Aeronautical Communications Research Articles

Adaptive Coding and Modulation for Large-Scale Antenna Array-Based Aeronautical Communications in the Presence of Co-Channel Interference

In order to meet the demands of “Internet above the clouds,” we propose a multiple-antenna aided adaptive coding and modulation (ACM) for aeronautical communications. The proposed ACM scheme switches its coding and modulation mode according to the distance between the communicating aircraft, which is readily available with the aid of the airborne radar or the global positioning system. We derive an asymptotic closed-form expression of the signal-to-interference-plus-noise ratio (SINR) as the number of transmitting antennas tends to infinity, in the presence of realistic co-channel interference and channel estimation errors. The achievable transmission rates and the corresponding mode-switching distance-thresholds are readily obtained based on this closed-form SINR formula. Monte-Carlo simulation results are used to validate our theoretical analysis. For the specific example of 32 transmit antennas and four receive antennas communicating at a 5-GHz carrier frequency and using 6-MHz bandwidth, which are reused by multiple other pairs of communicating aircraft, the proposed distance-based ACM is capable of providing as high as 65.928-Mb/s data rate when the communication distance is less than 25 km.

Mitigation of DME interference in LDACS1-based future air-to-ground (A/G) communications

In this article, an algorithm for mitigating distance measuring equipment (DME) interference in L-band digital aeronautical communication system type 1 (LDACS1)-based aeronautical communication sys...

A QoS Guarantee Based Hybrid Media Access Control Protocol of Aeronautical Ad Hoc Network

In order to meet different data rate and timeliness requirements of different services in aeronautical network communications based on frequency and time-hopping mechanism, a hybrid media access control protocol based on pre-allocation of transmission time slots and immediate access is proposed. It is based on network capacity simulation analysis of burst service frames, channel immediately access capability is reserved for high-priority service frames, and time slot pre-allocation strategies and network access permissions are designed for middle- and low-priority service frames. Time sensitive demand of high-priority service frames is guaranteed, and transmission of middle- and low-priority service frames to the greatest extent is ensured at the same time. The simulation results verify the effectiveness of the protocol.

Full Spectrum Sharing in Cognitive Radio Networks Toward 5G: A Survey

With the development of wireless communication technology, the need for bandwidth is increasing continuously, and the growing need makes wireless spectrum resources more and more scarce. Cognitive radio (CR) has been identified as a promising solution for the spectrum scarcity, and its core idea is the dynamic spectrum access. It can dynamically utilize the idle spectrum without affecting the rights of primary users, so that multiple services or users can share a part of the spectrum, thus achieving the goal of avoiding the high cost of spectrum resetting and improving the utilization of spectrum resources. In order to meet the critical requirements of the fifth generation (5G) mobile network, especially the Wider-Coverage , Massive-Capacity , Massive-Connectivity , and Low-Latency four application scenarios, the spectrum range used in 5G will be further expanded into the full spectrum era, possibly from 1 GHz to 100 GHz. In this paper, we conduct a comprehensive survey of CR technology and focus on the current significant research progress in the full spectrum sharing towards the four scenarios. In addition, the key enabling technologies that may be closely related to the study of 5G in the near future are presented in terms of full-duplex spectrum sensing, spectrum-database based spectrum sensing, auction based spectrum allocation, carrier aggregation based spectrum access. Subsequently, other issues that play a positive role for the development research and practical application of CR, such as common control channel, energy harvesting, non-orthogonal multiple access, and CR based aeronautical communication are discussed. The comprehensive overview provided by this survey is expected to help researchers develop CR technology in the field of 5G further.

Cancelation of Distance Measuring Equipment Interference for Aeronautical Communications

The L-band digital aeronautical communications system (L-DACS1) is subject to strong interference caused by distance measuring equipment (DME). For efficient statistical processing of interference, we adopt a Gaussian mixture (GM) distribution to model the impulsive nature of DME signals. Hence, we drive the parameters of the GM model in terms of properties of DME signals. This allows us to redesign the optimum receiver for mitigating DME interference. We also provide a simple pulse detector to estimate the presence of DME signals utilizing the null subcarriers of the L-DACS1.

