Time-varying metamaterial-enabled directional modulation for physical layer security in wireless communication links
Various embodiments comprise systems, methods, architectures, mechanisms and apparatus providing secure physical layer (PHY) transmission via metamaterial (MTM) leaky-wave antennas (LWAs) using directed modulation (DM) transmitters such as for orthogonal frequency-division multiplexing (OFDM) and non-contiguous (NC) OFDM transmissions, where the DM functionalities exploit the property of time-modulated arrays (TMAs) realized in 1-D and 2-D spaces through the MTM-LWAs.
1 . A transmitter, comprising:
first and second transmission lines, each transmission line comprising a predefined number of unit cells separated from each other by a distance p, each first transmission line unit cell cooperating with a corresponding second transmission line unit cell to form thereby a respective unit cell stage having two inputs and two outputs; and
a plurality of DPDT switches, each DPDT switch disposed between respective prior and subsequent unit cell stages;
wherein the second transmission line unit cells comprise microstrip unit cells configured to propagate therethrough an input signal to provide thereby a transmission signal configured for free space radiation;
wherein the first transmission line unit cells comprise lumped element unit cells having a circuit model equivalent to that of corresponding second transmission line microstrip unit cells;
wherein the DPDT switches are controlled in a manner causing directional modulation (DM) of the transmission signal such that the transmission signal exhibits a low bit error rate (BER) to a receiver at a desired location.
2 . The transmitter of claim 1 , wherein the input signal comprises a dual carrier modulated signal.
3 . The transmitter of claim 1 , wherein the input signal comprises a single carrier modulated signal.
4 . The transmitter of claim 1 , wherein the input signal comprises an OFDM modulated signal.
5 . The transmitter of claim 4 , wherein the OFDM modulated signal comprises a non-contiguous (NC) OFDM modulated signal.
6 . The transmitter of claim 1 , wherein each of the first and second transmission lines comprise respective cascades of composite right/left-handed unit cells configured to form thereby a metamaterial leaky-wave antenna (CRLH LWA).
7 . The transmitter of claim 6 , further comprising:
at least one additional CRLH LWA, wherein each CRLH LWA is separated from an adjacent CRLH LWA by a distance d; and
a plurality of phase delay modules, each phase delay module configured to receive a respective common input signal and provide a respective phase delayed input signal to a respective CRLH LWA.
8 . The transmitter of claim 7 , further comprising a power divider configured to divide an input signal into a plurality of common input signals for use by respective phase delay modules.
9 . The transmitter of claim 6 , wherein the transmitter comprises time-modulated array (TMA) formed as a plurality of TMA branches, each TMA branch configured to receive a common input signal for transmission thereby;
each TMA branch comprising a phase delay module and a composite right/left-handed metamaterial leaky-wave antenna (CRLH MTM LWA), the phase delay module configured to receive the common input signal and provide a respective phase delayed input signal to the respective CRLH MTM LWA for transmission thereby during an on-state of the branch, the CRLH MTM LWA being separated from a CRLH MTM LWA of an adjacent TMA branch by a distance d;
each branch having an on-off state controlled in a manner causing directional modulation (DM) of the transmission signal such that the transmission signal exhibits a low bit error rate (BER) to a receiver at a desired location.
10 . The transmitter of claim 9 , wherein each TMA branch further includes a radio frequency (RF) switch configured to couple the common input signal to a respective phase delay module during an on-state of the TMA branch.
11 . The transmitter of claim 9 , wherein:
the TMA transmitter comprises M TMA branches, wherein Mis an integer greater than 1; and
each CRLH MTM LWA comprises N CRLH cells, wherein Nis an integer greater than 1.
12 . The transmitter of claim 1 , wherein the DM is controlled to provide a usable modulated signal in a desired 2D space.
13 . A 2D directional modulation (DM) transmitter, comprising:
a time-modulated array (TMA) formed as a plurality of TMA branches, each TMA branch configured to receive a common input signal for transmission thereby;
each TMA branch comprising a phase delay module and a composite right/left-handed metamaterial leaky-wave antenna (CRLH MTM LWA), the phase delay module configured to receive the common input signal and provide a respective phase delayed input signal to the respective CRLH MTM LWA for transmission thereby during an on-state of the branch, the CRLH MTM LWA being separated from a CRLH MTM LWA of an adjacent TMA branch by a distance d;
each branch having an on-off state controlled in a manner causing directional modulation (DM) of the transmission signal such that the transmission signal exhibits a low bit error rate (BER) to a receiver at a desired location.
14 . The TMA transmitter of claim 13 , wherein each TMA branch further includes a radio frequency (RF) switch configured to couple the common input signal to a respective phase delay module during an on-state of the TMA branch.
15 . The TMA transmitter of claim 13 , wherein:
the TMA transmitter comprises M TMA branches, wherein Mis an integer greater than 1; and
each CRLH MTM LWA comprises N CRLH cells, wherein Nis an integer greater than 1.
16 . A 2D directional modulation (DM) transmission method, comprising:
receiving a common input signal for transmission at each of a plurality of branches of a time-modulated array (TMA);
each TMA branch imparting a respective a phase delay to a received common input signal and, during an on-state of the TMA branch, transmitting the respective phase delayed common input signal via a respective composite right/left-handed metamaterial leaky-wave antenna (CRLH MTM LWA) separated from a CRLH MTM LWA of an adjacent TMA branch by a distance d;
each branch having an on-off state controlled in a manner causing directional modulation (DM) of the transmission signal such that the transmission signal exhibits a low bit error rate (BER) to a receiver at a desired location.