44,785 research outputs found
Energy and Sampling Constrained Asynchronous Communication
The minimum energy, and, more generally, the minimum cost, to transmit one
bit of information has been recently derived for bursty communication when
information is available infrequently at random times at the transmitter. This
result assumes that the receiver is always in the listening mode and samples
all channel outputs until it makes a decision. If the receiver is constrained
to sample only a fraction f>0 of the channel outputs, what is the cost penalty
due to sparse output sampling?
Remarkably, there is no penalty: regardless of f>0 the asynchronous capacity
per unit cost is the same as under full sampling, ie, when f=1. There is not
even a penalty in terms of decoding delay---the elapsed time between when
information is available until when it is decoded. This latter result relies on
the possibility to sample adaptively; the next sample can be chosen as a
function of past samples. Under non-adaptive sampling, it is possible to
achieve the full sampling asynchronous capacity per unit cost, but the decoding
delay gets multiplied by 1/f. Therefore adaptive sampling strategies are of
particular interest in the very sparse sampling regime.Comment: Submitted to the IEEE Transactions on Information Theor
Optimization flow control -- I: Basic algorithm and convergence
We propose an optimization approach to flow control where the objective is to maximize the aggregate source utility over their transmission rates. We view network links and sources as processors of a distributed computation system to solve the dual problem using a gradient projection algorithm. In this system, sources select transmission rates that maximize their own benefits, utility minus bandwidth cost, and network links adjust bandwidth prices to coordinate the sources' decisions. We allow feedback delays to be different, substantial, and time varying, and links and sources to update at different times and with different frequencies. We provide asynchronous distributed algorithms and prove their convergence in a static environment. We present measurements obtained from a preliminary prototype to illustrate the convergence of the algorithm in a slowly time-varying environment. We discuss its fairness property
Wind Technology: A Framework for the Evaluation of Innovations’ Impacts on the Diffusion Potential
This paper proposes a framework based on which innovations in wind power technologies can be evaluated from the standpoint of their contribution to diffusion expansion. The framework helps build up a missing link between the technical literature on innovations and policy-oriented contributions concerned with the diffusion potential of wind power in national energy systems. The ideas are applied for the evaluation of wind technology innovations adopted in Spain. The framework can help policy-makers prioritize their innovation objectives and funding, so as to support the adoption of innovations that deserve the highest priority, given the country’s resources and energy system characteristics
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