A channel-enhancement approach to the secrecy capacity of the multiantenna wiretap channel

The secrecy capacity of the multiantenna wiretap channel was recently characterized independently by Khisti and Wornell and Oggier and Hassibi using a Sato-like argument and matrix analysis tools. This paper presents an alternative characterization of the secrecy capacity of the multiantenna wiretap channel using a channel-enhancement argument. Compared with the approach of Khisti-Wornell and Oggier-Hassibi, this characterization is by nature information- rather than matrix-theoretic. Moreover, it extends the previous results from the average total power constraint to the more general matrix power constraint.