Recent Developments in Aircraft Wireless Networks file:///X:/www-docs/cse574-06/ftp/aircraft_wireless/index.html1 of 13 5/9/2006 7:36 PMRecent Developments in Aircraft Wireless NetworksObi Orjih, [email protected] report discusses some key recent developments in the area of wireless networking on aircraft. We discussthe products and services in commercial aviation that have been driven by the demand for in-flight entertainmentand connectivity. We also touch on the research that has enabled this technology. Lastly, we mention thedevelopments in military aircraft wireless networks, and the standards behind them.See also:Table of Contents1. Introduction2. Research Developments2.1 Integration and Interoperability2.2 Interference2.3 Mobility2.4 Quality of Service3. Commercial Developments3.1 Satellite Services3.2 Airline Services4. Military Developments4.1 Link-164.2 JTRS5. Summary6. References7. List of Acronyms1. IntroductionIn recent years, wireless networking has become more commonplace than wired networking. One applicationdomain in which wireless networks are of far greater practical use is aviation, since planes are scattered all overthe world. In this paper we discuss recent and future developments in aircraft wireless networks (AWNs). Incommercial aviation, the major goals is to provide in-flight Internet connectivity to passengers. We discuss someresearch which has enabled this technology as well as some current and future services, such as Connexion byBoeing and OnAir, which satisfy this demand. The military uses wireless networks to improve tactical situationalawareness for war-fighting aircraft. It is important to note that the AWN paradigm is different in militaryapplications, where the intent is not to connect to the public Internet. The military domain is also where thedevelopment of AWNs is the most mature in terms of standardization and ubiquity. We discuss two of the mostrelevant military AWN standards, Link-16 and JTRS.Back to Table of ContentsRecent Developments in Aircraft Wireless Networks file:///X:/www-docs/cse574-06/ftp/aircraft_wireless/index.html2 of 13 5/9/2006 7:36 PM2. Research DevelopmentsIn this section, we discuss research work dealing with AWNs. Since the motivation for the work in this area issupport of in-flight passenger communication, our focus is on research concerning network connectivity fromwithin an aircraft to the outside world. A common architecture for these services found in research and industryis shown in Figure 1. It consists of three basic segments: an aircraft, a satellite link, and a ground station. On theaircraft, a wireless access point can be used to provide connectivity to passengers and crew members. Thesatellite link provides a connection to the ground station, which is connected to the Internet.Figure 1 - Example commercial airline network topologyA common thread among the research projects examined here is that each aims find a way to enable AWNs to bemore useful and efficient. In fact, some of the research and development work eventually had useful applicationin industry. The major issues in AWN research that we examine are interoperability, interference, mobility, andquality of service (QoS).Interoperability is important because airlines are looking to provide different services to their passengers, whichrequires the use of multiple different technologies. Two of the key services considered are Internet and cellularconnectivity. To provide these services, an aircraft must have access points for receiving both kinds of wirelesssignals and be able to transmit traffic from both systems to the ground via the satellite link. Interference comesinto play because it is undesirable for these transmissions to interfere with the navigational and communicationssystems needed for operation of the aircraft. Case studies have shown that there have been times wherepassenger personal electronic devices (PEDs) have caused aircraft systems to malfunction. However, someresearch studies indicate that this should not be the case.The physical movement of the aircraft makes mobility and QoS issues of concern. An aircraft and the groundstations with which it communicates must be mobility-aware, as the aircraft is essentially a moving network. Asit moves, an aircraft must register with each new ground station it encounters in order to establish a path fortraffic to and from the aircraft. The ground station must also handle routing to the multiple nodes which resideon each aircraft connected to it. The process of switching between satellites and/or ground stations can cause aRecent Developments in Aircraft Wireless Networks file:///X:/www-docs/cse574-06/ftp/aircraft_wireless/index.html3 of 13 5/9/2006 7:36 PMloss or degradation of service for passengers. The architecture of the communication system should be such thatthe impact of handovers on QoS is minimized. We examine research dealing with these issues in the followingsubsections.2.1 Integration and InteroperabilityOne research project developed to demonstrate interoperability in AWNs was the Terrestrial HybridEnvironment for Verification of Aeronautical Networks (THEVAN). As the name suggests, the platform was notactually an aircraft, but a modified ambulance chassis loaded with racks of wireless networking equipment. Theintent was to demonstrate the integration of different technologies which could be used to provide networkservices in an aircraft. These technologies included a Ku-band satellite system, a medium data-rate satellitesystem (MDSS), a commercial Very High Frequency (VHF) radio, and IEEE 802.11b. The Ku satcom phasedarray antenna was used to provide a full-duplex 2 Mbps/256 kpbs (downlink/uplink) connection to a fixedground station via satellite. The MDSS was composed of 16 L-band Globalstar-compatible satellite phonesproviding an aggregate data rate of 112 kbps. The VHF data radios were commercial modems which provided a19.2 kbps full-duplex link. Cisco 802.11b (11 Mbps) access points were used with external bi-directionalamplifiers and omni directional antennas. The testbed was used to evaluate IP-based (Mobile IPv4 and IPv6)connections on a mobile platform. They demonstrated that TCP and UDP connections could be maintained as theplatform moved through a wide area. They also showed that the different networking technologies could beintegrated to provide Internet services, such as Hyper Text Transfer Protocol (HTTP) and File Transfer Protocol(FTP), to users. THEVAN
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