Datalink security in the L-band digital aeronautical communications system (LDACS) for air traffic management

Today's very high-frequency (VHF) voice-based air–ground communication system for tactical aircraft guidance is suffering from the VHF band's increasing saturation in high-density areas [1]. The air–ground1 communication infrastructure is therefore undergoing modernization to ensure the sustainable growth of the European air transportation system in the coming decades [2], [3]. One major goal of this effort is the introduction of computerized air traffic management applications and new digital communication links between aircraft and ground systems.

Application of cognitive radio and interference cancellation in the L-Band based on future air-to-ground communication systems

The Very High Frequency band (VHF) currently used for aeronautical communications is becoming congested, and future Air-to-Ground (A/G) communication will require much greater use of data communications. For meeting future capacity requirements in aeronautical communications, we propose two new approaches one of which is a cognitive radio based A/G communication network that provides dynamic spectrum access to airplanes to overcome the spectrum scarcity problem in the VHF band. Another approach involves use of a new spectrum in the Ultra-High Frequency band (UHF) to create a new A/G link. In this paper, we propose and investigate the possibilities for developing a spectrum sensing approach to detect idle band in the VHF spectrum and analyze the possible interference between future L-band Digital Aeronautical Communication System (L-DACS) and legacy aeronautical systems.

Pulse-Pair Interference Automatic Detection and Mitigation for L-Band Aeronautical Communication System

Pulse-pairs (PP) generated by distance measuring equipment (DME) cause severe interference to the L-band digital aeronautical communication systems. Unlike previous works that mainly improved receiver structure for mitigating the DME interference, this paper proposes a novel and practical time domain PP mitigation method without changing the existing receiver structure. Our method is composed of three parts and utilizes a specific property, i.e., a relatively fixed waveform of DME PP. First, the complex-valued waveform of PP is automatically detected through an iterative weighted average method. Then, on the basis of the detected PP waveform, each PP is reconstructed according to its amplitude, position, and initial phase, which are estimated through a sparse representation algorithm. Finally, the reconstructed PPs are subtracted from the contaminated signal. Numerical experiments show that compared with recently published methods the bit error rate obtained by our method is approximately 5 dB better, while the complexity is maintained at the same level.

FBMC and L-DACS Performance for Future Air-to-Ground Communication Systems

Recently, two different L-band digital aeronautical communication systems (L-DACS), i.e., L-DACS1 and L-DACS2, have been proposed as two future communication infrastructure candidates for air-to-ground (AG) communication systems, with L-DACS1 selected as the best candidate. In this paper, we describe a filter bank multicarrier (FBMC)-based communication system and show its advantages over the L-DACS systems. We provide simulation results for all three communication systems to fairly compare their power spectral density, peak-to-average power ratio (PAPR), and bit error ratio (BER) performance. We show that in a measurement-based AG communication channel model, FBMC has better performance (and spectral containment) than the L-DACS schemes, and this is particularly true in the presence of actual interfering signals from distance measuring equipment (DME). Simulation results show that FBMC can substantially reduce the out-of-band power and can suppress DME interference by at least 19.5 dB, due to its well-localized subcarrier prototype filters. FBMC can also increase throughput and spectral efficiency by reducing the number of guard-band subcarriers and removal of the cyclic prefix, postfix, as well as windowing techniques used in L-DACS1. These results show that an FBMC-based communication system can be an appealing candidate for future AG communication systems.

