Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Capacity of Gaussian Channels with Duty Cycle and Power Constraints   In many wireless communication systems, radios are subject to a duty cycle
constraint, that is, a radio only actively transmits signals over a fraction of
the time. For example, it is desirable to have a small duty cycle in some low
power systems; a half-duplex radio cannot keep transmitting if it wishes to
receive useful signals; and a cognitive radio needs to listen and detect
primary users frequently. This work studies the capacity of scalar
discrete-time Gaussian channels subject to duty cycle constraint as well as
average transmit power constraint. An idealized duty cycle constraint is first
studied, which can be regarded as a requirement on the minimum fraction of
nontransmissions or zero symbols in each codeword. A unique discrete input
distribution is shown to achieve the channel capacity. In many situations,
numerically optimized on-off signaling can achieve much higher rate than
Gaussian signaling over a deterministic transmission schedule. This is in part
because the positions of nontransmissions in a codeword can convey information.
Furthermore, a more realistic duty cycle constraint is studied, where the extra
cost of transitions between transmissions and nontransmissions due to pulse
shaping is accounted for. The capacity-achieving input is no longer independent
over time and is hard to compute. A lower bound of the achievable rate as a
function of the input distribution is shown to be maximized by a first-order
Markov input process, the distribution of which is also discrete and can be
computed efficiently. The results in this paper suggest that, under various
duty cycle constraints, departing from the usual paradigm of intermittent
packet transmissions may yield substantial gain.

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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: eess
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: physics
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The categories of this paper are: patt-sol
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex