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Bluetooth provides wireless networking among proximate nodes. The Bluetooth nodes are usually battery-powered, which puts a strong demand on the design of energy-efficient network structures. In the conventional piconets and scatternets, the roles of master, slave, and bridge are assigned to the nodes in a semi-static manner. This produces unfairness, since the master and bridge roles have higher activity and thus higher energy consumption. The logical piconet/scatternet structure decreases the energy efficiency by requiring packet forwarding even when a direct wireless link is possible. In this paper, we propose Blue-Park, a flexible networking structure that achieves energy efficiency and fairness, without requiring change to the Bluetooth Specification. Blue-Park utilizes the Bluetooth park mode and can be described as a self-referencing structure, where each node parks all the other nodes as a master. The packets are exchanged between nodes with dynamic park/unpark procedures, which results in dynamic role assignment. We evaluate the Blue-Park in two scenarios - comparison with a piconet and comparison with a scatternet among nodes that are physically within a single hop. The simulation results show that, when the incoming traffic at each device is bursty, in both scenarios Blue-Park can achieve higher energy efficiency and lifetime. Furthermore, the delay is not increased significantly due to the dynamic link establishment.

Emerging indoor technologies including wireless multimedia and personal area networks (WPANs) entail high-rate systems capable of supporting multiple users (piconets) with variable rates. These requirements motivate the design of multiband (MB) ultra-wideband (UWB) radios for their simplicity in handling pronounced frequency selectivity, agility in coping with interference, scalability in providing multirate operation, and their potentially low cost. Relative to baseband UWB radios, MB-UWB systems have gained popularity in the IEEE standards for short-range wireless links. However, multiple-access (MA) schemes must be designed carefully to harness the diversity benefits provided by the MB-UWB propagation, in a spectrally efficient manner. To this end, we introduce a crossband flexible UWB MA scheme for multipiconet WPANs. The resultant design that we term FLEX-UWB offers resilience to multiuser interference, can conveniently accommodate various spreading alternatives, enables full multipath diversity, and can effect scalable spectral efficiency (from low to medium and high data rates). Simulations confirm the merits of FLEX-UWB radios in comparison with various alternatives

In this paper, we focus on the Bluetooth wireless network, analyzing its ability to support the Quality of Service (QoS) requirements defined by QoS sensitive applications. The QoS perceived by the application depends on the scheduling mechanisms chosen at the medium access layer. Hence, we propose to evaluate the ability of different Bluetooth scheduling algorithms (1-RR/FIFO, 1-RR/EDF, E-RR/FIFO and E-RR/EDF) to guarantee bounded transmission delays. First, we establish a bound on the worst case response time of any sporadic message using a worst case analysis. We then compare the computed bounds with the worst case response times obtained by simulation for different traffic distributions and show in which configurations our bounds are tight. We finally compare those different schedulings and show how to extend our results on worst case response times taking into account message segmentation.

Bluetooth is a radio technology for wireless personal area networks in the 2.4 GHz ISM frequency band and allows short-range devices to be connected in the form of ad hoc networks. The Bluetooth medium access control protocol is based on a strict master/slave concept wherein any communication between slave devices has to go through the master. While this model is simple, the use of such a nonoptimal packet forwarding scheme incurs much longer delays between any two slave-devices as double the bandwidth is used by the master. In addition, if two or more devices want to communicate as a group, this can only be achieved by either multiple unicast transmissions or a piconet-wide broadcast from the master. To handle these issues efficiently, we propose a novel combination of dynamic slot assignment (DSA) and piconet partitioning. With DSA, the piconet master dynamically assigns slots to slaves so as to allow them to communicate directly with each other without any intervention from the master. Our proposed communication architecture provides for enhanced quality of service (QoS), better admission control, and multidevice conversation, which make a multicast-like communication feasible within the piconet. To widen the scope of DSA, we propose a QoS-aware enhanced DSA (EDSA) version where dynamic piconet partitioning and scatternet support are exploited by grouping devices into piconets as per their connection endpoints, enabling it to be employed over a scatternet. We have performed extensive simulations and observe that these schemes drastically enhance Bluetooth performance in terms of the delay and the throughput, while significantly reducing the network power consumption

Bluetooth is a most promising technology for the wireless personal area networks and its specification describes how to build a piconet. Though the construction of scatternet from the piconets is left out in the specification, some of the existing solutions discuss the scatternet formation issues and routing schemes. Routing in a scatternet, that has more number of hops and relay nodes increases the difficulties of scheduling and consumes the bandwidth and power resources and thereby impacts on the performance of the entire network. In this paper, a novel routing protocol (LARP) for the Bluetooth scatternet is proposed, which reduces the hop counts between the source and the destination and reconstructs the routes dynamically using the location information of the Bluetooth devices. Besides, a hybrid location-aware routing protocol (HLARP) is proposed to construct the shortest routes among the devices with or without having the location information and degenerate the routing schemes without having any location information. Experimental results show that our protocols are efficient enough to construct the shortest routing paths and to minimize the transmission delay, bandwidth and power consumption as compared to the other protocols that we have considered.

