The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Caching is a common technique to improve efficiency of data access in MANETs (Mobile Ad hoc Networks), where users communicate using small portable devices connected by resource constraint wireless networks. In some MANET applications, controlling/reducing the cache locations are desirable due to security issues, restricted shared memory and maintenance cost. However, reducing the number of caches...
Geographic routing is assumed to be the most potential routing scheme in wireless sensor networks (WSNs) due to its scalability and efficiency. Recently more and more research work about geographic routing pay attention to its application scenarios in duty-cycled WSNs because of the natural advantage of saving energy consumption with duty-cycling. However, it may cause significant latency issue when...
Mobile devices have become popular to access the information on-the-move. However, the physical restrictions of mobile devices such as display size and input capabilities and the changes of users' contexts may affect the users' information needs and search behaviors. In order to design a new search service which takes mobile users' situation into consideration, it is essential to understand search...
People carry around mobile devices all the time in their daily life and get various information from the Internet in various situations. When searching for information (content) by using mobile devices, users' activities (e.g., walking and standing) and their situations (e.g., commuting in the morning and going out downtown in the evening) often change and this change may affect their degree of concentration...
Recently, many studies exploit mobile sinks to collect sensor data for environmental observations or weather forecasting. Mobile sinks travel in sensing areas and collect data directly from each sensor. By using mobile sinks, we can reduce communication traffic further than that for the case of constructing sensor networks. However, in many methods, the mobile sink collects data from all sensors that...
Smart-phone users can search for information about surrounding facilities or a route to their destination. However, it is difficult to get or search for information while walking because of low legibility. To address this problem, users have to stop walking or enlarge the screen. Our previously proposed system for smart-phone switches the information presentation policies in response to the user's...
In Wireless Sensor Networks (WSNs) a multitude of location-dependent applications have been proposed recently, which is very intriguing for researchers to discover and design more accurate and cost-effective localization algorithms. In an isotropic networks, the Euclidean distance between a pair of nodes may not correlate closely with the hop count between them because the corresponding shortest path...
In mobile ad hoc networks (MANETs), to acquire only necessary data items, it is effective that each mobile node retrieves data items using a top-k query, in which data items are ordered by the score of a particular attribute and the query-issuing mobile node acquires data items with k highest scores. In our previous works, we proposed query processing methods for top-k query for reducing traffic and...
In this paper, we extend an energy-efficient data gathering method, named ODAS/SS, to improve the accuracy of monitoring applications in wireless sensor networks. ODAS/SS adopts spatial interpolation and sleep scheduling mechanisms in order to suppress the energy consumption and the variation in residual energy among nodes. In the original ODAS/SS, nodes which keep awake are selected only based on...
Due to the recent development of information technologies, streaming delivery on hybrid broadcasting environments has become popular. Hybrid broadcasting environments consist of broadcasting systems and communication systems such as digital TV and Internet. In streaming delivery on hybrid broadcasting environments, clients receive streaming data such as video or audio from both systems and play them...
Network lifetime is one of the most critical issues for wireless sensor networks (WSNs) since most sensors are equipped with non-rechargeable batteries with limited energy. To prolong the lifetime of a WSN, one common approach is to dynamically schedule sensors' active/sleep cycles (i.e., duty cycles) with sleep scheduling algorithm. In this paper, we propose a new sleep scheduling algorithm, named...
Flooding is one of the most fundamental approaches to deliver information that is likely to be of interest to surrounding mobile nodes in mobile ad hoc networks. A number of research groups have proposed flooding protocols on purpose to reduce the redundant retransmissions from neighboring nodes. In those approaches, unnecessary transmissions are not minimized in an area where no nodes are interested...
Top-k query is a very useful and important query in wireless sensor networks (WSNs), aiming to find the k nodes with highest readings among the sensor nodes. In WSNs, there are generally two kinds of networks: always-on WSNs (AO-WSNs) in which sensors always keep awake and duty-cycled WSNs (DC-WSNs) where sensors dynamically sleep and wake. To the best of our knowledge, there are a lot of work about...
Focusing on achieving better geographic routing performance of the two-phase geographic greedy forwarding (TPGF) in duty-cycled wireless sensor networks (WSNs) when there is a mobile sink, this paper proposes a geographic distance based connected-k neighborhood (GCKN) algorithm. The algorithm analysis and simulation results show that GCKN can obtain shorter length of the transmission paths explored...
Location information of nodes is the basis for many applications in wireless sensor networks (WSNs). However, most previous localization methods make the unrealistic assumption: (i) all nodes in WSN are always awake and (ii) the radio range of nodes is an ideal circle. This overlooks the common scenario that sensor nodes are duty-cycled to save energy and the radio range of nodes is irregular. In...
In mobile ad hoc networks (MANETs), location based service (LBS) is a typical application. In a LBS, it is effective for each node to acquire data using a k Nearest Neighbor (kNN) query, which retrieves the information on the nearest k nodes from the location specified by the query. However, existing methods for kNN query processing in wired networks and wireless sensor networks cannot be applied...
In this paper, we propose an autonomous and energy-efficient data gathering mechanism with transmission reduction for wireless sensor networks (WSNs). In our proposed mechanism, sensor nodes schedule their message transmission timing in a self-organizing manner such that they can gather sensor data over a whole WSN and transmit that data to a sink node while switching between a sleep state and an...
In this paper, we propose a dynamic route construction method based on measured characteristics of radio propagation in a real environment. Our method first measures characteristics of radio propagation for each link, and determines a communication route from every node to the sink node and its transmission power based on the measured characteristics. While operating the system, our method dynamically...
It has been shown recently that using Mobile Agents (MAs) in wireless sensor networks (WSNs) can help to achieve the flexibility of over-the-air software deployment on demand. In MA-based WSNs, it is crucial to find out an optimal itinerary for an MA to perform data collection from multiple distributed sensors. However, using a single MA brings up the shortcomings such as large latency, inefficient...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.