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Bluetooth is a low power, short range and inexpensive wireless technology that has limited resources. Therefore, the performance of a scatternet is highly dependent on the number of relays and their degree. The existence of unnecessary relays may increase scheduling overhead and consume system resources. In another instance, a large number of links that pass through a single relay may also decrease the system performance. Therefore, an optimum number of relays must be obtained for an efficient scatternet performance, while the system works with limited resources. The dynamic relay management (DRM) protocol is proposed to achieve the said objective and the solutions will be based on relay reduction and load balancing strategies. Through the DRM, a master reduces unnecessary relays to an optimum number and subsequently assigns them the special role as backup relays. In the event when a large number of links pass through a single relay, the master activates one of the backup relays to resolve the bottleneck, by which the load is balanced over a number of relays. Using this relay management technique, analytically the DRM protocol has reduced control overhead from O(n^2) to O(1). Empirically, through simulation of the DRM protocol, the backup relay activation has reduced delay and improved throughput (between 40% and 60%). Also, the simulation results have demonstrated an improvement on network lifetime and packet loss. All these results are evidence that the DRM has outperformed the RVM and LORP protocols for the same issue. Hence, the inefficiency of the inter-piconet scheduling in a scatternet of a Bluetooth network can be resolved by implementing the DRM protocol.

In this paper, an efficient technique for enhancing the QoS of multimedia service for an WiMedia network applying distributed cooperative medium access (D-MAC) protocol is proposed. D-MAC protocol has been proposed to support high-rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia supports all devices to be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However the WiMedia D-MAC can`t prevent reduce the throughput degradation occurred by mobile nodes with low data rate. Therefore, a distributed cooperative MAC protocol for multi-hop UWB network is proposed in this paper. The proposed technique can intelligently select the transmission path with higher data rate to provide real-time multimedia services with minimum delay, thus enhances QoS of multimedia service.

This letter analyzes the communication success probability of two randomly selected devices in mmWave wireless personal area networks (WPANs). Devices are randomly distributed in a piconet, each device is equipped with a directional antenna, and the antenna direction of each device is randomly chosen and fixed during the communication. The communication of the selected pair can be performed either directly or via relaying devices. In the analysis, the probability density function of the distance for devices is used and transmissions with ideal antenna and practical antenna are considered. Numerical results show an optimal beamwidth enables efficient spatial reuse to maximize the successful communication probability of a pair of devices. It also shows that the communication of a pair of devices is difficult when the directions of antennas of devices are fixed and the transmission through sidelobe of a transmitter gives a good effect in some circumstances. The obtained results will provide a criterion for the practical design of mmWave network systems, for implementing appliances using high data rate, and for developing the technology of mmWave band.

We investigate the performance of simple cognitive personal area networks (CPANs) with cooperative sensing. Nodes are equipped with small buffers of capacity K each, and each node is allowed to transmit a batch of up to μ packets in one transmission cycle. Upon transmission, each node must support the operation of the CPAN by performing sensing duty in the amount obtained by multiplying the number of packets sent in a batch by a variable penalty coefficient. We model this system and show the relationship between values of design parameters and piconet performance. We also show that performance and bandwidth utilization can be improved by a simple technique of dynamically adjusting the duration of the superframe to cater to instantaneous traffic volume. Copyright © 2011 John Wiley & Sons, Ltd.

Millimeter-wave (mmWave) communications is a promising enabling technology for high rate (Giga-bit) multimedia applications. However, because of the high propagation loss at 60 GHz band, mmWave signal power degrades significantly over distance. Therefore, a traffic flow being transmitted over multiple short hops can attain higher throughput than that over a single long hop. In this paper, we first design a hop selection metric for the piconet controller (PNC) to select appropriate relay hops for a traffic flow, aiming to improve the flow throughput and balance the traffic loads across the network. We then propose a multi-hop concurrent transmission (MHCT) scheme to exploit the spatial capacity of mmWave WPANs by allowing nodes to transmit concurrently in communication links without causing harmful interference. The analysis of concurrent transmission probability and time division multiplexing demonstrates that the MHCT scheme is capable of improving the time slot utilization. Extensive simulations are conducted to validate the analytical results and demonstrate that the proposed MHCT scheme can improve the average traffic flow throughput and network throughput.

Bluetooth has become a ubiquitous technology present in almost every electronic device. A question often asked by manufacturers and final users is whether it can be used for uses other than the ones for which it was designed; in particular, for improved multimedia traffic support, with the fewest modifications in the implementation of the protocol (both hardware and software). In this article we analyze the impact on performance of the lowest levels of the Bluetooth architecture through a relevant parameter known as the polling time, Tpoll. Here, we report on simulations of specific algorithms that allow to dynamically adapt the network to an optimal value of Tpoll during transmission. We place special emphasis on the role of the kind of traffic on the network (e.g., constant bit rate, burst, multimedia-like). In addition, we analyze the results of simulations by comparing these algorithms with the static allocation value defined in the Bluetooth specification. Our results provide insight on how to optimize the transmission of multimedia traffic over piconets at the lowest layers of the Bluetooth architecture.

Bluetooth is a technology for short range wireless real-time data transfer between devices. It is becoming increasingly more prevalent in modern society, with technical gadgets now ranging from mobile phones and game controllers to PDAs and personal computers. In Bangladesh, use of technology has not reached its maximum potential and it is yet to spread among the majority of population and devices like PDA/Smart phones/Laptops that consist of WLAN feature is not widely used in public environments. But the use of basic mobile phones (consisting of Bluetooth feature) is greatly increasing over the years. This paper proposes a way to implement the Bluetooth Standard as a communication medium for a social network like a university in order to send and receive valuable information and services which can be used as a cheaper solution and replacement to WLAN devices. However, Bluetooth has security threats too; hence this paper also addresses the potential weaknesses and vulnerabilities in security protocols of this technology so that protection against malicious attacks, identity theft and eavesdropping can be insured. Due to the public nature of this network some application level security features have been incorporated to make it a safer network. Finally, the paper concludes with some recommendations for the future works regarding this Bluetooth networking concept. General Terms Wireless, Bluetooth, networking, Piconet, security threats, counter measures.