Bluetooth networks can be constructed as piconets or scatternets depending on the number of nodes in the network. Although piconet construction is a well-defined process specified in Bluetooth standards, scatternet formation policies and algorithms are not well specified. Among many solution proposals for this problem, only a few of them focus on efficient usage of bandwidth in the resulting scatternets. In this paper, we propose a distributed algorithm for the scatternet formation problem that dynamically constructs and maintains a scatternet based on estimated traffic flow rates between nodes. The algorithm is adaptive to changes and maintains a constructed scatternet for bandwidth-efficiency when nodes come and go or when traffic flow rates change. Based on simulations, the paper also presents the improvements in bandwidth-efficiency and reduction in energy consumption provided by the proposed algorithm. © 2006 IEEE.

The Bluetooth discovery process requires use of the inquiry substate which not only consumes significant power, but prevents normal data traffic flow and simultaneously acts as a potential noise source for neighboring networks. Therefore, the inquiry substate dwell time should be limited to discovering an acceptable number of neighboring devices. Although an estimate of the probability density function of the time to discover scanning devices is straightforward, the complex temporal and spectral interactions between two devices make precise inquiry time characterization difficult. We characterize these interactions and derive detailed analytical expressions for the probability distribution of the inquiry time for a Bluetooth-enabled device that follows v1.1 of the Bluetooth specification and uses the default 11.25 ms inquiry scan window that opens every 1.28 s. Subsequently, we show a single inquirer will locate 99 percent of all scanning devices within transmission range in 5.12 seconds rather than the 10.24 s recommended in the specification. Using specification v1.2, we show that the inquiry time can be reduced to 3.84 seconds and 1.28 seconds using the standard and interlaced inquiry scan modes, respectively. Substantial inquiry time reduction results in reduced power requirements and increased throughput by increasing data traffic and reducing interference with neighboring piconets. Our results are validated via comparison with existing simulation models and measurement studies. The models used to derive the distribution also lend themselves to characterizing the discovery time with variations in the discovery process

In this letter, we propose a symbol repetition technique combined with parallel channel encoding for multiband orthogonal frequency division multiplexing systems with ultra wideband channels. It can resolve timing asynchronous cochannel interference from another simultaneously operating piconet. Our simulation results demonstrate that the proposed scheme can effectively reduce the effect of the interference.

Bluetooth is a low cost, low power, short-range radio technology used for wireless personal area networks (PANS). Bluetooth scatternet is a set of piconets interconnected via bridge devices. Good interpiconet schedulings are necessary for bridge devices to switch among piconets they participate in. This paper proposes an interpiconet scheduling algorithm named "Traffic-Aware Scatternet Scheduling" (TASS), for bridges in Bluetooth scatternets. According to masters' traffic information, TASS can adaptively switch the bridge to high traffic load masters, and increase the usage of the bridge. In addition, TASS can reduce the number of failed "unsniffs" and the overhead of "bridge switch wastes" to further increase overall system performance. Simulation results show that TASS outperforms existing interpiconet scheduling in both network throughput and adaptability for various traffic loads.

We propose a statistical multiplexing-based hybrid frequency-hopping orthogonal frequency-division multiple-access (HFH-OFDMA) system to increase the downlink user capacity of orthogonal frequency-division multiplexing (OFDM)-based ultra-wideband (UWB) indoor radio access networks (RANs). The downlink user capacity is here defined as the maximum allowable number of users served with a given data rate in a piconet. Statistical multiplexing, as noted by Walrand and Varaiya in 2000, is a method in which multiple users with intermittent transmissions efficiently share a link. The adoption of a statistical multiplexing concept enables the HFH-OFDMA system to accommodate many more users than the conventional FH-OFDMA system can. In OFDM-based UWB indoor RANs, the downlink user capacity of the HFH-OFDMA system is limited by either the total number of available subcarriers in a piconet (resource-limited) or the FCC UWB emission limit (power-limited). We analyze the downlink user capacity of the proposed HFH-OFDMA system in both single-piconet and multipiconet environments. In the single-piconet environment, the proposed HFH-OFDMA system which operates in 3.168-3.696-GHz band accommodates 256 users with a data rate of 532.5 kb/s in an OFDM-based UWB indoor RAN, while the proposed HFH-OFDMA system in the multipiconet environment, under the same conditions of the single-piconet environment, accommodates 110 users with a data rate of 532.5 kb/s.

Designed for high data rate wireless personal area networks, the IEEE 802.15.3 medium access control (MAC) protocol fits well with emerging technologies like ultra-wideband. Peer discovery is essential in 802.15.3 piconets in w3:22 hich devices (DEVs) exchange MAC frames in a peer-to-peer manner. If two peer DEVs are unreachable, the standard peer discovery method will fail after unproductive backoff retransmissions, and a costly network layer routing is required. For DEVs uniformly distributed over the maximum coverage area of a piconet, such failures occur in up to 41.3% of intra-piconet peer discoveries. In this paper, we propose a novel third-party handshake protocol (3PHP) that provides more reliable and prompt peer discovery than the standard method. Especially, between directly unreachable DEVs within the same piconet, 3PHP replaces network layer routing by an efficient MAC layer forwarding that utilizes the available self-learning rate information to establish optimal routes. The mean peer discovery time for 3PHP is 100 µs lower than the standard method between directly reachable DEVs. More significantly, between directly unreachable DEVs within the same piconet, 3PHP has a much lower failure probability, and is up to 10 times faster than the standard method in establishing a peer-to-peer connection as the latter fails and network layer routing is invoked.

