A Statistical Approach to MPEG Video Stream Characterization

As video consumes a significant percentage of the available network bandwidth, understanding video bandwidth requirements will translate into better network control schemes. In this study, several commercially available video streams are statistically analyzed and several modeling approaches are developed. The segmentation techniques are found to be rewarding. However, the improvements due to complexity of the polynomial models are insignificant

Multistep Parametric Processes in Nonlinear Optics

We present a comprehensive overview of different types of parametric interactions in nonlinear optics which are associated with simultaneous phase-matching of several optical processes in quadratic nonlinear media, the so-called multistep parametric interactions. We discuss a number of possibilities of double and multiple phase-matching in engineered structures with the sign-varying second-order nonlinear susceptibility, including (i) uniform and non-uniform quasi-phase-matched (QPM) periodic optical superlattices, (ii) phase-reversed and periodically chirped QPM structures, and (iii) uniform QPM structures in non-collinear geometry, including recently fabricated two-dimensional nonlinear quadratic photonic crystals. We also summarize the most important experimental results on the multi-frequency generation due to multistep parametric processes, and overview the physics and basic properties of multi-color optical parametric solitons generated by these parametric interactions.Comment: To be published in Progress in Optic

Message reduction rules (MR(2)): A reduction methodology for message-based multimedia systems

Messages in multimedia systems possess distinct characteristics: they exhibit strong correlations, restrictions and degrees of freedom in end-user utilization patterns. In this work, we introduce application\u27s sense of correctness in the transmission and optimization of multimedia messages. We formalize the relations between messages in terms of application defined concepts. Resultant formalization has led to Message Reduction Rules, MR\sp2, which provide an abstract machine to explore message optimizations. The optimization concepts developed, which includes, neighborhood; a mechanism to shift responses in response domain to improve the response timing, active prediction; a scheme to proactively match user\u27s needs before requests are made if possible, passive prediction; a method to maintain most likely to be accessed past and future responses by application provided semantics, composibility; a scheme to combine messages whenever user can be served more efficiently, inclusion: a scheme to eliminate close-by requests to serve user more effectively; message deadlines; a method to eliminate messages that are no longer relevant to the service quality have been tested in our testbed, MMTP. Our performance studies on independent and inter-dependent class data applications have revealed significant improvements: The end user response time has been reduced in the order of several magnitude. The delay variation has been decreased significantly, providing a more predictable service. The server and network load has been reduced considerably. The maximum delay bounds for the system has been derived and verified. In our experiments, we have found that inclusion rules to be very effective to reduce the maximum delay, while the composition rules to boost the throughput, and (past and future) caching schemes to reduce the server and network load. By employment of MR\sp2, tremendous performance gains have been achieved and applications not feasible under normal circumstances have exhibited satisfactory performance

Microphotonic header-recognition architecture for high-speed optical networks

We demonstrate a MicroPhotonic optical header-recognition architecture based on delaying the optical headers within an optical cavity and detecting them using a photoreceiver array. The MicroPhotonic architecture overcomes the issue of optical interference encountered in conventional single-detector header-recognition structures. A 4-bit MicroPhotonic header-recognition architecture is simulated and experimentally demonstrated at 200 Mb/s

Ratiometric Wavelength Monitor Based on Singlemode-Multimode-Singlemode Fiber Structure

An all-fiber ratiometric wavelength monitor for optical wavelength measurement is proposed and is investigated theoretically and experimentally. Two edge filters with opposite slope spectral responses based on singlemode-multimode-singlemode (SMS) fiber structures are developed. A ratiometric wavelength measurement system employing the developed SMS edge filters demonstrates a high discrimination range of 20.41 dB and a potential wavelength measurement resolution of 10 pm over a wavelength range from 1530 to 1560 nm