Device Discovery in Frequency Hopping Wireless Ad Hoc Networks

This research develops a method for efficient discovery of wireless devices for a frequency hopping spread spectrum, synchronous, ad hoc network comprised of clustered sub-networks. The Bluetooth wireless protocol serves as the reference protocol. The development of a discovery, or outreach, method for scatternets requires the characterization of performance metrics of Bluetooth piconets, many of which are unavailable in literature. Precise analytical models characterizing the interference caused to Bluetooth network traffic by inquiring devices, the probability mass function of packet error rates between arbitrary pairs of Bluetooth networks, and Bluetooth discovery time distribution are developed. Based on the characterized performance metrics, three scatternet outreach methods are developed and compared. Outreach methods which actively inquire on a regular basis, as proposed in literature, are shown to produce lower goodput, have greater mean packet delay, require more power, and cause significant delays in discovery. By passively remaining available for outreach, each of these disadvantages is avoided

Throughput Performance Evaluation and Analysis of Unmodified Bluetooth Devices

The Air Force relies on the application of new technologies to support and execute its mission. As new technologies develop, the integration of that technology is studied to determine the costs and benefits it may provide to the war fighter. One such emergent technology is the Bluetooth wireless protocol, used to connect a small number of devices over a short distance. The short distance is a feature that makes using the protocol desirable. However short, there is still a vulnerability to interception. This research identifies ranges at which several commercially available Bluetooth devices are usable. Various combinations of both distance and orientation are varied to determine a 360 degree map of the Bluetooth antenna. The map identifies distances at which certain throughput thresholds are available. This research shows that baseline 1 mW Bluetooth antennas are capable of throughput levels of 100 kbps at over 40 meters, which is four times the minimum distance specified in the protocol standard. The 3Com PC card was the best performing PC card, capable of throughputs at or near 100 kbps out to 40 meters. The other PC Cards tested had similar performance. The Hawking USB dongle was the best USB antenna tested, achieving throughputs of over 200 kbps in three of the four orientation, and over 150 kbps at the fourth. The 3Com dongle was a close second, the Belkin dongle a distant third, while the DLink antenna was not able to achieve 100 kbps at any distance tested

CBS: constraint-based approach for scheduling in bluetooth networks

In Bluetooth networks, devices are organized into small piconets and large scatternets, and each node acts as the role of master, slave or gateway. Due to dynamic topology changes, different bandwidth available and unpredictable interference of media in Bluetooth networks, the congestion of data flow will inevitably emerges on the link, and the gateway has to switch between piconets on a time division basis, so its presence in the different piconet has to be controlled by scheduling mechanism such as inter- and intra -piconet scheduling. However, the time division in gateways will limit the network capacity and introduce bottleneck points in the network, and the switch between piconets will prevent the packet from transmitting smoothly and efficiently. Most of the published work on Bluetooth scheduling has focused on the polling scheme between master and slaves. In this paper, we put our approach on the inner constraints of Bluetooth networks and present a constraint-based scheduler (CBS), to adaptively cater to the changing role of each node throughout Bluetooth ad hoc networks, thereby it will save time and definitely enhance fairness and efficiency on packet scheduling in Bluetooth environment.Facultad de Informátic

