AeroMACS

An IEEE 802.16 Standard-Based Technology for the Next Generation of Air Transportation Systems

Behnam Kamali

• Publisher: Standards Information Network
• Year: 2018
• ISBN:
  9781119281122
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

This is a pioneering textbook on the comprehensive description of AeroMACS technology. It also presents the process of developing a new technology based on an established standard, in this case IEEE802.16 standards suite.

The text introduces readers to the field of airport surface communications systems and provides them with comprehensive coverage of one the key components of the Next Generation Air Transportation System (NextGen); i.e., AeroMACS. It begins with a critical review of the legacy aeronautical communications system and a discussion of the impetus behind its replacement with network-centric digital technologies. It then describes wireless mobile channel characteristics in general, and focuses on the airport surface channel over the 5GHz band. This is followed by an extensive coverage of major features of IEEE 802.16-2009 Physical Layer (PHY)and Medium Access Control (MAC) Sublayer. The text then provides a comprehensive coverage of the AeroMACS standardization process, from technology selection to network deployment. AeroMACS is then explored as a short-range high-data-throughput broadband wireless communications system, with concentration on the AeroMACS PHY layer and MAC sublayer main features, followed by making a strong case in favor of the IEEE 802.16j Amendment as the foundational standard for AeroMACS networks.

AeroMACS: An IEEE 802.16 Standard-Based Technology for the Next Generation of Air Transportation Systems covers topics such as Orthogonal Frequency Division Multiple Access (OFDMA), coded OFDMA, scalable OFDMA, Adaptive Modulation-Coding (AMC), Multiple-Input Multiple-Output (MIMO) systems, Error Control Coding (ECC) and Automatic Repeat Request (ARQ) techniques, Time Division Duplexing (TDD), Inter-Application Interference (IAI), and so on. It also looks at future trends and developments of AeroMACS networks as they are deployed across the world, focusing on concepts that may be applied to improve the future capacity. In addition, this text:

• Discusses the challenges posed by complexities of airport radio channels as well as those pertaining to broadband transmissions
• Examines physical layer (PHY) and Media Access Control (MAC) sublayer protocols and signal processing techniques of AeroMACS inherited from IEEE 802.16 standard and WiMAX networks
• Compares AeroMACS and how it relates to IEEE 802.16 Standard-Based WiMAX

AeroMACS: An IEEE 802.16 Standard-Based Technology for the Next Generation of Air Transportation Systems will appeal to engineers and technical professionals involved in the research and development of AeroMACS, technical staffers of government agencies in aviation sectors, and graduate students interested in standard-based wireless networking analysis, design, and development.

1
Airport Communications from Analog AM to AeroMACS

1.1 Introduction

The safety of air travel and air operations is critically linked to the availability of reliable aeronautical communications and navigation systems. Owing to the fact that flight safety is the highest priority in aviation, extreme measures must be taken to protect the aeronautical communication systems against harmful interference, malfunction, and capacity limitation.

In the early days of commercial aviation in the 1940s, analog double-sideband transmitted-carrier (DSB-TC) amplitude modulation (AM) over VHF band was adopted for aeronautical radio. This selection was made mostly for the reason that analog AM was the only fully developed and proven radio communications technology at the time. The number of VHF radio channels increased over the decades subsequent to the end of the World War II. In the 1980s, the VHF band of 118–137 MHz was allocated to aeronautical radio. With channel spacing of 25 kHz, 760 VHF AM (25-AM) radio channels became available. During the same decade, the avionics community predicted that early in the next century growth in flight operations and air traffic volume would demand communication capacity ¹ that would be well beyond what was available in those days.

The air-to-ground (A/G) and ground-to-air (G/A) VHF communications system for civil air traffic control consisted of AM voice networks, where each flight domain had its own dedicated network. These networks were not interconnected and actually operated independently; however, their architecture was roughly the same. The pilot-to-control tower (uplink; UL, also known as reverse channel or reverse link; RL) and controller-to-pilot (downlink, DL also called forward channel or forward link, FL) radio voice links were half-duplex connections and operated on a “push-to-talk” basis. Backup radio channels were provided in the event of system malfunction, power failure, or other unexpected situations. The VHF radio equipment was digitally controlled with the total of 760 channels, of which 524 channels were dedicated to A/G and G/A communications for air traffic control (ATC) purposes. The remaining channels were used by airlines for airline operational control (AOC). The AOC predominantly used and still uses a data service called the aircraft communications and address reporting system (ACARS) to manage and track the aircraft. However, the radio link can also be used for voice communications between pilots and airline agents [1]. Currently, the bulk of ground-to-ground (G/G) communications on the surface of airports is supported by wired and guided transmission systems, primarily through buried copper and fiber-optic cable loops. The G/G communications is also supported by a number of wireless systems, among them are VHF AM radio, airport WiFi system, and even some airport radar facilities.

