  In this paper, we consider the design of a new secrecy transmission scheme
for a four-node relay-eavesdropper channel. The key idea of the proposed scheme
is to combine noisy network coding with the interference assisted strategy for
wiretap channel with a helping interferer. A new achievable secrecy rate is
characterized for both discrete memoryless and Gaussian channels. Such a new
rate can be viewed as a general framework, where the existing interference
assisted schemes such as noisy-forwarding and cooperative jamming approaches
can be shown as special cases of the proposed scheme. In addition, under some
channel condition where the existing schemes can only achieve zero secrecy
rate, the proposed secrecy scheme can still offer significant performance
gains.