The engines in vehicles today are smaller in size and lighter in weight but are still required to produce high output power. These characteristics have been found to induce thermal problems in the engine. In solving this thermal problem, temperature measurement in the piston of the engine plays an important role. However, owing to the environment of the piston, it is difficult to measure the temperature in the piston. Thus, developing a method to measure the temperature of the piston is currently an important research topic. This paper presents a piston temperature telemetry system that was developed using Bluetooth. This system is advantageous in that it makes it possible to measure multipiston temperature using a Bluetooth wireless network, which is an area that has yet to be investigated in more depth. The telemetry system is composed of the piston part and the data acquisition part. To evaluate the performance of the telemetry system, experiments were conducted using a 2359 cm31 DOHC engine produced by the Hyundai Motor Company. The experimental results show that the piston telemetry system is applicable to real commercial engines for measuring piston temperature.

Bluetooth technology permits wireless interconnection for local area communication. While the specification defines how up to eight devices can connect using the same radio channel to form a piconet, piconets may overlap, permitting the formation of much larger networks called scatternets. To create connected scatternets, a wide range of decentralized protocols (algorithms) have been proposed. In this paper we address the centralized optimization of topological characteristics that affect scatternet performance. Knowledge of optimized scatternet topology is useful when comparing decentralized protocols and the scatternets they produce. This paper introduces the first multiple objective optimization framework for scatternets, which operates by optimizing node sequencings that represent scatternets. Using NSGA-II, the framework is described, tuned and applied to determine the trade-offs between competing optimization objectives. Finally, the results are used to benchmark the performance and characteristics of four existing protocols from the literature.

In network with a shared channel in TDMA mechanism, it is a core issue to effectively allocate channel time to provide service guarantees for flows with QoS requirements. This paper proposes a simple and efficient time allocation scheme called MES-ESRPT (MCTA at the End of Superframe-Enhanced Shortest Remaining Processing Time) for delay-sensitive VBR traffic in accordance with IEEE 802.15.3 standard. In this algorithm, PNC (piconet coordinator) allocates one MCTA (Manage- ment Channel Time Allocation) for each stream which is the process of communication at the end of superframe. During the MCTA period, each transmitter should report current fragments number of the first MSDU (MAC Service Data Unit) and the fragments number of the remainder MSDUs to PNC. In the next superframe, PNC firstly allocates part CTAs (Channel Time Allocation) for each stream based on the remainder fragments number of the first MSDU by SRPT rule, then allocates remainder CTAs for each stream based on all fragments number of remainder MSDUs by the same SRPT rule. Simulation results showed that our proposed MES-ESRPT method achieves significantly better performance in QoS for multimedia streams compared to the existing schemes.

Bluetooth is one of the cable-replacement technologies. It uses short-range radio links to replace connecting cables. Bluetooth enables portable devices to form short-range wireless ad hoc networks. A set of Bluetooth devices sharing a common channel can form a personal area network called a piconet. Several piconets can also be interconnected to establish a scatternet. Zaruba, Basaghi and Chlamtac proposed a mechanism for forming a distributed scatternet called the Bluetree. The algorithm is based on selecting an arbitrary node serving as the Blueroot. The Blueroot initiates the construction of the Bluetree. Though the algorithm is very simple, there are some weak points. For example, being a tree limits its routing choices. There are also the problems of overloading on the Blueroot and the many master/slave bridges on any routing path. In this paper, we will improve the weaknesses of Bluetree by eliminating the bottleneck in the Blueroot and by reducing the number of bridges to half for almost any path. We call the new algorithm Bluegon since polygons (cycles) will be formed in the scatternet. Simulation results indicate the efficiencies of our algorithm. Copyright © 2006 John Wiley & Sons, Ltd.

Recent updates of the Bluetooth specification have introduced significant changes in the Bluetooth protocol stack, including optional flow control. When the Bluetooth piconet is used to carry TCP traffic, complex interactions between TCP congestion control mechanisms and data link layer controls of Bluetooth will occur. In this paper, we model the performance of the piconet with TCP traffic, expressed through segment loss probability, round-trip time, and goodput, through both probabilistic analysis and discrete-event simulations. We show that satisfactory performance for TCP traffic may be obtained through proper dimensioning of the Bluetooth architecture parameters. Copyright © 2006 John Wiley & Sons, Ltd.

The packet error rate between two piconets depends on the temporal alignment of their packets and the spectral alignment of the intervals from which the frequencies in their hop sequence are chosen. The relationship between two randomly paired piconets is one of over 828 billion possible relationships. We define these relationships and derive an expression for determining the packet error rate for a specific pair of piconets using single-slot packets. We derive the probability mass function for the packet error rate and extend it to provide the possible packet error rates for an arbitrary number of neighboring piconets. We also derive a probability mass function for the goodput of a piconet with a neighboring piconet. The probability mass functions for the packet error rate is bimodal, meaning the expected value of the goodput or packet error rate is not a good choice for piconet performance analysis.

If the PNC is shutting down or wants to leave the WPAN, it uses the handover process to give control to another device in the piconet. However when the PNC is selected, only the device capability information is checked in the WPAN standard specification and no detail criteria is described. In this paper, the PNC selection method with considering the number and density of device to maximize the piconet data throughput in the WPAN is studied. From the numerical analysis results, the considering with the devices concentration has higher data throughput compared with the uniform distribution. For the efficient performance, the device distribution within the piconet should be considered in the PNC selection.

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.