Bluetooth is a low power wireless technology designed to connect various short-range devices such as laptops, cameras, cell-phones, head-phones, navigators, etc. Bluetooth has limited resources and its devices are connected in ad hoc fashion. The Bluetooth specification allows only eight active devices to communicate within its smallest networking unit known as piconet. Multiple piconets can be connected together through at least one common device, known as relay to form a bigger network called a scatternet. The performance of a scatternet is highly determined by the performance of the relay since it acts as a switch between multiple piconets, where inter-piconet scheduling is the main task to perform. However, the presence of too many relays in the network may cause inefficient use of the limited resources. In contrary, less number of relays may lead to congestion problem because each relay has to participate in multiple piconets and supports several connections. One possible solution is to reorganize the nodes in the scatternet, in order to increase the available bandwidth and to reduce the traffic flows on the congested link. Hence, primarily this paper addresses the issues of traffic congestion on a link by analyzing traffic load in the network. To achieve this, activation of a backup relay is performed by applying role-switching operation, and this technique is called Dynamic Congestion Control (DCC). With DCC, the route length is assured not to increase as to alleviate message and packet overheads in scheduling. The simulation results are evidence that DCC has reduced transmission delays and has increased the scatternet lifetime from 25% to 50% as compared to RVM and LORP techniques.

During Bluetooth device discovery process, nodes enter inquiry substate to discover other nodes within the range by periodically sending inquiry packets on a predetermined frequency partition of hop frequencies used by neighbouring piconets. Intuitively, potential collisions will occur between inquiry packets and packets exchanged between piconet nodes during connection state, which lead to degraded network performance and longer discovery process. So, the authors developed an analytical model for interference caused by a single inquiring node, and extended the model to account for interference levels due to multiple inquirers. The authors further validated the analytical model through a simulation scenario and found that the probability of packets interfered and disrupted during inquiry procedure is periodic by repeating every 3.16 s. Analytical and simulation results reveal that a single inquiring node can disrupt up to 1.5% of network packets for approximately half of this period, and with the increased number of inquiring nodes, the interference levels become more crucial approaching 35.3%.

In recent years Bluetooth has been a growing technology for ad-hoc wireless communication between embedded devices, in a range of 10m. Such a network is called a piconet, in which a master employs round-robin mechanism to poll and serve the slaves. Many new products have become Bluetooth enabled recently, which may cause a complex mix of traffic. Two types of connection are being offered in this network: the Synchronous Connection-Oriented (SCO), and the Asynchronous Connection-Less (ACL). ACL is proper for best-effort service as in IP networks, which has gained more importance as now a day's most of the applications have moved to IP, and may carry bursty traffic. In this paper, to analyze the Bluetooth ACL, a general model for complex mix of traffic, which is the superposition of many ON-OFF mini-sources, is considered. Moreover, due to unreliable nature of wireless media, a Channel Failure Rate (CFR) has been assumed. This system has been investigated analytically and its performance has been evaluated. The effects of channel failure and packet size on the mean delay and waiting time have been studied by simulations as well.

[EN] The monitoring of different parameters in the smart garden environment requires thousands of nodes and actuators. They form a multi-hop communication network. The scatternets formed with Bluetooth protocol is a communication solution. However, there is no current algorithm that considers the different capabilities of the devices (sensors or actuators) and assigns a role according to these capabilities. In this paper, we present a network topology formation algorithm for role assignment and connection establishment which considers the capabilities of the devices and use slave-slave Bridge to communicate the piconets. We design the algorithms needed for this protocol and test it. We have simulated the algorithms in order to evaluate the time needed for role assignment and to establish the first connections of the piconet. The results include different scenarios composed by one or two masters and one to seven slaves. In addition, we evaluate the established connections in piconets and bridges in a real case of the smart garden sensor network. Finally, we present the changes in the piconet connections after the deployment of two nodes in an existing network., This work is partially found by the European Union with the “Fondo Europeo Agrícola de Desarrollo Rural (FEADER) – Europa invierte en zonas rurales”, the MAPAMA, and Comunidad de Madrid with the IMIDRA, under the mark of the PDR-CM 2014-2020” project number PDR18-XEROCESPED. This work has been partially supported by the "Ministerio de Economía y Competitividad" in the "Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia, Subprograma Estatal de Generación de Conocimiento" within the project under Grant TIN2017-84802-C2-1-P. This work has also been partially supported by European Union through the ERANETMED (Euromediterranean Cooperation through ERANET joint activities and beyond) project ERANETMED3-227 SMARTWATIR.

Fast-paced city life, people have no time to make friends by traditional methods. Appreciated when we encountered a stranger in the public place, but do not know each other, we have no effective way to understand each other.The study survey on making friends behavior,research on the 3G mobile application development technology, put forward a more immediate and more private mode to making friends. Propose out a mobile instant messaging software using Bluetooth technology blueprint. The study opened up a more direct and open innovational making friends mode compared with the other online instant messaging software. The study is innovative and has significant commercial value. The obtained theory and experience can be a meaningful reference to other studies in relevant fields.

