18246433
FERMA: An Efficient Geocasting Protocol for Wireless Sensor Networks with Multiple Target Regions
Some sensor applications are interested in collecting data from multiple regions. For supporting such applications with multiple target regions, most conventional protocols are based on either a network flooding or multiple unicastig to cover those more than one target region. Either one will result in a lot of redundant packets to transmit by energy scared sensor nodes. To alleviate this problem, we propose a novel geocasting scheme which can make a suitable shared path among multiple target regions. We utilize the theorem of “Fermat Point,” in order to find an optimal junction point branching into each region. By using this shared path, an interest dissemination can be performed very efficiently. Our simulation study shows that the proposed scheme FERMA reduces a lot of network traffic and achieves significant energy saving as the number of target regions increase.
771096
UAMAC: Unidirectional-Link Aware MAC Protocol for Heterogeneous Ad Hoc Networks
In heterogeneous ad hoc networks, high-power nodes could potentially interfere with any on-going transmissions of low-power nodes. In this paper, we propose a unidirectional-link aware MAC protocol (UAMAC) which prevents such an interference problem by reserving the wireless channel of unidirectional high-power node selectively over one-hop. Our preliminary performance results show that the UAMAC works well in these heterogeneous environments with unidirectional links.
28860469
An Efficient Neighbor Knowledge Based Broadcasting for Mobile Ad Hoc Networks
Although a flooding is the most commonly used method for one-to-all communications, it often results in huge traffic in mobile ad hoc networks. Several optimization schemes have been proposed to alleviate this problem. However, none of them offers a complete solution and has their own limitations, such as, lack of reliability, high latency or excessive control packet overhead. In this paper, we propose the FONIAH (Flooding based on One- hop Neighbor Information and Adaptive Holding) scheme to overcome these limitations.
17586941
Performance Evaluation of Transcoding-Enabled Streaming Media Caching System
We evaluate the performance of transcoding-enabled streaming media caching proxy system (TeC). TeC is designed for efficient delivery of rich media web contents to heterogeneous network environments and client capabilities. Depending on the connection speed and processing capability of an end user, the proxy transcodes the requested (and possibly cached) video into an appropriate format and delivers it to the user. We study the TeC performance by simulation using real traces derived from enterprise media server logs.
14442246
Distributed and energy-efficient target localization and tracking in wireless sensor networks
In this paper, we propose and evaluate a distributed, energy-efficient, light-weight framework for target localization and tracking in wireless sensor networks. Since radio communication is the most energy-consuming operation, this framework aims to reduce the number of messages and the number of message collisions, while providing refined accuracy. The key element of the framework is a novel localization algorithm, called Ratiometric Vector Iteration (RVI). RVI is based on distance ratio estimates rather than absolute distance estimates which are often impossible to calculate. By iteratively updating the estimated location using the distance ratio, RVI localizes the target accurately with only three sensors' participation. After localization, the location of the target is reported to the subscriber. If the target is stationary or moves around within a small area, it is wasteful to report (almost) the same location estimates repeatedly. We, therefore, propose to dynamically adjust a reporting frequency considering the target's movement so that we can reduce the number of report messages while maintaining tracking quality. Extensive simulation results show that the proposed framework combining RVI and the movement-adaptive report scheduling algorithm reduces the localization error and total number of the transmitted messages up to half of those of the existing approaches.
11234364
Robust routing in wireless ad hoc networks
A wireless ad hoc network is a collection of mobile nodes with no fixed infrastructure. The absence of a central authorization facility in dynamic and distributed environments requires collaboration among nodes. When a source searches for a route to a destination, an intermediate node can reply with its cached entry. To strengthen correctness of such a routing discovery process, we propose a method in which the intermediate node requests its next hop to send a confirmation message to the source. After receiving both a route reply and confirmation message, the source determines the validity of a path according to its policy. As a result, this strategy discourages malicious nodes from intercepting packets. Simulation results show a remarkable improvement in throughput (30% higher delivery ratio and 10% less data transmission overhead) with a moderate increase of control messages.
7782422
Wireless Ad Hoc Multicast Routing with Mobility Prediction
An ad hoc wireless network is an infrastructureless network composed of mobile hosts. The primary concerns in ad hoc networks are bandwidth limitations and unpredictable topology changes. Thus, efficient utilization of routing packets and immediate recovery of route breaks are critical in routing and multicasting protocols. A multicast scheme, On-Demand Multicast Routing Protocol (ODMRP), has been recently proposed for mobile ad hoc networks. ODMRP is a reactive (on-demand) protocol that delivers packets to destination(s) on a mesh topology using scoped flooding of data. We can apply a number of enhancements to improve the performance of ODMRP. In this paper, we propose a mobility prediction scheme to help select stable routes and to perform rerouting in anticipation of topology changes. We also introduce techniques to improve transmission reliability and eliminate route acquisition latency. The impact of our improvements is evaluated via simulation.
18035365
A Web Service Approach to Universal Accessibility in Collaboration Services
The enormous growth in wireless communications and miniaturized handheld devices in the last few years, have given rise to a vast range of new services, for heterogeneous user environments. In this paper, we investigate the nature of designing distributed services that accommodate pervasive devices. We introduce Universal Accessible Web service architecture, CAROUSEL Web service. We present our collaborative Web services model linked with an event brokering service, NaradaBrokering. We discuss how a rich synchronous and asynchronous collaboration environment can support virtual communications while being built on top of a Web service infrastructure, based on industry standard portal technologies such as XML, Apache’s Jetspeed, and WSDL. The linkage of the event brokering system with a Web service based architecture is one of the critical design issues in message-based collaborative application. We also describe the approach to universal access mechanisms in our collaborative Web service model. Also included is a discussion of the prototype collaborative SVG (Scalable Vector Graphics) browser that we developed as a Web service.