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Bluetooth is a short-range, packet radio system designed to connect various low power, resource constrained devices. Devices form autonomous ad hoc networks of up to 8 active devices, referred to as piconets. Piconets may be interconnected by one or more bridge devices to form a scatternet. Bridges have an added responsibility of sharing their active time between the piconets that they are connected to. This could lead to a disproportionate energy usage pattern at the bridge nodes, as compared to other nodes in the piconet. When a bridge node dies, it could create a partition in the scatternet, leading to packet loss and delays. In this paper, we consider two related issues. 1. Enhance the lifetime of the scatternet by simply improving the lifetime of the bridge. 2. Extend the lifetime of the bridge by making a fair distribution of the role of being a bridge among different devices in the piconet. To achieve these goals, we propose a policy for managing bridge devices based on both prevalent traffic conditions and the energy available at devices using a weighted credit scheme.

In this paper, we describe a novel architecture to enable a secure communication among mobile devices using different wirelesstechnologies like wireless LAN, Bluetooth, cellular systems or even infrared. Making use of the combination of these technologies for the data transmission and for the signaling of the communication, we analyze several scenarios with increasing complexity. The complete picture appears in the last scenario where all technologies are involved and the network is composed of heterogeneous mobile nodes. The paper also presents a solution for the setup of a secured communication channel (i.e. a Virtual Private Network connection) between several heterogeneous mobile nodes controlled by the cellular network operator. The mobile nodes can be either cellular aware or non-cellular aware in this framework. We propose to setup the heterogeneous network communications via the cellular network using the cellular aware nodes.

The Bluetooth standard is considered a promising technology for implementing ad-hoc networks. This paper addresses issues related to Bluetooth performance in Nakagami-m fading channels. This distribution allows a better channel characterization for mobile and wireless communications. The throughput of Bluetooth links using asynchronous packets is investigated. Useful relations between packet error rate and node distances are derived. These results can be used as benchmarks for performance analysis or incorporated into Bluetooth network simulation tools. As an example, we evaluate by computer simulation the performance of a scatternet in a Nakagami fading scenario.