Conventional software radios take advantage of vastly improved A/D converters and DSP hardware. Our approach, which we refer to as virtual radios, also depends upon high performance A/D converters. However, rather than use DSPs, we have chosen to ride the curve of rapidly improving workstation hardware. We use wideband digitization and then perform all of the digital signal processing in user space on a general purpose workstation. This approach allows us to experiment with new approaches to signal processing that exploit the hardware and software resources of the workstation. Furthermore, it allows us to experiment with different ways of structuring systems in which the radio component of communication devices are integrated with higher-level applications. This paper describes the design and performance of an environment we have constructed that facilitates building virtual radios and of two applications built using that environment. The environment consists of an I/O subsystem that p...

Distributed multimedia applications will be an important part of tomorrow's application mix and require appropriate operating system (OS) support. Neither hard real-time solutions nor best-effort solutions are directly well suited for this support. One reason is the coexistence of real-time and best effort requirements in future systems. Another reason is that the requirements of multimedia applications are not easily predictable, like variable bit rate coded video data and user interactivity. In this article, we present a survey of new developments in OS support for (distributed) multimedia systems, which include: (1) development of new CPU and disk scheduling mechanisms that combine real-time and best effort in integrated solutions; (2) provision of mechanisms to dynamically adapt resource reservations to current needs; (3) establishment of new system abstractions for resource ownership to account more accurate resource consumption; (4) development of new file system structures; (5) ...

The problem this research addresses is how to modify an existing operating system's I/O subsystem to support new high-speed networks and high-bandwidth multimedia applications that will play an important role in future computing environments.

Abstract not found

Commodity PCs are on the verge of being capable of performing a variety of signal processing tasks that previously required special purpose hardware. Advances in the speed and width of their processors and internal buses allow these machines to manipulate data at rates that would allow their users to interact with a diverse range of sampled media, such as the raw RF spectrum and ultrasound. However, today's PCs lack an I/O system capable of delivering the appropriate bandwidth to these signal processing applications. These applications demand high continuous throughput I/O that smooths the inter-sample jitter introduced byinterrupts, I/O bus latency, scheduling latency, etc. This paper presents a system that provides this functionality. Our system is composed of two tightly integrated parts: a PCI device that provides high raw I/O bus throughput and operating system enhancements to manage the device and provide low overhead transfers across the boundary between kernel and user space. The performance is excellent, providing up to 512 Mbits/sec of continuous throughput for an application. A description of both parts of the system is given, along with performance measurements,and a brief description of an application. 1

Our proposed effort is aimed at the design, prototype implementation, and demonstration of an integrated high-speed networking and middleware infrastructure. This infrastructure will provide QoS specification and enforcement features to program, provision,andcontrol advanced, high-speed networks, and QoS-enabled middleware for Next Generation Internet (NGI) applications. Our architecture (shown in Figure 1) integrates and enhances the following technologies we have developed under previous and ongoing sponsorship: A very high-speed network infrastructure operating at Gigabit speeds: This infrastructure includes (1) the highperformance WUGS switch with hardware support to efficiently handle multicast traffic, (2) an advanced ATM interface capable of link speed in excess of 1 Gbps and (4) intelligent port controllers for the switch that provide network layer processing, as well as support for QoS mechanisms and active networks.

Conventional software radios take advantage of vastly improved A/D converters and DSP hardware. Our approach, which we refer to as virtual radios, also depends upon high performance A/D converters. However, rather than use DSPs, we have chosen to ride the curve of rapidly improving workstation hardware. We use wideband digitization and then perform all of the digital signal processing in user space on a general purpose workstation. This approach allows us to experiment with new approaches to signal processing that exploit the hardware and software resources of the workstation. Furthermore, it allows us to experiment with different ways of structuring systems in which the radio component of communication devices are integrated with higher-level applications. This paper describes the design and performance of an environment we have constructed that facilitates building virtual radios and of two applications built using that environment. The environment consists of an I/O subsystem that p...