12,464 research outputs found
Fault Tolerant Wireless Sensor MAC Protocol for Efficient Collision Avoidance
In sensor networks communication by broadcast methods involves many hazards,
especially collision. Several MAC layer protocols have been proposed to resolve
the problem of collision namely ARBP, where the best achieved success rate is
90%. We hereby propose a MAC protocol which achieves a greater success rate
(Success rate is defined as the percentage of delivered packets at the source
reaching the destination successfully) by reducing the number of collisions,
but by trading off the average propagation delay of transmission. Our proposed
protocols are also shown to be more energy efficient in terms of energy
dissipation per message delivery, compared to the currently existing protocol.Comment: 14 page
On feedback in network source coding
We consider source coding over networks with
unlimited feedback from the sinks to the sources. We first show
examples of networks where the rate region with feedback is
a strict superset of that without feedback. Next, we find an
achievable region for multiterminal lossy source coding with
feedback. Finally, we evaluate this region for the case when one
of the sources is fully known at the decoder and use the result
to show that this region is a strict superset of the best known
achievable region for the problem without feedback
Education in India: An Overview of Challenges and Philanthropic Opportunities
India's young population and productive workforce are a remarkable asset to the country, but large gaps in the education sector hinder it from realizing the true potential of this gift. Where are the needs and how can donors help
On achievable rates for multicast in the presence of side information
We investigate the network source coding rate region for networks with multiple sources and multicast demands in the presence of side information, generalizing earlier results on multicast rate regions without side information. When side information is present only at the terminal nodes, we show that the rate region is precisely characterized by the cut-set bounds and that random linear coding suffices to achieve the optimal performance. When side information is present at a non-terminal node, we present an achievable region. Finally, we apply these results to obtain an inner bound on the rate region for networks with general source-demand structures
On Zero-Error Source Coding with Feedback
We consider the problem of zero error source coding with limited feedback
when side information is present at the receiver. First, we derive an
achievable rate region for arbitrary joint distributions on the source and the
side information. When all source pairs of source and side information symbols
are observable with non-zero probability, we show that this characterization
gives the entire rate region. Next, we demonstrate a class of sources for which
asymptotically zero feedback suffices to achieve zero-error coding at the rate
promised by the Slepian-Wolf bound for asymptotically lossless coding. Finally,
we illustrate these results with the aid of three simple examples
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