Browsing by Subject "Bluetooth technology."

Now showing 1 - 5 of 5

Open Access
Contextproxy : a location-aware HTTP proxy server to support web based context-aware services and applications
(2005) Uluçınar, Alper Rifat
The pervasion of computing in our physical world promises more than the ubiquitous availability of computing resources; totally new and exciting interaction schemes are to be explored. Context-awareness, one of the most important aspects of ubiquitous computing, enables applications that make use of their users’ context to provide dynamically adapting information and services to their users or to other applications. Although the technological infrastructure to support ubiquitous and context-aware applications is being deployed rapidly, the standards and the best practices for the interactions of various components in a context-aware application are still missing. In our work we have developed a location-aware HTTP proxy server, called ContextProxy that runs on the popular Symbian platform. ContextProxy acts as a standard HTTP proxy server from the client application’s perspective but it augments the service request of the client with the available location information while submitting the request to the service provider. This allows the existing nomadic applications to immediately become locationaware if they can be configured to make use of a standard HTTP proxy which is a common scheme for web based applications. And also it is possible to write new nomadic applications without considering the context-awareness aspect at the service requestor level. The contextual information added by ContextProxy can then be utilized by the service provider to dynamically adapt its services according to the service requestor’s context.
Open Access
Contructing efficient bluetooth scatternets
(2004) Topal, Tağmaç
Among various technologies for short-range wireless networking, Bluetooth has received a particular attention from users as well as from vendors. It is the main technology that supports wireless personal area networking. Bluetooth Special Interest Group (SIG), which is a consortium established to develop and promote the technology, produces the specifications of Bluetooth standards. The Bluetooth standards specify the building blocks to construct Bluetooth networks of arbitrary size, i.e. scatternets, but they do not specify the policies and algorithms that can be used in constructing these scatternets. There may be various approaches for forming Bluetooth scatternets which will result in different topologies for the same set of nodes. In this thesis, we first define and provide some performance metrics that can be used to evaluate various scatternet topologies that can be the output of different scatternet formation algorithms. Then, we provide a new Bluetooth scatternet construction algorithm that differs from other algorithms in that it also considers the traffic pattern of users (i.e. traffic requirements of nodes among themselves) in establishing a scatternet. Then we evaluate the performance of our algorithm through simulations by observing the properties of the constructed scatternets. In a scatternet that is the result of our algorithm we particularly look to the weighted average shortest path lengths that traffic flows follow, the ratio of satisfied users, and the utilization of the scatternet capacity. The results show that we can achieve a good ratio of satisfied users, a high network utilization, and a reasonably small value for average path lengths using our algorithm. The algorithm is currently centralized, but can be extended to a distributed one in the future.
Open Access
Distributed construction and maintenance of bandwidth-efficient bluetooth scatternets
(2004) Tekkalmaz, Metin
Bluetooth is currently the mainstream technology used for short range wireless communication due to its low power and low cost properties. In order to communicate, Bluetooth enabled devices can form networks called piconets, which consist of at most eight members. To construct larger Bluetooth networks, which are called scatternets, any number of piconets can be combined. Although piconet construction process is standardized by Bluetooth Special Interest Group, scatternet construction policies and algorithms are not yet clarified. There have been many solution proposals for the scatternet construction problem each of which focuses on different aspects of it like the efficiency of the construction algorithm, ease of routing in the resulting scatternet and number of piconets that constitute it. Although various considerations came into picture, bandwidth efficiency of the resulting scatternet topology, which depends on the placement of nodes and communication demand among them, did not take much attention. In this thesis, we provide a distributed and adaptive algorithm that constructs a scatternet and based on collected traffic flow information, modifies it to minimize the overall bandwidth usage. As consequences of efficient use of available bandwidth, reduce in average latency and total energy consumption as well as increase in available bandwidth for new communication demand are also aimed. Moreover, performance of the proposed algorithm is presented, based on the evaluation criteria described.
Open Access
Energy-efficient bluetooth scatternet formation based on device and link characteristics
(2003) Pamuk, Canan
Bluetooth is a promising ad hoc networking technology. Although construction and operation of piconets are well defined in Bluetooth specifications, there is no unique standard for scatternet formation and operation. In this thesis, we propose a distributed and energy-efficient Bluetooth Scatternet Formation algorithm based on Device and Link characteristics (SF-DeviL) that is compatible with Bluetooth specifications. SF-DeviL handles energy efficiency using classes of devices, battery levels and the received signal strengths. SF-DeviL forms scatternets with tree topologies that are robust to battery depletions, where devices are arranged in an hierarchical order in terms of battery power and traffic generation rate. SF-DeviL is dynamic in the sense that the topology is reconfigured when battery levels are depleted, thereby increasing the lifetime of the scatternet. Unlike many of the algorithms in the literature SF-DeviL is also multihop, i.e., there is no requirement for each node to be in the transmission range of all other nodes.
Open Access
GSM and UMTS mobility simulator
(2005) Öner, Mehmet
In this thesis, a mobility simulator for GSM and UMTS has been designed and implemented using Visual C#.Net. The objective has been to design and implement such a simulator that can be used to create and study different traffic load scenarios and mobility patterns that can cause congestion situations. The modular approach adopted for the GSM and UMTS simulator allow us to evaluate the performance of new services. The simulator uses propagation simulation results and terrain profile data to produce capacity and performance metrics related to GSM and UMTS networks. The capacity and the service quality of the network are assessed in a long-term system level simulation scheme. Mobility generation is the core of the simulator program. It generates random paths for the mobile users in the simulation. Then the effects of the mobility patterns of the users on the system capacity are investigated. In GSM mobility simulator, mobility, traffic generation, call-admission and handover are implemented. In UMTS, in addition to GSM modules, power control and soft handover generation is implemented.