Frequency Position Modulation for high-throughput interference-resistant communications

Simultaneously achieving the objective of high data rate communications that is resistant to interference (RTI) is a challenging problem. Communications systems typically operate at a reduced information rate for RTI operation. To achieve the objective of high data rate and RTI operation, we have developed a modulation called Frequency Position Modulation (FPM) in which the absolute position of the tones in frequency correspond to a symbol. The tones themselves are spread over an extremely wide instantaneous bandwidth resulting in a communications system that is difficult to intercept. FPM leverages carefully shaped nonlinearities generated by the high-power amplifier (HPA) of the transmitter that become a part of the symbols in the constellation. The addition of nonlinearities improves the diversity of the FPM constellation for resilience in the face of interference. Information at the receiver is recovered by mixing the incoming spectrum with multiple tones in conjunction with a comb filter before digitization. This enables using commercial of-the-shelf (COTS) high dynamic range analog-to-digital converters sampling at a fraction of the rate of the bandwidth over which the symbols are spread. FPM can provide nearly an order of magnitude improvement in processing gain over conventional RTI communications (e.g., CDMA) and facilitates the ability to operate in interference-laden environments where conventional receivers would fail. We quantitatively analyze the symbol error rate (SER) and processing gain (PG) for a maximum likelihood (ML) based FPM demodulator and demonstrate its performance in interference-laden conditions.