2 research outputs found
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
Cooperative Binning for Semi-deterministic Channels with Non-causal State Information
The capacity of the semi-deterministic relay channel (SD-RC) with non-causal
channel state information (CSI) only at the encoder and decoder is
characterized. The capacity is achieved by a scheme based on
cooperative-bin-forward. This scheme allows cooperation between the transmitter
and the relay without the need to decode a part of the message by the relay.
The transmission is divided into blocks and each deterministic output of the
channel (observed by the relay) is mapped to a bin. The bin index is used by
the encoder and the relay to choose the cooperation codeword in the next
transmission block. In causal settings the cooperation is independent of the
state. In \emph{non-causal} settings dependency between the relay's
transmission and the state can increase the transmission rates. The encoder
implicitly conveys partial state information to the relay. In particular, it
uses the states of the next block and selects a cooperation codeword
accordingly and the relay transmission depends on the cooperation codeword and
therefore also on the states. We also consider the multiple access channel with
partial cribbing as a semi-deterministic channel. The capacity region of this
channel with non-causal CSI is achieved by the new scheme. Examining the result
in several cases, we introduce a new problem of a point-to-point (PTP) channel
where the state is provided to the transmitter by a state encoder.
Interestingly, even though the CSI is also available at the receiver, we
provide an example which shows that the capacity with non-causal CSI at the
state encoder is strictly larger than the capacity with causal CSI