# GAE and OBE Enhanced Interference Mitigation Techniques in LDACS
)1 Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Institute of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Institute of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Institute of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Institute of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Institute of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Institute of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Institute of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Institute of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai 345055, United Emirates; [EMAIL_ADDRESS] (M.  
Meanwhile, disagreeing with the popular belief, studies about the spectrum occupancy revealed that large portions of the spectrum are used less frequently [3,4]. The utilization of major pieces of the spectrum is even below 10% [3]. Among them, the spectrum utilization of the aeronautic spectrum band for air-ground communications (A/G) is found to be 12.5%. The same band is anticipating severe spectrum scarcity in future. Currently, aircraft are connected to air traffic controllers and air operational controllers via voice and data communication systems. The media in voice communication are still analogue and operated via open broadcast channels without any embedded protective measures. The existing VHF double sideband amplitude modulation (DSB-AM) will be used for many more years, as it works safely and reliably with the use of low-cost communication equipment. Data communication to the cockpit is also provided by ground-based equipment operating within HF or VHF radio bands. The communication systems use narrowband radio channels with a data throughput of some kilobits per second. The existing HF and VHF data links fail to provide broadband services to flight crews now or in the future due to the lack of the available spectrum. This situation becomes a hindrance in the employment of enhanced air traffic management (ATM) operations, such as trajectory-based operations (TBO) and 4D trajectory negotiations [5]. Hence, the International Civil Aviation Organization (ICAO) recommended future communications infrastructure (FCI) to enhance the existing communication links between aircraft and ground controllers with new optimal data link protocols. This led to the development of L-band digital aeronautical communication systems (LDACS) as an inlay system between the legacy users [2] in 960-1164 MHz to face the challenge of the saturated VHF spectrum and spectrum congestion. For further studies and enlargement, ICAO selected two candidates: LDACS1 derived from IEEE 802.16 wireless system [6] and LDACS2 derived from the global system for mobile communication (GSM) [7]. LDACS1 makes use of modern modulation techniques and advanced network protocols applied in the current commercial standards, and LDACS2 exploits the knowledge from aviation specific standards, using protocols that offer high QoS communications. Both these systems are foreseen to house the air traffic requirements without compromising the standards put forth by the aeronautical community.