4 research outputs found
Delay Optimal Secrecy in Two-Relay Network
We consider a two-relay network in which a source aims to communicate a
confidential message to a destination while keeping the message secret from the
relay nodes. In the first hop, the channels from the source to the relays are
assumed to be block-fading and the channel states change arbitrarily -possibly
non-stationary and non-ergodic- across blocks. When the relay feedback on the
states of the source-to-relay channels is available on the source with no
delay, we provide an encoding strategy to achieve the optimal delay. We next
consider the case in which there is one-block delayed relay feedback on the
states of the source-to-relay channels. We show that for a set of channel state
sequences, the optimal delay with one-block delayed feedback differs from the
optimal delay with no-delayed feedback at most one block
To Obtain or not to Obtain CSI in the Presence of Hybrid Adversary
We consider the wiretap channel model under the presence of a hybrid, half
duplex adversary that is capable of either jamming or eavesdropping at a given
time. We analyzed the achievable rates under a variety of scenarios involving
different methods for obtaining transmitter CSI. Each method provides a
different grade of information, not only to the transmitter on the main
channel, but also to the adversary on all channels. Our analysis shows that
main CSI is more valuable for the adversary than the jamming CSI in both
delay-limited and ergodic scenarios. Similarly, in certain cases under the
ergodic scenario, interestingly, no CSI may lead to higher achievable secrecy
rates than with CSI.Comment: 8 pages, 3 figure