Aeronautical Communications Research Articles

Doppler Mitigation in OFDM-Based Aeronautical Communications

Doppler spectrum in an aeronautical channel is modeled with dual-Doppler shift instead of classical Jakes model. Orthogonal frequency division multiplexing (OFDM)-based systems are sensitive to Doppler shifts/spread, since the time variation of the channel causes inter-carrier interference (ICI). ICI analysis is provided here for OFDM-based systems in the aeronautical channel. The effect of ICI on the received signal is presented and its power is derived. As compared with terrestrial channels, where ICI is generally overcome by increasing the subcarrier spacing and bounding the normalized Doppler frequency (NDF), we propose to mitigate the effect of Doppler shifts in aeronautical channels, as follows. First, we use parametric spectrum estimation methods to extract the Doppler shifts by exploiting the predictable number of paths. Then, a beamforming-based method is introduced to resolve the incoming rays by separating them individually. Finally, paths are Doppler-compensated and combined using diversity combining techniques. Computer simulations are performed to provide numerical results. It is shown that a mean square error (MSE) performance ofis achieved with the parametric estimation methods, and bit error rate (BER) performance approaching the no-Doppler scenario is obtained with the beamforming-based mitigation method.

Future Trends in Spectrum Management and Technology Choices for Broadband Aeronautical Communications

The aircraft of the future will have an increased need for airborne communications among aircraft and between aircraft and the ground. Communications will include traffic such as on board passenger generated internet traffic, aircraft telemetry and information on air traffic control and weather. The likely data requirements are such that the data generated by passengers will be far greater than the aircraft generated data traffic. Passengers will expect data service on the aircraft similar to what they typically experience on the ground. Multimedia activities such video streaming are very bandwidth intensive and the provision of these services presents a serious technical challenge. On the ground, fibre optic cables are the method of choice for the provision of high speed data service and in contrast an airborne high speed data communications solution will need to be a wireless one.

AeroMACS: A new perspective for mobile airport communications and services

Broadband wireless technologies are becoming more and more pervasive in several fields of application to supply new services and to satisfy operational constraints. Among them, this article deals with the use of WiMAX technology in future air traffic management system. This technology is expected to increase the safety and to allow the exchange of large volumes of data among heterogeneous users, including aircraft. In particular, Eurocontrol and ICAO identified a WiMAX-based technology for communications on the airport surface, named Aeronautical Mobile Airport Communication System (Aero- MACS). The scope of this article is to provide an overview of AeroMACS, with a description of its main features, requirements, PHY and MAC profile choices, and related network architecture. Finally, the article highlights some open issues for AeroMACS that represent critical aspects and require, at this time, additional investigation.

Cosite Coexistence between Future L-DACS2 and Legacy DME Systems

We analyze the coexistence between the L-band Digital Aeronautical Communication System?option 2 (L-DACS2), which is a preselected candidate to support future continental communications, and the distance measuring equipment (DME), which is an L-band radionavigation system in use for decades, now implemented in all aircrafts. We focus on the impact of L-DACS2 interference on the DME performance under the cosite scenario, where both equipment are located in the same aircraft. After a brief presentation of both systems, we study this critical scenario (from the system coexistence viewpoint), by proposing a new approach (different from classical frequency-domain analysis) that takes into account system dynamics and their technology characteristics. Based on various implementation methodologies, we show in the last part of the paper, the effect of some parameters on the coexistence between the on-board L-DACS2 transmitter and the on-board DME receiver.

Recognition of MQAM Signals in the Aeronautical Communication

For the complex recognition of signals in the aeronautical communication, the recognition of the star-type MQAM signals is studied under the aeronautical channel. The different scenarios of the aeronautical channel are analyzed and the reasonable channel model is established. The high order cumulant recognition algorithm which applies to the aeronautical channel is proposed, the invariant classification characteristics of modulation signals are constructed by this algorithm, and this algorithm is improved by using the receive diversity technique. Simulation results show that this algorithm significantly improves the correct recognition rate of the received signals has the good anti-fading and anti-noise performance and meets the requirements of the modulation recognition of MQAM signals under the aeronautical channel.

