Retrodirective Coherency Linking Advanced Squads to Squads (ReCLASS)

The US Army has demonstrated great support of developing robust communications in a contested and congested electromagnetic environment.  Communication is often key to mission success and with growing amounts of co-channel interference and adversaries developing advanced threats aimed at detecting, geolocating, and jamming US assets, it is of the utmost importance that US troops are equipped with communication technology that can operate in these increasingly difficult conditions.  Distributed beamforming is a technique that allows a wireless network of distributed transceivers to adjust their signal transmissions such that their signals coherently combine at a desired recipient’s antenna(s).  The combined signal improves signal-to-interference-plus-noise ratio (SINR) at the intended recipient and reduces the residual signal in the environment that can be observed by adversarial sensors.  As a result of the increased SNR at the intended recipient, the distributed transmit network can either extend their communication range or reduce the transmit power on individual transceivers to continue operating at a fixed range and lower their probability of detection and interception.  Distributed beamforming techniques can also be used by the recipient to provide anti-jam capabilities.  We are proposing two tasks that would help develop these distributed communication capabilities in a contested and congested environment.  First, we would complete a feasibility study using the C5ISR tool TacticalComm.  If successful, these simulations would allow us to develop a waveform and protocol capable of robust distributed communication in C5ISR’s desired scenarios.  The simulations would address key challenges such as channel estimation with short coherence time, power control, time and frequency synchronization, data distribution, interference suppression, and scalability, and we would examine several performance metrics such as BER, detectability, and interference suppression over various parameter sweeps using TacticalComm’s batch mode.  Second, we would build a software-defined radio testbed that would allow us to examine channel reciprocity with real radios.  This testbed would also be the foundation for a future prototype system that would allow us to test and demonstrate the protocol we develop over the air in realistic scenarios.