Out-phased array linearized signaling (OPALS): A practical approach to physical layer encryption

Traditional methods of securing communications rely on methods, such as encryption, which require coordination between the transmitter and the receiver. Physical layer encryption techniques propose exploiting transmit arrays to cover the transmitted signal with beamformed noise or to generate directional modulation to provide security without requiring coordination a priori between the transmitter and receiver. These techniques suffer from implementation difficulties such as high computational requirements and higher amplifier linearity requirements. In this paper we propose out-phased array linearized signaling (OPALS) which provides a practical approach to physical-layer encryption through spatial masking. Our approach modifies just the transmitter to employ the outphasing amplifier design to generate a unique masking signal to each element of an antenna array. This approach improves the peak-to-average power ratio (PAPR) of the transmitter, provides a high degree of confidentiality, and requires no coordination with or modification to the intended receiver.