Bluetooth is a highly promising, low-cost, and low-power technology for short-range wireless communication. It is intended to replace existing cables between electronic devices. Bluetooth is an open specification. Even whose MAC protocol is designed for facilitating the construction of ad hoc networks, the issue of scatternet formation is left open in the Bluetooth Specification. Several researchers have proposed various solutions to form a scatternet. But most of them focused on static environment. This investigation presents an Adaptive Scatternet Formation Scheme (ASFS) for forming a scatternet for Bluetooth devices. Unlike earlier work, the proposed method is designed to work with dynamic environment where nodes can arrive and leave arbitrarily. ASFS consists of two parts, formation and maintenance. In formation, a coordinator is used to monitor the flow of nodes (arriving and leaving). This information is then used to assign the new arrival node a suitable role (Sub-coordinator, Master or Slave) to establish the link and assign it to an appropriate piconet. In maintenance, nodes are allowed to arrive and depart arbitrarily. The proposed method can incrementally extend the topology and heal the partitions of scatternet due to nodes arriving or missing. It dynamically adjusts the scatternet to minimize the number of piconets. We employed the Network Simulator, NS-2, as the simulation and analyzed the predicted results when nodes arrive in various conditions. The simulation result demonstrates that ASFS achieves better results than TSF (Tree Scatternet Formation, the algorithm is proposed by Tan et al.[17] and works well in dynamic environment) in packet transmission time and number of the piconets. The scatternet formation time reflects the advantage of parallel formation.

Bluetooth is a low cost, low power consumption, short-range radio technology working on the 2.4 GHz frequency band. Recently, several typical polling schemes have been presented to enhance the performance on asymmetric transmissions between the master and slave. However, such polling algorithms consider only either the uplink queue or the downlink queue state for scheduling. In this paper, we propose an algorithm for Bluetooth Piconets scheduling, called the Uplink and Downlink queue Polling Scheme (UDPS). The goal of this scheduling algorithm is to alleviate the wasted bandwidth by diminishing the visit to inactive slaves. Distinguishing from previous polling schemes that have been proposed, this algorithm considers on both uplink and downlink queue states for increasing the throughput and reducing the delay time of the piconets communication. This study proposes UDPS, a new Polling Scheme for Bluetooth piconets addresses both Uplink and Downlink queues, considering to remain fair and efficient in asymmetric flow rates. Simulations confirm that the performance of the UDPS compares favorably with that of traditional polling approaches.

Bluetooth is a promising technology for short-range wireless communication and networking, mainly used as a replacement for connected cables. Since the Bluetooth specification only defines how to build a Piconet, several solutions have been proposed to construct a Scatternet from the Piconets in the literatures. The process of constructing a Scatternet is called the Scatternet formation. We find that a tree shape Scatternet, called Bluetree, has three defects: First, it lacks efficiency in routing because the Bluetree may form a skewed tree instead of a balanced tree, resulting in serious longer routing path. Second, the parent nodes in Bluetree are very likely to become the bottlenecks of communication. Third, it is not reliable. When a parent node is lost, several separate subtrees will be caused. In this thesis, we present a method that generates the Bluetree hierarchically; that is, the nodes are added into the Bluetree level by level. This hierarchical grown bluetree (HGB) topology resolves the defects of conventional Bluetree. During growing up, HGB always remains balanced so as to preserve shorter routing paths. Besides, the connections between the siblings provide alternative paths for routing. As a result, the traffic load at parent nodes can be greatly improved and only two separate parts will be induced if a parent node is lost. Better reliability is therefore achieved.

The Bluetooth wireless transmission standard provides a low-power data link between electronic devices over relatively short ranges. These links, also known as piconets, transmit using frequency hopping spread spectrum (FHSS) to send information over the air. As more applications for Bluetooth technology become available, the number of Bluetooth devices will continue to increase. With this increase in use, there will be a decrease in performance that can be attributed to Bluetooth "inter-piconet" interference. To date, very little has been published on the subject of inter-piconet interference. Previous studies have derived mean packet error rates for an increase in the number of piconets present. To come up with the mean rate, many papers make the assumption that the probability of a Bluetooth device hopping to a channel is random. However, making this assumption does not explain what happens in real time. This research gives some insight into what really happens when multiple piconets are interfering in real time. Bluetooth devices actually use a frequency hopping algorithm to determine the hopping sequence. This algorithm has been implemented in software to test various aspects of inter-piconet interference. Previous studies have shown that synchronizing the clocks among neighboring piconets will result in an increase in performance. This study shows that there are cases where synchronization alone will not provide sufficient improvement. Experimental testing has been conducted to validate some of the simulated results. Adjacent channel interference was observed during experimentation. This contradicts previous research, which has assumed that adjacent channel interference is insignificant. / Master of Science

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Bluetooth standard is intended to provide short-range (10-100 meter) wireless connectivity between mobile and desktop devices. It was developed as a replacement for short cables, and has the ability to form ad-hoc networks. This paper explores the feasibility of using Bluetooth devices for structural health monitoring telemetry applications. We describe the configuration of a small ad-hoc network using Bluetooth modules and micro-controllers to simulate a telemetry application and thus evaluate the general framework of distributed, reliable, and secure, wireless communications required for telemetry.

