Dynamic Topology Construction in Bluetooth Scatternets Mukesh Kumar : Dept. of CSE, I.T.B.H.U, Varanasi Navin K Sharma : Computer Associates, Hyderabad Rajarshi Roy : Dept. of ECE, IIT Kharagpur Shamik Sural : School of IT, IIT Kharagpur

Introduction Bluetooth Technology Piconet and Scatternet Master, Slave and Bridge Frequency Hopping Synchronization with Master Power Constraint Scatternet Formation Algorithms: Bluetooth Topology Construction Protocol (BTCP), Distributed Tree Scatternet Formation Protocol (DTSFP), Bluetree and Bluenet Protocol, etc.

Continued……. Few Commonalities : -> Assumption of a leader election process -> Topology optimization starting with a fixed set of Bluetooth nodes -> Deferring the problem of topology reconstruction as a future extension -> Approach the topology construction problem as a stand-alone problem and not as an outcome of specified properties of Bluetooth nodes Dynamic Topology Construction : -> Bottom up Approach -> Dynamic approach instead of one-time stand alone approach -> Topology formation specific properties integrated with the normal operations of Bluetooth nodes -> A practical approach

Dynamic Topology Construction Algorithm Attempts to form fully connected and balanced network Fault Tolerant Network Four roles are defined: -> Isolated (I) -> Master (M) -> Slave (S) -> Bridge (B) The complete algorithm consists of five routines: -> Start-Up Routine (SUR) -> Next State Routine (NSR) -> Piconet Formation and Modification Routine (PFMR) -> Scatternet Formation and Modification Routine (SFMR) -> Normal Communication Routine (NCR)

Continued…. Each routine resides within every Bluetooth device and gets called depending on the current role of the device and discovery of other devices. Certain Terminologies used for smooth progression of algorithm: -> PI : probability with which an isolated node goes to Inquiry state -> PM : probability with which a master goes to Inquiry state -> TI : time for which a node will stay in Inquiry state -> TIS : time for which a node will stay in Inquiry Scan state -> P(i) : Piconet containing node i -> B(i,j) : Bridge node between two piconets having node i and j as their master -> NBS(i) : Total no. of non bridge slaves of the piconet whose master is i. -> n(i) : Total no. of slaves of the piconet whose master is i. -> F(mi,pi) : A function of the memory ‘m’ and power ‘p’ of a node i.

Start-up Routine(SUR)

Piconet Formation and Modification Routine (PFMR)

Isolated Node (Inquiry) Isolated Node (I-Scan) M 1 S 1 M 2 S 2 S 3 S 4 S 1 S 2 S 4 M 2 S 5 S 3

Scatternet Formation and Modification Routine (SFMR)

M 1 S 1 S 2 M 2 S 4 S 3 S 6 S 5 S 7 M 1 S 5S 1 S 2 M 2 S 3 S 6 S 4 S 7

M 3 S 8 S 9 S 10 M 1 S 5 S 1 S 2 M 2 S 3 S 6 S 4 S 7 M 1 S 5 S 1 S 2 M 2 S 3 S 6 S 4 S 7 M 3 S 8 S 9 S 10

M 1 S 5 S 1 S 2 M 2 S 3 S 6 S 4 S 7 M 3 S 8 S 9 S 10 M 4 S 11 M 1 S 5 S 1 S 2 M 2 S 3 S 6 S 4 S 7 M 3 S 8 S 9 S 10 S 11 S 12

Simulation Results

Conclusions and Future Scope This algorithm address a dynamic scenario Balanced and minimum hope connectivity Minimize inter piconet communication delay No need of leader election Distributed and fault tolerant Very low computational cost An efficient scheduling and routing algorithm can be incorporated

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