In wireless personal area networks (WPANs), the successful design of channel time allocation algorithm is a key factor in guaranteeing the various quality of service (QoS) requirements for the stringent real-time constraints of multimedia services. In this paper we propose a dynamic channel time allocation algorithm for providing delay guarantees to multimedia traffics such as MPEG streams in the IEEE 802.15.3 high-rate WPANs. The dynamic algorithm exploits the characteristics of MPEG stream, wherein devices (DEVs) send their channel time requests near at the end of superframe. The algorithm uses mini packets for feedback control in order to deliver dynamic parameters for channel time requests from DEVs to the piconet coordinator (PNC). In this scheme, the duration of channel time allocated to a DEV during a superframe is changed dynamically depending on the MPEG frame type, traffic load and delay bound of the frame, etc. Performance of the proposed scheme is investigated by simulation. Our results show that compared to conventional scheme, the proposed scheme is very effective and has high performance while guaranteeing the delay bound.

PurposeTo present a combination of Bluetooth handoff techniques and scatternet formation to adapt to varying topologies and traffic changes.Design/methodology/approachThrough ad hoc networking with Bluetooth, devices could participate in multiple piconets, which form the scatternet. Although the details of scatternet implementation are not specified in the Bluetooth specification, much research has been carried out to propose different models of implementation. This paper presents a combination of the techniques of handoff and scatternet formation to adapt to varying topologies and traffic changes. Analysis of network performance is presented to confirm the feasibility of real implementation.FindingsProvides a novel and practical design, compatible with Bluetooth specification, which is shown by experimental results to be an efficient design in providing a scatternet formation approach, while at the same time maintaining a low data error rate to support data and voice.Originality/valueThis paper presents Bluetooth handoff and scatternet formation techniques to extend geographical coverage and increase system capacity with adaptation to varying topologies and traffic changes. The techniques presented are compatible with Bluetooth specifications 1.0, 1.1 and 1.2.

This article deals with the performance of Bluetooth scatternets in a real-life environment where different queues are implemented with finite buffers. Finite buffer size will introduce packet blocking at different queues along the packet path, which in turn causes changes in effective traffic load as well as retransmissions and ultimately affects end-to-end packet delays. The authors assume that the piconet masters use E-limited intra-piconet polling, while bridge scheduling is performed using the walk-in approach without rendezvous points. They present a detailed simulation model that allows them to obtain accurate measurements of blocking probabilities, end-to-end-packet delays, and overall throughput in the network as functions of network and device parameters. Some practical recommendations about the buffer size that will keep the blocking probability within reasonable limits are also given.

In this article, the authors shall propose a new method for the implementation of secure Bluetooth piconets. Two requirements for the systems must be considered, i.e., privacy and authentication. Privacy ensures that an eavesdropper cannot intercept conversations between two slaves in piconets. Authentication ensures that service is not obtained fraudulently in order to avoid charge for usage. Additionally, a new key distribution scheme is designed for practical implementation in low-cost and low-power Bluetooth piconets. The proposed method employs elliptic curve cryptography for the use in the Bluetooth network. We have proper solutions to Bluetooth devices registration and Bluetooth piconets establishment. Furthermore, compared with Seo and Lee's protocol, the proposed scheme has a lower computation cost.

Bluetooth is a promising short-range wireless communication technology with the characteristics of interference resilience and power efficiency, both desirable for wireless sensor networks. The new Intel Mote sensor devices have Bluetooth technology incorporated as the standard wireless communications interface. When using Bluetooth in applications where multihop routing is required, groups of Bluetooth piconets combine together to form a scatternet. However, most of the existing scatternet formation protocols are designed to facilitate communications between any two pairs of devices, regardless of the actual traffic demand pattern. For wireless sensor network applications with low-duty-cycle traffic patterns, an on-demand scatternet formation protocol can achieve significant power saving by avoiding unnecessary network connectivity. To that end, we introduce an on-demand scatternet and route formation protocol designed specifically for Bluetooth-based wireless sensor networks. Our protocol builds a scatternet on demand, and is able to cope with multiple sources initiating traffic simultaneously. In addition, our energy-aware forwarding nodes selection scheme is based on local information only, and results in more uniform network resource utilization and improved network lifetime. Simulation results show that our protocol can provide scatternet formation with reasonable delay and good load balance, which results in prolonged network lifetime for Bluetooth-based wireless sensor networks.

Bluetooth scatternets may be operated in a loosely coupled mode, called Walk-In Bridge Scheduling, in which the master polls all of its slaves and bridges using E-limited service. Using the theory of queues with vacations, we derive the stability criteria for packet queues in piconet masters, slaves, and bridges. We show that the stability of the slave queues is more critical under high traffic locality, whereas the stability of the bridge queues becomes progressively more important as the non-local traffic increases. Our analysis shows that the limited exchange mode, in which the bridge residence time in a piconet is limited, performs better and has a wider stability region than the complete exchange mode in which the bridge stays in the piconet until all queued packets are exchanged. Simulations show that this scheduling approach offers good performance and excellent scalability, while maintaining scatternet stability.

This paper describes the issue of piconet interconnection for Bluetooth technology. These larger networks, known as scatternets, have the potential to increase networking flexibility and facilitate new applications. While the Bluetooth specification permits piconet interconnection, the creation, operation and maintenance of scatternets remains open. In this paper, the research contributions in this arena are brought together, to give an overview of the state-of-the-art. First, operation of the Bluetooth system is explained, followed by the mechanism for link formation. Then, the issue of piconet interconnection is considered in detail. Processes for network formation, routing and intra- and inter-piconet scheduling, are explained and classified. Finally, the research issues arising are outlined.

