Multi-carrier based phased antenna array design for directional modulation

Directional modulation (DM) has been developed based on narrowband antenna arrays, which can form the desired constellation values in the directions of interest while scrambling the values and simultaneously maintaining a magnitude response as low as possible in other directions. In this study, for the first time, the authors develop a multi-carrier based DM framework using antenna arrays, where simultaneous data transmission over multiple frequencies can be achieved, so that a much higher data rate can be obtained. In addition, such a framework allows possible frequency division based multi-user access to the system and also provides the flexibility of using different modulation schemes at different frequencies. Then, they study the antenna location optimisation problem for multi-carrier based DM using a compressive sensing based approach by employing the group sparsity concept. Examples are provided for both the design of weight coefficients and the optimisation of antenna locations.