1. Secure M-PSK Communication Via Directional Modulation University of Luxembourg, University of Illinois in Chicago ICASSP, Shanghai, 2016 Ashkan Kalantari, Mojtaba Soltanalian, Sina Maleki, Symeon Chatzinotas, and Björn Ottersten

2.  What is directional modulation?  Motivation  Security analysis  Transmitter design  Benchmark  Simulation results  Conclusions Outline 1

3.  The modulation happens while the signal passes the channel  The antenna weights change as the symbol rate  Different locations get different symbols (constellations)  The symbol is recovered without equalization 2 What is directional modulation?

4.  Eavesdropper cannot compute the beamformer  Eavesdropper needs to estimate the symbols and suffers enhanced noise  Legitimate receiver can directly recover the symbols  The eavesdropper’s CSI is not required  The rate is not reduced (compared to secrecy rate) 3 Motivation: Why directional modulation?

5.  Signal model  The eavesdropper needs to estimate ”w”!  Strong eavesdropper:  Strong transmitter: 4 Security analysis

6.  Preserving a specific phase at each antenna  Satisfying a specific SNR at each antenna  Avoiding an NP-hard problem! 5 Transmitter design

7.  Transformed problem     : Last columns of   6 Transmitter design

8.  Benchmark: zero-forcing at the transmitter to neutralize interference  Signal model  Signal recovery at the eavesdropper (P is derived)  No need to multiply by ! 7 Benchmark

9.  Parameters: 8 Simulation results

10.  Parameters: 9 Simulation results

11.  Regardless of SNR, an eavesdropper with less antennas than the transmitter cannot estimate the symbol  An eavesdropper with more antennas can estimate the symbols with enhanced noise  The eavesdropper needs to have in the directional modulation, while it is in the ZF precoding  Directional modulation is an attractive choice to enhance security using massive MIMO systems 10 Conclusions

13.  Assumptions:  Rayleigh flat fading channel  M-PSK modulation  Unit energy symbol, 12 System model