Bluetooth is a short-range ad hoc networking technology, which enables formation of inexpensive personal area networks with low power consumption. Using Bluetooth technology, a small number of closely located devices can be interconnected within a piconet. Building larger ad hoc networks is possible by interconnecting multiple piconets to form a scatternet. As the Bluetooth topology grows from isolated piconets to a scatternet, energy-efficiency becomes a critical issue since additional power is consumed for multi-hop routing. A scatternet should be formed in such a way that batteries of mobile devices are efficiently used in order to lengthen scatternet lifetime. We discuss the problem of energy-efficient topology construction and maintenance for Bluetooth scatternets. An energy-efficient, distributed Bluetooth Scatternet Formation algorithm based on Device and Link characteristics (SF-DeviL) is presented. SF-DeviL forms scatternets with tree topologies and increases battery lifetimes of devices by using device types, battery levels and received signal strengths. The topology is dynamically reconfigured in SF-DeviL so that energy efficiency is maintained during the lifetime of the scatternet. It is shown through simulations that even without performing reconfiguration the network lifetime is increased by at least 229% compared to LMS algorithm and increased by at least 10% compared to BlueMesh algorithm in heterogeneous networks. (C) 2004 Elsevier B.V. All rights reserved

In a Bluetooth piconet, the Master essentially controls the channel. Due to an absence of coordination between independent Masters while accessing the wireless medium, devices will encounter high packet interference if several piconets are simultaneously operating in the same area. Since even a headset and a mobile phone can be connected with a Bluetooth link forming a piconet, it may not be unusual to find tens of independent piconets in crowded places like airports, international conferences, shopping malls, and so on. Study of packet interference is important because interference affects the throughput of a piconet. Motivated by the fact that applications will benefit, in terms of higher available data rate in one direction, by using multiple-slot packets in an asymmetric manner, in this paper, we present an analytical model of packet interference in a cluster of piconets using multiple-slot packets. Also, considering that all the portable devices can have a Bluetooth interface and people are highly mobile these days, it will not be uncommon to find a cluster of piconets of both the 79-hop and the 23-hop types in the same area. We then present an analytical model of interference of multiple-slot packets in a heterogeneous cluster of Bluetooth piconets. By a heterogeneous cluster we mean some piconets are of the 23-hop type and the rest are of 79-hop type. We show how the aggregate throughput in a cluster of piconets degrade under various traffic scenarios, such as 1-slot, 3-slot, and 5-slot packets in symmetric and asymmetric modes in synchronous and asynchronous conditions of Master clocks. Our analytic model is based on the idea of probabilistic graphs, where a node denotes a piconet and an edge denotes the probability of interference between two nodes. Though the 23-hop system has been phased out, our work gives a general approach to model packet interference in multiple, frequency-hopping systems that need not be Bluetooth systems.

Bluetooth is a low-power, low-cost, short-range wireless communication system operating in the 2.4-GHz industrial, scientific, and medical (ISM) band. Bluetooth links use frequency hopping whereby each packet is sent on a single frequency while different packets are sent on different frequencies. Further, there are a limited number of packet sizes. We show that we can exert indirect control over transmission conditions by choosing the packet size transmitted over each frequency as a function of the channel conditions. Our goal then is to provide a packet-size-selection algorithm that can maximize the throughput in a Bluetooth piconet in the presence of lossy wireless channels. We first develop a renewal-theory-based mathematical model of packet transmission in a frequency-hopping system such as a Bluetooth piconet. We use this model to show that a threshold-based algorithm for choosing the packet lengths maximizes the throughput of the system. We provide an algorithm that determines the optimal thresholds efficiently. We show the optimality of this algorithm without using standard optimization techniques, since it is not clear that these techniques would be applicable given the functions involved. Using simulations, we observe that this strategy leads to significantly better throughput as compared to other baseline strategies, even if the assumptions made to prove optimality are relaxed.

Topology of a network greatly affects the network performance. Depending on the purpose of a network, a specific topology may perform much better than any other topologies. Since the ad hoc networks are formed for a specific purpose, determining, and constructing the network topology based on the application requirements will enhance system performance. This paper proposes Bluetooth scatternet forming protocol in which the network topology is determined by three parameters. The parameters affecting the topology are the number of maximum slaves in a piconet, the number of maximum piconets that a gateway Bluetooth device can service, and the number of loops needed in the formed scatternet. These parameters can be read from a script file prior to the network formation. This process of reading the important parameters from the file would give users freedom in determining the network topology. The proposed protocol also includes a role negotiation process to accommodate different capabilities of the participating devices. The negotiation process of the protocol allows the resource-limited nodes to participate in the network. Different types of scatternet topologies like star, mesh, ring and line can be formed by specifying the parameters. This paper also discusses theoretical information necessary for calculating network topologies in detail. The protocol is verified with help of simulations, and implementations using commercially available Bluetooth devices. The detailed results are also presented in this paper.

