110,173 research outputs found
The Benefit of Encoder Cooperation in the Presence of State Information
In many communication networks, the availability of channel state information
at various nodes provides an opportunity for network nodes to work together, or
"cooperate." This work studies the benefit of cooperation in the multiple
access channel with a cooperation facilitator, distributed state information at
the encoders, and full state information available at the decoder. Under
various causality constraints, sufficient conditions are obtained such that
encoder cooperation through the facilitator results in a gain in sum-capacity
that has infinite slope in the information rate shared with the encoders. This
result extends the prior work of the authors on cooperation in networks where
none of the nodes have access to state information.Comment: Extended version of paper presented at ISIT 2017 in Aachen. 20 pages,
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Multiple Access Channels with States Causally Known at Transmitters
It has been recently shown by Lapidoth and Steinberg that strictly causal
state information can be beneficial in multiple access channels (MACs).
Specifically, it was proved that the capacity region of a two-user MAC with
independent states, each known strictly causally to one encoder, can be
enlarged by letting the encoders send compressed past state information to the
decoder. In this work, a generalization of the said strategy is proposed
whereby the encoders compress also the past transmitted codewords along with
the past state sequences. The proposed scheme uses a combination of
long-message encoding, compression of the past state sequences and codewords
without binning, and joint decoding over all transmission blocks. The proposed
strategy has been recently shown by Lapidoth and Steinberg to strictly improve
upon the original one. Capacity results are then derived for a class of
channels that include two-user modulo-additive state-dependent MACs. Moreover,
the proposed scheme is extended to state-dependent MACs with an arbitrary
number of users. Finally, output feedback is introduced and an example is
provided to illustrate the interplay between feedback and availability of
strictly causal state information in enlarging the capacity region.Comment: Accepted by IEEE Transactions on Information Theory, November 201
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