Current technologies, such as Bluetooth and IEEE 802.11b, can form ad hoc networks but is limited in that only single hop networks can be formed. This means that each node can only act as a host, whereas in a multi-hop ad hoc network all nodes act as routers. This thesis concentrated on the problem of adding multi-hop capabilities to existing ad hoc network platforms such as IEEE 802.11b. This capability will allow a network to be fully dynamic, self-organising and self-configuring. This thesis describes the design and implementation of picoNet a wireless ad hoc network for mobile handheld devices. As users are increasingly mobile it is more and more common for users to meet and communicate without prior planning and in environments where there is little or no networking infrastructure. Such a network is known as an ad hoc network, where the network is of a dynamic nature without centralised administration. The result was an implementation of the dynamic source routing protocol (DSR) for TCP/IP, for the PCs. The implementation enabled the PCs to form a multi-hop ad hoc network with 802.11b wireless cards. A DSR to IP gateway was also implemented and it allowed nodes in the DSR network to access external IP networks. Existing unmodified TCP/IP applications were able to run seamlessly on the picoNet network, providing a useful platform for future

Bluetooth is a key connectivity technology for the deployment of wireless Personal Area Networks as far as it is the most popular low power communication feature incorporated in devices such as laptops or smartphones. This paper proposes an analytical model to predict the delay of the transmissions in Bluetooth piconets employing Serial Port Profile (SPP), which is massively implemented by Bluetoothenabled equipments. The characterization includes the impact of the overhead and the segmentation imposed by the different protocols involved in the transmission as well as the delay provoked by the polling process that is executed to regulate the activity of the different slaves in the piconet. The model has been empirically evaluated and tested in actual Bluetooth piconets.

Bluetooth is an emerging mobile ad-hoc network that accredits wireless communication to connect various short range devices. A single hop network called piconet is the basic communication topology of bluetooth which allows only eight active devices for communication among them seven are active slaves controlled by one master. Multiple piconets are interconnected through a common node, known as Relay, to form a massive network called as Scatternet. It is obvious that the performance of Scatternet scheduling is highly dependent and directly proportionate with the performance of the Relay node. In contrary, by reducing the number of Relays, it may lead to poor performance, since every Relay has to perform and support several piconet connections. The primary focus of this study is to observe the performance metrics that affects the inter-piconet scheduling since the Relay node’s role is like switch between multiple piconets. In this paper, we address and analyze the performance issues to be taken into consideration for efficient data flow in Scatternet based on Relay node.

In this paper, we proposed the method called "DoublePico"(Double Piconet) forovercoming low data transmission rate in a scatternet. This needs a new Ad-hoc network topology to transmit with high rate. Every node performs the function of the relay station. DoublePico has two bluetooth devices that should form two different poconets; every node can make a link between two different piconets. Two different piconets are linked in one node by the link with two bluetooth divices thereby forming the Ad-Hoc network. In this paper, we shows the method of DoublePico which supports about 457kbps of the maximum data transmission rate. This method supports a higher data transmission rate than the traditional bluetooth's Ad-Hoc topology by using analysis and comparison of existing algorithm of bluetooth specification and simulation results. Specifically, this paper focuses on the impact of intererence on the PER (Packet Error Rate), throughput performance, and the throughput improvement with SAW(Stop and Wait)-ARQ scheme in DoublePico. 요 약

A Distributed Meduim Access Control (D-MAC) protocol had been proposed to support High Rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operation Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device's mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a "mobile" hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while other DRP reservations must be terminated and DRP negotiations for them have to be restarted although only a few Mass are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mecahnism to provent and resolve multi-hop range DRP conflicts due to each device's mobility in D-MAC environment.

In this paper, a multi-hop range conflict-free resource reservation scheme for UWB (Ultra Wide Band) WPAN (Wireless Personal Area Network) with D-MAC (Distributed Medium Access Control) is proposed. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia Alliance supports DRP (Distributed Reservation Protocol) mechanism which makes all devices be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However, since each device's mobility perspective in multi-hop environment has not been taken into account in the current WiMedia D-MAC, it may cause a "mobile" hidden node problem. In addition, once a DRP conflict occurs due to the mobile hidden node problem, only one of the DRP reservations involved in that DRP conflict maintains the reserved MASs, while the other DRP reservations must be terminated and DRP negotiations for them have to be re-started although only a few MASs are overlapped. Such DRP termination and renegotiation time delays due to the DRP conflicts can be a critical problem to the mobile devices transceiving real-time QoS traffic streams. Therefore, we propose a mechanism to prevent and resolve multi-hop range DRP conflicts due to each device's mobility in D-MAC environment and demonstrate its guaranteed Seamless QoS and prioritized real-time QoS performances via numerical analyses.

Bluetooth is a communication technology for personal area networks (PANs). To support communication with more than eight bluetooth-enabled devices, a scatternet must be formed in the PAN. Bluetree is one commonly used topology for scatternet formation. To reduce traffic load of the Bluetree scatternet, we use the piconet transfer concept to move piconets on a well-formed Bluetree scatternet. The piconet movements are performed based on a distributed manner using two well-known tree traversal procedures: post-order traversal and level-order traversal. These two procedures do not take much computation time, where time complexities are O(n"p) and n"p is the number of piconets on a Bluetree scatternet (not the number of nodes on a Bluetree). Compared with previous approaches, the proposed approach can greatly reduce the traffic load and computational costs. Finally, simulation experiments show the effectiveness of the proposed approach in improving the formation of Bluetree scatternet.

