Feeding back the output or sharing state, which is better for the state-dependent degraded wiretap channel with noncausal CSI at the transmitter?

In this paper, we show that a noiseless feedback link from the legitimate receiver to the transmitter increases the maximum achievable secrecy rate of Chen and Han Vinck's model of the degraded wiretap channel with CSI only available at the transmitter. Moreover, we find that in some particular cases, this feedback scheme performs even better than Chia and El Gamal's CSI sharing scheme on improving the maximum achievable secrecy rate of Chen and Han Vinck's model.