A Bluetooth ad hoc network can be formed by interconnecting piconets into scatternets. The constraints and properties of Bluetooth scatternets present special challenges in forming an ad hoc network efficiently. In this paper, we present and analyze a new randomized distributed protocol for Bluetooth scatternet formation.

With the success of wireless technologies in consumer electronics, standard wireless technologies are envisioned for the deployment in industrial environments as well. Industrial applications involving mobile subsystems or just the desire to save cabling make wireless technologies attractive. Nevertheless, these applications often have stringent requirements on reliability and timing. In wired environments, timing and reliability are well catered for by fieldbus systems (which are a mature technology designed to enable communication between digital controllers and the sensors and actuators interfacing to a physical process). When wireless links are included, reliability and timing requirements are significantly more difficult to meet, due to the adverse properties of the radio channels. In this paper, we thus discuss some key issues coming up in wireless fieldbus and wireless industrial communication systems: 1) fundamental problems like achieving timely and reliable transmission despite channel errors; 2) the usage of existing wireless technologies for this specific field of applications; and 3) the creation of hybrid systems in which wireless stations are included into existing wired systems. Keywords—Bluetooth (BT), fieldbus systems, hybrid systems, IEEE 802.11, IEEE 802.15.4, real-time communications, wireless technologies.

Abstract — A Bluetooth ad hoc network can be formed by interconnecting piconets into scatternets. The con-straints and properties of Bluetooth scatternets present special challenges in forming an ad hoc network efficiently. In this paper, we present and analyse a new randomized distributed algorithm for Bluetooth scatternet formation. We prove that our algorithm achieves O(logn) time com-plexity and O(n) message complexity. We show that, 1) in the scatternet formed by our algorithm, any device is a member of at most two piconets; and 2) the number of piconets is close to be minimal. I.

This paper presents a probabilistic treatment of the performance of a Bluetooth piconet under cochannel interference from other Bluetooth piconets. An upper bound on the packet error rate of a link is given, as well as a lower bound on the aggregated throughput of collocated piconets.

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.

Networks. A scatternet is an ad hoc network created by interconnecting several Bluetooth piconets, each with at most eight devices. Each piconet uses a different radio channel constituted by a frequency hopping code. The way the devices are grouped in different piconets and the way the piconets are interconnected greatly affect the performance of the scatternet in terms of capacity, data transfer delay, and energy consumption. There is a need to develop distributed scatternet formation algorithms, which guarantee full connectivity of the devices, reconfigure the network due to mobility and failure of devices, and interconnect them such a way to create an optimal topology to achieve gainful performance. The contribution of this paper is to provide an integrated approach for scatternet formation and quality-of-service support (called SHAPER-OPT). To this aim, two main procedures are proposed. First, a new scatternet formation algorithm called self-healing algorithm producing multihop Bluetooth scatternets (SHAPER) is developed which forms tree-shaped scatternets. A procedure that produces a meshed topology applying a distributed scatternet optimization algorithm (DSOA) on the network built by SHAPER is then defined. Performance evaluation of the proposed algorithms, and of the accordingly created scatternets, is carried out by using ns2 simulation. Devices are shown to be able to join or leave the scatternet at any time, without compromising the long term connectivity. Delay for network setup and reconfiguration in dynamic environments is shown to be within acceptable bounds. DSOA is also shown to be easy to implement and to improve the overall network performance. Index Terms—Bluetooth, multihop ad hoc networks, scatternet formation, topology optimization. I.

provides wireless solutions applicable for a number of com-munications needs. In addition, multiple independent piconets are possible and likely to occur within the same location, either intentionally or by chance. Bluetooth devices utilize frequency hopping and independent piconets operate on different hopping sequences. Although the use of independently selected hopping sequences reduces the likelihood of mutual interference, as the number of colocated piconets increases, mutual interference becomes more likely. Mutual interference is also dependent on the performance requirements dictated by the application utilizing Bluetooth technology as well as the environment in which the piconet is operating. A method for analytically evaluating mutual interference for Bluetooth technology is presented. Models were developed for a single Bluetooth interferer as well as multiple interfering Bluetooth piconets operating in an arbitrary environ-ment. The analytical models are based on two sets of parameters: Bluetooth interference and radio propagation. Empirical tests have been conducted to both support the derivation of the an-alytical models as well as to substantiate the analytical model results. The analytical results fall within the 95 % confidence bounds of the empirical test results. Mutual interference analysis is presented based on evaluating the analytical model over a wide range of the multidimensional parameter space. The analytical model presented is a general approach well suited for evaluating mutual interference for applications using Bluetooth for data communications. Index Terms—Analytical model, Bluetooth, interference, WPAN.

In this paper we propose a simple method to evaluate the impact of fading and inter-piconet interference on Bluetooth performance. We consider in detail the joint effect, on packet error statistics, of interference produced by adjacent Bluetooth piconets and fading. Hence, we illustrate the proposed method by investigating the potential performance tradeoff among the different radio packet formats supplied by Bluetooth, as a function of the radio channel conditions and interference levels.

Bluetooth ad hoc networks are constrained by a master/slave configuration, in which one device is the master and controls the communication with the slave devices. The master and up to seven active slave devices can form a small Bluetooth network called a piconet. In order to build larger network topologies, called scatternets, the piconets must be interconnected. Scatternets are formed by allowing certain piconet members to participate in several piconets by periodically switching between them. Due to the fact that there is no scatternet formation procedure in the Bluetooth specification, numerous different approaches have been proposed. We discuss criteria for different types of scatternets and establish general models of scatternet topologies. Then we review the state-of-the-art approaches with respect to Bluetooth scatternet formation and compare and contrast them.

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