In this paper, the effect of cochanneled Bluetooth (BT) piconets on a carrier-sense multiple-access (CSMA)-based wireless local area network (WLAN) is investigated. Specifically, the p-persistent CSMA protocol is considered for WLANs, and the probability of error of a WLAN packet is calculated in the presence of interfering BT packets of different lengths and variable piconet traffic loads and as a function of the BT's frequency-hopping guard time. The probability derivation is then used in conjunction with the p-persistent CSMA throughput and delay formulations to examine its net performance in the presence of BT interference. Simulations have been used to corroborate the analytical results, which indicate that the presence of just one fully loaded interfering BT piconet reduces the peak CSMA throughput by 42%. Furthermore, we show that under fully loaded BT traffic conditions, the effect of more shorter BT packet transmissions on the CSMA delay performance can outweigh the interference impact of a higher number of BT piconets with longer packet transmissions.

Wireless personal area networks (WPANs) are formed in a relatively small area, and coordinator that serves as a central control device plays an important role in the operation and organization of a piconet. Typical applications of WPANs include home automation systems, security systems and health monitoring systems. In these types of systems, guaranteeing seamless connectivity is very important, and communications cannot take place when the coordinator malfunctions. Thus, in the case of a breakdown, it is necessary to elect a new coordinator as soon as possible. For this reason, a distributed coordinator election scheme (DCES) is proposed that considers not only QoS support but also network connectivity in an effort to avoid possible network partition. Simulation results show that the proposed scheme can elect a new coordinator while maintaining QoS and guaranteeing connectivity for a limited period.

Co-channel interference (CCI) has become an important problem with the increasing deployment of wireless networks in the unlicensed frequency band. The existing Bluetooth scheme avoids collisions by modifying its hop sequences in the presence of WLAN. We propose a frequency diversity technique, namely dual channel transmission (DCT), which reduces packet error rate (PER) due to CCI when multiple Bluetooth piconets coexist with or without WLAN interference. The idea of DCT is to transmit the same packet on two distinct frequency hopped channels simultaneously and the power used in each channel is half of what would be used in single channel transmission (SCT). Since a packet is successfully received if at least one channel survives, the PER is reduced even when multiple piconets coexist. Further, the two channels of DCT are separated by at least 22 MHz to ensure robustness to WLAN interference. Theoretic analysis and numerical simulations on key metrics - PER, throughput, and transmission time are presented to validate the proposed approach and quantify its advantages. Comparisons to other coexistence mechanisms also demonstrate the effectiveness of DCT.

This paper describes a distributed database system implementation built on top of stand-alone mobile databases found on mobile devices. At the heart of the architecture are elected devices that take on the role of data directories which collect the schema of the databases and become the contact points for all nodes that wish to submit queries against the distributed database. The system is implemented on Pocket PCs that run the Microsoft WinCE operating system and communicate using Bluetooth, thus limiting the architecture to eight devices, which is a restriction imposed by piconets. Sample databases were configured on the devices that ran the SQL Server CE database engine, and a list of 170 sample queries of varying complexities were designed to conduct performance evaluation. This evaluation involved measurement of query response time, generated traffic, and device energy consumption. The obtained results indicated the feasibility of the system and its potential for providing mobile users with a framework for aggregating disparate data that are stored in mobile databases in the wireless ad hoc network.

In this paper, we propose an overlapping communication protocol using improved time-slot leasing in the Bluetooth WPANS. One or many slave-master-slave communications usually exist in a piconet of the Bluetooth network. A fatal communication bottleneck is incurred in the master node if many slave-master-slave communications are required at the same time. To alleviate the problem, an overlapping communication scheme is presented to allow slave node directly and simultaneously communicates with another slave node to replace with the original slave-master-slave communication works in a piconet. This overlapping communication scheme is based on the improved time-slot leasing (TSL) scheme which modified from the original TSL, while the original TSL scheme only provides the slave-to-slave communication capability. The key contribution of our improved TSL scheme is to offer the overlapping communication capability. With the overlapping communication scheme, we developed an overlapping communication protocol in a Bluetooth WPANs. Finally, simulation results demonstrate that our developed communication protocol achieves the performance improvements on bandwidth utilization, transmission delay time, network congestion, and energy consumption.

Bluetooth technology is specially designed for the wireless personal area networks to replace cable. Several challenges exist in Bluetooth scatternet formation and routing, since nodes can arrive and depart at arbitrary times. In this paper, novel route maintenance algorithms are proposed for the Bluetooth ad hoc networks, where nodes can enter or exit from the piconets time to time. Our protocols guarantee the connectivity among nodes and reconstruct the routes dynamically by considering location information of the nodes. Besides, it is proposed how to reduce the number of hops and to form the shortest route between the source and the destination due to addition of new nodes to a piconet. Performance analysis of our protocols show that they outperform in terms of end to end transmission delay, bandwidth consumption and average hop counts as compared to similar Bluetooth routing protocols that we have considered.

Device discovery and connection establishment are fundamental to communication between two Bluetooth (BT) devices. In this paper, we give an analytical model of the time it takes for the master in a piconet to discover one slave. We show that, even in the absence of packet interference, the discovery time can be long in some instances. We have simulated the discovery protocol by actually implementing it to validate the analytical model. By means of simulations, we show how discovery time is affected by (i) the presence of multiple potential slaves, and (ii) changes in the maximum backoff limit. Using simulation studies we observed the effectiveness of two proposed improvements to device discovery, namely, (i) avoiding repetitions of the A and B trains before a train switch, and (ii) eliminating the idea of random backoff, or reducing the backoff limit. We show that discovery time can be reduced by avoiding repetitions of the A and B trains before a train switch. However, complete elimination of the random backoff is not a good idea, as discovery time will be too long when the number of BT devices is large. Instead, choosing a small backoff limit of 250---300 slots is highly effective in reducing discovery time even in the presence of a large number (say, 50) of potential slaves.

