Bluetooth: Architecture, Protocols and Scheduling Algorithms

Abstract

The paper focuses on one of the emerging technologies for constructing a Mobile ad hoc network: Bluetooth. Bluetooth can be exploited on small scales, to build ad hoc wireless Personal Area Networks (WPAN), i.e., networks that connect devices placed inside a circle with radius of 10 m. The Bluetooth technology is just starting to appear on the market and its architecture and protocols are not widely known. For this reason, the first part of the paper contains a tutorial-oriented description of the Bluetooth architecture and protocols. In addition, in the paper we extensively discuss the performance of this technology by investigating, through simulation, the main performance figures: the protocol efficiency (channel utilization), the response time, and the system power (i.e., the ratio between throughput and delay). Specifically, the performance analysis focuses on the algorithms for scheduling the transmissions in a Bluetooth network. The Bluetooth Specification indicates a Round Robin scheduler as possible solution, that is each slaves is polled in a consecutive order. For this reason, we first study in depth the performance figures of a Bluetooth network with a Round Robin scheduler. Our results point out the inefficient Bluetooth behavior under asymmetric traffic conditions. To solve this problem we propose and analyze an innovative scheduling algorithm specifically tailored to the Bluetooth characteristic. This algorithm, named efficient double-cycle (EDC), dynamically adapts the polling frequency to the traffic conditions. A performance study indicates that our EDC scheduler always outperforms the Round Robin scheduler.