(19)

(11)

EP 0 377 687 A1

(12)

(43) Date of publication: 18.07.1990 Bulletin 1990/29 (21) Application number: 89904890.0 (22) Date of filing: 03.04.1989

(51) International Patent Classification (IPC):  H04L 27/ 00( . ) H04B 14/ 04( . ) H04L 9/ 10( . ) H04B 1/ 66( . ) H04K 1/ 02( . ) (86) International application number: PCT/US1989/001345 (87) International publication number: WO 1989/010661 (02.11.1989 Gazette 1989/26)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 29.04.1988 US 19880187766 29.04.1988 US 19880187685 (71) Applicant: MOTOROLA, INC. Schaumburg, IL 60196 (US)

(72) Inventors: KOTZIN, Michael, Dale Buffalo Grove, IL 60089 (US) VAN DEN HEUVEL, Anthony, Patrick Parkland, FL 33067 (US) CRISLER, Kenneth, J. Wheaton, IL 60187 (US) HIBEN, Bradley, Michael Glen Ellyn, IL 60137 (US) MOHL, Lawrence, M. Hoffman Estates, IL 60194 (US) POULIN, Mark, Richard Forest Park, IL 60130 (US) (74) Representative: Dunlop, Hugh Christopher, et al  Motorola, European Intellectual Property, Midpoint, Alencon Link Basingstoke, Hampshire RG21 7PL Basingstoke, Hampshire RG21 7PL (GB)