LC-LPD Waveform Radio

CNF proposes an indexed OFDM modulation and encoding scheme for extremely low SNR communications. This scheme is bandwidth scalable to achieve higher user rate, lower emergency rates, or operate in lower SNR environments. As a baseline for comparison, it achieves a channel capacity of 90 kbps at a bandwidth of 8 MHz with -20 dB SNR and 1/8 rate super-orthogonal Hadamard convolutional encoding.  This innovative scheme uses orthogonal Hadamard codes of length 64 to map encoded data bits on to 1024 OFDM subcarriers. A novel pilot scheme guarantees stability of symbol timing, carrier frequency alignment, and phase reference for up to 1000 OFDM symbols when using a 1 ppm clock and does not implement a cyclic prefix. Indexed OFDM allows for simplified receiver processing based on symbol correlation and mitigates cyclo-stationary detection.  CNF’s hardware approach uses a COTS MIL-STD 202g Xilinx Z7035 FPGA processing board and to design interchangeable interface and power/battery modules. In addition, CNF will design a lightweight custom chassis to meet MIL-STD-810g environmental specifications and achieve a unit cost of ~$2000 per unit.   CNF will oversee production, testing, as well as commercialization to market the units for customers requiring high-end, low-cost, ruggedized software defined radios.