| In recent years, there has been a lot of research on the topic of routing
in ad hoc networks, but the topic of topology creation has not received
due attention. This is because almost all ad hoc networks to date have
been built on top of a single channel, broadcast based wireless media,
such as 802.11 or IR LANs. For such networks the distance relationship
between the nodes implicitly (and uniquely) determines the topology of
the ad hoc network. Bluetooth is a promising new wireless technology, which
enables portable devices to form short-range wireless ad hoc networks and
is based on frequency hopping physical layer. This fact implies that hosts
are not able to communicate unless they have previously discovered each
other by synchronizing their frequency hopping patterns. Thus, even if
all nodes are within direct communication range of each other, only those
nodes which are synchronized with the transmitter can hear the transmission.
To support any-to-any communication, nodes must be synchronized so that
the pairs of nodes (which can communicate with each other) together form
a connected graph. Using Bluetooth as an example this paper first provides
deeper insights into the issue to link establishment in frequency hopping
wireless systems. It then introduces an asynchronous distributed protocol
for constructing scatternets which starts with nodes that have no knowledge
of their surroundings and terminates with the formation of a connected
network satisfying all connectivity constraints posed by the Bluetooth
technology. To the best of our knowledge, the work presented in this paper
is the first attempt at building Bluetooth scatternets using distributed
logic and is quite “practical” in the sense that it can be implemented
using the communication primitives offered by the Bluetooth 1.0 specifications. |