Institute for Systems Research

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Author: search.filters.author.Baras, John S.Subject: search.filters.subject.hybrid networks

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    Adaptive Data Broadcast in Hybrid Networks
    (1997) Stathatos, K.; Roussopoulos, N.; Baras, John S.; ISR; CSHCN
    Hybrid networks combine multiple communication modes and are fast, emerging as the most viable solution for the ever increasing demand for bandwidth and data services. Taking advantage of this new technology, we are proposing a hybrid scheme which effectively combines broadcast for massive data dissemination and unicast for individual data delivery. The goal is to build highly scalable systems with small response time. In this paper, we describe a technique that continuously adapts the broadcast content to match the hot-spot of the workload. We show that the hot-spot can be accurately obtained by, monitoring the ``broadcast misses'' observed through direct requests.

    This is a major departure from all other broadcast optimization schemes which are handicapped by their total reliance on complete knowledge of both ``hits'' and ``misses''. We also show that the proposed adaptive scheme performs effectively even under very dynamic and rapidly changing workloads. Extensive simulation results demonstrate both the scalability and versatility of, the technique. Another basic result obtained in this paper is that the overall, system's throughput depends only on the size of the hot-spot and not on the volume of the workload. This has far reaching implications for very large scale and high volume wide area information systems.

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    Adaptive Data Broadcasting Using Air-Cache
    (1996) Stathatos, K.; Roussopoulos, N.; Baras, John S.; ISR; CSHCN
    In the Data AirWaves Project at University of Maryland, we are integrating Direct Broadcast Satellite (DBS) systems with terrestrial networks to provide a hybrid and effective communication substrate lying between data resources and remote/mobile user applications. Smooth integration of these two media balances the need for rapid data dissemination to very large numbers of clients and on-demand interactive data services. This paper describes the air-cache, a method for effective data broadcasting and an algorithm which rapidly adapts the content of the cache based on the ﲭisses which result in explicit (on- demand) data requests. Simulation results show that the hypothesis of adapting based only on the misses performs quite reasonably and has very little deviation from a system that has complete information - both hits and misses.
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    ATM in Hybrid Networks
    (1996) Baras, John S.; ISR; CSHCN
    A discussion of the extensions or modifications required to integrate ATM into hybrid networks, i.e. seamlessly interconnected terrestrial and space, wireline and wireless networks will be presented. In this context, the discussion will include: interoperability problems and issues, asymmetric channels, and various data rates. Several issues with proposed standards will also be addressed.

    A revised version of this technical report has been published in Proceedings of Design SuperCon 1996, Vol. Day One, pp. 1-1 thru 1-13, Santa Clara, CA, January 30-February 1, 1996.