A-GR: A novel geographical routing protocol for AANETs

With the rapid growth of general aircraft and lack of ground facilities, air traffic control and aeronautical communication system face huge pressure, especially in low-altitude airspace. Aeronautical ad hoc networks (AANETs) are large scale multi-hop wireless network of aircraft, which could provide direct air-to-air communication between aircraft without ground infrastructures. However, the features of aircraft node present a great challenge to provide efficient and reliable data packet delivery in AANETs. In this paper, we present an Automatic dependent surveillance-broadcast (ADS-B) system aided geographic routing protocol (called A-GR) for AANETs. The proposed A-GR uses the position and velocity of aircraft provided by airborne ADS-B system to eliminate the traditional routing beaconing and presents a velocity-based metric for next hop selection, which could adaptively cope with the fast moving of aircraft and dynamic changes of network topology. Many simulations are performed and the results show that the proposed A-GR can effectively decrease the routing overhead, improve the packet delivery ratio and make good use of the network resources.

On Improved Noise Variance Estimation for Aeronautical Communications

The L-band Digital Aeronautical Communication System Type-1 (L-DACS1) has been considered as the potential standard for future aeronautical communications. As an important parameter for L-DACS1, the noise variance can be estimated via the well known Second-Moment-Fourth-Moment (M2M4) blind algorithm. However, due to influence from aeronautical fading channels, performance degradation is encountered by conventional M2M4 algorithm in L-DACS1. In this paper, channel responses obtained from L-DACS1 pilot symbols were carried out to compensate the estimation degradation brought by channel fading, which lead to an improved M2M4 algorithm for L-DACS1. It is shown through simulations that the proposed approach outperforms conventional M2M4 estimator in terms of estimation error for L-DACS1 in aeronautical fading channels.

Development of Aeronautical Communication System for Air Traffic Control Using OFDM and Computer Algebra Systems

Development of Aeronautical Communication System for Air Traffic Control Using OFDM and Computer Algebra Systems

VHF 대양 네트워크를 위한 Ad-hoc 기반 다중접속기법

In oceanic flight routes, HF radio and satellite data links have weather restrictions, long propagation delay and low data throughput. In this paper, we propose oceanic aeronautical communications scheme in the VHF band based on ad-hoc communication. The proposed scheme organizes autonomously a multi-hop network that is divided into multiple local network using aircraft to fly long-distance communication and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. In addition, several algorithms to apply spatial reuse of transmission to multi-hop long range communication environments have been proposed. The proposed system proves performance improvement on delay time as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

On-Line Construction of Irregular Repeat Accumulate Codes for Packet Erasure Channels

In many applications erasure correcting codes are used to recover packet losses at high protocol stack layers. The objects (e.g. files) to be transmitted often have variable sizes, resulting in a variable number of packets to be encoded by the packet-level encoder. In this paper, algorithms for the (on-line) flexible design of parity-check matrices for irregular-repeat-accumulate codes are investigated. The proposed algorithms allow designing in fast manner parity-check matrices that are suitable for low-complexity maximum-likelihood decoding. The code ensembles generated by the algorithms are analyzed via extrinsic information transfer charts. Numerical results show how the designed codes can attain codeword error rates as low as 10-5 without appreciable losses w.r.t. the performance of idealized maximum-distance separable codes. Finally, we apply the proposed codes to the upcoming aeronautical communication standard, showing large performance improvements and proving the efficiency and the flexibility of the developed method.

Performance Analysis of DSTBC over VHF Air-to-Ground Communication Channels

This paper is concerned with evaluating the performance of differential space time block coding (DSTBC) over very high frequency (VHF) aeronautical communication channels (i.e. air-to-ground). Differential phase shift key (DPSK) is one of the differential transmission schemes that transmit information without full channel state information (CSI) at the receiver. There are two main problems that degrade the performance of the communication over this channel, multipath fading which is a common problem in any wireless channel and Doppler shifts which result from aircraft speeds. In order to combat such fading and improve the bit error rate (BER) performance of the communication system over this channel, the paper investigated the usage of multiple input multiple output (MIMO) systems with differential transmission scheme. This was done through computer simulations that analyze the performance of DSTBC using two antennas at the transmitter and N antennas at the receiver. General Terms Wireless communication, multi antenna system.

Survey on the Future Aeronautical Communication System and Its Development for Continental Communications

We present in this survey new technologies proposed for the evolution of the aeronautical communication infrastructure. Motivated by studies that estimate the growth of air traffic flow, it was decided to develop a future communication infrastructure (FCI) adapted to the future aeronautical scenario. The FCI development involves researchers, industrials, and aeronautical authorities from many countries around the world, and started in 2004. The L-band Digital Aeronautical Communication System (L-DACS) is the part of the FCI that will be in charge of continental communication. The L-DACS is being developed in Europe since 2007 and two candidates were preselected: L-DACS1 and L-DACS2. In this paper, we first describe the motivations of the FCI. We then give an overview of its development activities from 2004 to 2009. After that, we provide some insights about both preselected L-DACS candidates, at their physical and medium access layers. Finally, we address the challenges on the development of the FCI/L-DACS.

