The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 21, 2002
Filed:
May. 26, 1995
Gregory J. Capone, Gapland, MD (US);
Richard M. Gardner, Gaithersburg, MD (US);
Matthew Mehdi Mohebbi, N. Potomac, MD (US);
Walter Robert Kepley, III, Gaithersburg, MD (US);
John Dennis Kenyon, Potomac, MD (US);
David Alan Roos, Boyds, MD (US);
AT&T Wireless Services Inc, Redmond, WA (US);
Abstract
Seamless hand-off of air-to-ground telephony calls is achieved autonomously within an aircraft by using one of at least two radio links to search for additional ground stations. The search for candidate ground stations for hand-off is expedited by eliminating ground stations exhibiting zero or negative Doppler effects. Other values indicating quality of the link corresponding to the channel over which the search is conducted is compared with the quality of the call and an alternate call is established using the call identification code previously established for the call in progress. The hand-off of the call may then be easily conducted by transferring the voice signal to the channel over which the search was conducted. This is preferably done at a time when the transmission quality of the two channels would be approximately the same or the quality improved on the channel to which hand-off is made.