Kaleido is a system for flexible concurrent processing of multimedia flows where applications are decomposed into building blocks called "active buffers" whose computation and I/O requirements are characterized so as to allow reservation of CPU and bandwidth resources. The input and output ports of active buffers in a Kaleido application are connected by channels. The active buffers in an application may themselves be mapped either to a single compute node, or to multiple compute nodes connected by a network. The Kaleido runtime system software transparently handles the resulting local and remote channels by providing the abstraction of a distributed "active backplane". This "active backplane" also allows dynamic applications whose functional partitioning among compute nodes can be adapted to network, server, and terminal resources. The paper also describes I/O-centric hardware extensions that we have developed for efficient handling of concurrent multimedia streams in Kaleido.

We study the performance of a unified power control and forward error correction control algorithm for mobile radio systems that attempts to maximize system capacity and minimize transmitter power utilization while satisfying user defined quality of service constraints. The algorithm is distributed, with each individual transmitter-receiver pair determining its own operating point with respect to power and error control parameters. Simulation results from a cellular system with mobile users show that this unified algorithm outperforms the schemes that use power control alone.

In the last decade the growth of wireless communication has been rapid. One critical issue in wireless systems is the efficient encoding of data to ensure correctness in the presence of noise and multipath fading. We propose some encoding schemes which span the FEC/ARQ spectrum and analyze them with respect to throughput and delay. We conclude with an adaptive algorithm for choosing the optimal encoding scheme based on observed error rates.