We explore the paradigm of multi-stream, object-based, audio-visual presentations that allow for user-interactivity. The VIP Presentation System, an end-to-end, streaming client/server system based on MPEG-4 specs, prototypes an interactive learning application. Issues such as media-object synchronization, error-resilient video decoders, and audio-visual scene composition is investigated. MORE>>

Due to the proliferation of Personal Digital Assitants (PDAs), the increase in demand for mobile computing, and the advancement of pervasive computing, we explore the possibility of developing real-time multimedia applications rooted in such environments. Currently, applications providing certain real-time services have been reported to be successfully built. For example, MS Portrait, which is capable of deliverying two-way live audio coupled with still images, will be included in the future Windows PocketPC releases. In this project, aided by our expertise in video coding and wireless networks, we want to advance further by building a real-time video conferencing package tailored for PDAs running in Access Grids (AGs). Due to the numerous limitations of such a practical system, we have faced numerous challenges in the project. MORE>>

IP-networks are not designed to provide Quality of Service (QoS). However, a level of QoS is required in the application of real-time video. We are currently developing a universal, encoder-initialized, error-control scheme that guarantees a level of QoS of the received video at the decoder-side. MORE>>

There exists an increased interest to transmit real-time data over the Internet in the form of audio and video. Because current networks only provide best effort services, real-time video performance is generally not satisfactory. In this project we adaptively change the video transmission rate according to the feedback of a video quality parameter based on an application-level, perceptual-video quality scheme. MORE>>

We study the performance of the Canon Broadband Photo and Printing Services (BPPS) in order to provide a thorough foundation for technical and business development. In order to effectively evaluate the BPPS system, a queueing model is built using OPNET, a commercial network simulation tool. We investigate the impact of sensitive parameters on the BPPS system through comprehensive simulations. A performance study is also conducted for upload-traffic under customized scenarios from Canon.

We propose a novel scheduling algorithm called Fair & Power-Efficient Channel-Dependent Scheduling, which schedules packet delivery to mobile stations in a fair manner while simultaneously taking into consideration the channel conditions for power efficiency for packet data traffic. Our performance study indicates that this approach is not only fair and energy-conserving, but consequently reduces interference as well. The algorithm is also extended to real-time traffic. With added delay information for real-time traffic, this approach aims at delivering real-time traffic in a timely manner, while maintaining an even balance between power conservation and fairness. Through comparative simulations with two conventional scheduling algorithms, we demonstrate that our scheme achieves better overall performance than comparable scheduling schemes.

A current challenge for wireless systems is to provide sustainable, high bit-rate for real-time multimedia applications. In this project, we propose to achieve an adaptive power and bit-rate control. The key concept in this research is to exploit the subtle multipath differences in sub-channels and treat them differently by adaptively allocating power and/or information bit-rate to each antenna. The outage probability is the main performance metric to reflect the effectiveness of the algorithm.

With the aid of modern, deep-submicron technologies, complex systems can be designed as a system-on-a-chip. Because most of the functionalities are now implemented on a chip, small network devices are now a reality. Such mobile and wireless network devices need efficient power management in order to conserve as much energy as possible. Much research has been initiated in efficient power management. We can categorize the work into several levels, depending on the power-saving objective. A system component can be designed to consume less power using low-power techniques that focus just on that component. An entire hardware system can be managed by following system-level power management techniques, including dynamic voltage-scaling and dynamic power management. Work in this research aim to save the energy on a system by using system-level information.

However, for devices where the workload of communication components dominates the actual calculation components of a system, the energy consumption of a system can be improved by exploiting information obtained from communication behaviors. For ad-hoc network environments without any infrastructure, energy management can also be utilized in order to save the total energy consumption of all the communication of devices in the network. In this project, we explore the use of communication information to save the energy of the whole system. By harnessing power-awareness as a major parameter, we investigate how to obtain the minimal total-energy consumption among communication devices in a network. We propose new protocols from the MAC layer to the network layer that facilitate energy-awareness in the context of communications between devices.

Communicating with sensors has long been limited either to wired connections or to proprietary wireless communication protocols. Using a ubiquitous and inexpensive wireless communication technology to create Sensor Area Networks will accelerate the extensive deployment of sensor technology. Bluetooth, an emerging, worldwide standard for inexpensive, local wireless communication is a viable choice for such networks because of its inherent support for some of the important requirements - low power, small form factor, low cost and sufficient communication range. In this project we outline an approach, centered on the Bluetooth technology, to support a sensor network composed of fixed wireless sensors for health monitoring of highways, bridges and other civil infrastructures. We investigate a topology formation scheme that not only takes into account the traffic generated by different sensors but also the associated link strengths, buffer capacities and energy availability. We also analyze the scheduling, routing and healing aspects of the resulting sensor-net topology.

Ultra Wide Band (UWB) is an emerging paradigm both in the field of radar applications and digital communications. The different technology options available for its realization are summarized below:

1) Traditional Impulse Radio approaches (sub-nanosecond pulse): Time hopping, PPM Direct Sequence, Bi-polar modulation, Pulsed PAM.
2) Non-traditional frequency based approaches: Pulsed OFDM, Pulsed Sub-bands.

The features that make UWB suitable for realising Wireless Sensor Networks are:

1) Capacity: Possibility of achieving high throughput, robustness to co-channel interference and narrowband jammers, and greater spectrum sharing.
2) Low Power and Low Cost: Can directly modulate a baseband pulse and no need for mixers or PA, allows for CMOS integration of most (if not all) components, high capacity can be achieved with much lower TX power levels and promising for mobile applications (low cost/low battery usage)
3) Fading robustness: Wideband nature of the signal reduces time varying amplitude fluctuations (fading) thus reducing fade margin in link budgets.
4) Position location capability: Short Impulse (wideband signal) allows for accurate delay estimates, which can be used for accurate position location.
5) Flexibility: Can easily and dynamically trade-off throughout for distance, making the technology compatible for a large number of applications based on sensor networks.