1. Scatternet Formation of Bluetooth Ad Hoc Networks Bin Zhen, Jonghun Park, Yongsuk Kim HICSS 2003

2. Outline Scenarios and questions Scenarios and questions Bluetooth and 802.11 protocol stack Bluetooth and 802.11 protocol stack Blue-Star island network formation Blue-Star island network formation Measurement metrics Measurement metrics Simulation results Simulation results Discussion and conclusion Discussion and conclusion

3. Scenarios File share system File share system Conference room Conference room File transfer File transfer Unicast or multicast Unicast or multicast Service discovery Service discovery Mouse + notebook + AP Mouse + notebook + AP

4. Some Questions What is the relation between network routing and network formation? What is the relation between network routing and network formation? Routing protocol mainly consider how many hops between source and destination Routing protocol mainly consider how many hops between source and destination In bluetooth, less number of piconet In bluetooth, less number of piconet Less neighbor piconet overlap Less neighbor piconet overlap More intra-piconet schedule More intra-piconet schedule

5. View of Routing and Network Formation 3 hops 3 piconets 3 hops 2 piconets

6. 802.11 Protocol Stack

7. Bluetooth Protocol Stack

8. A Simplified BT Protocol Stack

9. Blue-Star Island Network Formation(1/2) 1. All nodes are self-organized, multiple isolated “blue-star islands” maybe formed

10. Blue-Star Island Network Formation(2/2) 2. If a slave receive a RREQ message from another nodes, it check if the destination is in its reachable range If it is yes, RREP will send along the backward path to source If it is yes, RREP will send along the backward path to source If it is no, the node generate “Routing Trigger” to inform all reachable slave to seek the neighbor “blue-star island” If it is no, the node generate “Routing Trigger” to inform all reachable slave to seek the neighbor “blue-star island”

11. Measurement Metrics(1/2) The procedure of network establishment and maintenance The procedure of network establishment and maintenance Time complexity Time complexity The time of network convergence to a steady state, also denote network recovery time due to mobility The time of network convergence to a steady state, also denote network recovery time due to mobility Message complexity Message complexity The number of packets sent between nodes in network establish, maintenance and recovery The number of packets sent between nodes in network establish, maintenance and recovery Network robustness Network robustness The impact of local topology change to the total network, loop free network is easy routing, but it is sensitive to movement of some key points The impact of local topology change to the total network, loop free network is easy routing, but it is sensitive to movement of some key points

12. Measurement Metrics(2/2) The metrics of communication efficiency The metrics of communication efficiency Packet latency and latency variance Packet latency and latency variance Relate to all underlying factors, routing algorithm, inter-piconet, intra-piconet schedule algorithm and network topology Relate to all underlying factors, routing algorithm, inter-piconet, intra-piconet schedule algorithm and network topology Network diameter Network diameter Number of hops, loop free network makes more hops, because of the existence of key node Number of hops, loop free network makes more hops, because of the existence of key node Number of piconet Number of piconet The less the number of piconet is, the less packet collision probability is The less the number of piconet is, the less packet collision probability is

13. Simulation Results(1/3)

14. Simulation Results(2/3)

15. Simulation Results(3/3)

16. Conclusion and Discussion(1/2) To provide an always ready BT ad hoc network with consideration on piconet number, battery power and network maintenance cost To provide an always ready BT ad hoc network with consideration on piconet number, battery power and network maintenance cost Loop-free network has 3 main drawbacks Loop-free network has 3 main drawbacks Root becomes bottleneck of the route Root becomes bottleneck of the route Need more time on maintenance Need more time on maintenance Power consumption is larger Power consumption is larger

17. Conclusion and Discussion(2/2) The worst case is that all the “blue-star islands” are piconets, a tree style scatternet has to be formed The worst case is that all the “blue-star islands” are piconets, a tree style scatternet has to be formed The best case is that all node aggregate in a single “blue-star island” The best case is that all node aggregate in a single “blue-star island” The concept of “routing trigger” can also be used in the ad hoc mode of HyperLAN2 (because of it is connection oriented) The concept of “routing trigger” can also be used in the ad hoc mode of HyperLAN2 (because of it is connection oriented)

18. Thank You