In this paper, we present a graph-based model for analyzing interference between two frequency hopping systems for wireless communication. Informally, frequency hopping means that successive packets are transmitted on different frequencies from a pseudo-random sequence. The frequency band occupied by a packet may be narrow or wide. Our model is based on the concept of probabilistic graphs, where a node represents a ''channel'' and an edge denotes the probability of interference between two packets belonging to two different channels. Two packets on two channels are said to be mutually interfering if the two packets overlap in time and are transmitted on the same frequency. Thus, from the viewpoint of probabilistic graphs, the expected number of nodes with at least one incident edge is a measure of packet interference in a collection of wireless channels. We apply this model of packet interference to a heterogeneous cluster of Bluetooth piconets, where a piconet could be either of 79-hop type or of 23-hop type. Though the 23-hop type has been phased out, we use it as an example in this paper.

Bluetooth is a low-cost and short-range wireless communication technology. Two or more bluetooth devices connected form a piconet and two or more piconets connected form a scatternet through relay devices. Without the consideration of traffic flows, a scatternet may operate with serious congestion problem. Congestion problem can be resolved by either reduced traffic flows or increased bandwidth provision. In bluetooth, new piconet can be dynamically constructed to increase system bandwidth. However, as the number of piconet is increased, collision problem among piconets becomes a serious problem. The objective of this paper is to resolve the congestion problems in a scatternet through piconet restructuring which perform both flow analysis and distributed role-switching technique. Advantages of the proposed piconet restructuring mechanism includes the following: (1) the communication bottleneck can be released; (2) the communication path is shortened; (3) the transmission latency is reduced; and (4) the lifetime of piconets can be increased. Experimental results demonstrated that the proposed method could effectively increase the transmission efficient in each piconet and increase the performance of an entire scatternet.

The IEEE 802.15.3 medium access control (MAC) protocol is designed to support high-data-rate wireless personal area networks (WPANs). This protocol operates on a time-division multiple-access (TDMA) basis within a piconet, which guarantees interference-free connections. However, it is found that the protocol is not efficient for simultaneously operating piconets (SOPs). In the current protocol, SOPs can be linked by a parent/child (P/C) or parent/neighbor (P/N) configuration for interference mitigation. However, the throughput is limited because the same superframe is shared by the P/C and P/N piconets. In this paper, an adaptive channel time allocation (CTA) is proposed, including public and normal CTAs, to adaptively manage the interpiconet interference in SOPs. In a mobile environment, the public and normal CTAs can also be adaptively allocated based on the link status in the SOPs, thereby reducing interference and improving the efficiency of channel time usage. The proposed scheme is able to achieve a greater throughput than the P/C and P/N configurations. In addition, the link success probability can also be kept at a high value. Based on the SOPs of the direct-sequence ultrawideband (DS-UWB) system, the simulation results demonstrate that the proposed scheme effectively supports the coexistence of SOPs. Furthermore, it not only significantly improves the throughput of the SOPs but also maintains a high link success probability.

In this paper, we propose an efficient MAC protocol: the throughput maximized MAC protocol (TM-MAC), inspired by the availability that a number of ultrawideband (UWB) transmission parameters can be tuned to better match the requirements of data flow. In TM-MAC, we implement a concurrent multiuser access scheme instead of a mutual exclusion method such as TDMA and random access. For multiuser interference, we establish a model to adaptively adjust the data transmission rate to generate the expected signal to interference noise ratio (SINR) at the receiver side for reliable communications. We also analyze the relationship among the theoretical maximum channel capacity, achievable maximum channel capacity, and data transmission rate. According to network topology, TM-MAC redivides each piconet into several subsets in which communication pairs can make communication simultaneously and achieve the maximum throughput using the highest data rate. In subset formation, we propose a general analytical framework that captures the unique characteristics of shared wireless channel and throughput variance, as well as allows the modeling of a large class of systemwide throughput maximization via the specification of the per-link utilization function. For algorithm essential parameters design, we consider the influence of traffic type on the system performance. Heavy tailed distribution, compared to Poisson distribution for most existing work, is exploited to accurately model the real traffic to achieve the adaptation of our algorithm. Simulation results show that our algorithm can maximize throughput to achieve short latency.

This paper proposes a scatternet topology formation, self-healing, and self-routing path optimization algorithm based on Relative Neighborhood Graph. The performance of the algorithm using ns-2 and extensible Bluetooth simulator called blueware shows that even though RNG-FHR does not have superior performance, it is simpler and easier to implement in deploying the Ad-Hoc network in the distributed dynamic environments due to the exchange of fewer messages and the only dependency on local information. We realize that our proposed algorithm is more practicable in a reasonable size network than in a large scale.

When more than seven devices are connected in a Bluetooth scatternet, bridge devices are used to connect two piconets to the scatternet. To deal with possible data transmissions between different piconets, the bridge device must frequently switch to different masters. Suppose, however, that a bridge is serving a piconet and the master in another piconet is calling it at the same time, the calling master has to wait until the bridge completes the previous service. Such transmission delay may accumulate over a long period and the performance of the whole Bluetooth network will degrade significantly. In this work, two new scheduling protocols, namely the static schedule and the hybrid schedule were implemented in an effort to smooth this kind of transmission delay in Bluetooth networks. In this static schedule the rendezvous points between piconets are coordinated by distributing them by using a graph edge coloring technique. In case of a heavy traffic load, the static schedule is expected to perform well. On the other hand, in case of a light traffic load, the static schedule may cause long and unavoidable routing delays even when there is no transmission between piconets; in this case a naive random round-robin (RR) schedule in each piconet is more appropriate. Thus, in the hybrid schedule, each master initially runs a RR scheme in its piconet. When the traffic load is heavier than a predefined threshold value, it runs the static schedule. Finally, simulations were conducted by using an ns-2 simulator and Bluehoc to demonstrate the efficiency and effectiveness of the proposed scheduling protocols.

