Abstract: A terrestrial wireless telecommunication system is disclosed that uses an electronic scanning antenna to rotate a beam that carries communication messages between a base station and a plurality of wireless terminals. A base station transmitter transmits the communication messages to each wireless terminal, via the electronic scanning antenna, in a time-division multiplexed (“TDM”) data stream that is synchronized with the rotation of the beam, and a base station receiver receives the communication messages from each wireless terminal in a time-division multiple access (“TDMA”) data stream that is also synchronized with the rotation of the beam.
Abstract: A protocol for authenticating a mobile customer unit to a service provider where signaling messages are encrypted and where voice communications can be encrypted. A service provider assigns to each mobile customer unit a unique "secret", along with other information such as a telephone number. At the pleasure of the service provider, a directive is sent to the mobile customer unit to create a shared secret datum based on the secret. The shared secret datum is created with the aid of a bit string that is sent for thatpurpose by the provider. A portion of the created shared secret datum is used for encrypting speech and the same or other portion of the created shared secret datum is used as an input to a process for creating a second encryption key. That key is employed in the mobile customer unit to encode those of the control signals generated by the mobile customer until that affect the nature of the call in progress.
Type:
Grant
Filed:
September 13, 1991
Date of Patent:
December 15, 1992
Assignee:
AT&T Bell Laboratories
Inventors:
James A. Reeds, III, Philip A. Treventi
Abstract: A relatively secure, self-inverting, symmetric key cryptosystem designed for efficient implementation on an 8-bit microcomputer. The cryptosystem is especially well suited use in cellular telephony. The method of encryption is comprised of three stages: 1) an autokeyed encryption, 2) the use of a one-time pad encryption where the key is derived from a portion of the message as encrypted by the first stage, and 3) a second autokeyed decryption that is the inverse of the first.