We develop a network synthesis scenario, which is built around a concrete perimeter surveillance application, yet we believe captures a number of the challenges and requirements that are common to other tactical communication and computational network applications. The proposed scenario addresses the problem of binary population identification within a perimeter: our goal is to synthesize a sensing and computing network that classifies people moving within a given perimeter into one of two categories (e.g., friend or foe). We discuss several open challenges that we organize across the following clusters: sensor placement, communication network provisioning and optimization, computational task placement, dynamic re-synthesis and resilience under adversarial settings. We also briefly discuss approaches that attempt to address such challenges.
Multimedia systems use stream modules to perform operations on the
streams that pass through them. To create services, programmers hand-code modules together to form a pipeline. While some advances have been made in automating this process, none yet exist that create pipelines that are fully aware of the system's resources. In this paper, we present the design and evaluation of the Graph Manager (GM), a pipeline scheduler that determines, on-the-fly, the best way to satisfy requests using stream modules and reusing existing streams in the system.
KEYWORDS: Spatial resolution, Video, Mobile devices, Multimedia, Prototyping, Computer programming, Personal digital assistants, Switches, LCDs, Video compression
Since multimedia applications are known to be resource-hungry and mobile devices are resource-poor, in this paper, we propose techniques to reduce the energy consumption of streaming media applications running on mobile hosts. Our proposed techniques are proxy-based and involve power-friendly transformations on the requested streams so as to limit the energy required for receiving and decoding this data. Additionally, our proxy employs intelligent network transmission techniques to reduce the energy needs for network reception of streaming data. We implement our techniques into a prototype proxy and client and demonstrate their efficacy via an experimental evaluations. Our results show that our power-friendly transformations are effective over a range of bit rates and stream resolutions, while our intelligent transmission techniques can reduce the potential energy wastage during network reception by 65-98%.
An integrated multimedia file system supports the storage and retrieval of multiple data types. In this paper, we first discuss various design methodologies for building integrated file systems and examine their tradeoffs. We argue that, to efficiently support the storage and retrieval of heterogeneous data types, an integrated file system should enable the coexistence of multiple data type specific techniques. We then describe the design of Symphony -- an integrated file system that achieves this objective. Some of the novel features of Symphony include: a QoS-aware disk scheduling algorithm; support for data type specific placement, failure recovery, and caching policies; and support for assigning data type specific structure to files. We discuss the prototype implementation of Symphony, and present results of our preliminary experimental evaluation.
In this paper, we present two disk failure recovery methods that utilize the inherent characteristics of video streams to ensure that the user-invoked on-the-fly failure recovery process does not impose any significant load on the disk array. Whereas the first approach utilizes the sequential nature of playback of video streams to reduce the overhead of the on- the-fly recovery process, the second exploits the inherent redundancies present in video streams to facilitate efficient failure recovery. For the latter approach, we also present a disk array architecture that enhances the scalability of multimedia servers by: (1) integrating the recovery process with the decompression of video streams, and thereby distributing the reconstruction process across the clients; and (2) supporting graceful degradation in the quality of recovered images with increase in the number of disk failures. We compare and contrast our methods to the conventional disk failure recovery schemes.
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