Bluetooth is a radio technology for Wireless Personal Area Networking (WPAN) operating in the 2.4GHz ISM frequency band, and allows devices to be connected into short-range ad hoc networks. The Bluetooth medium access control protocol is based on the Master/Slave paradigm wherein any communication between slave devices has to go through the Master. While this model provides for simplicity, it incurs a longer delay between any two slave devices due to far from optimal packet forwarding, the use of double the bandwidth, and also additional energy wastage at the Master. Moreover, if more than two devices want to communicate as a group, this can only be achieved by either multiple unicast transmissions or a piconet-wide broadcast, clearly resulting in inefficiency. In this paper, we propose a novel Dynamic Slot Assignment (DSA) scheme whereby the Master device dynamically assigns slots to Slaves so as to allow them to communicate directly with each other without any Master intervention. This proposed communication architecture also provides for Quality of Service (QoS) requests, admission control, and multi-device conversation by which a multicast-like communication is implemented within a piconet. Through extensive simulation, we observe that DSA drastically enhances Bluetooth performance in terms of delay and throughput, while significantly reducing power consumption at the master and the overall piconet.

We analyze the performance of Bluetooth piconets under bursty traffic and finite buffer sizes. We model the joint probability distributions of uplink and downlink queues using the M[x]/G/1/K model with vacations and derive buffer blocking probabilities at slaves and at the master. The results, which are confirmed through simulations, provide some practical guidelines as to the sizing of device buffers. Copyright © 2005 John Wiley & Sons, Ltd.

Distributed object-oriented platforms are increasingly important over wireless environments for providing frameworks for collaborative computations and for managing a large pool of distributed resources. Due to limited bandwidths and heterogeneous architectures of wireless devices, studies are needed into supporting object-oriented frameworks over heterogeneous wireless environments and optimizing system performance. In our research work, we are working towards efficiently supporting object-oriented environments over heterogeneous wireless environments. In this paper, we report the issues and our research results related to the efficient support of Java RMI over a Bluetooth environment. In our work, we first implement support for Java RMI over Bluetooth protocol stacks, by incorporating a set of protocol stack layers for Bluetooth developed by us (which we call JavaBT) and by supporting the L2CAP layer with sockets that support the RMI socket. In addition, we model the cost for the access patterns of Java RMI communications. This cost model is used to guide the formation and optimizations of the scatternets of a Java RMI Bluetooth environment. In our approach, we employ the well-known BTCP algorithm to observe initial configurations for the number of piconets. Using the communication-access cost as a criterion, we then employ a spectral-bisection method to cluster the nodes in a piconet and then use a bipartite matching scheme to form the scatternet. Experimental results with the prototypes of Java RMI support over a Bluetooth environment show that our scatternet-formation algorithm incorporating an access-cost model can further optimize the performances of such as system. Copyright © 2005 John Wiley & Sons, Ltd.

Scatternet is a wireless network topology based upon Bluetooth technology. In essence, the scatternet is a network formed from multiple small personal networks called piconets. Piconets are centralized networks because they relay on a central node, called master node, to perform necessary link establishment and synchronization within a piconet. In order to realize inter-piconet communication, necessary protocols must be researched so that a cohesive network structure is formed, medium access conflicts are resolved, and packet transfer from source to destination is accomplished. Currently a few complete protocol solutions exist and the Bluetooth specification does not detail any protocols that could implement a scatternet. The focus of this paper is to detail a new routing algorithm necessary for development of a scatternet. The authors present this new algorithm and discuss its performance characteristics.

Bluetooth is an enabling technology for Personal Area 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.

We consider differentiated bandwidth allocation for a piconet in short-range wireless personal network systems : Bluetooth. Since bandwidth requirements nay vary among applications/services, and/or it may change over time, it is important to decide how to allocate limited resources to various service classes to meet their service requirements. We propose a simple and efficient bandwidth allocation mechanism which meets bandwidth requirements of various service types while saving power consumption by a Power saying mode, i.e., sniff node. We compare our proposed mechanism with a conventional (weighted) round-robin polling scheme and show that it achieves significant improvement of hroughput, delay, and power consumption.

Bluetooth is a radio technology for Wireless Personal Area Networking (WPAN) operating in the 2.4 GHz ISM frequency band. So far, there has been little research on how Bluetooth-enabled devices can effectively and efficiently have uninterrupted access to wide area networks (WAN) such as the Internet. We introduce a novel architecture (BlueStar) whereby selected Bluetooth devices, called Bluetooth Wireless Gateways (BWGs), are also IEEE 802.11 enabled so that these BWGs could serve as egress/ingress points to/from the IEEE 802.11 wireless network. We propose mitigating interference between Bluetooth and IEEE 802.11, by employing a hybrid approach of adaptive frequency hopping (AFH) and Bluetooth carrier sense (BCS) of the channels. AFH labels channels as "bad" or "good", and Bluetooth devices only access those channels in the "good" state, whereas BCS is used to avoid collision by sensing the channel prior to any transmission. By combining AFH and BCS, we drastically minimize the effect of the worst-case interference scenario wherein both a Bluetooth and an IEEE 802.11 interface are co-located in a single device. BlueStar enables Bluetooth devices, belonging to either a piconet or a scatternet, to access the WAN through the BWG without the need for any fixed Bluetooth access points, while utilizing widely deployed base of IEEE 802.11 networks. Moreover, we define the protocol stack employed by BlueStar as well as indicate how BWGs efficiently manage their capacity allocation through the different systems. We also mathematically derive an upper bound on the number BWGs needed in a Bluetooth scatternet so that uninterrupted access to all Bluetooth devices could be provided.

