Christoph Rihacek

B-AMC a system for future broadband aeronautical multi- carrier communications in the L-BAND

The Broadband Aeronautical Multi-carrier Communications (B-AMC) system is a candidate for a future aeronautical communications system to be operated in the L-Band (960-1164 MHz). It is based on the Broadband-VHF (B-VHF) system recently developed for aeronautical communications in the VHF band. As conditions in the L-Band significantly differ from those in the VHF band, basic physical layer parameters had to be adapted, which in turn required a re-design of the higher layers as well. B-AMC offers air/ground (A/G) as well as direct air/air (A/A) communication capabilities without ground relay. The physical layer has been designed to coexist with other systems located in the aeronautical L-Band. The B-AMC data link layer is optimized for low latency and low duty cycle data communication. The B-AMC study is funded by EUROCONTROL.

B-AMC — broadband aeronautical multi-carrier communications

The broadband aeronautical multi-carrier communications (B-AMC) system is a promising candidate for the future L-band radio system called L-band digital aeronautical communications system (L-DACS). In this paper, the design of the physical (PHY) as well as of the data link layer (DLL) is addressed. As B-AMC is intended to be operated in the L-band between two adjacent distance measuring equipment (DME) channels, the avoidance of mutual interference between existing L-band systems and B-AMC has been in the focus of the PHY layer design. In order to demonstrate the feasibility of the coexistence with DME, a draft frequency planning has been performed for Europe, resulting in successful frequency assignments in wide parts of Europe. The B-AMC DLL supports data link communication with low latency and high throughput. It is designed to be highly configurable and to support different service requirement sets and traffic profiles. In this paper, the current DLL configuration featuring a low RL duty-cycle and graceful degradation is discussed in detail.

Interference mitigation for broadband L-DACS

One deployment option for the future broadband L-band digital aeronautical communications system (L-DACS) is operating as an inlay system between two adjacent channels of the distance measuring equipment (DME) system. Investigations for the broadband aeronautical multi-carrier communications (B-AMC) [1] system, one candidate for the broadband L-DACS, have shown that interference originating from DME systems operating in adjacent channels has a strong impact on the B-AMC system. To enable the utilization of spectral gaps between two adjacent DME channels, two efficient methods for mitigating the impact of interference are proposed and investigated for the B-AMC system, namely pulse blanking and erasure based decoding. Simulations show that the impact of DME interference onto the L-DACS can be reduced considerably by choosing an appropriate coding scheme to make the transmit signal robust against interference. The impact of interference is mitigated by means of the proposed methods, resulting in a performance close to the performance in the interference-free case.

B-VHF - a multi-carrier based broadband VHF communications concept for air traffic management

In this paper, we introduce the B-VHF project which is funded by the European Commission and has started in January 2004. The prime goal of the B-VHF project is to verify the feasibility of broadband VHF aeronautical communications system based on multi-carrier technology and to demonstrate its benefits to the aeronautical community. The project deals with the investigation, design, and evaluation of a broadband overlay communications system for air traffic control (ATC) and air traffic management (ATM) communications in the VHF band. This overlay concept facilitates in-band transition from the current to a future ATC communications system and, thus, allows future ATC communications to remain in the advantageous and protected VHF band. The focus in this paper is on the technical approach for realizing the overlay concept and on the system architecture concept behind B-VHF. The proposed transmission system, which permits the parallel operation with the current DSB-AM system, utilizes multicarrier technologies which are based on orthogonal frequency-division multiplexing (OFDM)

Final Assessment of the B-VHF Overlay Concept

B-VHF is a proposal for a future aeronautical communication system in the very high frequency (VHF) band based on an overlay concept, i.e. during the transition phase the B-VHF system shares the same frequency band with legacy VHF systems without interfering with them. In this paper, the feasibility of the overlay concept is evaluated by simulations of the physical and higher layers as well as by laboratory measurements with a demonstrator. Simulation results show that the B-VHF overlay system works in presence of interference from legacy VHF systems. The protocol is designed to allow using the available resources very efficiently and to provide voice and data services with the required quality of service. In addition, the impact of mutual interference between the B-VHF system and legacy VHF systems is evaluated in laboratory test with a simplified B-VHF demonstrator and commercial VHF radios.

B-VHF - Selected Simulation Results and Assessment

B-VHF is a proposal for a future aeronautical communication system in the VHF band based on an overlay concept, i.e. during the transition phase the B-VHF system shares the same frequency band with legacy VHF systems without interfering with them. In this paper, the overlay concept is evaluated by simulations of the physical and higher layers. Simulation results show that the B-VHF overlay system works in presence of interference from legacy VHF systems. The protocol is designed to allow using the available resources very efficiently and to provide voice and data services with the required quality of service

Improvement of L-DACS1 design by combining B-AMC with P34 and WiMAX technologies

All currently pursued Air Traffic Management (ATM) concepts and associated roadmaps, i.e. Single European Sky ATM Research (SESAR) in Europe and Next Generation Air Transportation System (NextGen) in the USA, heavily rely upon trajectory exchange between airborne and ground automated systems. Facilitating such exchanges requires high performance Air-Ground (A/G) data link communications. The decision about what technology the future data link shall be based upon has not yet been taken, but it is obvious, that the selected data link technology must be globally accepted and standardized.

Integrated navigation and surveillance capability within L-DACS1

New ATM concepts developed in the course of Single European Sky ATM Research (SESAR) Program in Europe and Next Generation Air Transportation System (NextGen) in the USA rely upon powerful mobile aeronautical communications, and at the same time they require reliable and robust solutions for navigation and surveillance. Recent efforts focus on establishing communications services within the navigation bands, in particular in the lower part of the aeronautical L-band (960–1164 MHz). New technologies operating in the same frequency range could use synergies that could not be exploited with “separated” technologies used so far. Following the recommendations of the Future Communications Study, two options for a new L-band Digital Aeronautical Communication System (L-DACS) have been specified: L-DACS1 based on Orthogonal Frequency Division Multiplexing (OFDM) and L-DACS2 based on Time Division Multiple Access (TDMA). Both systems aim at providing high-performance, high-capacity aeronautical communications being deployed in the lower part of the aeronautical L-band (960–1164 MHz). The initial specification of L-DACS1 Air-Ground (A/G) data link [1] is based on the Broadband Aeronautical Multi-carrier Communications (B-AMC) technology that has been complemented by some desirable features of other broadband technologies, primarily TIA-902 (P34) and IEEE 802.16e (WiMAX). Any new communication system in the L-band has to co-exist with the existing L-band navigation and surveillance systems. Moreover, the performance of such a new system is limited by the interference received from existing systems. This paper discusses the motivation and the basic principles of integrating navigation (NAV) and surveillance (SUR) functions within the L-DACS1 communications (COM) system. The detailed concepts for these L-DACS1 functional enhancements are currently being developed in the course of an Austrian research project, called CoLB -Consolidated L-DACS1 based on B-AMC. The proposed concept aims at optionally providing configurable navigation and surveillance services to airspace users along with mandatory communications services. Additional services would be provided in a non-mandatory way, without introducing potentially dangerous coupling of CNS modes within the communications system itself.

Operational concept for multi-carrier broadband VHF communications

Operational air traffic management needs have led to the concept of the broadband VHF (B-VHF) aeronautical communications system. This explains the functional principles, architecture, and internal mechanisms of the B-YHF system, showing how it can be used to provide the existing aeronautical voice and data link communications services and a multitude of new data link services expected for the next decade or two.