37966786
Analysis of soft handoff algorithms with dynamic spreading WCDMA system
The undergoing 3G wireless network needs to support integration of voice and multimedia data services with varying QoS requirements. It is critical that the least BER for voice traffic, WWW traffic, and streaming video traffic be guaranteed at all time. With the capability of dynamically changing spreading factor, CDMA system could provide a range of QoS fitting the needs for different traffic type. In this paper, we extend our dynamic spreading admission control scheme to a multi-cell situation, by proposing a dynamic spreading enable soft handoff framework. The static system behavior is analyzed through the studying of the updating probability for both handoff mobile and target cell. Our analysis shows that the updating probability varies according the traffic of interest. A general expression of the joint updating probability is given assuming an equal distribution of traffic type. The processing time of the handoff request is analyzed. We found that the update process caused by handoff is the major component of delay. Further investigation shows that the update associated with handoff might consume too much access channel time, and increase the delay of handoff, especially when handoff traffic is heavy. We therefore adopt a batch mechanism such that multiple handoff requests could be processed simultaneously. The average delay is reduced from 1.12 seconds to 800 ms in heavy handoff rate.
13491789
Multimedia Support for Wireless W-CDMA with Dynamic Spreading
The emerging multimedia communication needs more support in operating systems in order to be successful over a wireless environment. The system needs to support a seamless integration (i.e., transparent application switching) of voice, audio and conventional data (e.g., e-mails, and ftp). It should also support multiple users with a guaranteed quality. In this paper, we investigate effective protocol design with dynamic spreading factors such that various QoS based on different traffic types can be provided. Increasing spreading factors can benefit the system because it will increase the desired signal strength linearly. The measured bit error rate can be reduced 75 times with a long spreading factor. By taking advantage of this benefit, we propose some middle-ware solutions to monitor the network load and switch the spreading factors dynamically based on the current load with multimedia traffic. These middle-ware solutions are implemented in mobile and base stations and experiments are performed to measure the actual system performance. The preliminary results indicate that our proposed system can always maintain a desired quality for all the voice connections. We further extend our protocol to guarantee a balanced support among different traffic types. While the voice communication is still guaranteed to be non-interrupted, the data traffic is proved to be served with reasonable response time by our proposed system.
43623999
A Partition-Based Parallel MPEG-2 Software Decoder
1151748
Scalable and Efficient Data Streaming Algorithms for Detecting Common Content in Internet Traffic
Recent research on data streaming algorithms has provided powerful tools to efficiently monitor various characteristics of traffic passing through a single network link or node. However, it is often desirable to perform data streaming analysis on the traffic aggregated over hundreds or even thousands of links/nodes, which will provide network operators with a holistic view of the network operation. Shipping raw traffic data to a centralized location (i.e., “raw aggregation”) for streaming analysis is clearly not a feasible approach for a large network. In this paper, we propose a set of novel distributed data streaming algorithms that allow scalable and efficient monitoring of aggregated traffic without the need for raw aggregation. Our algorithms target the specific network monitoring problem of finding common content in the Internet traffic traversing several nodes/links, which has applications in network-wide intrusion detection, early warning for fast propagating worms, and detection of hot objects and spam traffic. We evaluate our algorithms through extensive simulations and experiments on traffic traces collected from a tier-1 ISP. The experimental results demonstrate that our algorithms can effectively detect common content in the traffic traversing across a large network.
44717149
Peer-to-Peer Support for File Transfer and Caching Mechanism
In existing Internet file transfer mechanism, proxy servers play a major role in load balancing and reducing duplicate file access requests for services like FTP and WWW. However, proxy servers are usually unaware of the availability of cached contents on other peer proxy servers. This is a waste of time since duplicate requests are needed. Unnecessary traffic can be reduced if cooperation and coordination among peer proxies can be utilized. In this paper, peer-to-peer support was incorporated in ordinary file transfer and caching mechanism to reduce unnecessary processing time and storage. Through the location service, hosts requesting file services can dynamically determine if a copy is available and its current location. Work load for file servers will be greatly reduced, and personalization of file transfer configuration can be fully supported.
35219345
Integrated architectural modeling and analysis for high-assurance command and control system design
A real-time architectural specification (RAS) approach and its application to command and control (C2) systems are presented. The objective is to establish a formal foundation that will enable us to integrate existing rich but fragmented formal techniques for system specification and verification into practical and scaleable formal engineering methods to support the design and development of highly reliable real-time distributed systems. The contribution of RAS is twofold; first, it provides a formal system that integrates the system's timing requirements and the propagation of the requirements into the process of architectural modeling and design and provides a systematic way to enforce that the requirements are met in every step of the design process. Second, it offers an incremental and more scalable approach for design modeling. These two features together make RAS a suitable model for the design of C2 systems. Based on these features, we further present an incremental method for verifying timing properties of a RAS model that helps to reduce the complexity of analysis both at a given design level or across different design levels.
18137821
MILES: Multiple-Instance Learning via Embedded Instance Selection
Multiple-instance problems arise from the situations where training class labels are attached to sets of samples (named bags), instead of individual samples within each bag (called instances). Most previous multiple-instance learning (MIL) algorithms are developed based on the assumption that a bag is positive if and only if at least one of its instances is positive. Although the assumption works well in a drug activity prediction problem, it is rather restrictive for other applications, especially those in the computer vision area. We propose a learning method, MILES (multiple-instance learning via embedded instance selection), which converts the multiple-instance learning problem to a standard supervised learning problem that does not impose the assumption relating instance labels to bag labels. MILES maps each bag into a feature space defined by the instances in the training bags via an instance similarity measure. This feature mapping often provides a large number of redundant or irrelevant features. Hence, 1-norm SVM is applied to select important features as well as construct classifiers simultaneously. We have performed extensive experiments. In comparison with other methods, MILES demonstrates competitive classification accuracy, high computation efficiency, and robustness to labeling uncertainty
207156320
Livenotes: a system for cooperative and augmented note-taking in lectures
We describe Livenotes, a shared whiteboard system and educational practice that uses wireless communication and tablet computing to support real-time conversations within small groups of students during lectures, independent of class size. We present an interface design that enables group members to interact with one another by taking lecture notes cooperatively, as well as to augment student note-taking by providing instructor slides in the background to annotate over. Livenotes was designed to facilitate more efficient, stimulating modes of learning that other collaborative approaches do not. We report how the system impacts cooperative learning in an undergraduate class and how students interacted with background slides in the workspace. We conclude with directions for improving the system and learning practice.