1090 Mhz Channel Capacity Improvement In The Air Traffic Control Context

This paper is focused on the 1090 MHz SSR channel capacity increase by innovative transmission and decoding techniques. A lot of Air traffic control systems use the 1090 MHz channel: SSR downlink (on-board transponders), ADS-B messages, TIS-B, FIS-B. We focus the attention on the MLAT (Multilateration) system, useful to localize and identify transponder-equipped targets (aircraft and vehicles). Today multilateration receiver stations have omni-directional antennae, so considering the aircrafts traffic and including the extension of surveillance to cooperating vehicles, the reception of superimposed signals is more and more probable especially in high traffic density airports. In this paper we show the problem mitigation introducing a technique proposed in the international patent [1], and the decoding techniques proposed in [2] and [3]. We analyze the channel capacity improvement, then exploit the detection and the TOA estimation of the frequency-shifted and separated signals, and finally the EUROCAE requirements compliance [4].