  This paper investigates physical layer security (PLS) in wireless
interference networks. Specifically, we consider confidential transmission from
a legitimate transmitter (Alice) to a legitimate receiver (Bob), in the
presence of non-colluding passive eavesdroppers (Eves), as well as multiple
legitimate transceivers. To mitigate interference at legitimate receivers and
enhance PLS, artificial noise (AN) aided interference alignment (IA) is
explored. However, the conventional leakage minimization (LM) based IA may
exhibit confidential signal cancellation phenomenon. We theoretically analyze
the cause and then establish a condition under which this phenomenon will occur
almost surely. Moreover, we propose a means of avoiding this phenomenon by
integrating the max-eigenmode beamforming (MEB) into the traditional LM based
IA. By assuming that only statistical channel state informations (CSIs) of Eves
and local CSIs of legitimate users are available, we derive a closed form
expression for the secrecy outage probability (SOP), and establish a condition
under which positive secrecy rate is achievable. To enhance security
performance, an SOP constrained secrecy rate maximization (SRM) problem is
formulated and an efficient numerical method is developed for the optimal
solution. Numerical results confirm the effectiveness and the usefulness of the
proposed approach.
