Ad-hoc network construction with bluetooth

Abstract

Bluetooth is a wireless personal area network standard with frequency hopping technology over the 2.4 GHz band. At most 8 devices are synchronized in one piconet, which is sometimes used as a building block for a larger network, called scatternet. A piconet is composed of a master, which is a predetermined central coordinator, and slaves. In spite of the asymmetrical architecture of Bluetooth, some symmetric applications, such as exchanging multi-media name cards between portable devices and on-line games among nodes in sights, are promising, which need a symmetric connection establishment scheme. However, the current Bluetooth specification requires an asymmetrical connection and its connection delay may be intolerably high for the aforementioned applications. In this dissertation, we propose a random inquiry procedure that allows a symmetrical connection between a pair of nodes. Each party flips its state between the master and the slave until a successful match is found. We have adopted several optimizations on Bluetooth inquiry for quick connections between nodes. Moreover, we find the optimal state transition strategy through the analysis. Numerical results show that expected inquiry success time can be as low as about 30 ms with our random inquiry, which is small enough for name card exchange. Based on the above random inquiry scheme, we present an extended random inquiry scheme for multi-party, named Murani, for exchanging materials among several people and wireless on-line gaming among nodes in proximity. Murani makes no connection between nodes until the unique leader election and the neighbor discovery. It speeds up the connection when small number of nodes participate in a transaction. We analyzed the time needed for the procedure with Markovian chain model. With 1.8 s for timeout, 99.9% of inquiries succeed for 40 nodes. The original Murani performs better with up to 30 nodes than the conventional schemes in average, while contention-controlle...