Advances in processor and analog-to-digital conversion technology have made the software approach an increasingly attractive alternative for implementing radio-based systems. For mobile telephony base stations, the advantages with the new architecture are obvious: great cost savings by using one transceiver per base transceiver station (BTS) instead of one per channel, tremendous flexibility by moving system-specific parameters to the digital part, and allowing the support of a wide range of modulation and coding schemes. This paper considers the software implementation of a GSM BTS, and analyzes the performance of each of its radio interface modules. The performance of each software module is evaluated using both a % CPU metric and a processor-independent metric based on SPEC benchmarks. The results can be used to dimension systems, e,g., to estimate the number of software-based GSM channels that can be supported by a given processor configuration, and to predict the impact of future processor enhancements on BTS capacity. Two novel aspects of this work are the portability of the software modules and the platform-independent evaluation of their computational requirements.

This paper presents a novel loss recovery scheme, active reliable multicast (ARM), for large scale reliable multicast. ARM is "active" in that routers in the multicast tree play an active role in loss recovery. Additionally, ARM utilizes soft-state storage within the network to improve performance and scalability. In the upstream direction, routers suppress duplicate NACKs from multiple receivers to control the implosion problem. By suppressing duplicate NACKs, ARM also lessens the traffic that propagates back through the network, In the downstream direction, routers limit the delivery of repair packets to receivers experiencing loss, thereby reducing network bandwidth consumption. Finally, to reduce wide-area recovery latency and to distribute the retransmission load, routers cache multicast data on a "best effort" basis. ARM is flexible and robust in that it does not require all nodes to be active, nor does it require any specific router or receiver to perform loss recovery. Analysis and simulation results show that ARM yields significant benefits even when less than half the routers within the multicast tree can perform ARM processing.

We describe the software implementation of a GSM base station and consider the performance of each of its radio interface components. The performance of each software module is evaluated using both a % CPU metric and a processor-independent metric based on SPEC benchmarks. These results can be used to dimension systems, e.g., to estimate the number of GSM channels that can be supported by a given processor configuration, and to predict the impact of future processor enhancements on base station capacity.

No abstract available.

In compute-intensive multimedia applications, the computer not only manipulates media, but also digests it and performs independent actions based on media content. We present a design approach that applies the programming techniques of visualization systems to the development of compute-intensive multimedia applications. We describe an implementation based on this approach, and report performance measurements that demonstrate it is practical. We conclude with a description of some applications that have been implemented and a discussion of the implications for the design and engineering of operating systems.

Article SpectrumWare: a software-oriented approach to wireless signal processing Share on Authors: David L. Tennenhouse Telemedia Networks and Systems Group, Laboratory for Computer Science, MIT Telemedia Networks and Systems Group, Laboratory for Computer Science, MITView Profile , Vanu G. Bose Telemedia Networks and Systems Group, Laboratory for Computer Science, MIT Telemedia Networks and Systems Group, Laboratory for Computer Science, MITView Profile Authors Info & Claims MobiCom '95: Proceedings of the 1st annual international conference on Mobile computing and networkingDecember 1995 Pages 37–47https://doi.org/10.1145/215530.215551Online:01 December 1995Publication History 5citation535DownloadsMetricsTotal Citations5Total Downloads535Last 12 Months3Last 6 weeks1 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access

The VuNet is a gigabit-per-second desk-area ATM network that interconnects general-purpose workstations, network-based multimedia devices, and bridges to other networks, workstations access the multimedia devices over the network and coordinate the movement of information streams among the different parts of the system. This architecture presents several advantages over the traditional workstation-centric models, including the ability to easily share network-based devices, to access nonlocal devices, and to relieve the workstation of a portion of the I/O work. This paper describes the philosophy, implementation choices, advantages, and limitations of the VuNet ATM network implementation, as well as performance and current status.>

This paper describes applications built on the ViewStation, a distributed multimedia system based on Unix workstations and a gigabit per second local area network. A key tenet of the ViewStation project is the delivery of media data not just to the desktop but all the way to the application program. As processing power continues to improve, our approach enables applications that perform intensive processing of audio and video data. We hypothesize that as media data are shaped by this software-based processing, the resultant network traffic patterns will be dominated more by software behavior than by so-called real-time issues. We have written applications that directly process live video to provide more responsive human-computer interaction. We have also developed applications to explore the potential of media processing to support content-based retrieval of prerecorded television broadcasts. These applications perform intelligent processing on video, as well as straightforward presentation. They demonstrate the utility of network-based multimedia systems that deliver audio and video data all the way to the application. The network requirements of the applications are modeled as a combination of bursty transfers and periodic packet-trains.>

In computer-participative multimedia applications, the computer not only manipulates media, but also digests it and performs independent actions based on media content. We present a design approach that applies the programming techniques of visualization systems to the development of computer-participative multimedia applications. We describe an implementation based on this approach, and report performance measurements that demonstrate it is practical. We conclude by describing three applications written with the system, and suggest future directions for research in the area.

The VuNet is a gigabit-per-second desk/local-area asynchronous transfer mode (ATM) network built in the context of the ViewStation distributed multimedia project. The ViewStation system takes a software-intensive approach to multimedia where real-time data are processed at the application level and not in specialized hardware. The VuNet hardware is specifically designed to support this software model. The VuNet hardware and is described, and the results of experiments in which video is transported across the system are presented.

No abstract available.

AURORA is one of five US testbeds charged with exploring applications of, and technologies necessary for, networks operating at gigabit per second or higher bandwidths. The authors provide an overview of the goals and methodologies employed in AURORA and report preliminary results from the first year of research. AURORA is an experiment in collaboration, where government support has spurred interaction among centers of excellence in industry, academia, and government. The emphasis of the AURORA testbed is research into the supporting technologies for gigabit networking. The targets include new software architectures, network abstractions, hardware technologies, and applications. The AURORA testbed will provide a platform in which researchers can explore business and scientific applications of gigabit networks, while evolving the network architecture to meet the needs of these emerging applications.>

The current generation of protocol architectures, such as TCP/IP or the ISO suite, seem successful at meeting the demands of todays networks. However, a number of new requirements have been proposed for the networks of tomorrow, and some innovation in protocol structuring may be necessary. In this paper, we review some key requirements for tomorrow's networks, and propose some architectural principles to structure a new generation of protocols. In particular, this paper identifies two new design principles, Application Level Framing and Integrated Layer Processing. Additionally, it identifies the presentation layer as a key aspect of overall protocol performance.

Asynchronous Transfer Mode (ATM) has been advocated as the basis of multiservice telecommunications in the next century. However, the public telecommunication technology of the 1990's will be ISDN, which presents a circuit switched subscriber interface. An obvious approach to building a wide area ATM network is to build it on top of primary rate ISDN. In this paper we describe the lessons learned through the design and deployment of such a network.

A database management system supporting the Entity-Relationship model has been implemented to provide secure, controlled sharing of information within a user community. This paper describes the security requirements of the users, and how they have been implemented in the DBMS. In the basic security policy, each user belongs to one or more œaccess groups'. Each resource can be accessed only by members of a specific access group. This policy provides flexible control of security, and allows for convenient alteration of individual access rights. The mechanisms used for efficient implementation of the policy are described. Refinements were made to both the security mechanisms and the operations of the DBMS as the interaction of these two aspects was studied. Those refinements are discussed in some detail in this paper.