Degraded broadcast channels with rate-limited feedback

This paper studies the degraded broadcast channel with rate-limited feedback. The transmitter aims to convey a common message to receiver 1 and 2 in addition to a confidential message intended only for receiver 1. The feedback symbol, independent of the channel outputs, is introduced to serve as a secret key between the transmitter and receiver 1. The capacity-equivocation region of this channel model is obtained. A simpler and more intuitive derivation instead of the recursive argument is used to get the single-letter characterization of the upper bound. Furthermore, a novel coding scheme is presented to achieve the upper bound. This paper also derives the secrecy capacity of this channel which subsumes the secrecy capacity of the degraded wiretap channel with rate-limited feedback.