Partial Strong Converse for the Non-Degraded Wiretap Channel
This work addresses secure communication for scenarios with eavesdroppers, providing theoretical guarantees on rate limits, but it is incremental as it extends existing techniques to non-degraded channels.
The paper tackles the problem of secure communication over non-degraded wiretap channels by proving the partial strong converse property, showing that when the transmission rate exceeds the secrecy capacity, the probability of correct decoding at the legitimate receiver decays exponentially to zero, with the maximum rate remaining constant for error probabilities in [0,1).
We prove the partial strong converse property for the discrete memoryless \emph{non-degraded} wiretap channel, for which we require the leakage to the eavesdropper to vanish but allow an asymptotic error probability $ε\in [0,1)$ to the legitimate receiver. We show that when the transmission rate is above the secrecy capacity, the probability of correct decoding at the legitimate receiver decays to zero exponentially. Therefore, the maximum transmission rate is the same for $ε\in [0,1)$, and the partial strong converse property holds. Our work is inspired by a recently developed technique based on information spectrum method and Chernoff-Cramer bound for evaluating the exponent of the probability of correct decoding.