Distributed media access control (MAC) architecture has many merits to make it a favorable candidate for high-data-rate wireless personal area networks (WPANs) with physical layer (PHY) based on ultrawideband (UWB) technology. This paper focuses on the WiMedia MAC, which is the first distributed MAC for WPANs, approved as a standard. In such a MAC, all devices transmit their beacons to provide timing reference and to broadcast control and reservation information, that is, to maintain device synchronization. We investigate problems related to beacon collisions, which occur when multiple devices join a piconet almost at the same time. To join a piconet or to resolve a collision, a device chooses a slot for its beacon randomly within some window. We show that an improper slot choice scheme leads to repeated collisions, increasing the time overhead to achieve device synchronization. It also leads devices into trouble in joining and collision resolution, even into deadlocks, when devices have no chance to escape repeated collisions. We develop an analytical model to evaluate the performance of various slot choice schemes for multihop WPANs. The model is employed to compare the efficiency of these choice schemes and to optimize their parameters to achieve the best performance.

Mobil datakonsumtion har drastiskt ökat de senaste åren vilket belastar de existerande kommunikationsnätverken. I och med den ökade belastningen av existerande infrastrukturer krävs det nya kommunikationslösningar. Detta har i sin tur skapat ett behov för dataavlastning på fasta nätverk, exempelvis Wi-Fi-nätverk. I denna studie undersöker vi genom simuleringar hur vi kan underhålla ett storskaligt och dynamiskt Bluetooth meshnätverk i en miljö likt Stortorget under Malmöfestivalen. Vi implementerar en nätverkstopologi för Bluetooth, scatternettopologin, i nätverkssimulatorn NS-3 och utför simuleringar där vi provocerar förändringar i topologin. Resultaten av våra simuleringar visar på att nätverket lyckas återhämta sig vid förändring i topologin, att scatternettopologin minst klarar av 240 dynamiska mobila noder samt att max 3 noder påverkas vid förändringar i topologin för simuleringar av upp till 240 noder. Mobile data consumption has drastically increased in the recent years which stress theexisting communication networks. As an effect of the increased load a demand for newcommunication solutions has arisen, creating a need for data offloading onto fixed networks such as Wi-Fi. In this thesis, we aim to study how to maintain and reconstruct a large and dynamic Bluetooth mesh network in an environment such as Stortorget during Malmöfestivalen. We implement a network topology specific for Bluetooth, the scatternet topology, in the network simulator NS-3 and run simulations in which we provoke changes in the network topology. The result of our simulations shows that the network is able to heal itself when the topology changes, that the scatternet topology can manage up to 240 dynamic mobile nodes and that at most 3 nodes are affected when the topology changes during simulations of up to 240 nodes.

IEEE 802.15.3 is a standard that supports high data rate for wireless personal area networks. It implements a centralized topology for network monitoring and control. The centralized piconet coordinator (PNC) needs to be dynamically selected depending on a number of categories that measure its abilities as the most capable device compared to the surrounding devices in the network. This article presents an extension to the PNC selection criteria in IEEE 802.15.3 by modifying the reserved fields readily available in the standard to support user-centricity as well as other higher layer service dependent criteria. This article also develops the implementation process for the message header exchange between devices to support this new selection process. In addition, simulations are carried out that show the proof of concept of the manner in which this new criteria could be implemented in IEEE 802.15.3.

This paper describes a framework for establishment of UWB multi-hop ad hoc networks to improve the efficiency of standard-based multi-hop extension by constructing child or neighbor piconets. Bridge devices (BDEVs) are selected from usual devices with one single network interface by a bridge selection protocol. BDEV is a member of each interconnected piconet. Then, BDEVs are used to build the multi-piconet networks. Each piconet associated with a BDEV follows the 802.15.3 standard. Furthermore, distributed and centralized scheduling schemes are proposed to improve the performance of the scatter ad hoc networks. The distributed schemes are simple and flexible. However, the centralized scheme could achieve better scheduling efficiency. Through simulations, the proposed BDEV scheduling schemes are shown to be effective to extend network coverage in UWB home networks.

This paper proposes MiniMesh, an opportunistic transmission mechanism for the IEEE 802.15.3 medium access control (MAC) protocol; a key technology to realizing wireless personal area networks (WPANs). MiniMesh exploits the varying channel conditions to devices in a WPAN, thereby enabling the sender and receiver of a flow to transmit at high data rates when the channel condition is favorable. In addition, MiniMesh addresses the coverage problem that limits peer-to-peer communications and is backward compatible with the IEEE 802.15.3 specification. We have implemented MiniMesh and the DS-UWB physical layer that offers data rates ranging from 28 Mbps to 1 Gbps in the ns-2 simulator. Our results show devices obtain at least a three fold increase in throughput when only the piconet controller is serving as a relay; further increases are possible with additional relays. Moreover, a flow experiences faster recovery from packet loss and is able to maintain a high throughput even when channel conditions worsen.