Improving forwarding mechanisms for mobile personal area networks

This thesis presents novel methods for improving forwarding mechanisms for personal area networks. Personal area networks are formed by interconnecting personal devices such as personal digital assistants, portable multimedia devices, digital cameras and laptop computers, in an ad hoc fashion. These devices are typically characterised by low complexity hardware, low memory and are usually batterypowered. Protocols and mechanisms developed for general ad hoc networking cannot be directly applied to personal area networks as they are not optimised to suit their specific constraints. The work presented herein proposes solutions for improving error control and routing over personal area networks, which are very important ingredients to the good functioning of the network. The proposed Packet Error Correction (PEC) technique resends only a subset of the transmitted packets, thereby reducing the overhead, while ensuring improved error rates. PEC adapts the number of re-transmissible packets to the conditions of the channel so that unnecessary retransmissions are avoided. It is shown by means of computer simulation that PEC behaves better, in terms of error reduction and overhead, than traditional error control mechanisms, which means that it is adequate for low-power personal devices. The proposed C2HR routing protocol, on the other hand, is designed such that the network lifetime is maximised. This is achieved by forwarding packets through the most energy efficient paths. C2HR is a hybrid routing protocol in the sense that it employs table-driven (proactive) as well as on-demand (reactive) components. Proactive routes are the primary routes, i.e., packets are forwarded through those paths when the network is stable; however, in case of failures, the protocol searches for alternative routes on-demand, through which data is routed temporarily. The advantage of C2HR is that data can still be forwarded even when routing is re-converging, thereby increasing the throughput. Simulation results show that the proposed routing method is more energy efficient than traditional least hops routing, and results in higher data throughput. C2HR relies on a network leader for collecting and distributing topology information, which in turn requires an estimate of the underlying topology. Thus, this thesis also proposes a new cooperative leader election algorithm and techniques for estimating network characteristics in mobile environments. The proposed solutions are simulated under various conditions and demonstrate appreciable behaviour

Adaptive role switching protocols for improving scatternet performance in Bluetooth radio networks

[[abstract]]Bluetooth is a low-power, low-cost, and short-range wireless technology. A well structured scatternet, with the appropriate number of piconets and bridges for a specific traffic pattern, increases the performance of a Bluetooth network. However, the structure of a scatternet is difficult to control or predefine because the scatternet is formed using a distributed procedure, with the master and slaves of each piconet connected at random. The participation of mobile Bluetooth devices in a scatternet at different times also increases the difficulty of maintaining a good structure. A badly structured scatternet exhibits the following characteristics: too many bridges in the scatternet creates a guard slot overhead associated with bridge switching among the participating piconets, increasing the probability that a packet is lost; too many piconets in a communicative range causes packet collision and thus degrades the performance; unnecessary piconets also lengthen the routing path, delaying the transmission of packets from source to destination. The paper proposes a distributed scatternet reconstruction protocol for dynamically reorganizing the scatternet. Unnecessary bridges and piconets can be dynamically removed by applying a role switching operation, improving the packet error rate, saving guard slots, and reducing the average routing length. By experiment, it is shown that the proposed protocol improves the data transmission performance of a Bluetooth scatternet.[[conferencetype]]國際[[conferencedate]]20040905~20040908[[booktype]]紙本[[conferencelocation]]Barcelona, Spai

The AIVA fly-by-wireless UAV platform

The AIVA project concerns to an UAV aimed to perform aerial surveillance, forest fire detection and also to monitor high voltage cables for stress or failures. The global project involves the design and development of the required aerial platform, as well as the electronics, communications hardware and software, flight control, artificial vision and systems integration, in order to provide an autonomous takeoff, flight mission and landing manoeuvres. Relevant goals, regarding the design and development of the AIVA platform, initiated in September 2004, have already been achieved, and they will be described over next topics. [...

AN EFFICIENT COMBINED CONGESTION HANDLING=--A--cN-:cD~-­ ROUTE MAINTENANCE PROTOCOL FOR DYNAMIC ENVIRONMENT IN BLUETOOTH NETWORK

Bluetooth IS a widespread technology for small wireless networks that permits Bluetooth devices to construct a multi-hop network called a scatternet. A large number of connections passing through a single master/ bridge device may create the problem of congestion in a Bluetooth scatternet. In addition, routing in a multi-hop dynamic Bluetooth network, where a number of masters and bridges exist, sometimes creates technical hitches in a scatternet. It has been observed that frequent link disconnections and a new route construction consume more system resources that ultimately degrade the performance of the whole network. As, Bluetooth specification has defined piconet configuration, scatternet configuration has still not been standardized. The main objective of this thesis is to provide an efficient combined protocol for scatternet congestion handling and route maintenance. The methodology contains three parts

Bluetooth wireless communication for MEMSwear

Master'sMASTER OF ENGINEERIN