In addition to the allocated VHF spectrum, two other spectral bands were considered to become available for aviation on a shared basis with other applications. First is an L-band spectrum of 960–1024 MHz, originally allocated for distance measuring equipment (DME). The second one is a C-band spectrum over 5000–5150 MHz, traditionally earmarked for microwave landing system (MLS). This radio spectrum was later allocated as the frequency band to carry aeronautical mobile airport communications system (AeroMACS ). AeroMACS technology is the main focus of this text and at the time of its preparation, AeroMACS was already standardized and globally harmonized as a broadband IP data communication link for safety and regularity of flight at the airport surface. Currently, AeroMACS is being tested over several major U.S. airports and, barring any unforeseen complications, it is expected to be deployed globally by the year 2020. For future airports, AeroMACS is envisioned to constitute the backbone of the communications system for the airport surface, whereas older airports can form a communications infrastructure in which AeroMACS is complimented with the airport fiber optic and cable loops that are already in place.

1.2 Conventional Aeronautical Communication Domains (Flight Domains)

Aeronautical signals pass through several wireless communication channels before they reach the destination. Four possible transmission links exist in aeronautical communications path: aircraft (air)-to-controller (ground), A/G; controller-to-aircraft, G/A; ground-to-ground, G/G, and aircraft-to-aircraft; A/A links. The aircraft continuously communicates with the NAS (National Airspace System), or the global airspace system, throughout the flight duration. There are several different domains (channels) through which the aircraft may be required to communicate with a ground station. Each one is a wireless channel with its own particular conditions, constraints, and characteristics. For an overall aeronautical communications system design or simulation, each of the channels listed below must be considered and characterized.

1. Enroute Communication Channel: This is the domain when the aircraft is airborne and A/G and G/A transmissions are required. This is essentially a high-speed mobile communication link in which the aircraft flying is at high altitude and close to its maximum speed. This link can be modeled as a simple double-ray wireless channel, or a Rayleigh fading channel. However, in the majority of cases the channel contains a line-of-sight (LOS) path and a ground reflection. When the aircraft elevation angle is high the ground reflection takes place at a point very close to the ground station, therefore, the path length between the two rays is very small and hence they cannot be resolved by the receiver [2].
2. Flying Over a Ground Station: This is a special case of enroute channel during which the Doppler effect changes its sign. For design and simulation of the aeronautical communications links, this mode must be considered separately from the enroute case [3].
3. Landing and Takeoff Domain: The aircraft is airborne at low altitudes and moving at its landing and takeoff speed, it is engaged in A/G and G/A communications and is close to the control tower. The channel is multipath with a strong LOS component.
4. Surface (Taxiing) Channel: In this domain the aircraft moves rather slowly toward or away from the terminal, it is therefore a low-speed low-range mobile communications affected by multipath and some Doppler effect.
5. Parking Mode: This mode is applicable when the aircraft is on the ground and close to a terminal and traveling at a very low speed or is parked. This requires essentially a stationary wireless transmission of low range.
6. Air-to-Air: This channel is used for the purpose of communications between two aircraft while they are in flight.
7. Oceanic Domain: This channel has its own characteristics in the sense that it is a long-range communications channel for the most parts. VHF LOS transmission is not feasible for this domain.
8. Polar Domain: This is also a channel in which long-range communications take place. This domain has a limited satellite access.

In some literature, communications in domain 3 is referred to as terminal communications. Communications over domains 3–5 together are what is referred to as airport surface communication in this chapter. For oceanic and remote areas, such as polar regions, since LOS transmission to ground stations is not possible, HF (high frequency) band and satellite systems are used.

1.3 VHF Spectrum Depletion

It was long accepted that as a rule of thumb, and baring any unexpected sudden traffic increase, the aviation traffic is anticipated to have an annual growth of at least 2%. However, the spectrum that was allocated for various functionalities of aerospace management system remained fixed, except for the abovementioned L-band and C-band that later became available on a spectrum sharing basis. The safety, security, growth, and efficient operation of national and global aviation systems are vitally dependent on reliable communic...