8 research outputs found
Exploiting Full-duplex Receivers for Achieving Secret Communications in Multiuser MISO Networks
We consider a broadcast channel, in which a multi-antenna transmitter (Alice)
sends confidential information signals to legitimate users (Bobs) in
the presence of eavesdroppers (Eves). Alice uses MIMO precoding to generate
the information signals along with her own (Tx-based) friendly jamming.
Interference at each Bob is removed by MIMO zero-forcing. This, however, leaves
a "vulnerability region" around each Bob, which can be exploited by a nearby
Eve. We address this problem by augmenting Tx-based friendly jamming (TxFJ)
with Rx-based friendly jamming (RxFJ), generated by each Bob. Specifically,
each Bob uses self-interference suppression (SIS) to transmit a friendly
jamming signal while simultaneously receiving an information signal over the
same channel. We minimize the powers allocated to the information, TxFJ, and
RxFJ signals under given guarantees on the individual secrecy rate for each
Bob. The problem is solved for the cases when the eavesdropper's channel state
information is known/unknown. Simulations show the effectiveness of the
proposed solution. Furthermore, we discuss how to schedule transmissions when
the rate requirements need to be satisfied on average rather than
instantaneously. Under special cases, a scheduling algorithm that serves only
the strongest receivers is shown to outperform the one that schedules all
receivers.Comment: IEEE Transactions on Communication
Weakly Secure Symmetric Multilevel Diversity Coding
Multilevel diversity coding is a classical coding model where multiple
mutually independent information messages are encoded, such that different
reliability requirements can be afforded to different messages. It is well
known that {\em superposition coding}, namely separately encoding the
independent messages, is optimal for symmetric multilevel diversity coding
(SMDC) (Yeung-Zhang 1999). In the current paper, we consider weakly secure SMDC
where security constraints are injected on each individual message, and provide
a complete characterization of the conditions under which superposition coding
is sum-rate optimal. Two joint coding strategies, which lead to rate savings
compared to superposition coding, are proposed, where some coding components
for one message can be used as the encryption key for another. By applying
different variants of Han's inequality, we show that the lack of opportunity to
apply these two coding strategies directly implies the optimality of
superposition coding. It is further shown that under a set of particular
security constraints, one of the proposed joint coding strategies can be used
to construct a code that achieves the optimal rate region.Comment: The paper has been accepted by IEEE Transactions on Information
Theor
Sichere Kommunikation ĂŒber AbhörkanĂ€le mit mehreren EmpfĂ€ngern und aktiven Störsendern
We derive a state of the art strong secrecy coding scheme for the multi-receiver wiretap channel under the joint and individual secrecy constraints. we show that individual secrecy can utilize the concept of mutual trust to achieve a larger capacity region compared to the joint one. Further, we derive a full characterization for the list secrecy capacity of arbitrarily varying wiretap channels and establish some interesting results for the continuity and additivity behaviour of the capacity.FĂŒr den Abhörkanal mit mehreren EmpfĂ€ngern wird ein Kodierungsschema hergeleitet unter dem gemeinsamen als auch individuellem Sicherheitskriterium. Das individuelle Kriterium basiert auf dem Konzept des gegenseitigen Vertrauens, um eine gröĂere KapazitĂ€tsregion zu erreichen. Weiterhin wird eine vollstĂ€ndige Charakterisierung der SicherheitskapazitĂ€t fĂŒr den beliebig variierenden Kanals aufgestellt, sowie Eigenschaften bezĂŒglich der KontinuitĂ€t und des AdditivitĂ€tsverhalten bewiesen