Bluetooth Piconet has become an important area of research and development in the short-range wireless network system. It is well known that bluetooth causes disturbing interference since sharing frequency band is used in communication channels. This thesis proposes a new and efficient method to solve the retransmission problem that occurs in wireless interference. The proposed method is developed based on average transmit times and margin of grouping to find out the grouping rule of the Bluetooth Piconet. A computer simulation shows in this thesis that the performance of the proposed group assignment approach is much bettter than can be obtained by other conventional means. Furthermore, in order to reduce retransmit time and save time-slot, a new packet combine retransmit method is developed based on different reliability of packet's transmit conditions in this thesis. As a consequence, for total duty cycle and time slots, the proposed packet combine retransmit method obtains a better performance than the conventional retransmit method.

In this paper we propose a distributed algorithm to construct a scatternet for multi-hop ad hoc networks of Bluetooth devices. This algorithm is fully distributed and does not require the nodes in the networks being in-range(i.e., each pair of nodes in the network may be unable to communicate with each other directly). The role-selection process in existing scatternet formation mostly uses the strategy of message exchange and comparing their weights like IDs or power strength. This results in a large amount of control messages to be sent and a longer scatternet formation time. In our algorithm, the role selection procedure is simple. Nodes can decide their role by a randomly generated counter rather than their ¡¥weights¡¦. According to the proposed approach, nodes can determine their role of either a master or a slave of the piconet without recognizing its neighbors¡¦ ¡¥weight¡¦. The algorithm performs better time and reduces the number of control messages remarkably during the role-selection process. In this paper, we also define the gateways of 2-hops and 3-hops for evaluating the distance between two piconets.

Bluetooth is an emerging technology for providing short range, low power, low cost, and ubiquitous wireless environments. In a Bluetooth piconet, the Bluetooth device, known as master, dynamically allocates time slots by way of polling other individual Bluetooth devices called slaves. During the polling interval, a POLL packet will be sent if master has no data to send to the slave; while a NULL packet will be sent if slave has no data to send to the master. Both the POLL and NULL packets are of zero payload and each captures one time slot. In order to avoid transmitting POLL/NULL packets, many polling schemes have been proposed by skipping visit to the slaves that might have no data packet to be sent to the master, but they still have much space to be further improved. In this thesis, we devise a new, efficient and practicable polling scheme¡XCRR (Credit-based Round Robin). In this scheme, the visit to each slave is dynamically adjusted based on the current and historical traffic between the master and slave to reduce the visit to idle slaves. CRR improves the prior polling schemes on four key issues¡GThe first is to enhance the packet transmitting rate and packet receiving rate in a unit time. The second is to avoid unnecessary POLL/NULL packets to save bandwidth and power consumption. The third is to reduce the transmission delay. The fourth is to avoid the starvation and interruption effect. Our simulation results demonstrate that CRR can enhance the throughput among various numbers of active slaves and idle slaves, can improve the transmitting rate and receiving rate of data packets, can reduce the bandwidth by diminishing the visit to idle slaves, and can decrease the packets end-to-end delay. Moreover, to restrict the number of frames exchanged during a single visit to the slave, a threshold is used to prevent the starvation and interruption effect.

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A Wireless Personal Area Network (WPAN) is an ad hoc network that consists of devices that surround an individual or an object. Bluetooth® technology is especially suitable for formation of WPANs due to the pervasiveness of devices with Bluetooth® chipsets, its operation in the unlicensed Industrial, Scientific, Medical (ISM) frequency band, and its interference resilience. Bluetooth® technology has great potential to become the de facto standard for communication between heterogeneous devices in WPANs. The piconet, which is the basic Bluetooth® networking unit, utilizes a Master/Slave (MS) configuration that permits only a single master and up to seven active slave devices. This structure limitation prevents Bluetooth® devices from directly participating in larger Mobile Ad Hoc Networks (MANETs) and Wireless Personal Area Networks (WPANs). In order to build larger Bluetooth® topologies, called scatternets, individual piconets must be interconnected. Since each piconet has a unique frequency hopping sequence, piconet interconnections are done by allowing some nodes, called bridges, to participate in more than one piconet. These bridge nodes divide their time between piconets by switching between Frequency Hopping (FH) channels and synchronizing to the piconet's master. In this dissertation we address scatternet formation, routing, and security to make Bluetooth® scatternet communication feasible. We define criteria for efficient scatternet topologies, describe characteristics of different scatternet topology models as well as compare and contrast their properties, classify existing scatternet formation approaches based on the aforementioned models, and propose a distributed scatternet formation algorithm that efficiently forms a scatternet topology and is resilient to node failures. We propose a hybrid routing algorithm, using a bridge link agnostic approach, that provides on-demand discovery of destination devices by their address or by the services that devices provide to their peers, by extending the Service Discovery Protocol (SDP) to scatternets. We also propose a link level security scheme that provides secure communication between adjacent piconet masters, within what we call an Extended Scatternet Neighborhood (ESN).