10,024 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,
1 figur
Joint Source-Channel Coding over a Fading Multiple Access Channel with Partial Channel State Information
In this paper we address the problem of transmission of correlated sources
over a fast fading multiple access channel (MAC) with partial channel state
information available at both the encoders and the decoder. We provide
sufficient conditions for transmission with given distortions. Next these
conditions are specialized to a Gaussian MAC (GMAC). We provide the optimal
power allocation strategy and compare the strategy with various levels of
channel state information.
Keywords: Fading MAC, Power allocation, Partial channel state information,
Correlated sources.Comment: 7 Pages, 3 figures. To Appear in IEEE GLOBECOM, 200
Multiple Access Channels with Combined Cooperation and Partial Cribbing
In this paper we study the multiple access channel (MAC) with combined
cooperation and partial cribbing and characterize its capacity region.
Cooperation means that the two encoders send a message to one another via a
rate-limited link prior to transmission, while partial cribbing means that each
of the two encoders obtains a deterministic function of the other encoder's
output with or without delay. Prior work in this field dealt separately with
cooperation and partial cribbing. However, by combining these two methods we
can achieve significantly higher rates. Remarkably, the capacity region does
not require an additional auxiliary random variable (RV) since the purpose of
both cooperation and partial cribbing is to generate a common message between
the encoders. In the proof we combine methods of block Markov coding, backward
decoding, double rate-splitting, and joint typicality decoding. Furthermore, we
present the Gaussian MAC with combined one-sided cooperation and quantized
cribbing. For this model, we give an achievability scheme that shows how many
cooperation or quantization bits are required in order to achieve a Gaussian
MAC with full cooperation/cribbing capacity region. After establishing our main
results, we consider two cases where only one auxiliary RV is needed. The first
is a rate distortion dual setting for the MAC with a common message, a private
message and combined cooperation and cribbing. The second is a state-dependent
MAC with cooperation, where the state is known at a partially cribbing encoder
and at the decoder. However, there are cases where more than one auxiliary RV
is needed, e.g., when the cooperation and cribbing are not used for the same
purposes. We present a MAC with an action-dependent state, where the action is
based on the cooperation but not on the cribbing. Therefore, in this case more
than one auxiliary RV is needed
Can Negligible Cooperation Increase Network Reliability?
In network cooperation strategies, nodes work together with the aim of
increasing transmission rates or reliability. This paper demonstrates that
enabling cooperation between the transmitters of a two-user multiple access
channel, via a cooperation facilitator that has access to both messages, always
results in a network whose maximal- and average-error sum-capacities are the
same---even when those capacities differ in the absence of cooperation and the
information shared with the encoders is negligible. From this result, it
follows that if a multiple access channel with no transmitter cooperation has
different maximal- and average-error sum-capacities, then the maximal-error
sum-capacity of the network consisting of this channel and a cooperation
facilitator is not continuous with respect to the output edge capacities of the
facilitator. This shows that there exist networks where sharing even a
negligible number of bits per channel use with the encoders yields a
non-negligible benefit.Comment: 27 pages, 3 figures. Submitted to the IEEE Transactions on
Information Theor
- …