18 research outputs found
Channel Upgradation for Non-Binary Input Alphabets and MACs
Consider a single-user or multiple-access channel with a large output
alphabet. A method to approximate the channel by an upgraded version having a
smaller output alphabet is presented and analyzed. The original channel is not
necessarily symmetric and does not necessarily have a binary input alphabet.
Also, the input distribution is not necessarily uniform. The approximation
method is instrumental when constructing capacity achieving polar codes for an
asymmetric channel with a non-binary input alphabet. Other settings in which
the method is instrumental are the wiretap setting as well as the lossy source
coding setting.Comment: 18 pages, 2 figure
The Arbitrarily Varying Broadcast Channel with Degraded Message Sets with Causal Side Information at the Encoder
In this work, we study the arbitrarily varying broadcast channel (AVBC), when
state information is available at the transmitter in a causal manner. We
establish inner and outer bounds on both the random code capacity region and
the deterministic code capacity region with degraded message sets. The capacity
region is then determined for a class of channels satisfying a condition on the
mutual informations between the strategy variables and the channel outputs. As
an example, we consider the arbitrarily varying binary symmetric broadcast
channel with correlated noises. We show cases where the condition holds, hence
the capacity region is determined, and other cases where there is a gap between
the bounds.Comment: arXiv admin note: substantial text overlap with arXiv:1701.0334
The Arbitrarily Varying Relay Channel
We study the arbitrarily varying relay channel, and establish the cutset
bound and partial decode-forward bound on the random code capacity. We further
determine the random code capacity for special cases. Then, we consider
conditions under which the deterministic code capacity is determined as well.Comment: arXiv admin note: text overlap with arXiv:1701.0334
Communication Over Entanglement-Breaking Channels With Unreliable Entanglement Assistance
Entanglement assistance can improve communication rates significantly. Yet,
its generation can easily fail. The recently-introduced model of unreliable
assistance accounts for those challenges. Previous work provided an asymptotic
formula for the tradeoff between the unassisted and excess rates from
entanglement assistance. We derive a full characterization for
entanglement-breaking channels, and show that combining entanglement-assisted
and unassisted coding is suboptimal. From a networking perspective, this
finding is nontrivial and highlights a quantum behavior arising from
superposition