# ROAD Statistics-Based Noise Detection for DME Mitigation in LDACS  
[PERSON]  
1 Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai Campus, Dubai 345055, United Arab Emirates; [EMAIL_ADDRESS] (M.K. ); [EMAIL_ADDRESS] (A.R. )1 Department of Computer Science, Birla Institute of Technology and Science Dubai Campus, Dubai 345055, United Arab Emirates 1  
[PERSON]  
2 Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai Campus, Dubai 345055, United Arab Emirates 2  
[PERSON]  
1 Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science Dubai Campus, Dubai 345055, United Arab Emirates 2  
Footnote 8: email: email: [EMAIL_ADDRESS] (A.R. )1 Department of Electrical and Electronics Engineering, Birla Institute ofper second. These data links are insufficient to provide broadband services now or in the future with the existing VHF and HF spectrum [2]. Hence, the International Civil Aviation Organization (ICAO) has recommended Future Communications Infrastructure (FCI) to modernize the existing communication links with new spectrum-efficient and reliable infrastructure, which can support new ATM applications and broadband services. This led to the development of the L-band (960-1164 MHz) Digital Aeronautical Communication Systems (LDACS) [3]. In 2009, the specification of LDACS was proposed. ICAO suggested two possible standards: LDACS1 derived from the IEEE 802.16 wireless system [3] and LDACS2 derived from the global system for mobile communication (GSM) [4]. LDACS1 uses advanced network protocols of current commercial standards. It is a broadband multicarrier system based on orthogonal frequency division multiplexing (OFDM). LDACS2 uses protocols that offer high QoS communications. It is a narrow band single carrier system based on Gaussian minimum shift keying modulation (GMSK). It is expected to accommodate the huge increase in air traffic with the deployment of any of these subsystems of LDACS. As shown in Figure 1, L-band is already providing services to legacy users such as distance measuring equipment (DME), military tactical air navigation (TACAN) system and joint tactical information distribution system (JTIDS), which are used for navigation aids. Apart from these, universal access transceiver (UAT) at 978 MHz and secondary surveillance radar (SSR) and airborne collision avoidance system at 1030 and 1090 MHz are also allotted with fixed channels [5; 6; 7; 8]. However, studies about spectrum occupancy revealed that large portions of the L-band spectrum are used less frequently or underutilized [3; 4]. Hence, the LDACS system is deployed in the L-band either as an inlay system between the legacy users or as an overlay system in the unoccupied spectrum [9]. The overlay method is selected for LDACS2 (960-975 MHz). Though the method is less complex, spectrum scarcity is a noticeable challenge [10; 11; 12]. The inlay approach, chosen in LDACS1, is expected to overcome the challenge of spectrum scarcity by utilizing the 1 MHz spectral gap between legacy user DME, thereby increasing the spectrum utilization. The comparative studies between LDACS1 and LDACS2 affirmed that LDACS1 is the preferred choice over LDACS2. LDACS1 is highly capable of supporting high-speed delay-sensitive multimedia services and is also compatible with the cellular communication standards. LDACS1 is further referred to as LDACS [13; 14]. Hence, the work presented in this paper uses LDACS to refer to LDACS1 hereafter. LDACS involves two way communication: a forward link (FL) from the ground station (GS) to air station (AS) and a reverse link (RL) from AS to GS. It provides frequency division duplexing (FDD) of 63 MHz spacing between FL (962-1213 MHz) and RL (1025-1150 MHz) with the opportunistic access of paired spectrum. The deployment of LDACS in L-band gives rise to interferences to license users and vice versa.