Ultra wideband (UWB) network brings both chance and challenge to personal area wireless communications. Compared with other IEEE 802 small range wireless protocols (such as WLAN and Bluetooth), UWB has both extremely high bandwidth (up to 480 Mbps) and low radiation. Moreover, the structured MAC layer of UWB is the fundamental difference to WLAN. The top one is that only when two UWB devices belong to the same piconet can they communicate with each other directly, which means that we must jointly consider topology formation and routing when deploying UWB networks because the interaction between routing and topology formation makes separate optimization ineffective. This paper tries to optimize UWB network from a cross-layer point of view. Specifically, given device spatial distribution and traffic requirement, we want to form piconets and determine routing jointly, to maximize the overall throughput. We formulate the problem of joint optimization to mixed-integer programming and give a practical lower bound that is very close to the theoretical upper bound in our simulation. Furthermore, our lower bound is much better than an algorithm that only considers topology formation in UWB networks.

Bluetooth is a low-cost and short-range wireless communication technology. The Bluetooth device randomly searches and connects with other devices using the inquiry/inquiry scan and the page/page scan operations, resulting an uncontrolled scatternet topology. The unpredictable scatternet topology usually raises the problem of redundant traffic and causes inefficient communications. A traffic-aware restructuring protocol (TARP) is presented for partially restructuring a piconet or a pair of two neighboring piconets by applying role switch mechanism. The proposed TARP mainly consists of intra-piconet and inter-piconet restructuring protocols. According to the recent routes and their traffic load information, the intra-piconet restructuring protocol adjusts piconet structure by selecting the proper device to play a master role of a piconet and applies takeover operation to rapidly restructure the piconet topology. The inter-piconet restructuring protocol exchanges devices of two neighboring piconets to reduce the route length and thus improve the power and bandwidth consumptions and the end-to-end transmission delay. Performance results reveal that the proposed restructuring protocols reduce path length of recent routes and save power consumption, thus significantly improve the performance for a given connected scatternet.

This paper analyzes the performance of a Bluetooth piconet in error-prone environments. A statistical characterization of a waiting time, an end-to-end delay, and a goodput are derived analytically in terms of the arrival rates, the number of slaves, and the packet error rate (PER). For simplicity, half-symmetric piconet is assumed in this analysis. Both exhaustive and limited scheduling are considered. The analytic results are validated by simulations.

As Bluetooth is available in most personal and portable terminals (eg, cellular phone, PDA, videocamera, laptop, etc) Peer-to-peer video streaming through Bluetooth networks is now a reality. Camera equipped Bluetooth phones capture video and broadcast it to other Bluetooth devices and to the infrastructure. Tra ditionally, large scale Bluetooth networks were designed using scatternet concepts. However, many Bluetooth devices do not support Scatternet connections and, even if they support it, they provide only very limited features suitable mostly for static environments. In high mobility situations, a traditional Scatternet design is not useful because of frequent disconnections and reconnections. To overcome these problems, we propose overlaid Bluetooth Piconets (OBP) and simplified overlaid Bluetooth Piconets (SOBP) that interconnect Piconets forming virtual Scatternets. In OBP, every Piconet dynamically reconfigures to collect metadata from neighboring Piconets. If metadata shows the existence of useful data to transfer, an inter-Piconet connection is made to carry out the transfer. SOBP can be used instead of OBP once neighbor Piconets have already discovered each other. In this paper, we compare via analysis and simulation the throughput and efficiency of OBP, SOBP and Scatternet for video applications. We demonstrate the feasibility of video over OBP and SOBP for a representative application.

In a large scale Bluetooth network, the permanent Scatternet is regarded as the only method to interconnect Piconets. But, many Bluetooth devices do not support Scatternet. When they support it, features are limited. Moreover, in high mobility situations, the permanent Scatternet is not useful because of the extremely high overhead caused by frequent disconnections and reconnections. We propose Overlaid Bluetooth Piconets (OBP) and Temporary Scatternets (TS) to interconnect Piconets and form a virtual Scatternet. In OBP, every Piconet continuously changes its stages and collects metadata from Piconets within communication range. If metadata shows the existence of useful data to transfer, an inter-piconet connection is made and data is transferred. TS can be used instead of using permanent Scatternet to interconnect Piconets when needed. TS does not require large Scatternet formations and complex maintenance schemes. Moreover, it does not keep routing information. In this paper, we introduce and illustrate the OBP and TS concepts. We then compare throughput and efficiency of OBP and TS with respect to Scatternet.

Efficient communication in Bluetooth networks requires design of intra and inter-piconet scheduling algorithms, and therefore, numerous algorithms have been proposed. However, due to complexities of the Bluetooth MAC, the performance of these algorithms has been analyzed mostly via simulation. We present analytic results regarding the exhaustive, gated, and limited (pure round robin) scheduling algorithms in piconets with bidirectional and unidirectional traffic. We show that a piconet operated according to the limited scheduling algorithm is equivalent to a 1-limited polling system and present exact results regarding symmetric piconets with bidirectional traffic. Then, the difficulties in analyzing the performance of the exhaustive and gated algorithms in a piconet with bidirectional traffic are demonstrated. In addition, we present exact analytic results for piconets with unidirectional traffic. We show that, surprisingly, in symmetrical piconets with only uplink traffic, the mean waiting time is the same for the exhaustive and limited algorithms. This observation results from the differences between piconets and traditional polling systems and can be extended for time-division-duplex systems with arbitrary packet lengths. Furthermore, we show that the mean waiting time in a piconet with only uplink traffic is significantly higher than its corresponding value in a piconet with only downlink traffic. Finally, we numerically compare the exact results to approximate results, presented in the past.

