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:
Jun. 12, 2001
Filed:
Dec. 16, 1998
Daniel A. Voce, Germantown, MD (US);
Hughes Electronics Corporation, El Segundo, CA (US);
Abstract
A method and apparatus for predicting when to perform spot beam and satellite handover in a mobile satellite communication network that uses the position of the mobile subscriber. The method and apparatus perform all calculations with respect to a satellite-based coordinate system, thereby eliminating the need to model the shape of the geometrically complex spot beams on the surface of the earth. The position of a mobile subscriber unit that initiates a call is tracked relative to a set of spot beam boundaries that are located equidistant between a first spot beam within which the subscriber unit is located at the time of call initiation and a set of adjacent spot beams. An interval during which the subscriber unit will cross over one of the boundaries is estimated. The spot beam into which the subscriber is traveling is identified, and the interval is adjusted until a desired level of accuracy has been achieved at which time the call is transferred from the first spot beam to the adjacent spot beam at the estimated time. For satellite handover, an angle of elevation between the subscriber unit and the satellite is calculated and compared to a threshold angle. When the angle of elevation drops below the threshold angle due to the movement of the satellite, the call is transferred from a first satellite to a neighboring second satellite.