  To severely weaken the eavesdropper's ability to intercept confidential
message (CM), a precise jamming (PJ) idea is proposed by making use of the
concept of secure precise wireless transmission (SPWT). Its basic idea is to
focus the transmit energy of artificial noise (AN) onto the neighborhood of
eavesdropper (Eve) by using random subcarrier selection (RSS), directional
modulation, phase alignment (PA), and amplitude beamforming (AB). By doing so,
Eve will be seriously interfered with AN. Here, the conventional joint
optimization of phase and amplitude is converted into two independent phase and
amplitude optimization problems. Considering PJ and SPWT require PA, the joint
optimization problem reduces to an amplitude optimization problem. Then, two
efficient AB schemes are proposed: leakage and maximizing receive
power(Max-RP). With existing equal AB (EAB) as a performance reference,
simulation results show that the proposed Max-RP and leakage AB methods perform
much better than conventional method in terms of both bit-error-rate (BER) and
secrecy rate (SR) at medium and high signal-to-noise ratio regions. The
performance difference between the two proposed leakage and Max-RP amplitude
beamformers is trivial. Additionally, we also find the fact that all three AB
schemes EA, Max-RP, and leakage can form two main peaks of AN and CM around Eve
and the desired receiver (Bob), respectively. This is what we call PJ and SPWT.
