285,046 research outputs found
Beyond the Min-Cut Bound: Deterministic Network Coding for Asynchronous Multirate Broadcast
In a single hop broadcast packet erasure network, we demonstrate that it is
possible to provide multirate packet delivery outside of what is given by the
network min-cut. This is achieved by using a deterministic non-block-based
network coding scheme, which allows us to sidestep some of the limitations put
in place by the block coding model used to determine the network capacity.
Under the network coding scheme we outline, the sender is able to transmit
network coded packets above the channel rate of some receivers, while ensuring
that they still experience nonzero delivery rates. Interestingly, in this
generalised form of asynchronous network coded broadcast, receivers are not
required to obtain knowledge of all packets transmitted so far. Instead, causal
feedback from the receivers about packet erasures is used by the sender to
determine a network coded transmission that will allow at least one, but often
multiple receivers, to deliver their next needed packet.
Although the analysis of deterministic coding schemes is generally a
difficult problem, by making some approximations we are able to obtain
tractable estimates of the receivers' delivery rates, which are shown to match
reasonably well with simulation. Using these estimates, we design a fairness
algorithm that allocates the sender's resources so all receivers will
experience fair delivery rate performance
Engaging WUMB\u27s Community Beyond Broadcast
WUMB-FM, UMass Boston\u27s National Public Radio affiliate, has a listenership of more than 100,000 people weekly. Through its 7 station network, WUMB has a reach that extends through the greater Boston area and beyond into 4 neighboring New England States. Via the Internet, WUMB reaches listeners in all 50 states and 113 countries. As a media outlet for the University, WUMB engages in a variety of community service activities throughout the Greater Boston Area and beyond, acting as an independent non-profit media organization focused on serving the needs of the university\u27s local, regional and virtual constituents. WUMB draws upon these world-wide resources to engage in a variety of local community service activities beyond the daily operation of it core station
Memory performance of and-parallel prolog on shared-memory architectures
The goal of the RAP-WAM AND-parallel Prolog abstract architecture is to provide inference speeds significantly
beyond those of sequential systems, while supporting Prolog semantics and preserving sequential performance and storage efficiency. This paper presents simulation results supporting these claims with special emphasis on memory performance on a two-level sharedmemory multiprocessor organization. Several solutions to the cache coherency problem are analyzed. It is shown that RAP-WAM offers good locality and storage efficiency and that it can effectively take advantage of broadcast caches. It is argued that speeds in excess of 2 ML IPS on real applications exhibiting medium parallelism can be attained with current technology
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