With both Bluetooth and microwave ovens operating in the same frequency band, fears have arisen about the effects of microwave oven interference on Bluetooth networks. While Bluetooth devices use frequency hopping spread spectrum (FHSS), the high power output of microwave ovens may still pose a threat to Bluetooth networks. We therefore endeavored to characterize microwave oven behavior and understand its effect upon Bluetooth networks. Our experimental results show that Bluetooth devices will tolerate a high level of interference. With two Bluetooth devices forming a piconet placed within 1 m of an oven, the Bluetooth throughput was significantly greater than half of the maximum throughput rate. Moving to a distance around 10 m from the oven showed very little degradation to the throughput due to interference. The effects of microwave oven interference, while noticeable, are by no means fatal. The results also showed no gain from the forward error correction (FEC) used on some Bluetooth packets.

Bluetooth enables wireless communication via ad hoc networks. The basic topology (piconet) is a collection of slaves controlled by a master. A scatternet is a multihop network of piconets. We anticipate that most scatternets will be composed of only a few piconets. However, even in small scatternets, efficient data flow requires the design of inter-piconet scheduling algorithms. Thus, this article presents and evaluates a load adaptive scheduling algorithm tailored for small-scale scatternets. The main advantage of this algorithm is the use of the Bluetooth low-power hold mode, which allows greater flexibility than other low-power modes. A simulation model has been developed in order to evaluate the performance of the algorithm. We show that the results obtained by the model are very close to the analytic results. Then we evaluate the performance of various intra-piconet scheduling algorithms. Finally, we present simulation results regarding inter-piconet scheduling, and compare the proposed algorithm to algorithms using the sniff mode.

Performance of Bluetooth scatternets is critically dependent on the algorithm for bridge scheduling. As the current specification does not prescribe any particular algorithm, a number of proposals have been made. These proposals are classified into rendezvous-based and walk-in based algorithms, and their relative advantages and disadvantages are highlighted. Using the theory of queues with vacations, we derive the probability distributions for end-to-end packet delays (and a number of intermediate variables such as the duration of master-bridge exchanges, bridge cycle time, and piconet cycle time) under three different bridge scheduling algorithms. Analytical results are confirmed through discrete event simulation.

Bluetooth is a promising wireless technology aiming at supporting electronic devices to be instantly interconnected into short-range ad hoc networks. The Bluetooth medium access control protocol is based on the Master/Slave concept wherein any communication between slave devices has to go through the Master. While this model provides for simplicity, it incurs longer delay between any two slaves devices due to far from optimal packet forwarding, the use of double the bandwidth, and also wastes additional energy at the Master. Moreover, if more than two devices want to communicate as a group, this can only be achieved by either multiple unicast transmissions or a piconet-wide broadcast, clearly resulting in inefficiency. In this paper, we propose a novel Dynamic Slot Assignment (DSA) scheme whereby the Master device dynamically assigns slots to Slaves so as to allow them to communicate directly with each other without any Master intervention. This proposed communication architecture also provides for Quality of Service (QoS) requests, admission control, and multi-device conversation by which a multicast-like communication is implemented within a piconet. Through extensive simulation, we observe that DSA drastically enhances Bluetooth performance in terms of delay and throughput, while significantly reducing power consumption at the master and also of the overall piconet.

We analyze the performance of E-limited scheduling in Bluetooth piconets under bursty traffic for infinite and finite buffer cases. We show that E-limited service outperforms exhaustive service in terms of end-to-end delay and that the delays may be minimized through the proper choice of a single variable parameter: the number of packets to be exchanged during a single visit to a slave. Using analytical results for access delay and end-to-end delay, as well as suitable approximations thereof, we propose three novel admission algorithms. The simplest algorithm is based on queue stability, which makes it suitable for battery power-limited masters. The second algorithm estimates the access delay of the slave upon admission using the estimated first and second moments of the vacation times and makes the admission decision on the basis of predefined access delay bounds. The third algorithm is based on the predefined cycle time bounds, which makes it suitable for applications that generate constant-bit-rate data flows. We also present results for the performance of TCP traffic under E-limited scheduling.

Bluetooth has a master-slave configuration, called a piconet. Unspecified in the Bluetooth standard, the link polling policy adopted by a master may significantly influence the bandwidth utilization of a piconet. Several works have dedicated to this issue by A. Capone et al. (2001), I. Chakrabory et al. (2001), A. Das et al. (2001), M. Kalia et al. (1999) and M. Kalia et al. (2000). However, none of them addresses the asymmetry of traffics between masters and slaves, and the different data packet types provided by Bluetooth are not fully exploited. In this paper, we propose an efficient pattern matching polling (PMP) policy for data link scheduling that properly resolves these deficiencies. A polling pattern is a sequence of Bluetooth packets of different type combinations (e.g., DHf/DH3/DH5/DMf/DM3/DM5) to be exchanged by a master-slave pair that can properly reflect the traffic ratio (i.e., asymmetry) of the pair. By judiciously selecting a proper polling pattern together with polling times for the link, the precious wireless bandwidth can be better utilized. The ultimate goal is to reduce the unfilled, or even null, payloads in each busy slot. In addition, an overflow mechanism is included to handle unpredictable traffic dynamics. Extensive simulations are presented to justify the capability of PMP in handling regular as well as bursty traffics.

