Covertmimo: A Covert Uplink Transmission Scheme For Mimo Systems

The covert communication in the physical layer and WiFi network is an important tendency for the current research on covert channel. On the other hand, the MIMO beamforming technique used in the physical layer of WiFi networks provides great potential for developing covert transmission scheme. To fill this gap, this paper presents a novel covert channel based on the coordinated operations in the control channel and data channel of MIMO system, called CovertMIMO. Under this scheme, the covert transmitter can make some slight modification on the normal uplink process, such that the recovered physical layer signal at the receiver side deviates from the pre-agreed overt signal. Through the deviation, some covert information can be encoded and delivered. To implementing CovertMIMO, this paper considers two kinds of wardens that follow the minimum principle and distribution principle respectively. Against them, the parameter identification is transformed into solving an optimization problem or nonlinear equation set. The transmission capacity and undetectability of CovertMIMO are also analyzed in detail. At last, the effectiveness of CovertMIMO is validated through extensive experiments.