Overview of legacy systems in L-band and its influence on the future aeronautical communication system LDACS1

Currently, air traffc management is undergoing an extensive modernization process within SESAR [1] and Next-Gen [2] in Europe and the United States, respectively. This also includes the development of the future communication infrastructure (FCI) [3], which is jointly carried out by EUROCONTROL and the Federal Aviation Administration. Within the FCI, the L-band has been allocated for air-to-ground communications. Currently, two candidate systems for superseding the analogue voice communication system in the VHF band are taken into consideration. The frst candidate L-band digital aeronautical communications system type 1 (LDACS1) is a broadband system employing orthogonal frequency-division multiplexing (OFDM) and frequency-division duplex (FDD). LDACS1 has been designed as a combination of P34 (TIA 902 standard) and the broadband aeronautical multicarrier communications system [4]. The second candidate LDACS2 is a narrowband single-carrier system using time-division duplex as duplex scheme. This system is a derivative of the L-band digital link and the all-purpose multichannel aviation communication system.