Modified Cramér‐Rao lower bounds for joint position and velocity estimation of a Rician target in OFDM‐based passive radar networks

AbstractOwing to the increased deployment and the favorable range and Doppler resolutions, orthogonal frequency‐division multiplexing (OFDM)‐based L band digital aeronautical communication system type 1 (LDACS1) stations have become attractive systems for target surveillance in passive radar applications. This paper investigates the problem of joint parameter (position and velocity) estimation of a Rician target in OFDM‐based passive radar network systems with multichannel receivers placed on moving platforms, which are composed of multiple OFDM‐based LDACS1 transmitters of opportunity and multiple radar receivers. The modified Cramér‐Rao lower bounds (MCRLBs) on the Cartesian coordinates of target position and velocity are computed, where the received signal from the target is composed of dominant scatterer (DS) component and weak isotropic scatterers (WIS) component. Simulation results are provided to demonstrate that the target parameter estimation accuracy can be improved by exploiting the DS component. It also shows that the joint MCRLB is not only a function of the transmitted waveform parameters, target radar cross section, and signal‐to‐noise ratio but also a function of the relative geometry between the target and the passive radar networks. The analytical expressions of MCRLB can be utilized as a performance metric to access the target parameter estimation in OFDM‐based passive radar networks in that they enable the selection of optimal transmitter‐receiver pairs for target estimation.

OFDM Receiver Structure for a Subband-Selective Mitigation of Time-Variant Interference

System performance of orthogonal frequency-division multiplexing (OFDM) degrades in the presence of time-variant frequency-selective interference. In the literature, several pulse-blanking concepts have been introduced over the past few years, which are promising ways to mitigate impulsive interference for OFDM reception. However, blanking yields an attenuation of the signal and intercarrier interference (ICI). In this paper, a receiver structure is proposed, which consists of a frequency-selective pulse-blanking unit, a blanking mitigation unit, and an iterative ICI cancelation unit. The L-band Digital Aeronautical Communication System 1 (L-DACS 1) is regarded as an application that suffers from interference from the impulsive Distance Measuring Equipment (DME) system whose frequency bands partly overlap. It is shown that, by using the proposed mitigation scheme for impulsive interference, a reliable reception is possible, even in strong interference situations.

Cramér–Rao bounds for L‐band digital aeronautical communication system type 1 based passive multiple‐input multiple‐output radar

In this study, of concern is the achievable estimation accuracy for a non-coherent passive multiple-input multiple-output (MIMO) radar employing orthogonal frequency-division multiplexing (OFDM) based signals of opportunity. The motivation behind this investigation is the surveillance aspect of the air trac management modernisation process currently taking place in civil aviation. To this end, the surveillance capability of the OFDM-based L-band digital aeronautical communication system type 1 (LDACS1) is analysed. The extension of the LDACS1 communication system towards surveillance is of great importance since it would enable an alternative, non-cooperative surveillance application, and, together with the already validated navigation extension, establish a fully integrated LDACS1-based communication, navigation, and surveillance technology. The modied Cramer-Rao bound on the joint estimation of target location and velocity for a non-coherent passive MIMO radar, employing the OFDM-based LDACS1 signals as signals of opportunity, is investigated. The analysis is carried out assuming one target, multiple and widely separated transmit and receive antennas, orthogonal waveforms, independent reection coecients, and zero-mean white Gaussian noise. Closed-form expressions for the relevant elements of the modied Fisher information matrix are obtained. The results can be used to assess the estimation accuracy of a multiple antenna passive radar system employing any OFDM-based signals of opportunity.

Erratum: Cramér–Rao bounds for L‐band digital aeronautical communication system type 1 based passive multiple‐input multiple‐output radar

Erratum: Cramér–Rao bounds for L‐band digital aeronautical communication system type 1 based passive multiple‐input multiple‐output radar

English

English

A Tool for Beamforming and Real-Time Link Budget Analysis in Aeronautical Communications Using Kinematics

Aeronautical Communication (AC) systems are likely to be a part of future tiered communication network structures. Therefore maintaining a robust AC link with a minimum power burden on the host platform has a critical importance. In this paper, we analyze the AC systems from a link budget analysis point of view and define the requirements for the parameters of link budget with an emphasize on antenna gains. First, we study the link budget analysis in an AC system. Then, we present a mathematical framework to provide an end-to-end link budget analysis utilizing the platform kinematics. Finally, we present the numerical results for typical AC scenarios and discuss that these results can be used for calculating the real-time link budget and electronic beamforming to provide a robust link.

