Random user selection method for LPI in multiuser MISO-OFDMA system

The problem of wireless security for the downlink of MISO-OFDMA systems operating over a frequency-selective channel is investigated. By exploiting the dimensions provided by multiuser MISO-OFDMA systems for random user selection and beamforming, a novel physical-layer security method is to achieve low probability of interception (LPI), which let the attacker's equivalent channel be a random one, is proposed in the paper. Meanwhile, hypothesis testing is used to determine which subcarriers belong to him by any intended user without user selection information. Numerical results have verified the effective-ness.