Multiplex communications – Communication over free space – Repeater
Reexamination Certificate
2002-08-01
2003-11-04
Marcelo, Melvin (Department: 2663)
Multiplex communications
Communication over free space
Repeater
C370S401000, C709S238000
Reexamination Certificate
active
06643274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention generally relates to the routing of internet protocol (IP) packets. More particularly, the invention relates a system and method for routing IP packets to an aircraft that does not require the exchange of routing information via dynamic routing protocols between the aircraft and ground station routers.
2. Discussion
Although the Internet has often been referred to as one of the 20
th
century's greatest communications developments, a number of challenges still lie ahead. A particular challenge results from the increasing mobility of today's society. Indeed, the benefits of being able to access the Internet via a mobile terminal are numerous. For example, traffic updates, stock quotes, and e-mail messaging are but a few of the many services for which consumers would undoubtedly pay a premium in the mobile context. Thus, while the traditional desktop personal computer (PC) was once viewed as the basic tool for accessing the Internet, laptops, palm-held computers and wireless telephones are rapidly becoming the computer terminal of choice.
As the demand for Internet access via these new highly mobile terminals increases, the difficulties associated with transitioning traditional packet switched networks into over-air networks have become quite apparent. The data network industry has attempted to tackle these difficulties by developing a “Mobile IP” scheme in which a “bidirectional” link is established between the mobile computing device (i.e., client node) and the routers other hosts out on the network. The computing device and the routers all have IP addresses, and the bi-directional link essentially provides a one-to-one default relationship between the forward and return paths for IP packets. The path information is updated as the computing device moves from sub-network to sub-network. Thus, when a packet needs to be sent to such a device, the routers are better able to correlate a path for the content because the bi-directional link assists in the correlation. This ability is important because packet routing is often the single most difficult problem to be dealt with when implementing an IP networking system.
Although Mobile IP and traditional packet routing techniques have been satisfactory for “terrestrial-based” systems such as wireless phones, certain difficulties remain when the user terminal is located on an aircraft. For example, the traditional bi-directional link is difficult to maintain because the aircraft communicates with the ground via multiple unidirectional satellite links. In addition, the ground router will have to identify the subset of the available unidirectional links that a given aircraft is using to receive packets. Thus, the ground router might have sixteen forward channel chains to choose from, whereas the aircraft might only have the ability to listen to four of the channels. It is easy to understand that it is quite difficult to resolve a correct path to the aircraft under conventional routing approaches. Simply put, the complexity associated with using conventional routing exchange protocols to communicate with an aircraft eliminates the commercial viability of such a system. Routing exchangers also consume expensive air-to-ground bandwidths. It is therefore desirable to provide a method and system for routing IP packets to an aircraft that does not require the use of an air-to-ground routing protocol.
SUMMARY OF THE INVENTION
The above and other objectives are provided by a method for populating an Internet protocol (IP) packet routing table of a ground router in accordance with the principles of the present invention. The method includes the step of converting a tail number of an aircraft into a destination subnet address for the aircraft. Forward channel information for a ground router is determined based on the tail number. The method further provides for adding a route entry to the routing table based on the forward channel information and the destination subnet address such that the route entry enables the ground router to deliver IP packets to the aircraft.
Further in accordance with the present invention, a method for maintaining an IP communications link table is provided. The method provides for defining forward channel identifiers for a plurality of aircraft tail numbers. Preference metrics are defined for the plurality of aircraft tail numbers such that each tail number, corresponding forward channel identifier and corresponding preference metric represents an entry in the communications link table. The method further provides for dynamically updating the entries based on data from an airborne polling link.
In another aspect of the invention, an IP database has an aircraft configuration table, a communications link table and a ground switching table. The aircraft configuration table links a tail number of the aircraft to a corresponding aircraft identifier, while the communications link table links the tail number to forward channel information. The ground switching table links the forward channel information to a next hop address such that the database enables addition of a routing entry to a routing table.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute part of this specification. The drawings illustrate various features and embodiments of the invention, and together with the description serve to explain the principles and operation of the invention.
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Harness & Dickey & Pierce P.L.C.
Marcelo Melvin
The Boeing Company
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