The interest in Bluetooth technology has stimulated much research in algorithms for topology creation and control of networks comprised of large numbers of Bluetooth devices. In particular, the issue of scatternet formation has been addressed by researchers in a number of papers in the technical literature. This paper is an extension of the work presented in [14, 15]. In this paper we present a complete description of what we believe to be a promising scatternet formation protocol --- BlueNet, which was first proposed in [15]. Some modifications and enhancements are made to improve the connectivity of resulting scatternets. The metrics are chosen to evaluate the performance of resulting scatternets, such as the reliability, the routing efficiency, the piconet density, and the information carrying capacity. Based on the chosen metrics, performance is then compared among the scatternet samples generated by BlueNet and other two representative multi-hop scatternet formation protocols, i.e., BlueTrees [16] and LSBS [1]. Finally in the conclusion a discussion is presented on the compared scatternet formation protocols.

Bluetooth is a new technology for low-cost, low-power, and short-range wireless communication. By constructing a piconet, Bluetooth device establishes link and communicates with other device in a master-slave manner. Relay is a Bluetooth device that joins two or more piconets and forwards data from one piconet to another, providing multi-hop (or inter-piconet) communication services. In a Bluetooth scatternet, the number of relays and the degree of each relay are factors that significantly affect the performance of entire network. Unnecessary relays raise the difficulty of scheduling, leading to frequent packet loss. Relay switching among several piconets in turns also creates guard time overhead and increases the transmission delay. This study presents an effective protocol that can dynamically adjust the network topology by reducing the unnecessary relays. An efficient scatternet environment thus can be constructed with characteristics of connected, high bandwidth utilization and low maintenance cost. Additionally, a routing protocol is developed to reduce the path length and generate two disjoint routes for any pair of source and destination devices located in different piconets. Experimental results demonstrate that the proposed protocols perform well in terms of route length, bandwidth consumption, and transmission delay.

Recently, IEEE 802.15.4a(low-rate UWB) technique has been paid much attention to the LR-UWB communication system for WPAN. However, there are various interferences such as MPI(Multi Path Interference) or IPI(Inter Piconet Interference) in IEEE 802.15.4a wireless channel. In order to cancel various interferences occurred to WPAN environment, in this paper, we propose a UWB wireless communication system with high QoS(Quality of Service) which is a chaotic-OOK(On-Off Keying) system using unipolar ZCD(Zero Correlation Duration) spreading code in physical layer level. Furthermore, we analyze its performance via simulations and verify the availability of proposed system with prototype implementation.

In this paper, we analyze the performance of double-dwell hybrid initial acquisition in a direct sequence ultra-wideband (DS-UWB) system via detection, miss, false alarm probabilities, and mean acquisition time. In the analysis, we consider the effect of the acquisition sequence as well as the deployment scenario of the abundant multipath components over small coverage of the piconet in the DS-UWB system. Based on the simulation, we obtain various performance measures for the mean acquisition time by varying parameters such as the total number of hypotheses to be searched, subgroup size, and dwell time. We thereupon suggest the optimum parameter set for the initial acquisition in the DS-UWB system.

Timing synchronization of symbol boundaries is known to affect critically the performance of all coherent communication systems. Its effects are particularly pronounced in contemporary wireless technologies including ultrawideband (UWB) radios and wireless sensor networks (WSNs), where cooperative or ad hoc access is challenged by arbitrary asynchronism, intersymbol interference (ISI), receiver noise, as well as inter and intrapiconet interference arising from concurrently communicating nodes. To cope with these challenges, this paper introduces piconet-specific synchronization patterns and simple averaging operations at the receiving ends, which enable low-complexity timing acquisition through energy detection and demodulation by matching to a synchronized aggregate template (SAT). Pattern sequences are designed for both training-based and blind operation. Either way, the idea behind these designs is to periodically increase the transmit-power ("voice") of each piconet's synchronizing node with a period ("pace") characteristic of each piconet. Performance of the novel synchronization protocols is tested with simulations conforming to an UWB wireless personal area network (WPAN) setup

A Bluetooth scatternet is a network topology that is formed by inter‐connecting piconets. A piconet is a starshaped ad‐hoc networking unit that can accommodate eight Bluetooth devices, a master and up to seven slaves. By designating certain piconet nodes as bridges, or gateways, we can interconnect piconets by forcing the bridge nodes to interleave their participation in multiple piconets. Bridge nodes form an auxiliary relay connection between adjacent piconet masters and are fundamental for establishing scatternets. In this paper we present a new fault‐tolerant approach to scatternet formation that is selfhealing and operates in a multi‐hop environment. Our Bluetooth Distributed Scatternet Formation Protocol (BTDSP) establishes a flat scatternet topology, allows incremental node arrival, and automatically heals scatternet partitions by re‐incorporating disconnected nodes. By maintaining neighbor associations in soft state, existing links can also be re‐established quickly upon disconnection due to intermittent wireless connectivity. By only using slave/slave bridges, the algorithm is resilient to both node failure and wireless interference. It also prevents time‐slot waste due to master/slave bridges being away from their piconets.

Bluetooth wireless technology is a low power, low cost and short‐range RF technology that permits communication between bluetooth enabled devices, and focuses on replacement of cables between electronic devices. Communication between Bluetooth devices follows a strict master‐slave scheme. Each master device can have up to 7 active slaves and forms a so called piconet. In Bluetooth employing conventional scheduling policies such as Round Robin (RR), POLL or NULL packet is sent when the Master or Slave node does not have any data to send which causes a significant waste of resources. The DRR (Deficit Round Robin) scheduling algorithm can avoid the waste of time and slot of the RR scheduling at the sacrifice of fairness. In this paper we propose an improved DRR (IDRR) scheduling algorithm which effectively combines the DRR and bin packing algorithm. Computer simulation reveals that slot utilization is increased up to about 60% while the total number of used slots is decreased up to about 100%. The proposed IDRR scheduling is thus effective for not only basic data transmission but also real‐time multimedia data transmission.