There is a new type of service being developed that will take broadband into the air. The airborne Internet will not be totally wireless. There will be ground-based components for any type of airborne network in the air. Consumers will have to install an antenna in their home or business to receive signals from the overhead of the network hub. The networks will also work with established Internet Service Providers (ISPs), who will provide their high capacity terminals for use over the network. These ISPs have a fiber point of presence of their optical fibers already configured. What the Internet on board will do is provide an infrastructure that can reach areas that do not have broadband cables and cables.
The HALOT aircraft is under development and flight testing is expected in mid-1998. The aircraft has been specially designed for the HALOT network with the communications load sheath suspended from the lower belly of its fuselage. The HALOT aircraft will fly above the metropolitan center in a circular orbit five to eight nautical miles in diameter. The communications charging pod is mounted on a pylon under the fuselage. As the plane changes its roll angle to fly in the circular orbit, the communications payload pod will rotate on the pylon to stay flush with the ground.
The HALOT network will use a series of narrow-beam antennas on the HALOT aircraft to form multiple cells in the ground. Each cell covers a small geographic area, for example, from 4 to 8 square miles. Wide bandwidths and narrow beamwidths within each beam or cell are achieved using MMW frequencies. Small aperture antennas can be used to get small cells. One hundred parabolic antennas can be easily transported by the HALOT aircraft to create one hundred or more cells throughout the service area. If lens antennas are used, wider beams can be created by combining beams through each lens aperture and with multiple feeds behind each lens multiple beams can be formed per composite lens.
If 850 MHz of spectrum is assumed then a minimum capacity of one OC-1 full-duplex (51.84 Mbps) channel per cell is available. For example, a single platform reusing 850 MHz spectrum in 100 cells would provide the equivalent of two OC-48 fiber optic rings. The elements of the communications payload are shown below. It consists of MMW transceivers, pilot tone transmitters, high speed modems, SONET multiplexers, packet switching hardware and software, and associated auxiliary hardware such as power supplies, processors, etc.
Trends
Trend - The capacity limitations of the current hub / spoke system are leading to the desire to take advantage of the overcapacity of small / medium size airports. Topics to consider include:
• Most small and medium-sized airports have limited or no instrument landing equipment. Complying with the objective of the SATS to land during "all weather" conditions will require these airports to be equipped with sufficient communications and augmentation support equipment to provide separation during arrivals and departures at these airports.
• Exceeding the "one at a time" rule at smaller airports will require improved surveillance systems so that SATS aircraft can not only separate from one another, but also maintain separation of non-SATS aircraft. Today's NAS supports a wide variety of aircraft with even greater variation in avionics configuration on board. SATS jets will have to blend in with these less well-equipped jets. This requires SATS aircraft to assume primary responsibility for separation. SATS aircraft will need to be able to determine the position of their aircraft in relation to non-SATS equipped aircraft.
• Integrated cockpit communications, navigation, surveillance and management systems are required in cockpits. Navigation systems will require a level of increase that requires a real-time data link between the booth and ground support systems.
• To support the goal of single crew cockpits performing as efficiently as two crew cockpits, automatic or autonomous operations will eventually be required to compensate in case of pilot incapacitation or failure. A requirement for remote control would require the communications system to support hard-real-time communications between the flight management system and the ground controller / pilot
Trend - Frequency congestion and spectrum competition are driving the need for data link connectivity between pilots and ground personnel. Although it is likely that there is always a requirement for voice communication, numerous communication functions such as flight planning, delivery of dispatch, time requests, etc. Can be best performed through data link, releasing congested voice channels.