Motorola Corporation

Codex Corporation

Jeffrey T Klayman

Louis D Finkelstein

John A Perreault

Stephen Schroeder

Christopher L Clanton

Katherine A Unger

Fay Yew

The apparatus (101, 110) and method for authentication is provided by generating R and encrypting it using a selected algorithm K as the key in a primary station, encrypting the verification key, V using R as the key and encrypting the result using K as the key, transmitting both pieces of information (VAR1 and VAR3) to the secondary station (110), using K to decrypt VAR1 and VAR3 to obtain R and eventually V which is encrypted using R in the secondary station (110)verifying authenticity of the primary station (101) if the decrypted V matches the secret key portion of V that is stored at the secondary station (110).

Apparatus and method for authentication and session key exchange in a

A system (400) and apparatus (200, 300) for, and method (100) of, interfacing a demodulator and a forward error correction decoder enables a forward error correction decoder to be used in conjunction with an otherwise incompatible demodulator. Data received from the demodulator having a first encoding and formatted as M bits per baud at a first baud rate is encoded into data having a second encoding. The data having the second encoding is output to the forward error correction decoder as N bits per baud at a second baud rate as required by the forward error correction decoder.

System and apparatus for, and method of, interfacing a demodulator and a

An apparatus (101, 110) and method for adaptive forward error correction in a data communication system (100) provides for dynamically changing forward error correction parameters based upon communication channel conditions, such as noise levels or error rates. In the method embodiment of the invention, data having a current degree of forward error correction is received (305), and a channel parameter is monitored (310), such as packet or bit error rates. A threshold level for the channel parameter is determined (315), and the monitored channel parameter is compared to the threshold level (320). When the channel parameter is not within a predetermined or adaptive variance of the threshold level, a revised forward error correction parameter having a greater or lesser degree of forward error correction capability is selected (330, 340, 350, 360), and the revised forward error correction parameter is transmitted (370). The device receiving the revised forward error correction parameter, such as a secondary station (110), then transmits data encoded utilizing the revised error correction parameter (425).

Apparatus and method for adaptive forward error correction in data

A method (700) and device (1100) increase throughput of a data compression encoder or decoder by using children arrays instead of linked lists in the building and maintenance of the tree. A children array with elements corresponding to each of the input symbols is allocated to a node. An input character is used as an index into the children array. The search result is determined by the value in the children array. Where a search is successful, the value in the children array is a pointer to the child node. A node is added by storing a pointer to the node in the parent's children array at the location indexed by the input character and is deleted by storing a NULL value in the parent's children array where the child node had been. The search, add, and delete operations become very efficient, and each operation has a constant execution time.

Data compression method and device utilizing children arrays

A method (100) and device (200) increase efficiency of a data compression encoder or decoder by testing whether an input string is a maximum length string upon successful match of the input string in a dictionary. Where the length of the input string is equal to a predetermined maximum string length, the string matching process is terminated without processing an additional input character that would cause an unsuccessful string match. The maximum length string test is accomplished by testing a string length counter for the value zero, where the string length counter is set to the maximum string length value when the input string is NULL or alternatively is set to the maximum string length minus one when the input string is a one character string, and the string length counter is decremented for each input character that extends the matched input string.

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Canton, MA, United States of America

Jeffrey T Klayman