The aeronautical communication has been switched from the congested very high frequency (VHF) band to occupy the L-band, namely, L-band digital aeronautical communication system type I (LDACSI). Critical navigation system in this band is the distance measurement equipment (DME). However, the DME channels provide a severe interference to onboard LDACSI receiver. In this paper, a cognitive radio (CR) network is proposed to allow efficient spectrum reuse with coexisting primary DME channels. In LDACSI-CR network, the proposed spectrum sensing technique is performed by using an adaptive threshold DME energy detector to achieve the best trade-off between the DME signal detection and false alarm. Moreover, dynamic spectrum access, namely, hybrid spectrum access (HSA) is newly introduced to enhance the LDACSI-CR throughput. Joint effect of HSA with different frame structures on the LDACSI throughput is proposed. Besides, optimal power allocation using genetic algorithm that maximizes the LDACSI-CR ergodic throughput for HSA with different frame structures is proposed. In this work, the closed form expression for the probability of DME detection, false alarm, detection error, the LDACSI throughput and data loss are derived. Simulation is performed and the results show the LDACSI throughput and the data loss for the proposed techniques. Besides, ergodic throughput maximization for HSA under constraints of the average LDACSI transmitted power and tolerable interference power on the DME signal is performed. Moreover, simulation results show that the proposed LDACSI-CR system performance provides lower bit error rate and less complexity compared to the previous work.

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Summary Air‐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.

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