Cornell Research Foundation Inc.

Teknekron Communications Systems, Inc.

Cornell University

Toby Berger

Yi-Jen Chiu

Douglas S Chan

Keith Jarett

Daniel H Miller

Luan L Lee

Mikio Kawahara

Methods and systems to perform collision detection (CD) in a communication network are disclosed. Methods and systems over multipacket reception (MPR)-capable physical layers are also disclosed. In one embodiment, the method for transmitting information in a network includes the steps of initiating transmission over a communication channel, monitoring a feedback channel, modifying transmission parameters for the transmission over the communication channel (where modifying includes stopping transmission and adjusting transmission parameters), if a feedback transmission is detected while monitoring the feedback channel, a duration of the feedback transmission being smaller than duration of the transmission over the communication channel, and determining whether transmission was successful, if transmission continues after modifying transmission parameters. Other embodiments of methods for transmitting and receiving information, as well as systems that implement the methods, are also disclosed.

Systems and methods to detect and avoid collisions in channel sense multiple access communications with multipacket reception

Methods and Systems for communication using carrier sense multiple access (CSMA) with multipacket reception (MPR).

Methods and systems for channel sensing multiple access communications with multipacket reception

Two software-only prefix encoding techniques employ encoding look-up tables to produce contributions to the encoded bit stream that are incremented in integral numbers of bytes to facilitate accelerated encoding rates at the expense of an acceptable trade-off in increased memory size requirements. The first technique, referred to as offset-based encoding, employs encoding tables which eliminate most of the bit-based operations that need to be performed by a prefix encoder without inordinately expanding memory requirements. In offset-based encoding, a Huffman table is employed which contains information for each number of bits by which the length of a Huffman word is offset from an integral number of bytes. The encoding method generates bytes of encoded data, even though the Huffman code has variable length code words for each symbol to be encoded. The second technique, referred to as byte-based encoding, employs a byte-based Huffman encoding table which operates even faster than the offset-based encoding scheme because it does not employ any bit-based operations at all; however, this is achieved at the expense of a considerable expansion in memory requirements.

Byte-based prefix encoding

A method and system for compressing and decompressing video image data in real time employs thresholding and facsimile-based encoding to eliminate the need for computationally intensive two-dimensional transform-based compression techniques. The method operates first by forming a difference frame which contains only information pertaining to the difference between a current video image frame and a computed approximation of the video image frame. The difference frame is fed to a thresholder which categorizes each pixel in the frame as being either in a first set having intensities above or at a preset threshold, or a second set having intensities below a preset threshold. A facsimile-based compression algorithm is then employed to encode the first set of above or at threshold pixel locations. To compress the intensity data for each above or at threshold pixel, a quantizer and lossless encoder are preferably employed, with the quantizer serving to categorize the intensities by groups, and the lossless encoder using conventional coding, such as Huffman coding, to compress the intensity data further. Various techniques may be employed with the embodiments of the invention to adjust the actual amount of compressed data generated by the method and system to accommodate communication lines with different data rate capabilities.

Facsimile-based video compression method and system

The adaptive dynamic signature verification system of the invention includes a number of types of signature verification terminals which digitize signatures for further verification by statistical analysis. A feature set is employed that consists of a number of personalized features, some static and some dynamic, each of which is normalized with respect to both time and spatial dimensions and allows for a degree of inconsistency in both speed and size of genuine signatures without losing the ability to discriminate against forgery attempts. The statistical approach also develops and employs either an individual-specific or a common feature subset for accurate signature discrimination.

Adaptive method and system for real time verification of dynamic human

A method to encode two digital data signals is disclosed. Each of the digital signals is characterized by a bit stream. An N bit block from the first signal is mapped to a unique M bit third signal where M is greater than N. Further, the number of '0's' in the M bit third signal is less than M/2. The M bit third signal is transmitted in the event a bit from the second signal is 0, whereas the complement of the M bit third signal is transmitted in the event a bit from the second signal is 1.

Method of encoding two digital data signals

In the present invention a method of compressing a signature signal is disclosed. The signature signal is divided into a plurality of signature segment signals where each segment is encoded by using a modified ring-encoding method, such that the total number of grid points along the perimeter of all the rings can be stored in an 8-bit byte. In one embodiment of the method of the present invention, a Fibonacci series is used to determine the relative spacing of the rings. The present invention also discloses a method and apparatus for electronically processing a POS transaction with a human signature for verification of the transaction, as well as for request of extension of credit by a credit company. The signature is electronically captured, compressed and combined with a transaction signal which is representative of the transaction. The record signal is then processed by the credit company for verification of the transaction or for requesting extension of credit.

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Ithaca, NY, United States of America

Toby Berger