A novel polling scheme for intra-piconet scheduling in Bluetooth piconets is described. The scheme allocates time to each slave according to its current traffic, while trying to limit the maximum piconet cycle time. This approach makes scheduling of mixed asynchronous and constant-bit-rate (CBR) traffic much easier than do other known schemes. In this manner, the scheme is able to provide low delay and high throughput for asynchronous data traffic, guaranteed delay for CBR traffic, and inherent fairness among slaves with asymmetric traffic; in addition it has low complexity. A detailed queueing model of this policy is presented and simulations are conducted to confirm the analytical results. Simulations confirm that the new scheme performs as well as, or in some cases even better than, other common polling schemes.

In this paper we describe BlueMesh, a new protocol for the establishment of scatternets, i.e., multi-hop wireless networks of Bluetooth devices. BlueMesh defines rules for device discovery, piconet formation and piconet interconnection so to generate connected scatternets with the following desirable properties. BlueMesh forms scatternets without requiring the Bluetooth devices to be all in each other transmission range. BlueMesh scatternet topologies are meshes with multiple paths between any pair of nodes. BlueMesh piconets are made up of no more than 7 slaves. Simulation results in networks with over 200 nodes show that BlueMesh is effective in quickly generating a connected scatternet in which each node, on average, does not assume more than 2.4 roles. Moreover, the route length between any two nodes in the network is comparable to that of the shortest paths between the nodes.

In this paper, we propose a power-efficient and QoS (quality of service)-aware MAC (medium access control) scheduling algorithm for Bluetooth scatternet. If the inter-piconet scheduler in a bridge node between piconets operates simply by the round robin (RR) policy, a number of time slots may be wasted due to the guard time for piconet switching and the exchange of POLL-NULL packets. To overcome the link wastage problem in Bluetooth scatternet scheduling, several algorithms have been proposed. Although they can provide all of the links of a bridge node with fair service opportunities, they may cause waste of wireless resources since different Bluetooth devices may have various traffic characteristics. In addition, since Bluetooth devices are often required to operate under limited battery capacity, the number of unnecessary piconet switching has to be minimized for the power-efficient operation of a Bluetooth scatternet. Therefore, we propose a mechanism to support the power-efficient operation of a Bluetooth scatternet while guaranteeing various QoS requirements of Bluetooth devices. The proposed algorithm is compliant with the current Bluetooth specification, and we demonstrate its improved performance via simulations.

The emergence of Bluetooth as a default radio interface has allowed handheld electronic devices to be instantly interconnected as ad hoc networks. These short-range ad hoc wireless networks, called piconets, operate in the unlicensed 2.4-GHz ISM (Industrial-Scientific-Medical) band where devices may be used to configure single or overlapping piconets, known as scatternet. As all piconets operate in the same frequency band, the presence of multiple piconets in the vicinity may create interference on signal reception. This paper employs a signal capture model to study the piconet MAC performance, taking inter-piconet interference into consideration. This model leads to several important mathematical relationships for Bluetooth networks, including successful packet transmission probability. Furthermore, our model and anticipated throughput are validated using extensive simulation. These results indicate that Bluetooth throughput is affected by multiple piconet interference. Definitely, our model can be considered to provide a solid foundation for future interference aware Bluetooth protocols.

System-level simulations for ad hoc networks require the mean power that is received by an arbitrary unit of the piconet as an input parameter. Since the radio channel in piconets depends strongly on the environment in which two communicating units are located, easily applicable models for the mean received power must be determined by a few relevant, explicitly geometrical quantities. Starting from a very general description of the stochastic radio channel by an integral equation, it is shown that these quantities are the surface area and the volume of the domain in which the transmitter and the receiver can move. On the basis of an exponential path loss model with path loss exponent q, a lower and an upper bound for the mean received power are derived. The resulting analytical expressions are highly flexible and allow a quick calculation of bounds for the mean received power in many practically relevant cases.

In the emerging wireless personal area networks (WPANs), one of the active devices in a piconet is designated as a coordinator, which plays a critical roles, e.g., to provide the basic timing for operation of the piconet and manage the QoS requirements/power saving modes. To warrant maintenance of the coordinating function under some unpredictable situations such as sudden power-off or fast movement of a coordinator, it must be seamlessly switched. This paper proposes a new SCS (seamless coordinator switching) scheme to maintain the piconet by selecting a coordinator in the subsequent superframe without incurring the re-initialization overhead.

Validation of an System-on-Chip (SoC) design with networking capability needs global simulation of the whole system including the network as well as the SoC design itself. Especially, it is needed to validate the interoperability of SoCs from different vendors. In this paper, we propose a simulation environment and simulation techniques for efficient validation of such SoC designs and apply them to networked Bluetooth SoC designs. The environment enables two types of simulation. One is modular enough to include the simulation of other vendors' Bluetooth devices and the other is optimized to achieve fast simulation in developing in-house Bluetooth devices. Especially, the former is scalable in that it keeps the constant simulation runtime despite the increase of the number of Bluetooth devices. Since multiple simulators are involved, the global simulation is still slow. Thus, the simulation efforts need to be minimized to shorten the design cycle. We present two simulation techniques, a concept called grouped message for reduction in simulation runtime and a system debug scenario called fix---modify---restart for reduction in the number of simulation runs. The former is to reduce inter-process communication overhead between simulators in the global simulation. The latter is to reduce repeated simulation runs in the conventional design cycle. Experimental results show the scalability of the presented simulation environment, reduction in simulation efforts by two simulation techniques.