전송률 향상을 위한 거리정보 기반 VHF Data Link MAC 기법

VDL(VHF Data Link) Mode E uses TDMA(Time Division Multiple Access) based aeronautical communication technologies for airborne environments. In the VDL Mode E, aircraft uses RR(Reservation Requests) slot to request data slot. However, RR needs a long guard time, since aircraft communication spans a considerable distance. The more number of aircrafts causes a larger amount of guard times which can make a throughput decreased. In this paper, we propose an enhanced MAC to reduce the guard time by using the distance information of aircraft. The ground station sends management data including time stamp. And then all aircraft can measure their distance from the ground station.

航空通信の現状と課題( 将来航空交通システムの実現に向けた研究開発 第7回)

航空通信の現状と課題( 将来航空交通システムの実現に向けた研究開発 第7回)

An Access Router based NEMO Route Optimization Scheme in Aeronautical Passenger Communications Environment

An Access Router based NEMO Route Optimization Scheme in Aeronautical Passenger Communications Environment

대양항로에서 장거리 공대지통신을 위한 VHF Relay Network

In oceanic flight routes, HF radio and satellite data links have been used for air-to-ground communication, but these systems have long propagation delay and low data throughput. In this paper, we propose a reliable system to overcome the weakness of current HF radio and satellite communication systems for oceanic aeronautical flight routes. The proposed scheme uses only one aeronautical VHF channel in multi-hop oceanic communication environments and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. The proposed system improves performance on delay and throughput as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

Seamless networking for aeronautical communications: One major aspect of the SANDRA concept

In air transportation one major bottleneck stressing capacity limits is identified: aeronautical communications. By the 2025 timeframe aircraft operations are expected to double [1]. Well-founded concerns doubt that current air transportation systems will be able to cope with this growth, e.g., already VHF (Very High Frequency) communication capacity is expected to saturate in Europe by 2020-2025 [2]. Meeting these growing demands require systems providing flight information and processes in real-time including high flexibility. Also new security requirements are affecting the ability to move people and cargo efficiently. Ongoing research activities, projects, and programs are developing the fundamental methods, concepts, and technologies for future aeronautical communications enabling higher capacities in air transportation. In the following section, we give an overview of the current status, major activities and trends in the field of aeronautical communications. Finally, the European research project SANDRA (Seamless Aeronautical Networking through integration of Data links, Radios, and Antennas) is introduced and its recent results toward a seamless networking design are presented.

A Novel Fast Handoff Scheme in Aeronautical Passenger Communication based on Air Traffic Management information and Handoff Probability

A Novel Fast Handoff Scheme in Aeronautical Passenger Communication based on Air Traffic Management information and Handoff Probability

Analysis of noise in aircraft cabins through the VHF channel

PurposeThe purpose of this paper is to present a method to analyze the noise in aircraft cabins through the VHF Aeronautical Communication Channel, aimed at examining an environment that has the possibility of communication problems between the aircraft crew and the professionals responsible for the controls on land.Design/methodology/approachThis analysis includes equipment normally used for identification and comparison of electromagnetic noise, the cabin and the environment that are present in an airport, as well as equipment for frequency analysis and intensity of those signals. The analysis is done in a reverse way, eliminating situations that are not common in the examined environment, until the identification of the situation with the irregularity.FindingsAccording to the results, the implementation of the Fourier transform for noise analysis in the cabin was efficient. These results demonstrate that through this transformation, the noise sources can be identified in the environments in cases where there is much spectrum pollution.Research limitations/implicationsThis kind of noise analysis is important, considering the importance of having good accuracy in airport environment analysis.Originality/valueThe paper presents the main trends in the future of aviation communications, and describes the new applications that aim to minimize problems with the current VHF channel.

A Method for the Analysis of the Aeronautical VHF Channel

This paper presents a method for the analysis of the Aeronautical VHF Channel, in order to analyze an environment with the possibility of problems in the communication between the crew of the aircraft and the professionals responsible for controls on land. This analysis includes equipment normally used for identification and comparison of noise environments present in an airport, as well as equipment for frequency and signal intensity analysis. The analysis is done in reverse, through the elimination of situations not considered as environmental features, enabling the identification of the irregular transmission. Given such a scenario, there are also presented the main trends in the future of aeronautical communications, demonstrating the new features that aim to minimize problems with the current Aeronautical VHF Channel. The final results demonstrate the possibility of identifying instances even without knowledge of the propagator environment.