US Government As Represented by the Secretary of the Army

University System of Maryland

Brian M Sadler

Fikadu T Dagefu

Paul L Yu

John S Baras

Justin S Kong

Kamal Sarabandi

Gonzalo R Arce

Robert James Drost

Jihun Choi

Jake Perazzone

Sebastian Hoyos

Ricky Blum

Systems and methods for wireless communications comprising a plurality of agents, which together as the group, are configured to: (i) wirelessly broadcast an interference signal by forming a radiation pattern having null vectored substantially toward a client; (ii) wirelessly transmit a communication signal to the client by forming a radiation beam carrying the communication signal vectored substantially toward the client; and (iii) wirelessly broadcast a combined communication signal and interference signal to the client using phases of processes (i) and (ii). In some embodiments, the agents together as a group may be further configured to: allocate and adjust power for performing processes (i) and (ii) at substantially the same time.

Simultaneous beamforming and nullforming for secure wireless communications

A system and method for distributed wireless communications comprising a first group of agents selected and configured to wirelessly transmit a communication signal to a client, wherein the first group of agents is capable of forming a radiation beam carrying the communication signal vectored substantially toward the client, and a second group of agents selected and configured to wirelessly broadcast communication signal interference, wherein the second group of agents is capable of forming a radiation beam not vectored substantially toward the client. Consequently, the first group of agents securely communicates with the client and the second group of agents suppresses the ability of an unauthorized, eavesdropping receiver from intercepting the communications signal.

Distributed adaptive beamforming and nullforming for secure wireless communications

An active matching network for impedance matching to a miniature antenna, comprising a cross-coupled transistor pair, where each transistor has an emitter, base and collector, the emitter of a first transistor forms an input terminal, the emitter of a second transistor forms on output terminal, the collector of the first transistor coupled to the base of the second transistor, the collector of the second transistor coupled to the base of the first transistor, and a matching circuit coupled between the collectors of the first and second transistors. The matching network is configured to match an impendence near resonance of the high Q miniature antenna to an input impedance using a complex negative impedance comprising resistance, inductance and capacitance.

Active matching network design for electrically small resonant antennas

A method for wireless communication using a service side-channel signaling and authentication at the physical level. This method comprising the steps of creating at least one transmitting node and one receiving node within a wireless communication channel. Then choosing primary message and a secondary message and generating a valid transmission tag. Then superimposing the valid transmission tag and creating a set of secret codebooks in order to form a side-channel. Then applying key equivocation metric to measure key information leakage to an eavesdropper. Then transmitting said primary message and said secondary message. Then a receiver receiving said primary and said secondary messages detecting fingerprint estimating data combining a key set with the estimated data sending data and key set to a matrix to generate a secret codebook searching for valid tags authenticating and recovering side information.

Wireless communication method for secure side-channel signaling and authentication at the physical layer

The subject authentication scheme encompasses a large family of authentication systems which may be built over existing transmission systems. By superimposing a carefully designed secret modulation on the waveforms, authentication is added to the signal without requiring additional bandwidth. The authentication information (tag signal) is sent concurrently with data (message signal). The authentication is designed to be stealthy to the uninformed user, robust to interference, and secure for identity verification. The tradeoffs between these three goals are identified and analyzed. The use of the authentication for channel estimation is also considered, and improved bit errors are demonstrated for time-varying channels. With a long enough authentication code word an authentication system is achieved with very slight data degradation. Additionally, by treating the authentication tag as a sequence of pilot symbols, the data recovery may be improved by the aware receiver.

Wireless communication method and system for transmission authentication at the physical layer

A system and method for optimizing signal recognition in a light communication system by approximately maximizing the minimum distance between received constellation points; the method comprising identifying the constellation region containing points for transmitting symbols, identifying channel impairments, transforming the constellation region according to the channel impairments into a constellation region of potential received symbols, using signal processing circuitry to apply an algorithm that operates to maximize the minimum distance between constellation points to obtain a symbol constellation in the receiver constellation region, and inverting the transformation to obtain the designed transmitted-symbol constellation. The system comprises signal processing circuitry for performing a preferred methodology.

Method and system for optimizing signal recognition in a multiwavelength optical communication system

The replacement of secret keys is a central problem in key management. Typical solutions exchange handshaking messages, involve complex computations, or require the cooperation of trusted third parties. Disclosed herein is a key replacement method that exploits the randomness of Markov models to efficiently provide fresh keys to users. Unlike other methods, the proposed method removes the need for extra communications, intensive computation, or third parties. It is demonstrated that the proposed method has perfect forward secrecy as well as resistance to known-key attacks.

Method and implementation for information exchange using Markov models

Included are embodiments of a method for converting a received analog signal into a digital signal. Some embodiments of the method can include receiving an analog signal; periodically dividing the received analog signal into a plurality of discrete signals at a predetermined interval, wherein each of the plurality of divided signals is associated with a voltage; and quantizing the voltage associated with at least one of the plurality of divided signals. Other systems and methods are also provided.

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Laurel, MD, United States of America

Brian M Sadler