Cognitive Radio for Aeronautical Communications: A Survey

Novel air traffic management (ATM) strategies are proposed through the Next Generation Air Transportation and Single European Sky for ATM Research projects to improve the capacity of the airspace and to meet the demands of the future air traffic. The implementation of the proposed solutions leads to increasing use of wireless data for aeronautical communications. Another emerging trend is the unmanned aerial vehicles. The unmanned aerial systems (UASs) need reliable wireless data link and dedicated spectrum allocation for its operation. On-board broadband connectivity also needs dedicated spectrum to satisfy the quality of service requirements of the users. With the growing demand, the aeronautical spectrum is expected to be congested. However, the studies revealed that the aeronautical spectrum is underutilized due to the static spectrum allocation strategy. The aeronautical communication systems, such as air-air and air-ground communication systems, inflight infotainment systems, wireless avionics intra-communications, and UAS, can benefit significantly from the introduction of cognitive radio-based transmission schemes. This paper summarizes the current trends in aeronautical spectrum management followed by the major applications and contributions of cognitive radio in solving the spectrum scarcity crisis in the aeronautical domain. Also, to cope with the evolving technological advancement, researchers have prioritized the issues in the case of cognitive radio that needs to be addressed depending on the domain of operation. The proposed cognitive aeronautical communication systems should also be compliant with the Aeronautical Radio Incorporated and Aerospace Recommended Practice standards. An overview of these standards and the challenges that need immediate attention to make the solution feasible for a large-scale operation, along with the future avenues of research is also furnished.

航空激光通信系统的特性分析及机载激光通信实验

航空激光通信系统的特性分析及机载激光通信实验

Future railway communications [Guest Editorial

The growth of intelligent transportation systems (ITS) has recently accelerated as governments and regulators seek to use ITS to achieve important economic and policy goals. ITS must be efficient, environmentally friendly (green), and, of course, safe. The scope of ITS is broad, and all transportation modes will require communications, including future vehicular (automotive) systems and vehicle-to-vehicle/vehicle-to-infrastructure (V2V/V2I) communications, aeronautical communications, maritime communications, satellite communications, railway communications, and possibly others.

Statistical Digital Watermarks of Audio Signals

Introduction. Digital watermarks (DWM) refer to embedding additional information directly into audio signal for digital right management and automatic identification of radiotelephone transmissions in aeronautical, maritime and military VHF communication. The main part. The designed embedding algorithm is based on evaluation of sliding frame to embed information or no regarding to distortions introduced by DWM. Watermark location is grounded calculation of distances norm between received and maximum likelihood estimated signal vectors in the domain of Discreet Fourier Transform and doesn’t need for any marking and synchronizing measures. Robustness of DWM against quantization, filtering, additive Gaussian noise, digital format conversion is provided by multichannel narrowband DWM transmission and application of BCH (63,30,6) error-correction code. The proposed algorithm demonstrates watermark inaudibility because of preserving signal power before and after data embedding and searching the most suitable frames for DWM positioning. Conclusion. The proposed algorithms provide advanced compromising solution of audio watermarking process: data payload – inaudibility – robustness. The designed algorithms are applicable both in analog and digital channels for transmission monitoring and digital right management.

Impulse interference mitigation method based on joint compressed sensing and whitening of interference

To mitigate the deleterious influence of distance measure equipment( DME) interference on orthogonal frequency division multiplexing( OFDM) receiver of L-band digital aeronautical communications system 1( L-DACS1) operating as an inlay system,a new DME interference suppression method was proposed based on joint compressed sensing and whitening of residual interference. Firstly,the DME impulse interference was observed via null subcarriers channel of the OFDM receiver and reconstructed with convex optimization constrained l1 norm minimization method based on the sparse property of the DME impulse interference in time domain. Then the reconstructed DME impulse interference was transformed to frequency domain and eliminated from the received signal. Finally,to avoid burst errors of demodulator,the residual impulse interference was converted to white Gaussian noise by using the de-interleaver and inverse orthogonal transformer.The computer simulation indicates that the proposed method can reduce the impact of DME interference effectively,and improve the reliability of OFDM receiver of the L-DACS1 system significantly.