Spectrally shaped filter bank multicarrier systems for L-band aeronautical communication systems

Aeronautical communication systems will play an increasingly important role in the future. Due to increasing flight traffic, which is estimated to double by 2025, and the inadequacy of current aeronautical communication systems to support such an increase, the demand for new and state of the art communication systems is increasing. In this paper we investigate a new spectrally shaped Filter Bank Multicarrier (SS-FBMC) based communication system for air to ground communication. We study a 0.5 MHz spectrally shaped communication system as an inlay system between the 1 MHz separated distance measurement equipment (DME) channels in the L-band. The idea of using the gap in the spectrum that exists between DME channels was first proposed by EUROCONTROL in their L-DACS1 communication system. In the L-DACS1 communication system, which is based on CP-OFDM, the transmitting power is equally distributed among all subcarriers. In this paper we deviate from this convention by using FBMC and assigning different power levels to the subcarriers to mitigate DME interference. We propose a method to find the required guard subcarriers and optimize the amount of allocated power for each remaining subcarrier in order to obtain the best bit error ratio (BER) performance, without any error floor, for different QAM modulation orders and communication links. In so doing we increase the communication system's efficiency and performance. In prior work we have shown that our original FBMC system has higher spectral efficiency and better resilience to DME interference than L-DACS1, but in some cases still incurs a BER floor (as does L-DACS1). Via our spectral shaping approach we remove these BER floors.