement between devices. • Open Specification • Low power consumption • Devices can be connected to multiple devices at the same time. • Operate in Un-licensed band (2.4GHz ISM)

7. Bluetooth Technical Features: • 2.4 GHz ISM Open Band • Globally free available frequency • 79 channels (2400-2483.5 MHz ISM band) • Frequency Hopping & Time Division Duplex (1600 hops/second typically) • 10-100 Meter Range • Class I – 100 meter (300 feet) • Class II – 20 meter (60 feet) • Class III – 10 meter (30 feet) • Link Rate : 1 Mbps • Simultaneous Voice/Data Capable • SCO (Synchronous connection oriented) for voice • ACL (Asynchronous connectionless link) for data • Transmit Power: 0dbm • Receiver Sensitivity : -73dbm • Uses Binary GFSK

8. Bluetooth History: • King Harold Blatand, or Bluetooth, a Viking and King of Denmark 940-981, united Denmark & Norway • 1994 – Ericsson study on a wireless technology to link mobile phones and accessories

9. Bluetooth history (cont’d): • Originally conceived as a cable replacement technology • Other usage models began to develop: • Personal Area Network (PAN) • Ad-hoc networks • Data/voice access points (LMN) • Etc.

10. Bluetooth History (cont’d): • 1994 – Ericsson study complete/vision • 1995 – Engineering work begins • 1997 – Intel agrees to collaborate • 1998 – Bluetooth SIG (Special Interest Group) formed: Ericsson, Intel, IBM, Nokia and Toshiba • 1999 – Bluetooth Specification 1.0A • SIG promoter group expanded: 3Com, Lucent, Microsoft & Motorola • 2000 – Bluetooth Specification 1.0B, 2000+ adopters • 2001 – First retail products released, Specification 1.1 (JSR-82 Java for Bluetooth API based on Spec v1.1) • 2003 – Bluetooth Specification 1.2 • 2004 – Bluetooth Specification 2.0(?)

11. Bluetooth Network Topology: • PICONET - Collection of devices connected in an ad hoc fashion • One unit acts as master and the others as slaves for the lifetime of the piconet • Master – device that initiates a data exchange • Slave – device that responds to the master • Master determines hopping pattern, slaves have to synchronize • Each piconet has one master and up to 7 simultaneous slaves • Participation in a piconet = synchronization to hopping sequence

12. Cont’d: • Scatternet (intersecting piconets) • Two or more piconets form a scatternet • Devices can be slave in both or master in one and slave in other.

13. Piconet example:

14. Scatternet example:

15. The Bluetooth Stack:

16. Packet Format: • Access Code: timing synchronization, offset compensation, paging and inquiry. • Header: information for packet acknowledgement, packet numbering for out-of-order packet reordering, flow control, slave address and error check for header. • Payload: voice field, data field or both

17. Bluetooth MAC Protocol: • Facilitates communication among devices within the piconet • Assumes that all devices are synchronized with each other • Let’s see how it works!

18. Simulation Design: • One master and seven slaves • Only one is active at a given time (assumption) • Assigning address • If (node node address==0) • MASTER • else • SLAVE • Considers only ACL (data traffic) • Master polls • Poll-time is calculated

19. Cont’d: • Slave sends req.msg (if it has data to send) • Req. time is calculated. Req. msg contains this slave address and the one to which it wants to send data. It also show packet length. • If slave has no data to send, slot is wasted • Master sends, on specifying hops (according to demand), sends ACK • Ack. Time is calculated

20. Cont’d: • Slave sends its data • Transmit time is calculated. • The packet does not reach its destination if Pt <0.5mW • Finally overall time and useful time are calculated • Calculated time efficiency • Also graph drawn throughput versus load

21. Performance metrics: • Throughput • Time efficiency (delay)

22. Simulation results(1): Time efficiency = 19.8 Too low because of a lot of overhead of polling and setting up connection

23. Simulation results(2):

24. Comments: • Too much delay because • polling (high overhead) • If slave has no data to send, slot is wasted • Highly centralized

25. Bluetooth Future: • Bluetooth was originally intended to be a cable replacement, • but, has evolved to become an infrastructure for Personal Area Network (PAN) • 2001: 10 million devices produced • 2003: 70 million!

26. Thank you