Impact Assessment of the L-Band Digital Aeronautical Communications System on the Joint Tactical Information Distribution System

The L-band digital aeronautical communications system (LDACS) is the future air-ground communications technology currently undergoing the International Civil Aviation Organization standardization process. As LDACS is intended to operate in the frequency band 960-1164 MHz, compatibility tests between LDACS and the legacy systems operating in this frequency band are necessary to ensure that no system is harmfully interfered. One of these systems is the joint tactical information distribution system (JTIDS), a technology employed by the tactical data link Link 16. In this paper, we present the results of an impact assessment of LDACS on JTIDS conducted through simulations. The extent of the impact has been quantified by simulating a wide variety of interference configurations, which are expected to cover most realistic interference conditions between LDACS and JTIDS. Baseband simulation models of both systems have been implemented and an interference scenario between LDACS and JTIDS has been defined. To evaluate the impact, the degradation of the signal-to-noise ratio (SNR) of JTIDS by the presence of LDACS has been determined. Default JTIDS transmissions, where the information is repeated at distant frequencies, do not show a significant degradation by the presence of strong LDACS interference, with an SNR loss lower than 1 dB in any considered interference scenario. Comparatively, a certain dependency on the specific LDACS deployment is noticeable for less protected JTIDS transmissions. Based on the observed interdependencies, recommendations for the deployment of LDACS are given in this paper, such that the impact of LDACS on JTIDS is minimized.