Nested code division multiple access for distance measuring equipment interference mitigation in L‐band digital aeronautical communication system

Abstract

SummaryAir‐to‐ground (A/G) communications have been transferred from the congested very high frequency (VHF) band to occupy the guard bands between adjacent distance measurement equipment (DME) navigation channels within the L‐Band. However, the inlayed channels, called L‐band digital aeronautical communication system (LDACS) channels, experience severe interference with the coexisting DME channels. In this paper, a DME interference detection and mitigation technique is proposed to improve the performance of the LDACS in the presence of DME interference. The DME energy detector based on Neyman–Pearson test is proposed, which has more advantages than the other techniques due to its noncoherent nature and simplicity. Furthermore, the proposed DME detection technique is performed by using an adaptive threshold to achieve the best trade‐off between the DME signal detection and false alarm. The proposed DME interference mitigation technique relies on the proposed concept of nested RF upconversion, where the in‐phase and the quadrature components of an LDACS signal are forwarded to a code division multiple access (CDMA) block in which they are transmitted only over the quadrature branch once DME interfering signal is detected. In this work, the closed form expression for the probability of DME detection, false alarm, and the detection error rate are derived. Simulation is performed, and the results show that the proposed technique provides improvement in the probability of DME detection and the detection error rate compared to the previous work. Also, simulation results shows that the proposed technique provides lower bit error rate and less complexity compared to the previous work.