Multicarrier Spectral Shaping for Non-White Interference Channels: Application to L-band Aviation Channels

Abstract: In this paper, we investigate an algorithm to attain additive white Gaussian noise (AWGN) performance in spectrally non-white channels, using multicarrier communications, i.e., orthogonal frequency division multiplexing (OFDM) and filterbank multicarrier (FBMC). The non-white channel can be from non-white noise, or more commonly, interference. Our algorithm uses a simple optimization method to find usable subcarriers and assigns different power levels to the subcarriers to attain the equivalent AWGN channel bit error ratio (BER). Subcarriers that experience very high interference are assigned as null subcarriers. After describing our analysis, we show results for two non-white interference signal examples: the Gaussian pulse shaped distance measuring equipment (DME) pulses, and a classical rectangular-pulse interference signal. The DME example is pertinent for currently proposed aviation communication systems, where new multicarrier techniques, e.g., the L-band digital aviation communication systems (LDACS) have been designed as an inlay approach between the high-power DME channels in the L-band. Our results show how using this adaptive technique can improve performance and spectral efficiency, whereas fixed bandwidth schemes such as LDACS could suffer significant performance degradation. These results show the utility of this idea for future adaptive and cognitive radio applications for aviation or other non-white channels.